Last week we covered the peer-to-peer file sharing approaches. We covered the Napster style approach where we have a central server and it was similar like which I drew on the board here. We have some server and we looked at the ways for how to peers, how to different computers find resources and in the Napster approach the server stores an index of the resources. Think of the resources as files. And when a peer wants to find a resource it sends a query to the server. The server looks up the index and sends back the response where the response is some identity of the peer that stores that resource. That was the simple approach. Then we saw two different approaches, Nutella where we have no central server but peers flood a request or a query saying who has this resource and whoever has that resource response and then the fast track approach which joins the two together which has these super peers. So we have a combination of the centralized approach using a server and the distributed approach using Nutella the flooding. That was focusing on the search part which is one of the challenges for peer-to-peer systems is when you've got resources distributed amongst different peers how do you find those resources? What we want to focus on now is a way for accessing the resources. So with the Napster approach we said that the server sends back some address of the peer that has the resource. So if P3, let's make it a different one, has resource R4 and P1 does a query for R4 or in fact key 4 and the server knows okay P3, P3 has resource R4 so sends back a response and now it's up to P1 to access that resource to contact P3 and say I want that resource R4. So we didn't cover how to access the resource. We're going to go through BitTorrent and see the simple way or the basics of BitTorrent and see how peers can access resources. And of course in a peer-to-peer system if the system is large enough usually there'll be more than one peer that has the same resource. So now let's focus on files as our resources. Let's say both P3 and 4 have the same file. P1 wants that file, it sends a query to the server, the server sends back a response saying P3 and P4 have the file. So P1 can download that file from P3 or P4. Well we'll see what BitTorrent allows us to do is to not download from just one of those peers but to download parts of the file from P3 and other parts of the file from P4. So instead of just downloading the entire file from one computer download some parts from one computer on the internet and the other parts say the second half of the file from another computer and once you've received all parts put them back together and you have the file. And we'll go through a very simple example to show that in general we can have the advantage of possible faster downloads because we distribute the load amongst those peers. So we're focusing now on the download part or the access to the resources. How does that peer get access to those resources? Where the resources in our example are files. So let's first go through a simple example, it's not specific to BitTorrent but in general for two different ways in which we can download the file. And then we'll go through the concepts of BitTorrent and show how the protocol works. Let's keep it simple. Let's consider a case where we don't have a peer-to-peer system. You want to download a file and that file is stored on a server. So we have some server in our network and we have some peers or some computers, not a peer-to-peer system, we have some clients that want to download that file. And let's say we have five clients at the start. So this server stores the file and these are some clients that want to download. They all want to download the same file and let's say the server has a, to keep our calculations simpler, 1,000 megabit file, that's the size of the file, 1,000 megabits, I use megabits so we can calculate divided by the data rate easier. And the link that each device has into the network is one megabit per second, that are these links here. Same with the server, just to keep it simple in this case. So this cloud could be a simple switch or it could be the entire internet, but just for simplicity all devices have a 1 megabit per second full duplex link, which means at the same time they can download 1 megabit per second and upload 1 megabit per second. So like a 1 megabit per second link to your home, that's the capacity. And let's say the server has the file, five users come along and they want to download that file all at the same time. How long does it take to download the file? What does it depend upon? The server, the server bandwidth, okay, the capacity of the server in the link, assuming the server computer is fast enough. So to download, we'd contact the server and the server effectively sends or transfers the file to our computer. How fast can the server send the file to the computer? Well this computer can receive at 1 megabit per second. The server can send at 1 megabit per second, so 1000 megabits at 1 megabit per second would take 1000 seconds. That's if there's one client downloading, but there are five clients wanting to download from the server at the same time. So in that case, the server is sending the file to client one and at the same time sending a file to client two, client three, client four and client five. So if we focus on the link here for the server, the capacity can send at 1 megabit per second in total, but you think because it's sending to five different clients, it's effectively sending at one fifth of the speed to each client. It's sending the file at the same time to client one at a speed of 200 kilobits per second to client one, to client two, also 200 kilobits per second, assuming we're fair in that we use this capacity and equally, or it's fair amongst the different clients and in your assignment, you saw that that's usually the case under ideal conditions. So the speed at which the server is sending to each of the clients is 200 kilobits per second, one fifth of the capacity of the link. Because we have five clients, we need to share that capacity amongst five. How long does it take for one client therefore to receive the file?  If it was only this computer downloading, we've got 1,000 megabits at 1 megabit per second, 1,000 divided by 1, 1,000 seconds, but now we've got five computers downloading, so we've got one fifth of the speed, so that takes five times as long. After 5,000 seconds, computer one has downloaded the file. And also, so have two, three, four and five, because they all have the same download speed. So one server transferring the same file to five different clients using unicast, there's no multicast here, to five different clients at 200 kilobits per second each, 5,000 seconds to download the file. Any questions, the mathematics for this, make sure you, it's a very simple concept, but we'll use that in the next parts, the more important parts. Now five users downloaded that file, it's a popular file, now 100 more users come along into the network and they also want to download that same file. I'm not going to draw them, but imagine now there's 100 more computers here, different ones, same speeds, want to download the same file from that same server, how long does it take them? One of them, 100,000 seconds, because we've got, our limit is this link to the server. The capacity is 1 megabit per second, if we've got 100 computers downloading, we must share that 1 megabit per second amongst 100 users. Same file size, if we were sending it 1 megabit per second it would take 1000 seconds, if we're sending it 100th of the speed it would take 100,000 seconds. So here's that 100th computer, it takes 100,000 seconds for that computer to get the file. The more computers downloading from that server, the slower it's going to be. This is if we just have a server that everyone is trying to access, because the download speed depends upon the capacity that that server offers. In this simple example, that's what I've tried to capture on this slide where we've got two phases. First there's five users come along and download the file, then sometime later another 100 users want to download the same file, all accessing from the server. The first five users get it in 5,000 seconds, the next 100 users in 100,000 seconds. Let's try something different to speed it up. Let's say the first phase is the same, five users come along and they download the file from the original server, it still takes them 5,000 seconds, nothing changes. Now, our second phase of the new 100 users come along and instead of downloading from that server, download from the five users who have already downloaded the file. Because after the first phase, the server has the file, so does computer 1, 2, 3, 4 and 5. When 100 users come along, instead of all contacting the server, 20 of the users will contact computer 1 to download the file, another 20 computer 2 and so on and another 20 computer 5. That is, those 100 users download the file from those five different clients that have already downloaded the file. So, where can I write it? There are 20 users downloading from client 5, the same logic or the same math supplies, we have a limit of 1 megabit per second, therefore 20 users are downloading from there at the same time, so each of those users would take 20,000 seconds to download. Because we are only sharing that capacity amongst 20 users. And similar, another 20 users are downloading from computer 4, the capacity of 1 megabit per second is shared amongst 20 users and therefore those 20 users, it takes them 20,000 seconds to download the file and let's try to capture it on the next slide. So, a different scenario where the first five users do the same, they download from the central server, but then the next phase where 100 new users come along, they don't download from the server, they download from the other users who have already downloaded the file and it would only take them 20,000 seconds to download the file. Effectively we are sharing the load, instead of everything going by the server, now we are sharing it amongst the other computers, so instead of being limited by this 1 megabit per second link, we actually have five 1 megabit per second links that those 100 users can download via. And hence, we go from 100,000 seconds to 20,000 seconds to download, a five times improvement, five times shorter, this is the concept that many peer to peer file sharing applications or protocols use in that there are multiple peers that have the file, rather than downloading from one central server, the clients download from multiple peers, with the idea of distributing the load amongst those peers rather than concentrating the load on one server. That's a simplistic example, of course such a scenario will not happen in practice, it depends on many different factors, so we saw in the first case, if everything comes from the server, it takes 5,000 seconds in the first phase and then 100,000 seconds in the second phase, but if the first five download from the server it will take them 5,000 seconds, but then they download from the ones that already have it, it only takes 20,000 seconds, that is we speed up the download by distributing the load amongst the different clients, so we get a significant gain in performance, because it takes much less time for all 105 users to download the file, how much gain do we get from such a scenario, how much of an improvement in performance, it depends on how many initial servers, in my example we started with just one, but of course we may have multiple initial servers, these five users who initially downloaded the file and then others downloaded from them, we can call seed users, they start the download for those 100 other clients, so the performance improvement depends upon how many seed users there are or how many seeds, and in my example I had 100 users downloading in the second phase, how many there are will also impact on performance, so the number of downloading users, of course in my simple example everyone had the same upload and download rate, 1 megabit per second, in real life different users in the internet will have different upload and download rates and that will impact upon the performance of how fast in total does every user get the file, in this example if we download from the other clients it took the 5000 seconds plus another 20,000 seconds, so we can use a peer-to-peer network to download files faster potentially by downloading not from a central server but from other users who have already downloaded the file, and in fact it doesn't have to be limited to the file in which, how do we state this, user one downloaded the file from the server initially and then we said other users could download from user one, it doesn't have to be limited based on the file, user one can download parts of the file from the server and once it has those parts other users can start downloading from user one, so in fact the way that we structure the file can also assist, if we divide the file into pieces, our 1000 megabit file let's say each piece is 10 megabits, as soon as user