Axon postoffices

• How is this used in Axon?
• Example usage
• More detail
• Test documentation

A postoffice object looks after linkages. It can create and destroy them and keeps records of what ones currently exist. It hands out linkage objects that can be used as handles to later unlink (remove) the linkage.

THIS IS AN AXON INTERNAL! If you are writing components you do not need to understand this.

Developers wishing to understand how Axon is implemented should read on with interest!

po = postoffice()
c0 = component()
c1 = component()
c2 = component()
c3 = component()

link1 = po.link((c1,"outbox"), (c2,"inbox"))
link2 = po.link((c2,"inbox"), (c3,"inbox"), passthrough=1)
link3 = po.link((c0,"outbox"), (c1,"outbox"), passthrough=2)

po.unlink(thelinkage=link3)

po.unlink(thecomponent=c3)

po.unlinkAll()

Test documentation

Tests passed:

• All outboxes in a linkage chain sharing the same destination inbox will experience noSpaceInBox exceptions when and only when the destination inbox becomes full and any of them tries to send to it.
• Restrict the size of an inbox to 5 and you can send 5 messages to it without error.
• Send a 6th message to an inbox of size 5 and a noSpaceInBox exception will be thrown.
• Setting a size limit of None mean the inbox size is unrestricted.
• A size limited inbox that becomes the final destination in a linkage chain (because a link is broken) causes noSpaceInBox exceptions to be thrown as if it had always been the final destination.
• A size limited inbox that isn't the final destination in a linkage chain will not cause noSpaceInBox exceptions to be thrown.
• Setting a size limit then later changing it to None turns off inbox size restrictions.
• Collecting 3 items from a full inbox and you can put 3 more in before a noSpaceInBox exception is thrown.
• You can call mycomponent.inboxes[boxname].setSize(n) to set the box size.
• Simple outox to inbox link, followed by an inbox to inbox passthrough, created in the opposite order
• Outbox->Inbox->Inbox chain, then 2nd link (passthrough) is deleted
• Simple outbox to inbox link, preceeded earlier by an outbox to outbox passthough
• Simple outbox to inbox link
• Simple outox to inbox link, followed by an inbox to inbox passthrough
• Simple outbox to inbox link, preceeded later by an outbox to outbox passthough
• test_BoxAlreadyLinkedToDestinationException (__main__.postoffice_Test)
• postoffice can be instantiated with a debugger.
• postoffice can be instantiated with no arguments. Defaults to no debugger or registered linkages.
• __str__ - Checks the formatted string is of the correct format.
• test_componentlinksderegisters (__main__.postoffice_Test)
• test_linkderegisters (__main__.postoffice_Test)
• test_linkdisengages (__main__.postoffice_Test)
• test_linkdisengages_inboxinboxpassthrough (__main__.postoffice_Test)
• test_linkdisengages_outboxoutboxpassthrough (__main__.postoffice_Test)
• test_linkestablishes (__main__.postoffice_Test)
• test_linkestablishes_inboxinboxpassthrough (__main__.postoffice_Test)
• test_linkestablishes_outboxoutboxpassthrough (__main__.postoffice_Test)
• test_linkregistered (__main__.postoffice_Test)

Axon.Postoffice.postoffice