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Paul's presentation at SOA Workshop,Colombo,Sri Lanka identifies how ESBs fit into a Service Oriented Architecture, discusses when to use an ESB and when not to, looks at ESB patterns and anti-patterns, covers some simple ESB approaches and investigates how ESBs can fit into EDA.

Published in: Technology, Business


  1. 1. Enterprise Service Bus (ESB) and SOA Paul Fremantle CTO and Co-Founder, WSO2 VP, Apache Synapse
  2. 2. SOA – Enterprise Expectations
  3. 3. Standards • A set of extensible and composable standards that work together • Providing a common, standard, interoperable base to implement SOA SOA & SOAP Core Axis: WS with Apache Axis2 3 © WSO2 Inc. 2006
  4. 4. A Sample SOAP Message <soap:Envelope xmlns:soap=" ope/"> <soap:Header/> <soap:Body> <getProductDetails xmlns=""> <productID>827635</productID> </getProductDetails> </soap:Body> </soap:Envelope> SOA & SOAP Core Axis: WS with Apache Axis2 4 © WSO2 Inc. 2006
  5. 5. Key SOA Standards Orchestration Business Process Execution Language (BPEL)‫‏‬ SECURE RELIABLE TRANSACTIONAL WS-Policy WS-Security WS-ReliableMessaging WS-AtomicTransaction Composable WS-MetadataExchange (encrypt, sign, auth)‫‏‬ (ExactlyOnce, (2 Phase Commit ~XA)‫‏‬ Quality WS-SecureConversation InOrder delivery, ~JMS)‫‏‬ of (~SSL)‫‏‬ WS-BusinessActivity WS-Trust (Long running loosely coupled)‫‏‬ Service XACML WS-Addressing Messaging WSDL SOAP Transport HTTP, TCP, SMTP, UDP Wire interaction Metadata The Web services platform forms a complete framework for open standards enterprise middleware SOA & SOAP Core Axis: WS with Apache Axis2 5 © WSO2 Inc. 2006
  6. 6. Other key approaches for SOA • JMS – MQSeries, Tibco, Sonic – ActiveMQ, AMQP, Apache QPid – Loosely coupled, asynchronous reliable message passing • REST – A style of using HTTP – Representational State Transfer – Most HTTP applications are NOT “RESTful” – Key characteristics of a RESTful app: • Use HTTP Verbs properly • Use mime-types properly • Use linking everywhere • Permanent URLs
  7. 7. Bus concept
  8. 8. Busbar
  9. 9. A common ESB definition “Any to any data connectivity and transformation (including Web Services) built on an advanced, proven, reliable middleware infrastructure”
  10. 10. ESB definition “Any to any data connectivity and transformation (including Web Services) built on an advanced, proven, reliable middleware infrastructure” which means • Our existing middleware re-branded as an SOA platform, with some new web services adapters at the edges
  11. 11. Jason Bloomberg, Zapthink “You're a software vendor with a product line chock full of proprietary, tightly-coupled integration middleware… Your software, however, does not lend itself to SOA best practices – loose coupling, composable Services, and flexibility in general are all capabilities that you failed to build into your software… What to do? The only option is to slap Web Services interfaces on your stuff, call it an Enterprise Service Bus (ESB), and sell it as SOA middleware. Hopefully your customers won't notice the old wine in new bottles. After all, that's what marketing is for!”
  12. 12. My definition of an ESB “What does it do?” not “How does it do it?” • Services are independent of the transport and protocol used to access them • Monitors and manages services with minimal intrusion • Transforms and mediates messages • Bridges between different message exchange patterns • Helps implement service governance • Provides a common backbone to the SOA
  13. 13. Do you need an ESB to do SOA?
  14. 14. Do you need an ESB to do SOA?
