Ss Esb

ESBs and SOA Paul Fremantle [email_address] CTO and Co-Founder, WSO2 VP, Apache Synapse

Service Oriented Architecture SOA is the best practice for building distributed interconnected systems Using well-defined interactions between systems Moving from proprietary formats to open formats: XML, HTTP, SOAP Integration is dependent on external interfaces not on internal code

A common ESB definition “ Any to any data connectivity and transformation (including Web Services) built on an advanced, proven, reliable middleware infrastructure”

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

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!”

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

Loose Coupling Location and Access Scale up, failover, contingency Programming Language Work with available skills Integrate old and new Stack/Vendor No tie in to a particular proprietary solution Time Asynchronous interactions avoid gridlock

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

An ESB can simplify SOA deployment Integrated Registry/ Repository Virtualization Perf Mgmt Load balance Throttle Transport matching Access control Message transform Logging and auditability Web-based console

Pragmatic SOA scenarios SOA has been seeded “bottom-up” within a company, and now looking for a way to add order and consistency Looking to expose existing backend systems as services in a consistent way Need to provide scale-up and performance management for SOAP and HTTP systems including load-balancing and throttling Starting to expose services to partners and require a solution to managing access control, security keys and auditability Integrating Java and .NET systems with other stacks, need a simple independent way to manage WS-Security, Reliable Messaging

Apply those rules to an ESB Location and Access Must provide virtualization, multiple protocol support, transparency Programming Language Minimal tie to any one programming language Focus on dynamic languages and XML-centric approaches such as XPath, XQuery and XSLT Stack/Vendor Interoperability, works with clients and services from many systems No requirement to have a proprietary system everywhere Time Asynchronous, non-blocking, scalable

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

The Concentrator Pattern .NET service CRM service Apache Axis2 service C/C++ service Concentrator ESB Consistent access, security, logging, audit, monitoring But no transformation Data service Mashup/Web Application Dashboard

The Federated ESB pattern Enterprise ESB Routing, Audit Department ESB Department ESB Department ESB

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

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

Scenario – Financial Security blocking Database legacy flat file NEW YORK Existing System WSO2 ESB Poll Record->XML XML->XML Send LONDON WSO2 ESB Split/Iterate DBLookup/Filter Transform to MQ Send Existing System XML/JMS

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

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

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

ESB Market Proprietary IBM WebSphere Oracle/BEA Tibco Open Source Fuse/ServiceMix MuleSource/Mule WSO2 ESB/Synapse

What about JBI? JBI is the JCP/Sun sponsored standard for ESBs Allows a standard deployment and also standard adapters Can be seen as a follow-on to JCA JBI has had little market success Failed to bring true portability Based on a very code-centric deployment model inherited from J2EE JBI v2 was destined to fix those problems but has gone quiet Oracle/Sun acquisition has also thrown doubt on JBI

Openness Since the only standard for portability is flawed, I highly recommend: Using an Open Source ESB Avoid lock-in and proprietary approach Using open network protocols E.g. SOAP, HTTP, XMPP, AMQP Avoid lock-in to MQSeries or Tibco Use as many standards based approaches as possible XSLT, XQuery, E4X/JavaScript, SOAP Headers, WS-Security, WS-RM, etc

OSGi and ESBs OSGi is a pluggability and component model for Java Proven to be effective as the component approach for Eclipse Gaining strong traction with middleware vendors BEA/Oracle IBM SpringSource WSO2 Both ServiceMix and WSO2 ESB have strong OSGi basis ServiceMix Kernel WSO2 Carbon OSGi framework OSGi looks like a much stronger approach than JBI for plugging components into middleware runtimes

Understanding an ESB I’m an expert on the WSO2 ESB and Apache Synapse Both share the same core engine and model Scenario walkthrough Similar approaches will work with other Open Source ESBs

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

Built-in Mediators Drop (end) Sequence (call another sequence) Clone Callout (call a WS) Filter (if-then-else) Switch Iterate Aggregate Send Router Smooks (transform library) Rule (use a Rules engine) Entitlement (validate access against a XACML server) Property Header Validate DBReport DBLookup Class mediator Command Mediator Script Spring Throttle Cache XSLT XQuery

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

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

Event Driven Architecture Event Architecture takes the SOA one step further towards loose-coupling than the previous patterns: Its up to you to publish to the right place Its up to you to subscribe to the right events You own the wiring too Allows for situational integration In the previous patterns the wiring was encoded into the ESB

Eventing in Synapse Synapse Proxy Event Source Event Publisher Subs Mgr Subscriber Publisher Subscriber Subscriber subscribe Mediation Sequence

Event Driven Architecture with a Master Data Pattern

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

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

Resources Reclaiming the ESB http://wso2.org/library/2913 Open Source SOA (book) by Jeff Davis http://www.manning.com/davis/ http://en.wikipedia.org/wiki/Enterprise_service_bus Apache Synapse http://synapse.apache.org WSO2 ESB http://wso2.org/esb

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