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Conference bulova::decw_jan-89_to_nov-90

Title:	DECWINDOWS 26-JAN-89 to 29-NOV-90
Notice:	See 1639.0 for VMS V5.3 kit; 2043.0 for 5.4 IFT kit
Moderator:	STAR::VATNE

Created:	Mon Oct 30 1989
Last Modified:	Mon Dec 31 1990
Last Successful Update:	Fri Jun 06 1997
Number of topics:	3726
Total number of notes:	19516

391.0. "Questions from an OEM" by CURIE::WORRALL (Joe Worrall - MR04 DTN: 297-3402) Mon Mar 13 1989 10:37

Could Someone answer a couple customer questions about DECwindows under VMS:

1.	Can a callback be interrupted by another callback?

2.	An OEM of ours would like to replace the DIGITAL login logo
	with their own - how can they do this? Can they get sources
	to our module which does this?


thanks

joe

T.R	Title	User	Personal Name	Date	Lines
391.1		SDSVAX::SWEENEY	Roads? Where we're going we don't need..roads	`Mon Mar 13 1989 17:40`	15
	This is very confusing. Wasn't this question (2) asked earlier in this conference or in the programming topics conference on SHPLOG::DECWINDOWS_PROGRAMMING? (1) Callbacks are not interrupts. This is a fundamental concept. Callbacks are always from the same interrupt level as the main program. A callback is the exclusive thread of execution. The motivation for this is that in order to provide cross-operating-system implementations that developers could not use any techniques that were only found in VMS. AST's are only found in VMS. (2) Customization of the logo appears to be in the ULTRIX code that ships and is on a wish list for a future version of VMS.
391.2		CADSYS::YOST		`Tue Mar 14 1989 14:07`	11
	(2) confusing, I'll say. I remember a DECWindows quarterly approx. 2 years ago where the customize logo was stated as a requirement, not a wish item. Some of the audience remembered how badly third parties writing PRO applications wanted to customize the startup logo since POS V1.0. Oh well. Maybe you can write a new *login.exe or a specialized login.exe that occludes the Digital logo with your own? clay
391.3	Clarification?	AIRPRT::GRIER	mjg's holistic computing agency	`Sun Mar 19 1989 18:58`	17
	So the rule that people should assume is that only one callback is ever executing at a single given time? Even in a threaded environment? What about a case where in a callback, some "long" processing is to be done, and the client writer does some liberal checking/dispatching of the event queue during the processing? It WOULD be nice to see a complete statement about the intentions and realities of these points. Is any and all computation supposed to be done by means of a work procedure? Is a callback ever supposed to block execution of the entire process while waiting for something like I/O? These are some questions which keep getting addressed over and over from different angles each time, but never straight-on... -mjg