Difference between revisions of "Mailbox"
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* [https://docs.vmssoftware.com/vsi-openvms-system-services-reference-manual-getutc-z OpenVMS System Services Reference Manual] | * [https://docs.vmssoftware.com/vsi-openvms-system-services-reference-manual-getutc-z OpenVMS System Services Reference Manual] | ||
* [https://docs.vmssoftware.com/vsi-openvms-io-user-s-reference-manual OpenVMS I/O User’s Reference Manual] | * [https://docs.vmssoftware.com/vsi-openvms-io-user-s-reference-manual OpenVMS I/O User’s Reference Manual] | ||
| − | * [http:// | + | * [http://h41379.www4.hpe.com/openvms/journal/v9/mailboxes.pdf OpenVMS Mailboxes: Concepts, Implementation, and Troubleshooting by Bruce Ellis for OpenVMS Technical Journal V9:] |
Latest revision as of 11:53, 13 February 2023
A mailbox is a pseudo device used for interprocess communication and synchronization. The device code for mailboxes is MBAn.
Mailbox characteristics
Mailboxes can store a certain amount of information to be shared between processes, signal to a process when there is information to be read by that process. There is also a queueing mechanism for when multiple messages are being written to a mailbox. Multiple channels can be assigned to a mailbox. Mailboxes can be permanent and temporary. Temporary mailboxes are deleted when all channels to the mailbox have been deassigned; permanent mailboxes must be explicitly deleted. Mailboxes can have many writers and many readers. Mailboxes have a "size" determined by the buffer quota.
Protection
Mailboxes have four kinds of access: read (R), write (W), logical I/O (L), and or physical I/O (P).
Privileges
- TMPMBX is required to create temporary mailboxes
- PRMMBX is required to create permanent mailboxes
- SYSNAM or GRPNAM are required to place the logical name for the mailbox in the appropriate table
