Browse Prior Art Database

Putting locked messages

IP.com Disclosure Number: IPCOM000032459D
Original Publication Date: 2004-Nov-05
Included in the Prior Art Database: 2004-Nov-05
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Abstract

Placing messages to a queue in a locked state may offer advantages in systems where multiple putters and getters compete for messages.

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Putting locked messages

Messaging systems typically work either in a push mode or a pull mode: push mode - the act of putting a message causes it to flow out to a destination pull mode - the message is put, and the act of requesting the message causes it to flow to its destination.

.

Start

put

                      get (pull) move (push)

  Some systems work in both modes (for example to increase performance). In mixed mode systems a putting process is more efficient if it knows that the message being put will not disappear. Typically an extra step is used to lock the message once it has been placed. There is a window between putting the message and locking it where another process might 'steal' it.

.

Available

End

Start

put

get (pull)

End

lock

unlock

  To overcome the above problem, the message is put so that is locked immediately. This removes the gap between put and lock and prevents another process stealing the message. If the putting process wishes to move the message it has exclusive use of it. If the putting process decides not to move the message it releases the lock on it, making it available to other (eg pull) processes.

The state model looks like this:

Available

Locked

move (push)

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.

Start

put

put locked

lock

unlock

Available

Locked

get (pull)

move (push)

End

Note that the message never becomes available.

  Additional advantage accrues from the fact that the putting unit-of-work (transaction) can be completed bef...