6.6.4. Last Value Queue Command-line Example

The included programs drain and spout can be used for sending and receiving messages for testing purposes. The source code for the two utilities is included in the Python and C++ client library packages. The Python version can be run uncompiled using a Python interpreter.

Run the following qpid-config command to create a Last Value Queue:

qpid-config add queue my-queue --argument qpid.last_value_queue_key=type

qpid-config add queue my-queue --argument qpid.last_value_queue_key=type

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The header key 'type' is used to match messages in the queue.

Now start one or more browsers using the drain command:

./drain -f -c 0 'my-queue; {mode: browse}'

./drain -f -c 0 'my-queue; {mode: browse}'

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These browsers will see all the messages as they arrive in the queue in real-time.

Now use spout to send messages to the queue, setting a header value for the key 'type':

./spout -P type=a my-queue a1 
./spout -P type=a my-queue a2 
./spout -P type=a my-queue a3 
./spout -P type=b my-queue b1 
./spout -P type=c my-queue c1 
./spout -P type=c my-queue c2 
./spout -P type=a my-queue a4

./spout -P type=a my-queue a1 
./spout -P type=a my-queue a2 
./spout -P type=a my-queue a3 
./spout -P type=b my-queue b1 
./spout -P type=c my-queue c1 
./spout -P type=c my-queue c2 
./spout -P type=a my-queue a4

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The browsers started before these messages were published will see all messages as they arrive.

Now start a new browser:

./drain -c 0 'my-queue; {mode: browse}'

./drain -c 0 'my-queue; {mode: browse}'

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This browser will see only the last messages for each of the unique 'type' values.

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6.6.4. Last Value Queue Command-line Example

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