one has the first piece other users can start downloading from user one and therefore that would potentially reduce the time for those other users to access the files, so we'll see that peer-to-peer file sharing protocols use these concepts of download from other users at the same time, not just files but pieces of files, and that's some of the basic concepts of peer-to-peer file sharing, what are the advantages of doing this, we're not always dependent on the original server, once some of the users have downloaded the file from the original server, those 100 other users don't need to know about the original server, if the original server fails they can still download the file from these five other users, so there's no or less dependence on any one server in the network, there's redundancy in the network, in that the file is available from multiple different locations, the more people that download that file the more locations a new user can download it from, that's an advantage, and we distribute the load instead of the server being the bottleneck, everything going via the server, where we're limited by the server link and the server speed, we distribute that load amongst different users, what's the problem of this, it relies on the participation of other users, this only works if these first five users once they download the file make it available for others to download from them, if the 100 users cannot download from users 1, 2, 3, 4 and 5 we get no gain, so this relies on those that have downloaded the file to make it available to others, and these five users in this simple example were called the seed users, so as the number of seeding users decreases, instead of five if we have just three the performance decreases, and of course in practice this set of five users in a large network may vary over time, at one time instant there are 100 seed users and then five minutes later, because some of them have disconnected from the network there are only 80 seed users, so the performance will vary over time, the other problem with peer-to-peer file sharing is there's no control of accessing the content, if everything has to go via a single server the server can control who accesses that content, for example they can put a username and password on so you need some credentials to download that file, so we can control it, but in this peer-to-peer approach once these first five users have downloaded the file the server has no control over who else can access that file, so that's a problem in some scenarios, it's difficult to control who accesses the content and also to find the content, and that comes back to the techniques we looked at last week of how to index the content, if computers one two three four five have the file how do other users in the network know that those five have the file, well we saw some approaches last week of how to search how to index the content or index resources, in peer-to-peer file sharing most of the usage or the use of peer-to-peer file sharing is mainly for distributing in many places illegal content or copyrighted content, so there are a number of issues where whether it's good or bad, there are also issues with the security that is can we trust the users that we're downloading from, what if we want to make people pay to download that file, if we have a central server that control who accesses it and have some accounting to keep track of who needs to pay, in a peer-to-peer system that's much harder how do we do that, so there are many other issues for how to make peer-to-peer file sharing work, we're not going to touch upon those issues, we're going to look at about how the protocol works, how the data transfer works and look at the advantages in terms of network performance and we look at one example and one of the most popular peer-to-peer file sharing protocols called BitTorrent, so there are different protocols that use these concepts, BitTorrent is one of them Nutella is another protocol for transferring files and there are different applications, pieces of software that implement these protocols and provide some user interface and it gets confusing because BitTorrent from what we're discussing, we think of it as a protocol, it's a means for exchanging information, but in fact there's also a software, piece of software also called BitTorrent, but there is other applications that use the same protocol called BitTorrent and a piece of software that uses the BitTorrent protocol as long as they implement the same protocol then they can communicate with each other, but there are other protocols Nutella Napster and so on and different pieces of software, we're going to focus on the protocol called BitTorrent and let's see how it works, first we'll go through the terminology and then see the basic concepts, so in BitTorrent a file, in fact not just a single file, but a set of files is referred to as a torrent, so in my example I said we had a 1000 megabit file, we could say that is a torrent, but a torrent can actually contain multiple files, we'll see the structure in the moment of a torrent, but we can think of it, it describes a set of files, not just one file, often a file with the extension torrent is a file that describes that torrent, we'll see an example of how the format of describing it, by describing it it would include a list of files that are included, so we think of the concept of a torrent refers to a set of files, a dot torrent file describes that torrent, the users that are accessing a torrent are called peers, so all the users that are going to access this torrent download this file, peers, these peers may be downloading or uploading the files, or both, a peer that has downloaded the entire torrent that has the entire file or set of files is called a seed, so that's like our initial five users in our simple example, once I've downloaded the entire file they are making it available to others to download from, these users, these peers are called seed users, or seed peers or just seeds, and we say that those users are seeding the torrent, the other peers which haven't yet downloaded the entire file are referred to as downloading peers, downloaders sometimes are leeches, these are peers that want to get the entire file but only have a portion of it at some point in time, once they get the entire file, the entire torrent, they become seed peers, so peers in the network are either downloaders or seeds, once they've downloaded the entire file they become seeds, a swarm is the set of users connected to a torrent, so it's all the peers including the seeds, so if we have some network, we have some network with some computers attached to that network, so any set of computers in the internet, they have some IP address, we say that a set of those computers for a particular torrent, example dot torrent, we may have some downloaders and some seeds, and those set of users which are a combination of the downloaders and seeds are called a swarm, so all of these computers, the three seeds, the four downloaders are accessing a particular torrent, let's see if we've got a, not yet, before we go to a specific example, a few more concepts, instead of having to download an entire file before you make it available to others to download, the file is broken into pieces, so in fact I say a file is divided into pieces to be accurate, a torrent is divided into pieces, a torrent can be a single file or many files, so a torrent is divided into pieces, once a piece is downloaded by a peer, then it's made available for others to download from it, that is that peer can upload it to others, so when this peer has downloaded a particular piece, other peers in the swarm may download that piece from this one, pieces are further divided into blocks, so we have a torrent is divided, a torrent is made up of files, the torrent is divided into pieces and pieces are divided into blocks, they usually have some defined size, we'll give some examples later, let's see a picture of that shown here, so let's say we have three files that we want to share amongst a set of users and they're all related, file one, two and three, different sizes, a torrent, this example torrent contains these three files, so think of the three files are joined together, the dot torrent file and we'll see an example or some contents describes those three files, the file name for example, the size and other features, the torrent is divided into pieces, usually or they're equal size pieces except for the last piece, of course may be smaller than the others, example we have let's say three files, file one dot txt, one megabyte, file two dot mp3, nine megabytes and file three dot avi, nine hundred and ninety megabytes, three files let's say they're all related, so the torrent in this case, the torrent which contains these three files is 1000 megabytes and our peers want to access this torrent, they want to download it, which is equivalent to downloading the three files, a typical size of a piece, there are some varying numbers, but let's say is 500, or half a megabyte, 512 kilobytes is a typical size, one megabyte, 512 kilobytes, let's say each piece is half a megabyte, then we have in this torrent 2000 pieces, it's divided into 2000 pieces, once a peer downloads one of those pieces it can make it available to other peers to download from it and each piece is divided into blocks and a typical size of a block maybe 16 kilobytes, so each piece is divided into blocks and we see when we look at the download protocol you actually download blocks at a time, so equal size blocks and the piece, the last piece maybe smaller than the other pieces, we'll see that we what we normally do is the set of pieces that we download does not have to be in order, so and normally recommended not to be in order, so for example we may download random pieces, but we download the piece, we want to get an entire piece before we move on to another piece, so we'll see that the way to download a particular piece is there's a simple protocol for instead of saying download the entire piece, download the first block, make sure it's correct, do a check on it and then download the next block, so download parts of it at time, in case something goes wrong, in case you have to do a check some on that the protocol for exchanging and also informing about what's available we'll see is done on a block level, but the piece level is used to indicate is used if we number the pieces, how many pieces does the seed have in our example, the seed here, how many pieces in our example, how many pieces does the seed have, seed 2,000 pieces, remember by definition a seed has the entire torrent and our torrent of a thousand megabytes has 2,000 pieces, so the seed if we listed them has piece 1, piece 2, piece 1, 2,000, it has all of the pieces whereas the downloaders only have a subset of the pieces, they don't have all of them, by definition they don't have all 2,000 pieces, they may have many pieces but they have less than 2,000, we'll see we'll come back to the way that we request individual pieces in a moment, for now let's just go through the terminology of torrent is made up of one or more files, a torrent is divided into pieces, pieces are divided into blocks, the set of seeds and downloaders that are accessing a particular torrent is called the swarm or a swarm, there's a special server that manages the list of peers in a particular swarm, so there's some server called a tracker that has a list and says that if we give these numbers, these are our peers, then it would say that the tracker would have a list that says for the example dot torrent, if that's the name of our torrent, then the peers are 3, 5, 7, 8, 9 and 10 and of course it keeps the actual addresses of those computers in the internet, IP addresses port numbers normally, so the tracker keeps a list of all peers that are accessing a particular torrent, IP addresses port numbers and other information, we'll see some examples, some statistics about how much they've downloaded and uploaded as well, so there's a tracker needed for a particular torrent, there may be multiple trackers in the internet in our network, but for a particular swarm we say there's, in fact there may be multiple trackers for a particular swarm as well, but for simplicity there's one tracker for this swarm that keeps track of who are the peers accessing that torrent, these are computers on the internet in practice, they may appear and disappear at different times, here's a computer it may leave the network, therefore the tracker must get regular updates as to who is in the swarm, because if this one disappears it needs to update the list that it's no longer in this swarm, another device or another entity is an indexer, we need to keep track of or have a list of the available torrents in a particular network, so here we're focusing on just one torrent, I've called it example.torrent, this example.torrent refers to three files, file one, two and three, there may be many torrents in a particular network, an indexer is a server that manages a list of torrents, normally a website that allows a user