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- /* $XConsortium: README /main/2 1996/07/15 14:07:37 drk $ */
- This is CoEd, a shared text editor. Building CoEd requires DevGuide,
- C++, and ToolTalk (which is part of OpenWindows). CoEd is known to
- build with DevGuide 3.0.1, C++ from SPARCompilers 2.0.1, and either
- OpenWindows 3.1 or OpenWindows 3.2.
- NOTE: The libgolit in DevGuide 3.0.1 was based on the OW3.0.1/3.1 OLIT
- libraries, and has some incompatibilites with the OW3.2 OLIT
- libraries. A CoEd built with with libgolit 3.0.1 and running under
- OW3.2 will crash, e.g., if you press MENU or HELP over the OLIT
- textedit widget embedded in CoEd. However, the basic features of
- editing, selecting, copy/paste, drag-and-drop, and scrolling seem to
- work.
- Run it with "CoEd <filename>". (Of course, the ToolTalk dbserver must
- be installed on the machine that owns the file. See the ToolTalk
- Setup And Administration Guide.)
- Basically, it's an editor that uses ToolTalk so that multiple
- instances of the editor can edit the same file at the same time,
- and have all the changes keep in sync. It has some serious limitations:
- - CoEd has no facility for saving the edited file to disk.
- - All the CoEd's must come up before any typing occurs. We haven't
- implemented the part of the protocol where newcomers can request
- the current state of the file. CoEd's can quit at any time without
- messing up the others. Here's a sketch for the rest of
- the protocol, in case anyone is interested in completely implementing
- the dOPT algorithm (cf. C.A. Ellis and S.J. Gibbs,
- "Concurrency Control in Groupware Systems", Proc. 1989 ACM SIGMOD,
- Int. Conf. on the Mgt. of Data).
- * CoEd protocol
- * Notices every editor should register for
- * Text_File_Changed(
- in CoEdTextVersion appliesTo,
- in int changeNum,
- in int start,
- in int end,
- in string text )
- * Text_File_Poll_Version()
- * Used by the moderator to detect quiescence.
- * Text_File_Saved()
- * Text_File_Reverted()
- * Text_File_Renamed(
- in string newName )
- * Requests every editor should register to handle
- * Text_File_New_Moderator()
- * Sent by the Moderator when closing the file. Whoever
- handles it must register for the Moderator requests and
- act as the new Moderator.
- * Point-to-point notices the Moderator should be ready for
- * Text_File_Version_Vote(
- in CoEdTextVersion myVersion )
- * When a Text_File_Poll_Version notice is received,
- this notice is sent directly to the party that called
- for the version vote.
- * Requests the moderator should register to handle
- * Text_File_Join(
- out CoEdSiteIDList coEditors )
- * Sent every time an editor opens a file. If the request
- fails, then no one is editing the file and the requestor
- should become the Moderator -- i.e., register to handle
- this request. If the request succeeds, then issue a
- Text_File_Poll_Version notice, and wait until each
- coEditor responds with a Text_File_Version_Vote.
- Then send a Text_File_Update_Me request to catch up on
- what you've missed.
- * Text_File_Update_Me(
- inout CoEdTextVersion version,
- out string text )
- * Sent by new coEditors after they've received a
- Text_File_Version_Vote from each coEditor they learned
- about when they did their Text_File_Join. In the
- request, <version> is the earliest version of the text
- that would not leave the requestor with missing changes
- from any of the coEditors. In the reply, <version> is
- identical to or later than the requested version, and
- corresponds to the <text> in the reply.
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