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author | rjohnson <rjohnson@noemail.net> | 1998-03-26 14:45:59 (GMT) |
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committer | rjohnson <rjohnson@noemail.net> | 1998-03-26 14:45:59 (GMT) |
commit | 26a76b6c669bbb7629454ffa56a7f3f501a86dae (patch) | |
tree | 6e8c9473978f6dab66c601e911721a7bd9d70b1b /mac/Background.doc | |
parent | f91eedbd6219cd3648cf1085083990df5c0e77dd (diff) | |
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Initial revision
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diff --git a/mac/Background.doc b/mac/Background.doc new file mode 100644 index 0000000..8c4409d --- /dev/null +++ b/mac/Background.doc @@ -0,0 +1,92 @@ +Notes about the Background Only application template +==================================================== + +SCCS: @(#) Background.doc 1.1 97/11/03 17:05:54 + +We have included sample code and project files for making a Background-Only + application (BOA) in Tcl. This could be used for server processes (like the +Tcl Web-Server). + +Files: +------ + +* BOA_TclShells.¼ - This is the project file. +* tclMacBOAAppInit.c - This is the AppInit file for the BOA App. +* tclMacBOAMain - This is a replacement for the Tcl_Main for BOA's. + +Caveat: +------- + +This is an unsupported addition to MacTcl. The main feature that will certainly +change is how we handle AppleEvents. Currently, all the AppleEvent handling is +done on the Tk side, which is not really right. Also, there is no way to +register your own AppleEvent handlers, which is obviously something that would be +useful in a BOA App. We will address these issues in Tcl8.1. If you need to +register your own AppleEvent Handlers in the meantime, be aware that your code +will probably break in Tcl8.1. + +I will also improve the basic code here based on feedback that I recieve. This +is to be considered a first cut only at writing a BOA in Tcl. + +Introduction: +------------- + +This project makes a double-clickable BOA application. It obviously needs +some Tcl code to get it started. It will look for this code first in a +'TEXT' resource in the application shell whose name is "bgScript.tcl". If +it does not find any such resource, it will look for a file called +bgScript.tcl in the application's folder. Otherwise it will quit with an +error. + +It creates three files in the application folder to store stdin, stdout & +stderr. They are imaginatively called temp.in, temp.out & temp.err. They +will be opened append, so you do not need to erase them after each use of +the BOA. + +The app does understand the "quit", and the "doScript" AppleEvents, so you can +kill it with the former, and instruct it with the latter. It also has an +aete, so you can target it with Apple's "Script Editor". + +For more information on Macintosh BOA's, see the Apple TechNote: 1070. + +Notifications: +-------------- + +BOA's are not supposed to have direct contact with the outside world. They +are, however, allowed to go through the Notification Manager to post +alerts. To this end, I have added a Tcl command called "bgnotify" to the +shell, that simply posts a notification through the notification manager. + +To use it, say: + +bgnotify "Hi, there little buddy" + +It will make the system beep, and pop up an annoying message box with the +text of the first argument to the command. While the message is up, Tcl +is yielding processor time, but not processing any events. + +Errors: +------- + +Usually a Tcl background application will have some startup code, opening +up a server socket, or whatever, and at the end of this, will use the +vwait command to kick off the event loop. If an error occurs in the +startup code, it will kill the application, and a notification of the error +will be posted through the Notification Manager. + +If an error occurs in the event handling code after the +vwait, the error message will be written to the file temp.err. However, +if you would like to have these errors post a notification as well, just +define a proc called bgerror that takes one argument, the error message, +and passes that off to "bgnotify", thusly: + +proc bgerror {mssg} { + bgnotify "A background error has occured\n $mssg" +} + +Support: +-------- + +If you have any questions, contact me at: + +jim.ingham@eng.sun.com |