to search for dot torrent files by name and other information, and from the indexer once you find the dot torrent file we'll see the dot torrent file describes the tracker, so let's see how that works, so now with those different entities indexer, tracker, seeds and downloaders, four different types of nodes and the the types of torrents pieces and blocks see the basic steps for using bit torrent, so we have a peer, someone's computer, it's running a piece of software that implements the bit torrent protocol, we can say this peer is identified by an IP address in the internet and a port number, so we can think instead of some number 10 we actually have an IP address and a port number, initially this peer that wants to download a particular torrent doesn't know any other peers, the peer contacts an indexer and from the indexer obtains a dot torrent file, so to start downloading a file or a torrent you need the dot torrent file, where do you get it from, you get it from an indexer, so the peer contacts our indexer, the indexer maintains a list of dot torrent files and some description of each of them, for example the website maintains a list of dot torrent files, the peer does some search for what they're looking for and they get as a response a dot torrent file, how do they contact the indexer and download the dot torrent file, that's not part of bit torrent, so there's a bit torrent protocol, how to do that part is not specified that's separate, the normal approach is using a web browser there are web servers that act as indexers, they have a list of dot torrent files you can search and you download those dot torrent files usually using HTTP, once you have the dot torrent file the peer software uses that dot torrent file and they use it in the next step, the dot torrent file describes not only the files in the torrent but also the tracker or trackers, the dot torrent file says what is the IP address of the tracker so once our peer, let's say our new peer here has the dot torrent file, inside that file gives the identity of the tracker IP address port number, so then the peer contacts the tracker and asks the tracker what are the addresses of the other peers in this swarm, so our new peer contacts the tracker and says who is currently in this swarm and the tracker will send a response saying the current peers in this swarm are 3, 5, 7, 8, 9 and 10 and once that's done our new peer knows the addresses of the other peers in the swarm and once they know the addresses they will contact them to try and download parts of the torrent, so the tracker as we said keeps a list of the peers in the swarm a new peer contacts the tracker to get that list of peers how does it contact the tracker there's a a protocol for doing that which we'll see an example of once that peer knows about other peers in the swarm so our new peer here has just contacted the tracker it's found a list of other peers in the swarm it then contacts some of those other peers and starts downloading pieces of the torrent downloading some pieces from one peer other pieces from other peers until eventually it's downloaded all the pieces in the torrent and has the entire torrent and then it becomes a seed in that swarm and of course once this peer has started to download some pieces other peers who also want that torrent can download from it during this download phase the peer also maintains contact with the tracker giving some update that it's still in the swarm and some statistics about how much it's downloaded and how much it's uploaded so that as a result the tracker knows about all peers in the swarm and the statistics of which ones have downloaded and uploaded certain amounts so when a new peer comes along again they contact the tracker and then start contacting peers so three main steps a new peer obtains a dot torrent file from an indexer normally using a web browser and a web server using HTTP once you have a dot torrent file that describes the tracker the peer uses a protocol in BitTorrent for obtaining the list of peers from the tracker and then uses a different protocol for downloading pieces from peers in the swarm we need to go through those two two protocols the one for contacting the tracker and then how to download the pieces first let's look at the structure of the dot torrent file so let's say our new peer has contacted an indexer and downloaded example dot torrent the dot torrent file it's a smallish file that describes the torrent what does it contain so it's a text file of a particular format and the main pieces of information it includes some information about the files so our example dot torrent would include information about file one dot txt file two dot mp3 file three dot avi the set of files included in that time in particular file names the length of the file how big the pieces are and some unique identifier of each piece and the way that the unique identifier is obtained is using a hash everyone knows remembers hash functions who doesn't know hash functions you do hash functions anyone a hash function without going into the details given some file if we apply a hash function on that file we'll get a unique identifier as an output and the char char one hash function returns a 160-bit identifier if we have a different file and apply the same char hash function we get a different identifier as output usually they identify as random it's just a way to uniquely or uniquely identify a file when we have many different files we can't just use file names to identify them we use hash functions so what's inside the dot torrent information about the files in the torrent that's one set of information there's something called the announce which is really an identifier for the tracker it's a url for where the peer can contact the tracker and in fact there can be more than one tracker so there can be a list of trackers some creation date when the torrent was created and by who or what software and maybe some description of the torrent some comments so here's a selection of an example dot torrent file and this was a couple years old this was for ubuntu cd so to download the ubuntu operating system this was part of the dot torrent file it's not it doesn't contain the files it describes the files in the time we don't need to worry about the format there's some definition that says that okay we have some field a field field name and a field value and i've tried to highlight them in in different colors to identify them but of course they're just text in a file so this is saying this is the announce field and the value is a url which is the address of the tracker okay so the announce field identifies who the tracker is in the internet and we will use that the peer will use that announce field to contact the tracker some comment describes the the torrent some date there's some format for the dates to be created and some information in this case it contains the length of the torrent actually the length of the file in this case there was just one file inside the torrent potentially there can be multiple files it's 732 megabytes okay about 732 megabytes the name of the file is an iso so a disk image the length of each piece 524 kilobytes so about half a megabyte so in this example our file is 732 megabytes our piece is half a megabyte then then there then for each piece there is information about that piece in particular hash value and this doesn't make sense because what a hash value is when we'll see i'll show you an example is a random sequence of bits so in ascii it doesn't come out as any meaningful characters what's the mistake in this slide what's the mistake is a mistake in one of the numbers how many pieces should there be look at this the size of the file you've got a calculator how many pieces should there be how big is the file file is 732 megabytes approximately 732 megabytes each piece is half a megabyte okay so about 1400 pieces in the file not 27960 pieces this should be it's about 1000 and i think it's 1397 pieces in this torrent there are about 1400 pieces simply the file length divided by the piece length this number 27960 is the length of these hash values okay it's not the number of pieces that's this is wrong this number that is for each piece of these 1400 pieces so if we divide the file into different pieces and then we take a hash of each piece we get some unique number and that's what's listed here there'll be 1400 numbers identifying each of those pieces so a piece a piece has a unique id a unique number as a quick example of hash hash functions char1 is a common hash function md5 is another hash function you may have seen in in different systems uh we have some files so first example i have some audio file from this semester and an mp4 file we can calculate the hash i have some software called char1 some of the particular file this is the hash value it's just it calculates a almost unique identifier and it's 40 characters long or 40 hexadecimal digits or 160 bits long in this case that's the typical the common hash function used in in bit time and if we have a different file we can calculate another identifier and that should be unique in the set of files available of all the files in the world if you get a hash function of that file if the two files are different you'll get two different hash values two different identifiers just to illustrate that two text files here one says hello one one says hello two if we calculate the hashes of those files they differed just by that last character the hash values are completely different as if that their random identifies here so the idea is that any piece in our torrent has a unique id that's useful for checking the integrity of the file that's downloaded you can check that because in the torrent it describes all the hash values it lists them all once you download a piece you can calculate that hash value and check that you have the right piece so that someone cannot put a fake piece into the the file and you detect that if it happens so there's some security mechanism in place so just think of them as unique identifiers for pieces and they are listed those in our case 1400 values like this are listed in the dot torrent file they would be listed here so that's an example of a dot torrent file that's obtained from an indexer once our peer has this it looks in the announce field and then it contacts the tracker and the announce field is a url it tells it to contact your tracker in this case at torrent.ubuntu.com and a port number and the method for contacting the tracker is to use http so how does a peer contact the tracker and communicate with a tracker the tracker in fact implements a web server a http web server and the peer communicates with the tracker using http it's not for web browsing it's just using the same protocol for communicating some information between the the peer and the tracker and how it normally works is that the peer sends some http get request to the tracker where the url contains information about what the peer is doing some identity of the peer port number the peer is using the number of bytes that it has has uploaded and downloaded so far and the bytes remaining to download and whether it's currently downloading whether it stopped downloading or it's completed that is it's become a seed the peer sends a request containing this information to the tracker the tracker ascends back a response including the interval between which the client or the peer should contact the tracker the peer doesn't just contact the tracker once it does it on a regular basis say every 30 minutes and how often well the tracker tells the peer how often to contact it the tracker also tells the peer the number of peers or number of seeds and downloaders or leeches in the swarm and it gives a list of those peers including their ID address and port number so the peer sends a request to the tracker the tracker sends back a response containing a list of all peers the interval in which it should contact and some warning messages or error messages if needed then there's some optional information that may be included but that's the basic idea and here's a again another example of that trying to show the the request the blue one going from peer to tracker and the response coming back from the tracker to the peer and i've tried to structure the request in response to identify some of the important parts so it's using HTTP so the request is just a get request where we have get followed by some url but as you know with urls you can give parameters to those urls the format is we have some equals we have some field equals some value separated by ampersand sign for multiple fields i'm sure you've seen that in different urls so this is the information being sent from peer to tracker some information or hash value it's sending the identity of the peer the port number that the peer is using one one five four one the number of bytes it's uploaded and this is just at the start so it hasn't uploaded any bytes yet zero number of bytes downloaded zero the bytes left all bytes the 732 million bytes in this case so this is just at the