1 /* $XConsortium: README /main/2 1996/07/15 14:07:37 drk $ */
2 This is CoEd, a shared text editor. Building CoEd requires DevGuide,
3 C++, and ToolTalk (which is part of OpenWindows). CoEd is known to
4 build with DevGuide 3.0.1, C++ from SPARCompilers 2.0.1, and either
5 OpenWindows 3.1 or OpenWindows 3.2.
7 NOTE: The libgolit in DevGuide 3.0.1 was based on the OW3.0.1/3.1 OLIT
8 libraries, and has some incompatibilites with the OW3.2 OLIT
9 libraries. A CoEd built with with libgolit 3.0.1 and running under
10 OW3.2 will crash, e.g., if you press MENU or HELP over the OLIT
11 textedit widget embedded in CoEd. However, the basic features of
12 editing, selecting, copy/paste, drag-and-drop, and scrolling seem to
15 Run it with "CoEd <filename>". (Of course, the ToolTalk dbserver must
16 be installed on the machine that owns the file. See the ToolTalk
17 Setup And Administration Guide.)
19 Basically, it's an editor that uses ToolTalk so that multiple
20 instances of the editor can edit the same file at the same time,
21 and have all the changes keep in sync. It has some serious limitations:
23 - CoEd has no facility for saving the edited file to disk.
25 - All the CoEd's must come up before any typing occurs. We haven't
26 implemented the part of the protocol where newcomers can request
27 the current state of the file. CoEd's can quit at any time without
28 messing up the others. Here's a sketch for the rest of
29 the protocol, in case anyone is interested in completely implementing
30 the dOPT algorithm (cf. C.A. Ellis and S.J. Gibbs,
31 "Concurrency Control in Groupware Systems", Proc. 1989 ACM SIGMOD,
32 Int. Conf. on the Mgt. of Data).
35 * Notices every editor should register for
37 in CoEdTextVersion appliesTo,
42 * Text_File_Poll_Version()
43 * Used by the moderator to detect quiescence.
45 * Text_File_Reverted()
48 * Requests every editor should register to handle
49 * Text_File_New_Moderator()
50 * Sent by the Moderator when closing the file. Whoever
51 handles it must register for the Moderator requests and
52 act as the new Moderator.
53 * Point-to-point notices the Moderator should be ready for
54 * Text_File_Version_Vote(
55 in CoEdTextVersion myVersion )
56 * When a Text_File_Poll_Version notice is received,
57 this notice is sent directly to the party that called
59 * Requests the moderator should register to handle
61 out CoEdSiteIDList coEditors )
62 * Sent every time an editor opens a file. If the request
63 fails, then no one is editing the file and the requestor
64 should become the Moderator -- i.e., register to handle
65 this request. If the request succeeds, then issue a
66 Text_File_Poll_Version notice, and wait until each
67 coEditor responds with a Text_File_Version_Vote.
68 Then send a Text_File_Update_Me request to catch up on
70 * Text_File_Update_Me(
71 inout CoEdTextVersion version,
73 * Sent by new coEditors after they've received a
74 Text_File_Version_Vote from each coEditor they learned
75 about when they did their Text_File_Join. In the
76 request, <version> is the earliest version of the text
77 that would not leave the requestor with missing changes
78 from any of the coEditors. In the reply, <version> is
79 identical to or later than the requested version, and
80 corresponds to the <text> in the reply.