Scalable Persistent Message Brokering with WSO2 Message Broker
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The document discusses the architecture and functionalities of WSO2 Message Broker (MB) for scalable persistent message brokering, highlighting messaging systems like queues and publish/subscribe models. It emphasizes the use of Cassandra for scalability and reliability, detailing how distributed queues and publish/subscribe mechanisms operate with fault tolerance. Additionally, it outlines features, use cases, and future roadmap for WSO2 MB enhancements.
Scalable Persistent Message Brokering with WSO2 Message Broker
- 1. Scalable Persistent Message Brokering with WSO2 Message Broker Srinath Perera Senior Software Architect WSO2 Inc.
- 2. Outline • Understanding Messaging • Scalable Messaging • WSO2 MB Architecture • Distributed Pub/Sub architecture • Distributed Queues architecture • Usecases • Conclusion photo by John Trainoron Flickr http://www.flickr.com/photos/trainor/2902023575/, Licensed under CC
- 3. What is Messaging ? • We often program and design distributed systems with RPC style communication (E.g. Web Services, Thrift, REST) • RPC communication is • Request/Response (there is always a response) • Synchronous (client waits for response) • Non-persistent (message is lost if something failed) • But there are other 7 possibilities
- 4. Messaging Systems in Real World • Sensor networks • Monitoring/ Surveillance • Business Activity Monitoring • Job Scheduling Systems • Social Networks http://www.flickr.com/photos/imuttoo/4257813689/ by Ian Muttoo, http://www.flickr.com/photos/eastcapital/4554220770/, http://www.flickr.com/photos/patdavid/4619331472/ by Pat David copyright CC, http://www.fotopedia.com/items/flickr- 2548697541
- 5. Why Messaging? WSO2 Inc. 5
- 6. Messaging Systems • Message Broker(s) as the middlemen • There are two main models • Queues • Publish/Subscribe http://www.geograph.org.uk/photo/2639458 and http://www.geograph.org.uk/photo/1138150
- 7. Distributed Queues • A queue in the “Network” • API Operations • Put(M) – put a message • Get() – get a message (dqueue) • Subscribe() – send me a message when there is one • E.g. SQS (Amazon Queuing Service) • Use cases:- Job Queues, Store and process 7
- 8. Publish/ Subscribe • There is a topic space based on interest groups • Publishers send messages to brokers • Subscribers register their interest • Brokers matches events (messages) and deliver to all interested parties • Usecases: Surveillance, Monitoring WSO2 Inc. 8
- 9. Messaging APIs and Message Formats and Standards WSO2 Inc. 9
- 10. Scaling Message Brokers There are several dimensions of Scale Number of messages Number of Queues Size of messages Scaling Pub/Sub is relatively easy E.g. Narada Broker, Padres Scaling Distributed Queues is harder WSO2 Inc. 10
- 12. Scaling Distributed Queues (Contd.) Topology Pros Cons Supporting Systems Master Salve Support HA No Scalability Qpid, ActiveMQ, RabbitMQ Queue Distribution Scale to large number of Does not scale for large RabbitMQ Queues number of messages for a queue Cluster Connections Support HA Might not support in- HorentMQ order delivery Logic runs in the client side takes local decisions. Broker/Queue Networks Load balancing and Fair load balancing is ActiveMQ distribution hard WSO2 Inc. 12
- 13. MB2 Messaging Architecture WSO2 Inc. 13
- 14. WSO2 MB WSO2 Inc. 14
- 15. Cassandra and Zookeeper • Cassandra • NoSQL Highly scalable new data model (column family) • Highly scalable (multiple Nodes), available and no Single Point of Failure. • SQL like query language (from 0.8) and support search through secondary indexes (well no JOINs, Group By etc. ..). • Tunable consistency and replication • Very high write throughput and good read throughput. It is pretty fast. • Zookeeper • Scalable, fault tolerant distributed coordination framework
- 16. How Distributed Queues Works ?
- 17. How Distributed Queues Works (Contd..)
- 18. How Distributed Queues Works (Contd.) Users can publish to any node (to a topic) When published, the node writes the message to queue in Cassandra called “global queue” Each node have a queue in Cassandra called the node queue A worker running in a node reads message from global queue and writes messages to a node queue that has a subscription for that topic. A worker in each node reads messages from node queue and delivers to subscriber for that queue. Node deletes messages only when subscriber has acked the delivery
- 19. How Pub/Sub Works ?
- 20. How Pub/Sub Works (Contd.) ?
- 21. Fault Tolerance • We write the message to Cassandra once we receive the message • We always read, process and then only delete messages (e.g. at client delivery after receiving the Ack) • In case of a failure of nodes, then worse case there will be duplicates Copy right , http://www.fotopedia.com/items/flickr-6206406047:CC license
- 22. JMS support for MB2 Feature Yes Pub / Sub Yes Durable Subscriptions Yes Hierarchical Topics Yes Queues Yes Message Selectors No, planned for 3.0 Transactions No, planned for 3.0 WSO2 Inc. 22
- 23. How does MB2 Make a difference? • Scale up in all 3 dimensions • Create only one copy of message while delivery • High Availability and Fault Tolerance • Large message transfers in pub/sub (asynchronous style) • Let users choose between strict and best effort message delivery • Replication of stored messages http://www.flickr.com/photos/flickcoolpix/356684845 8/sizes/m/in/photostream/ in the storage
- 24. Usecase 1: Store and Process
- 25. Usecase 2: Message Bus
- 26. Future Work and Roadmap • WSO2 MB (2013 Q4) • Support for in-memory delivery through hazelcast (www.hazelcast.com) • AMQP 1.0 support • Transaction support • If you have thoughts, please chat with me or join us at [email protected] http://www.flickr.com/photos/24071429@N08/2 314391179/
- 27. Conclusion • Provides an alternative architecture for scalable message brokers using Cassandra and Zookeeper • It provides • A publish/subscribe model that does not need any coordination between broker nodes • A strict mode for distributed queues that provides in order delivery • A best-effort mode for distributed queue http://ambr0.deviantart.com/art/Looking-Back-Wolf- 310857819
- 28. Questions?