start of course as it starts to download bytes and upload bytes those values will change what else is some different fields here what's the status whether we've started stopped or completed the download in this case we've just started and some other information about the the peer the IP address of the peer the number of i think this is the number of peers that it wants back in the response it wants to receive a list of 200 peers in response or up to 200 so the peer sends this to the tracker the tracker who keeps a list of all other peers sends back a response a HTTP response and inside that response is the the what have we got the number of peers that have completed the download which is the number of seeds in the swarm the number of peers that have not completed the download which are the number of downloaders or leeches so the tracker tells the peer how many downloaders and seed seeds we have in the swarm at this point in time and then an interval in which the peer should contact the tracker this is 1800 seconds so every 30 minutes in this case so 30 minutes later the peer will send this another request updating the values for the upload download and left to inform the tracker of its current status and we'll get a response and then we have a list of peers so it's not shown here but it will contain information about the the different peers in the swarm at this point in time including IP addresses and port numbers as a result our new peer knows the addresses of other peers in the swarm so once we receive the response our peer knows about some other peers and can contact those other peers so there are three steps remember a peer contacts the indexer a peer then contacts the tracker and then the peer contacts other peers to download the torrent the first step of contacting the indexer is done using some other method normally just accessing a website and once you contact an indexer you download a dot torrent file inside that dot torrent file includes information about the swarm and in particular the address of the tracker so in the second phase the peer contacts the tracker using this hate these types of messages using htdp of sending a request to the tracker the tracker sends back a response containing a list of peers then the third phase the peer starts downloading pieces from other peers any questions on how bit torrent works exam in one week question on bit torrent in the exam any questions so far easy what's hard the exam's hard yes but what's hard about bit torrent you don't have course have to remember the structure of these messages but try and understand the concepts of what are the roles of the different entities that we have indexers trackers peers two different types of peers seeds and downloaders or leeches what defines them and how they communicate with each other the last part and maybe the most important part is once a peer knows about other peers in the swarm it needs to start downloading some pieces how does it do that out of the peers exchange pieces because we'll see as one peer wants to download pieces from one another peer then they may also want to eventually upload pieces to another peer as well exchange pieces in both directions so there's a peer exchange protocol we have 10 minutes left i don't think we'll finish today do you want to try and finish today or continue tomorrow let's finish tomorrow so tomorrow what we need to do is exchange explain how the peer exchange protocol works let's let's start on that tomorrow and we'll have a bit more time to go through that and you'll be able to answer some ask some questions about the the earlier parts


Alright, Henry, what should be the topic of my question Tuesday video? Pokemon! Alice, what should my question Tuesday video be about? Monkey Turtles! Monkey Turtles? Good morning, heck, it's Tuesday. It's Question Tuesday, the day that I answer real questions from real nerdfighters about Pokemons and Monkey Turtles. Oh, and look, it's a reunion video! We're all here together in the desert. I don't know what Monkey Turtles are. I also didn't know what a Monkey Turtle was, so I asked Alice, and she said, it's a monkey that turns into a turtle. Right. Yeah. Right. For why? Oh, I asked her that, and she said, for protection. And then I asked Alice how big Monkey Turtles were, and she said 100 big. It's big, actually. Well, or not. It's true. It depends on if it's millimeters. You need to learn units. Talking to Alice is like talking to a not very good AI. She's like a bad chatbot. Yeah. She said to me, Uncle Hank, I got this new water bottle, and I said, is it better than your old water bottle? And she said, it's pink, the other's purple. Like, it's like, I asked you a question, and you answered a different question, but you kind of were on the same topic. She's also like a chatbot in that a lot of times, if you ask her a question, she'll say, I don't want to talk about that. What is your favorite Pokemon, and why is it Charizard? It's not Charizard. It's Snorlax, because he's cute, and large, and powerful. Mine is Andrew. Andrew? Yeah. Have you seen the Andrew Pokemon? Is he a monkey turtle? No. He's just a guy. He plays guitar. What Pokemon could best keep a steady job? Oh, probably Andrew.   Oh my god, he can cook the burgers. Oh wow. What is the most underrated Pokemon? Oh, I think the most underrated Pokemon is Surfing Pikachu. I'm going to go with like the Wiggle Puffed. Jigglypuff? Or Spike Ladder. Spike Ladder. That's a real one. You ask Henry what he wants to be when he grows up. He says inventor, and then he pauses and says it's of Pokemon. John. Yes? How can I be the very best, like no one ever was? Come on. If you had to permanently dye your hair a non-natural color, what would it be? Silver? Ooh, well you're getting there already. I know, I'm on my way. When I was in college, I thought to myself, I want to have a job. When I turn 40, I can get a mohawk. And how I do. Hey, welcome to Crash Course Biochemistry. It's me, your cool teacher, Hank, with the 40-year-old mohawk. Doesn't all value derive from humans? No. I just want to say for the record, Hank is not taller than I am, it's just that he is standing on a rock. I was downhill. Hank, what is your favorite adjective to throw in when you want to spice up a sentence? Spicy. I don't like that at all. What do you think of that three-point shot, Hank? Spicy. I don't want to be like my friends will be like, yeah, Hank, the one who says spicy all the time. Oh yeah, Hank, spicy green, they call him. Who would win in a fight between a monkey turtle and a turtle monkey? Oh, definitely a monkey turtle, because it could turn into a turtle for protection. What is your favorite type of plate? Oh, for me, it's the kind that the Earth's crust is on. Ooh.  Sometimes you're at a really fancy restaurant and there's a plate on the table before the food comes out and then they take that plate away. Yes. And I'm like, what was that? Right. Why was that plate there? Yeah, just in case. Explain it to me. Just in case plate.  R2D2? Yeah. Because like whenever I hang out with you, I kind of feel like I do have C3PO in my house. That's true. Hank, what Pokemon do you think looks the most like you? I don't know either, but I'm excited to find out from our viewers. Isn't Mr. Mime the only one that walks on two feet? Or like it's vaguely human-shaped? I don't know of a greater insult than saying that someone looks like Mr. Mime. We're going to go keep walking, so goodbye friends. Bye, I'll see you now. You want to see our incredibly sophisticated tripod, by the way? It's Hank's Wallet and two rocks, doo-doop!


The Viking invasion of Britain and Ireland is one of the most famous and fascinating events in the history of these isles, but what if it didn't happen? How would our world of today be different if there was no Viking invasion of these isles? History is not a foregone conclusion, although it may seem that way from our vantage point of the present day. First up, and perhaps not what some of you would be expecting, is that the English language would be very different today if it wasn't for the Vikings. Numerous everyday words in the English language come from Old Norse from the Vikings, stemming from Viking raids in the period of the Danelaw, when Danes settled parts of modern-day England in the 9th and 10th century. Words such as egg, husband, anger, bag and slaughter are from Old Norse, a legacy of the Viking invasions. Without the Vikings, we might be confusing our eggs with our eyes, as the Old English word for egg was actually I, before it was replaced by the Old Norse word egg, perhaps to help save some confusion over our eggs and our eyes. Egg comes from the Old Norse word eggja, meaning to go down or in sight. Interestingly, to egg someone on is still an expression in English today, meaning to encourage or to incite. There are so many words in the English language that are connected to Old Norse, you can literally go berserk, get it? The Vikings also had a notable impact on many place names in these islands. For instance, Thames or cities end with By, by such as Derby, as usually a signal of some sort of Viking influence, as By by meant some sort of farmstead to the Vikings. Also place names that end with Thorpe, such as Skunthorpe, are probably connected to the Vikings in some way. The Scottish town of Wick gets its name from the Old Norse, Vic, meaning Bay. We could literally be here all day with place names, but I think you get the point. Secondly, some people would have a different sense of their own identity if the Vikings didn't invade. History, after all, informs how we see ourselves today. The Northern Isles of Ortony and Shetland are prime examples of this, and there is a growing independence movement in both countries, as both want a greater sense of autonomy over their own affairs. This was quite prominent during the 2014 Scottish independence referendum as well. After all, it was only in 1472 that Ortony and Shetland were absorbed into Scotland, and were previously under Norwegian control and Norse control prior to that. Modern politics obviously have a significant influence on this as well, but it is interesting the connections between Norway and these Northern Isles of Ortony and Shetland. Shetland still celebrates its Viking heritage, with his uphealier festival to mark the end of the Yule season. Earlier this year, Ortony's council voted 15-6 for a proposal which includes examining the archipelagos Nordic connections and looking into adopting models similar to crime dependencies such as Jersey. This leads nicely onto my third point, genetics. The Vikings had a pretty profound impact on the genetics of these Isles, and this is seen no more so than in Shetland and Ortony. In Ortony, there is a dramatic genetic legacy. In fact, the people of the British Isles study found that Ortony was the most genetically distinct part of the UK, with around 25% of Ortony's DNA coming from Norwegian ancestors, showing the clear significance of the Viking presence there. The Vikings didn't completely replace the indigenous Pictish population however, and intermarried with them. Shetland also has a significant Viking influence, and with around 20-25% of its population considered to be descendants of the Vikings. More broadly, the people of the British Isles study, which looked at the UK population as a whole, found that there was a notable Norwegian signal in all Scottish and Northern Irish samples they studied. However, this was less pronounced in Northern England, and even less so in Wales. A 2017 study that looked at Ireland more broadly, found that there was a surprisingly high level of Norwegian ancestry in Ireland, with Norwegian ancestry used as a proxy for the Vikings, and it's a way to separate or try and separate any noise in the data between the Vikings and the Anglo-Saxons. So if you used Danish DNA for instance, you would have introduced potentially Anglo-Saxon influences, particularly when you study in England as well, but all these studies essentially used Norway as a proxy for the Vikings. In fact, this Irish DNA Atlas study found that Ireland had the second highest Norwegian signal in their analysis, second only to Orkney, which had the strongest Norse Viking ancestry. Although highly influential militarily, politically, linguistically and culturally, there is no obvious genetic signature in England from the Dame Law period, which is quite surprising, according to the people of the British Isles study at least. Without Viking raids and invasions over the centuries, many people in these Isles would look differently, speak differently and think differently. Just small changes then. But what factors have I missed out? How else would the world be different without the Viking invasions in these Isles? Please let me know in the comments below. Speaking of the Vikings, what did the Vikings actually look like? To find out, please click here. Thanks for watching. For ways to support, I'll be in the description below. Thanks for everyone who does support this work, and thanks again for watching, and I'll see you next time.


