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The Question is: Can I find somewhere more information (an example) on how to use the IPC communication mecanism created between a virtual display (SMG) and its subprocess? There's a little bit information in the SMG$CREATE_SUBPROCESS and SMG$EXECUTE_COMMAND, but it's not enough to figure out, how the mailboxing mecanism is implemented! Thank you The Answer is : The protocol involves issuing smg$execute_command calls to pass in the command to be executed, and having the AST routine that was specified by smg$create_subprocess triggered for the output. Issue the smg$create_subprocess call, then pass in commands via calls to smg$execute_command. Output and status returns via AST calls. The key flag when passing in image data -- rather than new commands -- is the SMG$M_DATA_FOLLOWS flag. There is a BASIC example of using the call included directly in the SMG manual, in the section describing the sys$create_subprocess call. Additional examples are likely available via DSN and/or via the customer support center.
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