Application Programming Interface. A set of functions that can be called from an application program to access features of another program.
The Assembly class is the primary building block of the “system of systems” aspect of OpenMDAO. Each assembly has one or more Drivers that control iteration of Components within the Assembly. An assembly is also a Component, so hierarchies of assemblies can be created.
Axial-Flow Turbine Off-Design. A a computer code used for preliminary studies of the gas turbine system.
Git term for an ordered series of revisions (see revision below) that describes the history of a set of files.
Computer-Aided Design. An automated system for the design, drafting, and display of graphically oriented information.
Computer-Aided Engineering. Using computers to design, analyze, and manufacture products and processes.
Computational Analysis Programming Interface. CAPRI is a CAD vendor-neutral programming interface that supports direct communication of geometry data between an application and a CAD system.
An object containing a collection of names and values of inputs and/or outputs that are associated with a given ‘run’ or iteration of a model.
An object that iteratively supplies Case objects. This iterator could be tied to a simple file, a database, or some object that generates Case objects dynamically.
Computational Fluid Dynamics. A branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows.
Collaborative Optimization (CO). See Collaborative Optimization (CO).)
A component that runs a separate executable program via a system call.
Git command that records a change. A change is committed to a developer’s local repository.
An object with input and output variables that performs some sort of calculation.
See Component above.
Stands for “CONstraint MINimization.” CONMIN is a gradient descent optimization algorithm developed by NASA. The simple tutorial contains information on using CONMIN for an both an unconstrained optimization and a constrained optimization.
An object containing variables and possibly other Containers. It’s used as a way to give structure to groups of input or output variables.
A Python module that measures code coverage during test execution.
A Python module that aims to simplify the creation of well behaved decorators for the average programmer. A decorator is well behaved if the wrapped function that it returns has the same doc string, argument list, and other attributes of the function being wrapped.
Dynamically Loadable Library
A string that describes a module, function, class, or method definition. The docstring is a special attribute of an object. Docstrings are used to document OpenMDAO code as well as many packages written Python.
Docutils is a modular system for processing documentation into useful formats, such as HTML, XML, and LaTeX. For input Docutils supports reStructuredText, an easy-to-read, what-you-see-is-what-you-get plain text markup syntax.
A Driver’s function is to iterate over a Workflow until some condition is met. The simplest Driver executes a Workflow only once. Other Drivers, such as Optimizers or Parameter Studies, would execute the Workflow a variable number of times based on their inputs.
A zip file with a specified internal directory structure that contains a Python package or module. It is similar to a jar file in java. For more information on eggs, see PythonEggs.
See egg above.
A variable type which supports a list of discrete allowed values. The list of allowed values can be of arbitrary length, and elements can be of any type.
Fortran to Python interface generator.
An object that knows how to create objects of specific types.
Multiple Factory derived objects can be registered with the FactoryManager to allow creation of objects in various ways, e.g., locally via import and remotely via an ObjServer.
Fake Finite Difference
The Fake Finite Difference (FFD) method was developed to efficiently calculate gradients for mixed models, that is, models that contain components that can provide derivatives and components that cannot. When a component has a set of specified derivatives, they are used to replace the component’s output with the first-order Taylor series expansion whenever the optimizer initiates a finite difference estimation of the gradient. This is called Fake Finite Difference.
Finite Element Method. A numerical technique for finding approximate solutions of partial differential equations (PDE) as well as of integral equations. A structural analysis method which discretizes a continuum model of a complex structure to a discrete model of a finite number of degrees of freedom.
A variable type which represents a floating point number. It also also allows for the specification of units and specification of upper and lower bounds.
Genetic algorithm
OpenMDAO genetic algorithm optimizer based on the Pyevolve genetic algorithm, which is a complete genetic algorithm framework written in Python. (PyEvolve was developed and is actively maintained by Christian S. Perone.)
An open source distributed version control system.
A web community where projects using the git version control system are located.
Graphical User Interface. A computer operating system that is based upon icons and visual relationships rather than text.
An interface to an object having physical dimensions and shape, with properties that can be queried.
Individual Design Feasible. (See Individual Design Feasible (IDF).)
A variable type which represents numbers having integer values.
Interprocess communication
iteration hierarchy
A tree structure of Drivers and Components all operating within the same Assembly. Components are leaf nodes, and the branches coming from each Driver node are determined by the contents of the Driver’s workflow.
iteration coordinates
A dotted string in the form <workflow execution count>-<component index in workflow> for each level in the iteration hierarchy.
A small but fast and easy-to-use stand-alone template engine written in pure Python.
Jinja2 is the new and improved version of Jinja with new features and a simpler and faster runtime.
JSON, short for JavaScript Object Notation, is a lightweight computer data interchange format. It is a text-based, human-readable format for representing simple data structures and associative arrays (called objects).
Local Area Network. An interconnection of computers that are in relatively close proximity to each other, such as within a building.
Multi-disciplinary Analysis & Optimization
Metadata is information about an informational resource, such as a document (e.g,, a webpage), image, dataset or other resource. It describes context, content, and structure of the resource and its management through time.
Method of Feasible Directions
A gradient descent optimization algorithm used in CONMIN.
A hierarchical structure with an Assembly at its root.
Multidisciplinary Design Feasible. (See Multidisciplinary Design Feasible (MDF).)
Multiple Inputs, Multiple Outputs
A Python package for creating and manipulating graphs and networks.
A Fortran subroutine for solving linear and nonlinear constrained or unconstrained function minimization problems.
A unittest extension offering automatic test suite discovery and easy test authoring.
NumPy is the fundamental package needed for scientific computing with Python. See
A process that allows remote connections to a Component or Container object. An ObjServer can represent an entire model if its top-level object is an Assembly, or it can represent a single object if its top-level object is some other type of Component.
