A free implementation of the openstep standard
GNUstep provides an Object-Oriented application development framework and toolset for use on a wide variety of computer platforms. GNUstep is based on the original OpenStep specification provided by NeXT, Inc. (now Apple).
GNUstep is written in Objective-C, an object-oriented superset of the C programming language, similar to SmallTalk. However there exist a number of brigdes and interfaces to develop GNUstep programs using other languages like JAVA or Ruby.
The GNUstep core system consists of the following parts, which are jointly refered to as gnustep-core :
A set of scripts and makefiles that heavily ease the creation and maintenance of software projects.
The FoundationKit libraries for non-GUI tools providing everything from string and array classes, filemanager classes to distributed objects.
The ApplicationKit containing widgets, workspace classes and means for applications to interact with the user. This is the frontend of GNUstep's GUI part.
This is the backend of GNUstep's GUI part which does the actual rendering and event handling. It acts as a layer between gnustep-gui and the operating/drawing system. Backends exist for X11 (one using cairo, one using libart, one using xlib drawing) and win32.
Apart from the above, there exist a number of addon libraries, like Renaissance which allows developers to specify an application's user interface in xml. For database access, there is GDL2 - the GNUstep Database Library. Please refer to the GNUstep website for more information.
GNUstep per default is self-contained. That means that all GNUstep applications, tools, libraries and add-ons are installed into the GNUstep directory hierarchy. However as of gnustep-make-2.0.0 it is also possible to install everything in compliance with other filesystem hierarchies. See the FilesystemLayouts directory in the source package of gnustep-make for more information.
There are four domains which are searched for files: the System domain, which should only contain the core system files, the Local domain which stores all that has later been installed on the system, the Network domain which should be used for importing data from a remote system, and the User domain which resides in the user's home directory (mostly ~/GNUstep).
A complete description of the default GNUstep layout can be found in the filesystem.pdf.
In the world of GNUstep the term tool refers to command line programs whereas applications are fully fledged GUI programs. Naturally, tools reside in the domains' Tools folder, applications can be found in the domains' Applications folder.
Applications are either launched using the openapp command or from the Workspace.
In GNUstep applications globally offer functionality to other applications through services. They can be reached through the Services menu entry in an application's main menu. Apart from services offered by applications, there may be programs whose sole purpose is the offering of services. They can be found in the domains' Libary/Services folders.
The make_services tool makes sure the services are known to other applications when a application is newly installed.
A bundle is a collection of resources making up a discrete package for use. There are currently three types of bundles: applications, frameworks and loadable bundles.
A loadable bundle is a kind of plug-in. There are two types of loadable bundles, namely plug-ins and palettes. The plug-in is noramlly refered to as a bundle, which can make it a bit confusing. A plug-in is a bundle that can be loaded by an application to provide additional functionality, while a palette is a plug-in for GORM, the interface builder. A palette is used to extend GORM with custom UI objects. Palettes have a .palette extension.
The central place of the user interface is the Workspace or Workspace Manager which acts as an interface between the user and parts of the system like files, processes, etc. The GWorkspace application provides this functionality in GNUstep. See the GWorkspace website for more details.
What would a development environment be without the applications to create applications? The applications provided by GNUstep for Rapid Application Development are:
GORM is the interface modeler. With GORM you can quickly create the graphical interface of your application.
Project Center is the program where you can develop your program. It offers you automatic generation of GNUmakefiles , project maintenance and of course a code editor.
Official GNUstep website
GNUstep Wiki (lots of useful information)
GNUstep Project Page
GNUstep Documentation Library
Collaboration World, the home of GNUmail
The home of GWorkspace, JIGS, Renaissance and programming tutorials.
Mailing lists and mailing list archives.
#GNUstep on FreeNode
You are invited to join the #GNUstep IRC channel on FreeNode (irc.freenode.net).
GNUstep was at first a collaboration of two projects that wanted to create a single GNUstep project that complied to the OpenStep specification provided by NeXT Computer, Inc. and SunSoft, Inc. Development of this joint effort started around 1993-1994. For a more detailed history description see the GNUstep Documentation Library referenced in the SEE ALSO section.
GNUstep is developed and maintained by a large number of people. Please see <http://www.gnustep.org/developers/whoiswho.html> for a list.