*Problem :
*
WSO2 MB currently does not support JMS expiration. Previous attempts to
provide the feature have been rolled back due to;
1. time consuming searches within message store and
2. additional overhead at node queues when removing expired message
references.
A configurable solution with minimal overhead at above flows is needed. The
change is required for MB version 3.0.0.
Redmine link : https://redmine.wso2.com/issues/2769
*JMS Expiration :
*
This allows to specify when a message should be considered irrelevant
within a Broker. JMS 1.1 spec provides two parameters to enable expiration:
1) JMSTimestamp - the time a message is handed off for sending. (Java
Long Date format)
2) JMSExpiration [1]
<http://docs.oracle.com/javaee/1.3/jms/tutorial/1_3_1-fcs/doc/advanced.html#1024689>
- time to live for the message since JMSTimestamp ( in milliseconds)
Expiration of obsolete messages is crucial to resource-intensive consumers
as well as message brokers to reduce redundant data overheads.
*Product Background : *
With reference to [2]
<http://abeykoon.blogspot.com/2013/10/wso2-message-broker-internal.html>
and discussions with MB team, I have created a technical diagram [3]
<https://creately.com/diagram/hwaifq5p1/KtVPRsWWenfecedUoniZi3XUg%3D> to
understand the flow and architecture of WSO2 MB version 3.0.0. Please
mention if there are any corrections.
*Plan for Solution (As discussed with the MB team)*
*@ Server Initialization*
Add and use configuration property : "JMSExpirationCheckInterval"
(milliseconds)
Add new Cassandra Column Family (MessagesForExpiry queue) for storing
MessageIDs with expiration time appended to key - sorted by expiration time
*When Receiving a Message*
Check if message contains JMSExpiration header, and add to
MessagesForExpiry queue
*On a separate thread*
Run a worker at configured time interval ("JMSExpirationCheckInterval") to
1. Collect all records from "MessagesForExpiry" queue past the current
time-stamp
2. Delete each message from "MessagesForExpiry", Global Queue, and node
queues.(Modify existing "messagedelete" function)
-------------------------------------------------------------------------------------------------------------------------------------
Do let me know if this approach can be further improved or if i have missed
anything.
References:
[1] :
http://docs.oracle.com/javaee/1.3/jms/tutorial/1_3_1-fcs/doc/advanced.html#1024689
[2] : http://abeykoon.blogspot.com/2013/10/wso2-message-broker-internal.html
[3] : https://creately.com/diagram/hwaifq5p1/KtVPRsWWenfecedUoniZi3XUg%3D
[4] :
http://docs.oracle.com/javaee/1.3/jms/tutorial/1_3_1-fcs/doc/advanced.html#1023387
[5] : http://martinfowler.com/articles/lmax.html
Thanks and Cheers,
Hasitha Amal De Silva
Software Engineer
Mobile : 0718133463
WSO2 Inc.: http://wso2.com ( lean.enterprise.middleware. )
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