gah@arnor.uucp (11/29/90)
Two questions...
1) Is it possible to use X to read an X resource files without
being connected to a server? If it is possible, how would
I do it?? I am currently using r3 & Motif 1.0. If it makes
a difference, can r4 or r5 do such stuff .. but not r3??
2) If I open a display, then fork I presume both processes are
sharing a connection to the server. If one process only
wishes to read X resource files is there any problem with
not explicitly synchronizing the processes? Or does any
database operation require server contact?
thx, gargv@turnpike.Eng.Sun.COM (Dan Heller) (11/29/90)
In article <1990Nov28.191838.4990@arnor.uucp> gah@ibm.com (Gary Hoffman) writes: > 1) Is it possible to use X to read an X resource files without > being connected to a server? No. You must be connected to the server in order for the Xlib routines to access the database associated with it (you can have a resource file unique to every server). > 2) If I open a display, then fork I presume both processes are > sharing a connection to the server. Nope. Just the parent. The child's connection *must* be closed. You can reopen a -new- connection to the server and rebuild widgets or do whatever you want. I submitted a program called "vines" to comp.sources.x several months ago which demonstrates this. Basically, it just sits there and forks allowing each child to draw colored vines all over your screen. If you are using Motif to do things, your child process will have to build those widgets specific to that process. Thus, it is best to fork early in a program since forking causes the entire dataspece to be copied. Since running X programs can be large, your forked process should try to do whatever it can quickly and get out soon. > If one process only > wishes to read X resource files is there any problem with > not explicitly synchronizing the processes? Or does any > database operation require server contact? None of this will work. -- dan ---------------------------------------------------- O'Reilly && Associates argv@sun.com / argv@ora.com Opinions expressed reflect those of the author only.
mikel@teda.UUCP (Mikel Lechner) (11/30/90)
argv@turnpike.Eng.Sun.COM (Dan Heller) writes: >In article <1990Nov28.191838.4990@arnor.uucp> gah@ibm.com (Gary Hoffman) writes: >> 2) If I open a display, then fork I presume both processes are >> sharing a connection to the server. >Nope. Just the parent. The child's connection *must* be closed. >You can reopen a -new- connection to the server and rebuild widgets >or do whatever you want. Actually the child process could keep the connection, but in this case the parent should close it's connection and obtain a new connection to the X server. Both cannot use the same connection. Also, if the child keeps the connection it cannot "exec" a new program and keep the connection, since this would almost certainly confuse the client code in the new program. -- Mikel Lechner UUCP: teda!mikel Teradyne EDA, Inc. 5155 Old Ironsides Drive | If you explain so clearly that nobody Santa Clara, Ca 95054 | can misunderstand, somebody will.
mouse@LARRY.MCRCIM.MCGILL.EDU (12/03/90)
> 1) Is it possible to use X to read an X resource files without being > connected to a server? Yes, provided you really mean "file". > If it is possible, how would I do it?? The R4 way would be to use... To retrieve a database from disk, use XrmGetFileDatabase. XrmDatabase XrmGetFileDatabase(filename) char *filename; filename Specifies the resource database file name. I don't know whether R3 is capable of similar things, though I would assume it is. > 2) If I open a display, then fork I presume both processes are > sharing a connection to the server. (I assume you're using UNIX.) Yes. > If one process only wishes to read X resource files is there any > problem with not explicitly synchronizing the processes? Or does > any database operation require server contact? As you may have gathered from the above and from other postings, server access is not necessary for reading resource files. Leaving the connection open in both parent and child will not harm anything, *provided* that only one of the two processes ever tries to do anything with it after the fork. (Two processes both trying to use the same server connection will almost certainly get Xlib in a hopelessly confused state. You don't want to do it[%].) [%] Unless, of course, you're willing to take on the task of putting the necessary synchronization code into Xlib. This would be a major effort. Actually, you don't even want to XCloseDisplay() in the process that won't be using the connection; this could flush buffered data twice. Either ignore the X connection entirely or close its file descriptor without letting Xlib know: close(XConnectionNumber(dpy)). der Mouse old: mcgill-vision!mouse new: mouse@larry.mcrcim.mcgill.edu