The Cavalcade of America, sponsored by Dupont, maker of Better Things for Better Living through Chemistry, presents Richard Arlen in U-boat Prisoner. Week, we bring you news of Better Things for Better Living through Chemistry, and often chemistry holds the gift of life itself. For instance, in X-ray film and screens where chemistry converts invisible X-rays into visible images, enabling doctors to locate bullets or shrapnel in the body in a matter of seconds. X-ray screens and film are but two examples of how science and industry work together to save lives and bring better health to all. Tonight with Richard Arlen as Archie Gibbs' ordinary seaman, Dupont presents U-boat Prisoner, the thrilling story of a merchant seaman rescued by the very submarine which had torpedoed his ship and killed his shipmates. Our play tonight was especially written for Cavalcade by Arthur Aaron and is based on the true story in Archie Gibbs' own book, U-boat Prisoner, and stars Richard Arlen on the Cavalcade of America. This is the story of a man who was torpedoed twice on the same voyage. When his first ship was blown apart, he drifted on a raft in the Caribbean until they hauled him aboard another merchantman. Two hours later, it started all over again. First, there was just the sound of the men asleep in the focusel. And the careful throbbing of the ship's engines. Then the sudden bellow of the second officer on the bridge. And then, like the crack of judgment day, the torpedo. Just to make sure. And then the ship breaking in half and men spilling over into the sea. Yes, this is the story of a man who was torpedoed twice in one day. But that's not why we're telling it. Lots of seamen get it twice before they make port. But how many of them ever get picked up by a German submarine and spend the next four days as a prisoner on a U-boat? My name is Archie Gibbs. That's right. Archie. Kind of a fancy handle for a guy that grew up in the North in the sound and learned what the world looks like from a deck of a cargo ship. Of course I've done other things too. From hand, dishwasher, railroad worker, pearl diver and a couple of other odds and ends and etc. But the most fun I ever had out of life and the most useful I've been to the human race in my country was by way of taking a ship loaded with ammunition from one place to another. With a lot of ocean in between. The story begins at the National Maritime Union Hall in New York City. That's right. It was December, which is kind of a nice time of the year to be on dry land.  I tell you, this convoy set up is a bug. One out of three, that's what we lose and enough Navy for checking us. Y'all move, Joe. Can't we make the run to my men's? Enough big sigh, he did. Boy, them stookers. I hear you're good for 20 minutes if you get it up there. One minute more in that water and you're stiff as a mackerel. That's right. That's for me. December 2nd, November 19th, November 28th, November 12th. November 12th for the ordinary. Who can beat November 12th? I can, Mike. Let me see your card. This little piece board says I got back on my last trip November the 2nd. That gives me top priority. November 2nd's right. That does it. The job goes to Archie Gibbs. He told me the name of the scowl and when she was sailing. I can't tell him to you, but she wasn't noon, she wasn't fast. Oh, not that that bothered me. Somebody's got to sail the slow ones and up to then I've been pretty lucky. That's me knocking on wood. Anyhow, I had worked up a good healthy case of hate against them Nazis and it made me feel good. Yeah. Hate your enemy, that's my motto. That way you get things done that gotta be done. Well, it was a few days later when we were out in the Caribbean part of a big convoy that things began to happen.  Just sighted another empty raft and some wreckage. It must have been hit so hard a refrigerator busted open. Those potatoes and oranges and quarters of beef all floating by. You could almost stick out your hand and grab one. Oh, I didn't, Jase. Because there was other things too. Bodies, three of them face down in the water. That's why I didn't stick out my hand, Archie. I got a feeling we're gonna get it tonight.  I got a feeling we're gonna catch ourselves a nice big tin fish.  So is the one that got it that them bodies were on. Only they weren't bodies then. They were alive, walking and talking like we are now.  We're going to get it today, Archie. We got a feeling about these things. You want to bet, Irish? Would you get a risk, a couple of bucks? Lay it even money, we get it in 24 hours. Only take a risk. Not in the way you guys think anyhow. The only risk is whether I'll be alive to collect. Exactly three hours and 20 minutes later, I was in the Caribbean Sea looking around for something to hang on to. Out of nowhere, there had been a crash like something you never heard in your life. A blinding flash of light and ship-shaking like a big hand had got hold of it and squeezed it. The next thing you knew, there were heads bobbing around the water, yours and others. What happened, Irish? Well, that torpedo exploded in the engine room. Irish was in there at the time making a little bet with the chief engineer by another ship in the convoy. They gave me some dry clothes and I went below. It seemed like I had just shut my eyes when the whole crazy merry-go-round started all over again. First off, it was quiet there in the focusing. All you could hear was the sound of men breathing in their sleep. And the careful quiet throbbing of the ship's engine. And then the sudden hollering of the second officer on the bridge. Mark the time, men! The ship's getting hit! And then, like the crack of judgment day, the torpedo. One more just to make sure. And pretty soon, I was back in the Caribbean again. Somewhere, as I don't remember, I picked up a flashlight. I turned it on and there I saw heads bobbing around the water again. Then I saw something else. It was a shadow that came up under my feet. Like one of those platform elevators that come out of a sidewalk. And before I knew what hit me, I was rolling around on the fourth deck of a German submarine. Go down to the rail or you'll be washed overboard. Okay? Yeah, yeah now. You know what this is? Yeah, it's a revolver. Looks like a 38. Good. Then you will answer my questions.  No. It's not healthy to lie when I ask questions. I'm not lying. I was an ordinary seaman on that tub you torpedoed last night. Last night, huh?  What was the name of the ship I just sank? I wasn't aboard long enough to find out. What was the name of your own ship? Answer me! The North Arrow? Good. Where was she from? New York. I don't know. The Navy Department never confided in me. What kind of cargo? I said what kind of cargo? Empty drums. What do you say? Empty drums do not explode? Was she a warship or a merchant one? A merchant one. And a pretty old one at that. You lie. I never seen such an old scowl. Couldn't figure out what kept her afloat. Reinhold! You go down now. You mean down there? Yeah. There's a man there who wishes to speak with you. No, I don't want you going off on the wrong tack about me. I know a hero, see. Even if the previous conversation sounded kind of fancy for a guy who was you broke prisoner, the truth is I expected to be shot, so what did I have to lose? If I told them what they wanted to know, what would it get me? Nothing but a funny feeling when St. Peter inquired if I was a good guy or what did I ever do for my country? I was thinking about these things and making up my mind how I'd act as we climbed down the control room ladder.  And when he talked, it was with what they call a Knoxford accent. Come over here, you. Where are your papers? In my safety bag. You've got it there in your hand. Sir? Sir? This is very good, this bag. Yeah. Sir? Who makes it? Norwegian. His name is Count Mourner. He's one of the guys you didn't get when you walked in there. Sir? Thank you. He also invented a life-saving soup. An account of it, a whole lot of American seamen are alive today. That is enough. Well, I just thought you'd like to know, sir. You are very intelligent for a sailor.  After the second officer left, I had a look around. I figured this U-boat must have been at sea for quite a while. The torpedo cradles along the bulkhead were empty. The floor plates bare. Up forward, there were four torpedo tubes. But they were locked and I couldn't tell whether they were loaded or not. I sat down on one of the bunks. Four sailors stopped playing cards and stared at me like I was something special. Nobody said a word. I guess maybe I was a little nervous. So I was just looking around for something to grab if they started getting rough when one of them finally broke the ice. And he said... San Francisco is very beautiful. I like very much San Francisco. Glad to hear it, mister. I got kind of a soft spot for San Francisco, myself. Charleston, South Carolina is very beautiful. I like very much Charleston, South Carolina. Sorry, mister, never been there. I go to Velcrois, oh, to San Francisco, Yokohama. 