OpenDoc

OpenDoc was a multi-platform software componentry framework standard for compound documents, inspired by the Xerox Star system and intended as an alternative to Microsoft's object linking and embedding (OLE).

Description

The basic idea of OpenDoc was to create small single-purpose reusable components responsible for a specific task, such as text editing, bitmap editing or browsing an FTP server. OpenDoc provided a framework in which these editors could run together, and provided a document format for storing the data being generated by each component. These documents could then be opened on other machines, where the OpenDoc frameworks would substitute suitable editors for each part, even if they were from different vendors.

In this way users could "build up" their documents from parts. Since there was no main application and the only visible interface was the document itself, the system was known as document centered. It was envisioned that OpenDoc would allow smaller 3rd party developers to re-enter the office software market, able to build one good editor instead of having to provide a complete suite.

OpenDoc was initially created by Apple Computer in 1992 after Microsoft approached Apple asking for input on a proposed OLE II project. Apple had been experimenting with software components internally for some time, based on the initial work done on its publish and subscribe linking model and the AppleScript scripting language, which in turn was based on the HyperCard programming environment. Apple reviewed the Microsoft prototype and document and returned a list of problems they saw with the design. Microsoft and Apple, who were highly competitive at the time, were unable to agree on common goals and did not work together.

At about the same time a group of 3rd party developers had met at WWDC '91 and tried to hammer out a standardized document format, based conceptually on the Amiga's IFF. Apple became interested in this work, and soon dedicated some engineers to the task of building, or at least documenting, such a system. Initial work was published on the WWDC CD's, as well as a number of follow-up versions on later developer CD's. A component document system would only work with a known document format that all the components could use, so it was only a matter of time before the standardized document format was pulled into the component software effort. From then it quickly changed from a simple format using tags to a very complex object oriented persistance layer.

Initially the effort was code named "Exemplar", then "Jedi" and "Amber" before being released under the name OpenDoc. The development team realized in mid-1992 that an industry coalition was needed to promote the system, and created the Component Integration Laboratories ("CI Labs") with IBM and WordPerfect. In 1996 the project was adopted by the Object Management Group.

Kurt Piersol from Apple Computer was the best known of the architects of OpenDoc, but Jed Harris (later president of CILabs) was just as critical to the early designs. Mark Ericson from WordPerfect provided the vision for a port to Windows that included seamless interoperability between OpenDoc and OLE.

OpenDoc was one of Apple's earliest experiments with open source development methods. Apple and its partners did not release the source code for wide reuse, but did make the complete source available to developers for feedback and for testing and debugging purposes.

Release

OpenDoc was initially released to run on Mac OS System 7.5 to provide a document-based, rather than application-based, computing experience. Documents were made of modular parts, which could contain different types of content, such as pictures, spreadsheet information, text or even Quicktime multimedia elements. Parts relied on specific part editors to allow the user to modify the content, or part viewers to display the content without allowing the user to edit the part.

OpenDoc's primary distinction from other compound document architectures lay in the depth of its support for dynamic media. OpenDoc containers could include embedded live content, and could perform arbitrary real-time composition of the content. The architecture used a design pattern which insulated container from embedded content using intermediate objects, greatly enhancing interoperability and simplifying testing of part handlers. Any part could serve as a container for any other part.

The WAV word processor was a semi-successful OpenDoc word processor; the Numbers & Charts package was a spreadsheet and 3D real-time charting solution from Adrenaline Software, the CyberDog web browser was created by Apple as an OpenDoc application; the Nisus Writer software by Nisus incorporated OpenDoc. RagTime, a completely integrated office package with spreadsheet, publishing and image editing was ported to OpenDoc shortly before OpenDoc was cancelled. Apple's 1996 release of ClarisWorks 5.0 (the predecessor of AppleWorks) featured support for OpenDoc components.

From IBM’s involvement in Taligent, there was an implementation of OpenDoc in OS/2 Warp 4. IBM also contributed a large amount of development to the underlying object technology, the Common Object Request Broker Architecture (CORBA).

OpenDoc had several hundred developers signed up, but the timing was poor. Apple was losing money, the Java programming language, JavaBeans and Web-based applications were all being hyped as the next new way of building applications. Before long, OpenDoc was scrapped, with Steve Jobs noting that they "put a bullet through [OpenDoc's] head", and the entire team was laid off in a big reduction in force in March 1997. Other sources say that Microsoft hired away the key developers and no one was left to continue development. [1] (http://www.swiss.ai.mit.edu/%7Ebob/clarisworks.php#oregon)

External links

• Apple's OpenDoc Documentation (http://developer.apple.com/documentation/macos8/Legacy/OpenDoc/opendoc.html)
• C2 about OpenDoc (http://c2.com/cgi/wiki?OpenDoc)
• ClarisWorks 5.0 with OpenDoc components (http://www.swiss.ai.mit.edu/%7Ebob/clarisworks.php#oregon)
• Overview of OpenDoc (http://www.sundialsystems.com/articles/opendoc.html)it:OpenDoc