A process that spawns a child process (ObjServer) encapsulating an instance of a particular Component or Container type.
Outer Mold Line
Open Source
The Open Source Initiative (OSI) is a non-profit corporation formed to educate the community about open source (OS), to advocate for the benefits of OS, and to build bridges among different constituencies in the open-source community. For more information, see Open Source Initiative.
Portable Batch System (PBS) is a queueing system. Jobs are submitted to the queue that reflects the resources needed, and a scheduler decides which ones to run when nodes become available. These decisions are made on the basis of length of run, how long a job has been waiting, and fair sharing of resources among different users.
Tools for using a Web Server Gateway Interface stack.
A tool to load, configure, and compose WSGI applications and servers.
A pluggable command-line frontend, including commands to setup package file layouts
Process id
Python Imaging Library
Installs Python packages. It is a replacement for easy_install and uses mostly the same techniques for finding packages, so packages that were made easy_installable should be pip-installable as well. Currently works with source distributions only.
An object that interacts with a host aplication to provide specific functionality without changing the host application.
See plugin
A free terminal emulator application that can act as a client for SSH, Telnet, rlogin, and raw TCP computing protocols.
A key generator. It generates pairs of public and private keys to be used with PuTTY, PSCP, Plink, and the PuTTy authentication agent, Pageant.
A complete Python genetic algorithm framework
Pygments is a syntax highlighting package written in Python.
A Web framework
A Python parsing module
A YAML parser and emitter for Python.
Git term for a store of revisions. See revision.
An object responsible for allocating CPU/disk resources for a particular host, cluster, load balancer, etc.
An object that manages a number of child objects that are responsible for allocating CPU and disk resources, either locally or for a particular cluster or a particular load balancer. The RAM can be queried to determine the current allocation of resources for the given system. This includes host and PID information for all Components.
An object containing information defining system attributes required to select a viable place to run a code.
A plain-text markup syntax and parser system used for in-line program documentation (such as Python docstrings), for quickly creating simple Web pages, and for standalone documents. The reStructuredText parser is a component of Docutils.
Git term for a snapshot of the state of files and directories, including their content. A revision also has some metadata associated with it, including who committed it, when it was committed, a commit message, and the parent revisions from which it was derived.
A Python module for roman numerals.
A Routing package for Python that matches URLs to dicts (dictionary network protocols) and vice versa.
A collection of Python modules that are useful for scientific computing.
Tools for downloading, building, installing, upgrading, and uninstalling Python packages.
Simple, fast, extensible JSON encoder/decoder for Python.
A Python documentation generator. It translates reStructuredText markup language into HTML. (See the Sphinx home page for more information.)
Database Abstraction Library
A placeholder for a plugin within a Component.
A list that holds only objects that provide a particular interface.
See Slot.
Simplified Wrapper and Interface Generator. A software development tool that connects programs written in C and C++ with a variety of high-level programming languages. Go to for more information.
A git nickname for a particular revision. A tag is typically used to mark a release of the software so you can easily refer to it later.
Tempita is a small templating language for text substitution.
A ticket is a file contained within an issue (or bug) tracking system that contains information about a request, often by an end user, to fix a bug or make some other change to a computer software package. A ticket has a unique reference number (ticket number) that allows the submitter, software developer, or other technical staff to quickly locate, add to, or communicate the status of the submitter’s issue or request. Once OpenMDAO’s bug-tracking tool is in place, all changes to the software will require a ticket, and the ticket number will identify the software branch where the change is being made.
An open source, web-based project management and bug-tracking tool. OpenMDAO uses Trac to track bugs, enhancements, and requirements and to host
A software package from Enthought, Inc. A trait is a type definition that can be used for normal Python object attributes, giving the attributes some additional characteristics. See
A tuple is an immutable list. It is defined in the same way as a list, except that the whole set of elements is enclosed in parentheses instead of square brackets. The elements of a tuple have a defined order, and tuples indices are zero-based, just like a list, so the first element of a non-empty tuple is always t[0]. Negative indices count from the end of the tuple. Slicing works too, but when you slice a tuple, you get a new tuple.
A package used by OpenMDAO that provides unit conversion capability for variables.
The base class used when creating a new Variable type.
A component’s inputs and outputs that are visible to other components in the framework. In general, a variable is a wrapper for data passed between framework components. It has a value, a default value, and may contain additional attributes like upper and lower bounds and units. Variables can also perform their own validation when being assigned to another variable.
Virtualenv is a tool used to create isolated Python environments. You can create a new Python environment to run OpenMDAO and install all package dependencies into the virtualenv without affecting your system’s site-packages or vice versa. If you need to upgrade a package to see how it affects your app, you can create a new virtualenv, install/copy your app into it, run your tests, and delete it when you are finished.
Vehicle Sketch Pad. VSP is a rapid geometry creation tool used to create a wide range of aerospace vehicles from a combination of predefined components. It provides highly interactive sketching of concepts with immediate visual feedback.
A Python package for Web error handling and exception catching.
A library of helper functions intended to make writing templates in Web applications easier. It’s the standard function library for Pylons and TurboGears 2. It also contains a large number of functions not specific to the Web, including text processing, number formatting, date calculations, container objects, etc.
WSGI request and response object
Helper to test WSGI applications. This wraps any WSGI application and makes it easy to send test requests to that application without starting up an HTTP server.
A Workflow controls the execution order of a group of Components. The default workflow class is Dataflow, which orders Components based on their input and output connections.
Web Server Gateway Interface. WSGI is a standard interface for Python Web applications to communicate with Web servers.
Zope is an open source application server for building content management systems, intranets, portals, and custom applications. Zope is written in Python, an object-oriented scripting language.
A package that provides an implementation of object interfaces for Python.
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