17 trips. San Francisco is very beautiful, nice people. Yokohama is no good. Oh, that's swell. Then when we get through with it, it won't be much of a loss. Japan is no good people. America wins from Japan quickly. But I not like to see America fight Germany. Maybe you tell me, if I America make fight on Germany. Not a kind of a guy named Hitler, your boss. Also, if I remember correctly, you declared war on us, December the 8th. Right after Pearl Harbor. German newspapers say America declared war first on the Germans. Can you top that? These guys really believed what they read in their newspapers. I tried to convince them, but it wasn't any use. They just smiled like maybe I was a little bug house. Then one of them brought over a book. Acting kind of pleased and proud, he turned the pages so I could see the pictures. Very interesting. Very pretty picture, Snow. Now only I saw him before. You have seen these pictures? Sure, in a movie about your guys in Poland. It was called Victory in the East. Yeah. Yeah, that's it. The show dish in America? Certainly they showed it in America. We can also get a copy of my comp and any bookstore. You make a joke, no? No. In America you can read anything and say anything you like. We figure it's a good idea to listen to what the other guys got to say, so we'll know how wrong he is. That's democracy. You had better not speak like this, than you see him. Him? Who? A Lloyd-Nottieman. He is our political officer. He will ask you questions. It is best for you that you speak. You say soft to Lloyd-Nottieman. Neckarl? Yeah, soft. Very soft. You are listening to Richard Arlen on the Cavalcade of America in Newboat Prisoner, an exciting story of heroism at sea presented by Dupont, maker of better things for better living through chemistry. Richard Arlen plays the role of Archie Gibbs, American merchant seamen, who was torpedoed, rescued, torpedoed again, and picked up by a German submarine. With the German sailors, Gibbs has learned of the existence of a mysterious political officer on board, who as our play continues is shortly to question Gibbs. A couple of days went by, and pretty soon I lost track of time. I was treated fairly well by the men, just the same I was worried. It was this Lieutenant Zimmer guy, the political officer. You see, by this time I wasn't so sure they were going to shoot me. What I mean is I had hopes. And this Zimmer not sending for me or anything worried me. What was he waiting for? What did he want to know? Suppose he offered to set me free and give me a raft and some grub if I answered some questions. Questions like what was the naval installation at Trinidad and things like that. What should I do? Tell him to go jump in the lake or play along and try to bluff it. And if I did, could I get away with it? Well, it got more and more complicated in my head until I finally decided to quit worrying. Sort of smell things out as I went along. And then one afternoon something funny happened. I was asleep. And all of a sudden I heard a familiar noise. It was dark in the war room, but I finally made out somebody standing by wireless. It was one of the sailors, the big guy they called Carl. He looked around quick like he was being careful about something. Then he twisted the dial. No, Carl, no, that is not the one. Turn it some more, Carl. Turn it some more. What were they looking for? Maybe a secret sending station in South America. Maybe instructions about refuelling or attacking a new convoy. Maybe I was going to be the only American ever listening to a secret message coming in from the high command all the way over there in Berlin. I got so choked up I stopped breathing. And suddenly Carl whispered, Yeah, yeah, I had it. It is coming in now. And then as he tuned up the volume I heard it, well, you could have knocked me over with a pincushion. Yeah, yeah, yeah, good, good. Yeah, yeah. Good evening. Okay, sir. I give you to the friendly ministrations of our political officer, Lieutenant Zimmer. German name. Not since William the Conqueror, eh? My parents and grandparents were born in America and one of my grandfathers was an American Indian. Savage. Interesting. Did your ship come through the Yucatan Straits? I can't tell. I'm not a navigator. And, sir. Okay. Before Pearl Harbor we used the Straits because we didn't want any trouble with you Nazis. Now we don't use them and we're looking for it. These photographs are found in your bag. They are your children? They're my sister's kids. Very healthy looking. They are not so healthy. We are pleased to hear that. Hands up. I haven't thought about it. Perhaps one day the shoe will be on the other foot. Maybe. This is your club card? My union card. Tell me. Can your club force you to go back to sea? How do you say sign on again if you do not wish? I ask only out of curiosity. It ain't a club. It's a union. A trade union. I ask again.  My union? Okay. My club cannot force me to do anything I do not wish. In America I do not have to do anything I do not wish. The United States government does not make men go to sea if they do not wish. Sir, it is better that you do not go to sea again. Does that mean you're going to let me go? Yes. On one condition. You wish to hear this condition? Sure. What have I got to lose? That is very sensible. How many American destroyers are Trinidad? How do I know? You've been there? Yeah, but I never counted them. Make an estimate. Okay. 200. 200 for the question of bombing planes. How many? How many bombers are Trinidad? Two motor or four motor? I am being very patient, Mr. Gibbs. What's that? Depth charges. One of your destroyers, no doubt. One of the 200. Now, Mr. Gibbs, about those bombing planes. How many? Kind of close, wasn't it? You know what this is? Say, will you tell me something? Why do you Nazis always stick a gun under a guy's nose and ask him if he knows what it is? Of course I know what it is. It's a gun. It would be wise to answer my questions.  How would I know how many bombs? Hey, that was real close. For the last time, Mr. Gibbs, how many bombing planes are based on Trinidad? And for the last time, I'm telling you I don't know. All I know is there's at least one of them because the thing you think is a destroyer is a bomber and the next agate laser is going to be right on our heads. And that's exactly where it was, right on our heads. I was blown to the surface with a couple of other guys. Then an American crevette picked me up and landed me in a certain place in South Merritt. What happened to Herr Lieutenant Zimmer and the rest of the baby killers I never found out? And I ain't particularly worried. Well, when I finally got back to New York, they gave me a medal and they took my picture. I made a little speech over the radio. In it I mentioned how it felt to be torpedoed and what it was like inside of a German submarine. I also mentioned how important it was for our soldiers to receive the stuff our ships carried to them and that every nickel invested in war bonds would kill the ship or a gun or a plane that maybe one day would kill a Jap or sink a U-boat like the one I was on. Which is a very good idea indeed. Very good idea indeed. But there's one little incident Archie Gibbs neglected to mention. It took place just a few weeks after he landed in New York from his adventure with that U-boat. The scene is again the Siemens Hiring Hall in New York City. Attention please. Second, April 24th, April 9th. Who can beat April 9th? I can, Mike. Read it and wait. That does it, April 7th. The job goes to Archie Gibbs. Now to join all Americans in saluting the gallant men who sail the Seven Seas, delivering the materials of war to our armed forces. Mr. Arlen will return to the microphone in a few minutes. Meanwhile, here is Clayton Collier with a story from DuPont. A technical problem that has bothered mankind for all the years of recorded history and probably bothered our caveman ancestors before that is how to make things stick to other things. From the Egyptians down to the present day, people have tried just about everything from egg whites to fish glue as cement and glue. Modern chemical research now provides adhesives of entirely new compositions and they are accomplishing important wartime jobs. Polyvinyl resins, for instance. Polyvinyl resins are chemical derivatives of acetylene, the same gas that used to light old-time bicycle and automobile lamps. These resins provide a whole new series of adhesives. One bonds wood to metal so tightly that the wood actually splits and tears apart before the adhesive gives way. Other polyvinals replace natural latex in rubber cement. There are polyvinyl adhesives for metal, leather, wood, cork, ceramics and paper. Another resin adhesive manufactured by DuPont, a white powder soluble in water, has no odor, cannot harm foodstuffs, does not corrode metal and for all practical purposes is weather-proof. Right now it is used in making paperboard and fiberboard containers for the armed forces. Boxes made with it have to pass a test. They must stand being anchored in the surf for 24 hours and gives you some idea of the rough treatment these new adhesives will take. DuPont manufactures still other adhesives of an entirely different type, synthetic elastic compositions. Some of these can be vulcanized like rubber. Some vulcanize themselves slowly with ordinary exposure. One of these is fair-preen cement, which is especially designed to resist oils and greases. Another protects against corrosion. Each cement has its own special properties. Last but by no means least, the little tube of DuCo cement that has been a familiar friend and helper in your home for years now serves in the wartime manufacture of radio and telephone coils, signal lights and electrical fuses, among other things. DuCo cement is still available to you and when the war is won, all of these adhesives, which are now giving splendid wartime service, will serve industry and you as DuPont better things for better living through chemistry. And now here is Richard Arlen, star of tonight's cavalcade. Thank you very much, ladies and gentlemen. Archie Gibbs of the Merchant Marine, the hero of tonight's play, was not a character of fiction, but a real man. In the fullest meaning of the word, the men of the merchant marine are real men, often serving their country under conditions of danger and hardship, not exceeded in any branch of the armed force. America is very proud of its valiant men who go down to the sea and ships, the men of the merchant marine. With Alfred Drake, star of Broadway's greatest hit, Oklahoma, and Jackie Kalk, popular young radio star, cavalcade next week presents Bull's Eye for Sandy, an exciting story of our Navy's submarine chaser service. The story of P.C. 627, the little boat that fired the first shot in the invasion of Sicily on July 10th. Again next Monday, DuPont invites you to join the cavalcade audience when we'll present Alfred Drake and Jackie Kalk in an exciting drama of a little-known branch of the Navy. The submarine chasers that played such a vital role in the invasion of Sicily six months ago. The orchestra and musical score tonight were under the direction of Donald Voorhees. Cavalcade is pleased to remind its listeners that Richard Arland's next picture is the Paramount production Minesweeper. This is Carl Franks sending best wishes from cavalcade sponsor the DuPont Company of Wilmington, Delaware. This is the National Broadcasting Company.