  15. 15. SOA can end up as spaghetti • Too many point-to-point links • Multiple protocols, different qualities of service • No clear picture of all available services
  16. 16. An ESB can simplify SOA deployment Virtualization Perf Mgmt •Load balance •Throttle Transport matching Access control Message transform Logging and auditability Integrated Registry/ Repository Web-based console
  17. 17. ESB Patterns and Anti-Patterns • How are ESBs used effectively • How are they abused – High-level patterns • How the ESB fits into an organization • How the ESB fits into an Enterprise Architecture – Low-level patterns • How the ESB fits into a specific message flow or business problem
  18. 18. The Concentrator Pattern Mashup/Web Application Dashboard Concentrator ESB Consistent access, security, logging, audit, monitoring But no transformation .NET CRM Apache C/C++ Data service service Axis2 service service service
  19. 19. The Federated ESB pattern Department ESB Enterprise ESB Routing, Audit Department ESB Department ESB
  20. 20. The mini-ESB pattern • Use a lightweight ESB • Co-locate on the same hardware/VM as the service • Transformation, polling, protocol translation, etc • Why? – In the control of the team who own the services – Keeps the SOA model (ownership) with a simple effective approach to exposing services • What about the embedded ESB model? – e.g. embed transformation and logging into your Service Hosting platform
  21. 21. Active vs Passive • The concentrator pattern is effectively passive – The ESB reacts to messages/requests from the front-end • Active ESBs: – Poll file systems/FTP/SFTP for updated work – Actively call remote services based on timers – Integrate passive services
  22. 22. Scenario – Financial Security blocking Existing System XML/JMS legacy flat file Existing System WSO2 ESB Split/Iterate DBLookup/Filter Transform to MQ Send WSO2 ESB Database Poll Record->XML XML->XML Send NEW YORK LONDON
  23. 23. Push-Me Pull-You
  24. 24. Push-me Pull-you
  25. 25. Anti-Patterns • Anti-Pattern #1 – Implement all your business logic in the ESB – Why not? • Mixing Infrastructure logic and Business Logic • Maintainability • Tooling and Skills • Anti-Pattern #2 – Apply waterfall and application deployment approaches to the ESB • Long project cycles • No iterative approach – Why not? • Lose all flexibility and agility • Once the ESB becomes a static, code-driven system then you would be better off updating your applications
  26. 26. Anti-Pattern #3 • “Big Brother” – The ESB is hosted, managed and controlled by a central IT team – Because of organizational issues using the ESB is complex: • e.g. – It takes months of meetings to get access – The Central IT team is trying to recoup the investment and internally charges $000/year to use the ESB – The central IT deployment model holds up users – Departments and divisions actually sneak behind the ESB • Set up peer-to-peer communications • Avoid the ESB at all costs
  27. 27. The biggest Anti-Pattern of all • Use an ESB because: – You heard it was a good idea – The salesman told you that you need one (over a nice dinner) – You need a new TLA on your resume/CV – Its an excuse to spend several months learning and going to conferences
  28. 28. ESB Market • Proprietary – IBM WebSphere – Oracle/BEA – Tibco • Open Source – Fuse/ServiceMix – MuleSource/Mule – WSO2 ESB/Synapse
  29. 29. Core model of the ESB • Two main approaches – “Proxy” approach • Messages come into a proxy – Proxy = { inSequence, targetEndpoint, outSequence, faultSequence} – Sequence = { ordered list of mediators } – Mediator = Unit of function – Rule/Policy based approach • All messages come to a central sequence – Sequence categorizes and routes requests based on the message • Known in Synapse as the “main” sequence
  30. 30. Sequence concept
  31. 31. Built-in Mediators – Drop (end) – Property – Sequence (call another – Header sequence) – Validate – Clone – DBReport – Callout (call a WS) – DBLookup – Filter (if-then-else) – Class mediator – Switch – Command Mediator – Iterate – Script – Aggregate – Spring – Send – Throttle – Router – Cache – Smooks (transform library) – XSLT – Rule (use a Rules engine) – XQuery – Entitlement (validate access against a XACML server)
  32. 32. Understanding performance • Performance of an ESB can be critical • Key Measurements are – Throughput (can the ESB cope with the required load) – Latency (does the ESB add unacceptable time) – Concurrency (does the ESB run out of threads) • Two key technologies – Streaming and Streaming XML • Ability to operate in constant memory and handle XML without building a full tree – Non-blocking IO • Ability to manage large numbers of connections with constant thread pool
  33. 33. Case Study • Mobile phone ringtone/media provider • Every request goes via the ESB – Performance and Streaming are critical – Streaming and non-blocking are key • Continuous Availability – Ability to upgrade the system live – Without losing transactions – Under load
  34. 34. Governance and ESBs • Governance is a key issue for SOA • Governance is fundamentally about ensuring standards around Enterprise IT – Policies – People – Processes • ESBs can be very important for this – Policy Enforcement Point – Monitoring Point – Central Access Point for enterprise services
  35. 35. Summary • We have – Identified how ESBs fit into a Service Oriented Architecture – Discussed when to use an ESB and when not to – Looked at ESB patterns and anti-patterns – Covered some simple ESB approaches – Investigated how ESBs can fit into EDA
  36. 36. Questions
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