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SOA Pattern Event Driven Messaging

This document provides an overview of event-driven architecture and how it is supported by the WSO2 platform. It defines key concepts like events, publishers and subscribers, and how these interact in an event-driven system. It also describes how WSO2 products like the ESB, message broker, CEP and BAM can be used to implement event-driven patterns for messaging, complex event processing, and business activity monitoring. The document concludes with a demonstration of how to build an event-driven system on WSO2 to detect delayed flight events.

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SOA Pa1ern: Event-­‐Driven Dakshitha Ratnayake Last Updated: Jan. 2014 Messaging Chathura Kulasinghe
2 About the Presenter(s) ๏ Dakshitha Ratnayake ๏ Associate Technical Lead – Technical Sales ๏ Experience with Java/J2EE technologies in the fields of health-­‐ care informaOon systems and content management systems for telecommunicaOons providers prior to her employment at WSO2. ๏ Prior to joining the SoluOons Architecture team she worked with the WSO2 Developer Studio team. ๏ Chathura Kulasinghe ๏ SoluOons Engineer ๏ Experience with Java/J2EE, .net based enterprise (banking) applicaOons design and development prior to his employment at WSO2. ๏ UX design and iOS app development. ๏ He has also contributed to the developments of the WSO2 App Factory.
3 About WSO2 ๏ Global enterprise, founded in 2005 by acknowledged leaders in XML, web services technologies, standards and open source ๏ Provides only open source plaorm-­‐as-­‐a-­‐service for private, public and hybrid cloud deployments ๏ All WSO2 products are 100% open source and released under the Apache License Version 2.0. ๏ Is an AcOve Member of OASIS, Cloud Security Alliance, OSGi Alliance, AMQP Working Group, OpenID FoundaOon and W3C. ๏ Driven by InnovaOon ๏ Launched first open source API Management soluOon in 2012 ๏ Launched App Factory in 2Q 2013 ๏ Launched Enterprise Store and first open source Mobile soluOon in 4Q 2013
4 What WSO2 delivers
Overall PresentaOon Goals ๏ Understand Event-­‐Driven Architecture (EDA) and Messaging ๏ Understand the benefits of EDA and how it fits into SOA ๏ How CEP extends EDA ๏ Introduce how EDA and CEP concepts are supported through the WSO2 plaorm ๏ DemonstraOon of an event-­‐driven messaging scenario
What is an Event? 6 Image Source -­‐ h7p://www.flamemedia.com.vn/images/ slide/?cke?ng-­‐header.jpg
DefiniOon of an Event in Event Architecture ๏ A set of informaOon (properOes) about an object (or objects) at a given Ome ๏ Usually encapsulated as a message 7
Event CharacterisOcs ๏ Represents a change in state ๏ Self-­‐contained ๏ A pure and complete representaOon of a specific event ๏ No references to other data sources ๏ Reduces dependencies, loosens coupling ๏ Uniquely IdenOfiable ๏ Enables idempotent handling of events ๏ Allows correlaOon with related events ๏ Time relevant, not Ome sensiOve ๏ Sourced using messaging ๏ Observable ๏ Published events can be observed by mulOple subscribers ๏ Event stream processing 8
Event Driven Architecture (EDA) ๏ A method of building enterprise systems in which events flow between decoupled components and services ๏ A maintainable, sustainable, and extensible model for building complex, distributed applicaOons ๏ Well suited for asynchronous, unpredictable environments 9
Event Driven Architecture
Publish / Subscribe ๏ A distribuOon model for events ๏ Events are Oed to some logical model -­‐ “Event Streams” / “Topic” (the most used model) ๏ A Topic is a tree-­‐based model or namespace that makes it easy to organize Events 11
Event Producers and Consumers Event Producers/Generators/ Sources ๏ Publish messages represenOng an event ๏ Olen oblivious to the consequences of the generated event Event Consumers/Subscribers/ Sinks ๏ Subscribe to events by topic/type/ selector ๏ Handle events asynchronously ๏ No performance penalty for addiOonal consumers 12
Why is EDA a1racOve? ๏ Incredibly loosely coupled ๏ The sensor doesn’t need to be aware of the actuator ๏ The actuator doesn’t need to be aware of the sensor ๏ Events can be re-­‐distributed ๏ The topology can change ๏ New actuators or sensors can be added seamlessly ๏ Topic or Event Streams give the ability to self-­‐organize
Examples: Event Based Models ๏ Publisher updates Facebook status -­‐> Subscribers’ Facebook walls display Publisher’s status update ๏ Same goes with Twi1er, Instagram etc. ๏ Older models: nntp, irc, mailing lists
How is EDA different from SOA? Service Oriented Architecture ๏ ApplicaOons are composed at design-­‐Ome ๏ Linear flow between services ๏ Predictable behavior ๏ Request/Response is common, overused Event Driven Architecture ๏ ApplicaOons are composed at run-­‐ Ome ๏ Asynchronous components ๏ ReacOve behavior ๏ Natural fit for distributed systems 15 Another Architecture??!!? EDA Complements SOA!