Have you ever had any comments made about your autism that's made you laugh and noisy? When people will say, you're not like, you know, those ones who have it really badly. I find that kind of quite offensive. I know that people don't really understand it well, but it upsets me because people don't understand it. In reality, our mind and our mindset and the way that we think is very similar to that. People kind of undermine it as like, you know, not a big deal, which I think that's quite hurtful because it is a big part of our lives and it does cause a lot of stress.


Hello and welcome back here to the channel We are staring down the hill or the shoot of road Atlanta at the back of a s14 Because is is going to be the first episode of this week's driver spotlight We are going to be doing a whole week of driver spotlights leading up to round one of FD this weekend So make sure you guys follow me on all social media all of which are found in the description box below So let's get to it So we are taking a look at this s14 by Jamie Healy if I pronounce your last name wrong I apologize. He sent it over. This is his 2021 ESTA Competition car and you know, there's a lot of s chassis in ESTA, but there's not many 14s There's a lot of 15s and stuff stuff like that so it's definitely cool to see this car definitely loves the lightning bolt and Tribal style livery looks like we got you know a very cool color scheme with the red the blue and everything like that and This car has some gorgeous looking wheels on it Haven't actually seen those wheels on any car other than this so far So of course, we got to give some credit where credit is due There is a note in here about a big thing to a dat guy Nirvana So if you guys know Nirvana has been around a while and he's been on a few of my videos and back when I was in you know Usual suspects. So base model of this car was done by AC Workshop Oh my hooteness the BCL wing J's garage and the physics were done by VDC Chris Witowski if I pronounce any guys names wrong. I do apologize if I butchered it. So this car is definitely a fun looking 14 Definitely has a very different sound to it and I'm very excited So we are gonna be going full send here on road Atlanta because well round one road Atlanta. Let's go full center road Atlanta here So we got the wheel cam turned out We're gonna back up because we're gonna have to go to the burnout box and warm up these tires on this bad boy, which I'm gonna have to turn my Tire indicator. No, I closed it. I want my tire indicator on so definitely been running a lot more Stuff with tire indicators. So I have that so we're gonna heat up these tires These tires are dead cold because the cars been sitting on the line First thing I noticed just in burnout box for this car. This car has very Snappy transition just in doing this so it's something I would be mindful of but of course it is VDC physics Which definitely coincides with the snappiness Probably gonna run out of gas before we actually get these tires warmed up. Yep, there's the gas light So we're at least gonna get one run before we have to go to pitch We're laying out definitely not an easy track to Accomplish with this entry so we're gonna try and see what we can do Kind of do a nice easy kind of roll in Little easy roll in we kind of got the entry not the greatest But you know first run out in a new car that I've never driven downshift in the Kind of miss that outer zone We've taken out that cone kind of bringing it back into that front clip Quick troll quick transition a little bit on your steer So for first run out not a bad run because like I said these driver spotlights definitely Challenging me to drive all these different styles of cars and I definitely love doing them So you guys want to be part of driver spotlight, you know to best me on Instagram and or in discord With information about your car and we can get you a driver spotlight But like I said, this is the first of the week of driver spotlights leading up to around one of fd Super excited. Let me know what you guys think is going to happen this season here in fd We need to get some more gas So we're gonna go another full send and you know, we're gonna end this at urban dale Where we end all of these driver spotlights, but I wanted to bring it to road Atlanta Definitely having some fun with Some new cars I'm working on on road Atlanta and other tracks that have never been able to drive before so We'll send try to get a better initiation this time I think it's so much power. Oh And there's that snap I was talking about Yeah, we're just gonna finish that run out that was bad that would have been a wreck person behind me Would have smacked into me. Oh We're able to get out to that zone then Kind of floating this thing on full lock this car once you get get it to where you need it to go Kind of just hang and it's definitely a very solid car. Probably shouldn't be right there, but We got enough gas to do one more run so Gotta get this entry down this this transition, you know the snappy transition of this car It's definitely something I gotta get used to and you know, that's why I love like I said I love doing these driver spotlights. So big. Thank you to jimmy hayley for giving me access to his s14 Allow me to rip it here in today's spotlight This gear let's try to get another better flick Oh Dr Dang who was started that earlier? Oh, I think we would have popped the tire If I were to start said a little earlier it probably would have worked out better, but unfortunately A little too much socks road Atlanta. Like I said, it's a very tough course I used to be good at this car this course in forza when I was You know trying to compete and esda and all that stuff, but here in a set out. This is a different roster It's not as easy as it was in other games. So Of course, you know cars that I'm not used to is another factor Do a lazy entry Little bit of a lazy entry but an entry nonetheless if we can get all the way up out to this outer zone It did kind of a Little last but then try to not Pull the e-brake coming into this transition High angle snap back and there's that high snap That gets me every time the vdc physics are very snappy and you know a lot of people Can handle them and I'm just not one of them right now I don't drive the vdc style cars enough, but I think I'm gonna start trying to broaden my horizons into More snappier transitioning cars You know in a more comp style. So we have one more run here and then we're gonna go to urwindale Where we always end this off All this car is no lift Oh, we're in the grass I mean We're going in the grass that was actually a very decent entry Surprisingly Car does have no lift shift it appears or I just broke the gearbox one of those two It appears it does have no lift Yeah, it's got no lift shift or a form of it So we can take this car to urwindale and see what we can do on the bank of urwindale So I'll catch you guys when we grow it up Once again, we are here at urwindale once again a big thank you to jamie hayley Like I said if I put your name, I do apologize But a big thank you to you for giving me access to this amazing s14 Definitely loves the styling of it with the cutout trunk. I see a radium fuel cell back there and it's definitely a clean car so urwindale We love it. We hate it always end it here because When you get the bank runs right, it's an amazing time So we'll see what we can do and hopefully we don't over snap on that inner Clip with the way this car transitions. I feel like this car's gonna be fifth gear all the way on the bank Man, yep quick snappy transition No handbrake Sausage it up to the wall a little bit of left foot brake there Oh, wow, okay Whoa, wall tap David. Oh Oh, if it wasn't for that wall tap that would have been great Man, that was almost that had the makings of a great run a quick snappy initiation into the bank Hard flick all power no handbrake no brake just snapped it and kind of went where needed to massage it up to the wall So it's if we can do that again All right, we try it one more time if we can do that exact same thing again a little bit lazier of an entry but Little mid to high bank massaging it up.  So this car is definitely a lot of fun and Super excited that I got a chance to drive this 14. We're gonna go one more full full on send lab With trying to do a hard flick entry In the 14 so make sure you guys follow me on all social media all of which found the description box below I appreciate you guys coming back. I hope you guys are excited for fd this weekend I know I am and my family is and we're all ready for it. So We've been doing more driver spotlights all week pro cars on pro tracks and of course Irwindale and you know, it's just leading up to the start of the fd season Try to know the ship Too much of a Send but we managed to somehow hold that Don't ask me how So I think that'll do it here for this episode here on a set of course up Once again, a big thank you to jimmy haley for access to his esda 14 as I wrecked it. Sorry, dude I do apologize for that. So as always, I think I should come back and watching. I'm evil rabbit. See you guys on the track


Bismillah ar-Rahman ar-Rahim. As-salamu alaikum my dear respected viewers and welcome to the Treaties of Rights series. One of the most well-known pieces of work known to the Muslim society by the fourth imam Imam Zain al-Abdin, peace and blessings be upon him, is the Treaties of Rights. Imam Zain al-Abdin's Treaties of Rights is the only work attributed to him other than supplications or relatively short sayings and letters. A glance at the Treaties of Rights will quickly show that the word rights might better have been translated as duties, obligations or responsibilities since the Treaties is not directly concerned with the rights of the individual but rather with the rights of others which the individual must observe. Islam views the individual in his total context which means that it considers first his relationship with God then his relationship with God's creatures. What is important for the individual and his relationship with God is that he attains to salvation and in other words that he follows God's guidance which is based upon mercy and directed towards his own best interest. In short Islam devalues the individual's perspective since human beings on their own can see no further than their immediate interests during life but this devaluation of individualism is not a devaluation of the individual on the contrary it raises him to the ultimate pinnacle of importance since everything is directed towards his happiness in the next world. Islam merely recognizes the ignorance of human beings and their inability to perceive their own ultimate good without divine guidance then it sets about to undermine and destroy individual ignorance a process which involves deflating the ego and eliminating all self-centered desires as a result the human self or soul the nefs has few rights but many duties and responsibilities or rather the soul has only one true right the right to salvation. The individual's right to salvation follows naturally upon God's right which is to be worshiped without any partner i.e. to hate the way to salvation is to obey God and hence it is the soul's right to be employed in obedience towards him but his very nature since his mercy precedes his wrath God displays compassion and guidance and through obedience the servant opens himself up to the full range of this compassion in other words partaking of God's mercy and compassion depends upon following his guidance and following his guidance means following the shariah as revealed through the holy Quran and the Sunnah. Hence the Imam speaks of being employed in obedience as the self's key right since only that can bring about its deliverance. The Imam peace and blessings be upon him starts by saying in the name of Allah the all merciful the all compassionate know God have mercy upon you that God has rights against you and that these encompass you in every movement through which you move every rest through which you rest every way station in which you reside every limb which you employ and every instrument which you put to work some of these rights are greater and some less here the Imam peace be upon him describes that everything surrounding us has a right towards us every move we take and every step we make forward will be accounted for everything that we use in this world has many rights towards us this means that we must use them and treat them in a correct manner now the magnitude of these rights varies some being higher up the scale and some being lower mom's in an abidin al sajad peace and blessings be upon him then proceeds to the right of Allah against us as humans regarding this mom sajad says the greatest of Allah's rights against you is that the right which he has made incumbent upon you for himself and which is the root of all the rights then those which he has made incumbent upon you and yourself from your crown to your foot in keeping with the diversity of your organs this part is quite magnificent and important because it is through knowing this right that we can continue and proceed to knowing the remainder of the rights the root of all rights is Allah's right it is mandatory of us to worship only Allah and no one else it is our duties as human beings to worship him and to do as he says in the holy Quran Allah's rights upon his creation are the rights that must be kept the most Allah is the sole creator and the sustainer of the universe he is the Almighty who created everything with absolute wisdom Allah is the one who initiated every being from nothing he is the one who protects humans and their mother's wombs as infants as children's and as adults he alone sustains all humans and provides them with food and every aspect of life in the holy Quran it says and Allah has brought you out from the wombs of your mothers while you know nothing and he gave you hearing sight and hearts that you might give thanks to Allah chapter 16 verse 78 Allah only wants mankind to worship him alone and ascribe no partners with him in worship and truly be his slaves he wants them to surrender to his will as they surrender to his control for the means of their lives it is only fair to worship only the the one who holds the existence of everything and everyone is in his hands one should thank Allah who alone provides for him by worshiping him alone Allah SWT has said in the holy Quran and whatever of blessings and good things you have it is from Allah then when harm touches you unto him you cry allow it for help holy Quran chapter 16 verse 53 let's go for a quick short break we'll be right back welcome back my dear viewers what Allah wants from us is to worship him with sincerity and to perform religious deeds five prayers a day brings forgiveness from him and purity in the heart Muslims must try to perform prayer in the best form so fear Allah as much as you are able chapter 64 verse 16 Allah SWT also wants his slaves to pay a small amount of their money to the poor the needy strangers who have no money the indebted and to others who are eligible to take the money from zakat zakat is so minimal that it does not harm the rich yet it provides tremendous benefits for the poor Allah also requires fasting in the lunar month of Ramadan in the holy Quran it says so whoever of you cites the crescents of the first night of the month of Ramadan he must fast on that month and whoever is ill or on a journey the same number of days he misses from other days chapter 2 verse 185 also the Hajj or the pilgrimage to Mecca once in a lifetime is mandatory upon all Muslims if they are able to do so in general we have the obligation to abide by all of Allah's orders and stay away from all he had made forbidden upon us above mentioned are the duties of Allah slaves towards him they are not difficult to perform the reward outweighs the requirements by far the reward is and whoever is removed away from the fire and admitted to paradise he indeed is successful the life of this world is only the enjoyment of deception chapter 3 verse 185 mom's the judge peace be upon him then proceeds to talk about the rights of oneself regarding this mom's in an abideen says he has given your tongue a right against you your hearing a right against you your sight a right against you your hand a right against you your leg a right against you your stomach a right against you and your private part a right against you these are the seven organs through which acts of or if I'll take place therefore we must respect the rights of our body parts that Allah has given us in order to honor ourselves we should seek God's help in doing so as Sheikh Tabarsi said the Arabic word nefs meaning self is used to mean the spirit or the soul as we can read in the following verse it is God that takes the souls of men at death and those that die not he takes during their sleep those on whom he has passed the decree of death he keeps back from returning to life but the rest he sends to their bodies for a term appointed verily in this are signs for those who reflect the holy Quran chapter 39 verse 42 another example where self is used to mean the soul is found in the following verse then guard yourselves against the day when one soul shall not avail another nor shall intercession be accepted for her nor shall compensation be taken from her nor shall anyone be helped from outside the holy Quran al-Baqarah chapter 2 verse 48 Sadr al-Mutaahleen Shirazi coded the Sheikh al-Rais Abu Ali Sina from Shafa there are three divisions for the self at first we have the plant self that is the first degree of perfection for an organic natural being having the ability to feed and grow the second division is the animal self that is the first perfection of an organic natural being which only has the ability to feel and move combined with will the third is the human self which is the perfection of an organic natural being with the ability to think understand and draw conclusions then the various properties and characteristics of these divisions are presented in the 22nd chapter of Risaleh Fusous al-Hakam Abu Nassal Farabi known as the second teacher said the following regarding the self indeed the perfection of the self is in the recognition of God's first right incumbent upon oneself this will result in a state of self-confidence Mr. Ilahi Gumshee made the following comments on this there are many aspects of the speaking self it is called the lascivious self because it is highly inclined to animal lustful desires as lust overtakes it the self considers obscene acts to be the beautiful ones thus it is called the adorning self also it uses trickery to do his animalistic acts and is deceitful it is called the deceitful self as it returns to his own nature and blames himself whenever he commits a wicked act it is called the reproachful self as whenever it is freed from his eagerness or for animalistic lustful desires it benefits from mental pleasures it is called the confident self whenever it fully submits to the will and pleasure of his true lover being God and destroys his own will and pleasure then it is called the pleased self for a confident self the only form of pleasure and perfection is derived from the recognition of Allah's first right that is to purify the soul from the filthiness of the body we shall discuss these aspects of the self as viewed in the Holy Quran with this we conclude and we hope to see you next time and for the next episode may Allah peace and the reappearance of our beloved Mahdi was salam Aleykum wa rahmatullahi wa barakatuh


I see it engaging more, thankfully, through the institutionalisation of the LPAA, the Lima Paris Action Agenda, what is currently becoming the Global Climate Action Agenda. It provides an interesting platform for the private sector to be mobilised. In the context, the private sector has already been mobilising. We've noticed, all of us, a very important change, a paradigm shift in how the private sector has been contributing to the concrete, tangible solution to the climate change challenges all over the world. The predictability is very important for the private sector. And in that context, first of all, we have the Paris Agreement. In the INDCs, we have about 100 and more than 160 INDCs that were submitted, representing 189 parties to the UNFCCC. And those INDCs provide a very interesting platform to provide predictability and reassure the sector that all kinds of national actors are coherent in the way they approach the issue. On top of that, if we are to use the Moroccan example, coherence in public policy is very key to enabling sustainable and substantive investment from the private sector. In particular, for example, in the case of Morocco in 2012, we reduced, we started phasing out fossil fuel subsidies because we want to be coherent with our effort to improve and enhance the capacities of our country in renewable energy. What I find very interesting and very creative about the Paris Agreement that provides us with a more global legal framework for climate change action is the bottom-up approach that relies strongly on the willingness of all the parties and the drive of all the parties to address the issue of climate change at a national level that makes sense to the means and makes sense to the priorities that they happen to have at the national level. So when I think of it from a legal perspective, I find that the main challenge that we have to think of is really the domestic level to provide more of a sense of ownership of all those different parties to the UNFCCC about the INDCs that they committed to. Because each INDC comes with legal implications as to how they should reframe their own landscape. There is the global landscape and solutions such as the one that is being driven by this very forum in terms of having a global framework for a more individualized action is also a very key component to that. My hopes are a bit more than hope, they're expectations. I think there's a very strong drive and urge to make sure that concrete resorts are reached in Morocco. And in that context, we have identified five areas where we feel that we can definitely reach some concrete outcomes. The first one would be the implementation of the Paris Agreement per se. There's a set of decisions that have to be taken for more than we have to make sure that the machine, all the gears are turning the way it is supposed to and well greased. And thankfully we still benefit from what we call the spirit of Paris, this constructive spirit that emerged among negotiators, ministers and truly all the citizens of the world to make the Paris Agreement a success that it is. Well, first of all I was, I mean I was about to say I was very impressed by the calibre of the presentation I've seen, but I was expecting them to be that good because I attended the event last year and it was just very very inspiring. When it comes to more concrete things that have been very interesting to see, gave me food for thought, has been really the realization that there is at the same time that we are trying to move past the economic value system to have metrics to drive investment, we are still aware that when it comes to trying to showcase and drive a paradigm shift in the investment behavior it is important to not lose sight of them and how we can really showcase that they can be concrete financial positive and competitive financial returns from investing in that field is in sustainable landscapes is something that I was happy to see in the morning and I want to keep on learning more today in the afternoon as well.