SOA Pa1ern: Event-­‐Driven Messaging EDA Complements SOA! ๏ Problem: How can service consumers be automa?cally no?fied of run?me service events? ๏ SoluBon: The consumer establishes itself as a subscriber of the service. The service, in turn, automa?cally issues no?fica?ons of relevant events to this and any of its subscribers. ๏ ApplicaBon: A messaging framework is implemented capable of suppor?ng the publish-­‐and-­‐subscribe MEP and associated complex event processing and tracking. 16
Event Transports ๏ JMS ๏ WS-­‐EvenOng / SOAP ๏ Stomp/…/… ๏ AMQP ๏ XMPP ๏ MQTT 17
EDA with SOA Event Generator Event Generator Message Broker Event Consumer Event Consumer Event Consumer BAM Event Bus / Channel CEP
EDA + SOA with WSO2 Event Generator Event Generator Message Broker Event Consumer Event Consumer Event Consumer BAM Event Bus / Channel CEP
Event Bus / Channel ๏ Usually an Enterprise Service Bus ๏ Emi1ers and consumers connected through the bus ๏ Different interfaces / message formats ๏ GeneraOng events from the bus itself ๏ IntegraOng non-­‐event based systems ๏ WSO2 ESB ๏ WS-­‐Even?ng based interac?ons / integra?ons ๏ Transforming to and from WS-­‐Events and general triggers ๏ Reliable delivery with a JMS broker
Pub/Sub with WS-­‐EvenOng 21
Pub/Sub with JMS 22
Message Broker ๏ SupporOng different messaging pa1erns ๏ Queue based and pub/sub ๏ Reliable delivery of messages/events ๏ WSO2 Message Broker ๏ Support for JMS v1.0 and v1.1 API and Advanced Message Queuing Protocol, the only industry standard protocol for interoperable reliable messaging ๏ Interoperability with many languages / plaTorms via AMQP clients for Java, .Net, C, C++, PHP, Ruby and more ๏ Support for in memory message store to improve performance. ๏ Scalable, distributed message storage based on Cassandra ๏ Distributed queuing
Pub/Sub with WSO2 ESB and WSO2 MB 24
Event Processing ๏ Simple Event Processing ๏ AcOng on single events ๏ e.g. a <filter> in the ESB or Is this a gold or plaOnum customer? ๏ Event Stream Processing ๏ Looking across mulOple events ๏ Finding pa1erns – e.g. the CPU uOlizaOon has been more than 90% for the last 10 minutes ๏ Complex Event Processing ๏ Looking across mulOple event streams ๏ e.g There has been a significant increase in overall trading acOvity AND the average price of commodiOes has fallen 2% in the last 4 hours
Business AcOvity Monitoring ๏ Monitoring end-­‐to-­‐end business message flow ๏ IdenOfying/collecOng/tracing business transacOons ๏ WSO2 BAM ๏ Scalable analy?cs using Hadoop ๏ Scalable data storage model, Cassandra ๏ Flexible deployment model (external Hadoop cluster and external Cassandra ring) ๏ Intui?ve and powerful dashboards
WSO2 Business AcOvity Monitor
Complex Event Processing ๏ Reading mulOple conOnuous event streams real-­‐Ome ๏ IdenOfy different pa1erns from these events ๏ WSO2 CEP ๏ Extremely High Performant Processing Engine ๏ Processes more than 2.5M events/sec on single server commodity hardware. ๏ Powered by WSO2 Siddhi Query Language. ๏ Filter events by condi?ons. ๏ Join event streams and create new streams. ๏ Execute temporal queries using various windows. ๏ Detect and respond to various event pa7erns and sequences. ๏ Process historical data in RDBMS in real-­‐?me.
29 WSO2 Complex Event Processor
Demo Outline -­‐ Publisher-­‐Subscriber with WSO2 ESB -­‐ WSO2 ESB as the Event Publisher -­‐ Topic -­‐ Web service instances as the Subscribers -­‐ Complex Event Processing with WSO2 CEP -­‐ Delayed flights detecOon
WSO2 ESB as Event Publisher Client ApplicaOon WSO2 ESB topic Web Service 1 Web Service 2
WSO2 ESB as Event Publisher WSO2 ESB Topic Main Sequence Subscribers Subscriber 01 Subscriber 01 Event Mediator
Demo
Delayed Flight AlerBng System External Systems/Devices Flights informaOon system Processing WSO2 CEP events when a delayed flight is detected. Data Stream
JMS Consumer Demo Sample Setup Data Stream publisher Processing WSO2 CEP events when a delayed flight is detected. JMS Queue Data Stream
Complex Event Processing flightStatsStream Flight 01 -­‐ Delayed Flight 02 -­‐ On-­‐Ome Flight 03 -­‐ On-­‐Ome WSO2 CEP Detects one Delayed Flights delayedFlightStream Flight 01 (InformaOon) from flightStatsStream [status != 'On-­‐Time'] select flightName, flightId, flightType, arrivalTime, trackNo insert into delayedFlightStream
Demo
Summary 38 ๏ Event Driven Architecture is a good thing ๏ Adding Complex Event Processing can significantly add value ๏ WSO2 Supports Event Driven Architecture and Messaging through various products. i.e. ESB, Message Broker, Business AcOvity Monitor and Complex Event Processor
Resources ๏ h1p://rangasiriwardena.blogspot.com/2014/03/ pubsub-­‐with-­‐wso2-­‐mb-­‐and-­‐wso2-­‐esb-­‐using.html ๏ h1p://soapa1erns.org/design_pa1erns/ event_driven_messaging ๏ h1ps://docs.wso2.com/display/ESB481/Working+with +Topics+and+Events ๏ h1p://www.informit.com/arOcles/arOcle.aspx? p=1577450
40 Business Model
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