SOAP vs REST web services

Comparing SOAP to REST for building web services is a bit like comparing apples with pears: SOAP is a protocol, REST is a pattern, and you could, if you felt so inclined, write RESTful services using SOAP.  However, when people ask this question, they usually mean: SOAP (as in WSDL, perhaps RPC style, WS-* standards), as opposed to REST (as in JSON/XML over HTTP)

Assuming you mean this, below are some pros and cons for each, but note this: REST is increasingly becoming the de-facto standard across the web, being used by the big public API providers in preference to SOAP. I reckon it's just a matter of time before this question will just go away.

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Extensible Web Service API

The only constant in life is change, and this is no different for Service-oriented Architecture (SOA). Services must be built with this in mind: that they will have to adapt to new or changing requirements. Extensibility is the ability for services to adapt whilst preserving existing consumer contracts.

We would expect the following types of changes to services to have no impact on other consumers:
- internal source code changes
- interface changes
- take on of new consumers
- environmental changes

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What is Service-Oriented Architecture - Canonical Data Model

You won't be doing Service-Oriented Architecture (SOA) for long before you encounter the concept of a Canonical Data Model (CDM). The idea is that you analyse your business processes, and derive a set of standard data types that you model using XML schema and use in your services - the Canonical Data Model. Perhaps you go one step further and bring in an industry model like IBM's IFW and use that as a starting point.

In the real world however, there is an estate of legacy systems that will tend to have a narrower view of data types than that proposed by the CDM. Some will only be interested in a particular aspect of the CDM types, some subset of the attributes, whereas others will have a different view completely. The issue is that there are different ways to model things.

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What is SOA - XML appliances

An XML appliance is a specialised piece of almost ESB-like hardware offering facilities like:

• Hardware encryption/decryption
• Digital signature creation/verification
• Fine grained Authentication, Authorization, and Auditing
• XML threat protection
• Dynamic routing
• Message filtering
• MIME, DIME, and MTOM attachment processing
• XML acceleration
• Web services management
• Service level monitoring
• EIS integration (Protocol conversion, MQ, JMS, Database, Webservices)
• WS-* support with registry/repository integration

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Migrating Weblogic to JBoss (2)

Hmmm, I may have spoken a tad early.

The XSLT scripts I found only translate the very basic deployment descriptor elements. The remaining elements are usually of the vendor-specific performance optimisation type which often don't have a 1-1 equivalent, if they have one at all.

The JBoss community forums are very quiet on these fronts. Perhaps there is a conspiracy to drive me to JBoss.com's migration programme...

Grumble.

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What is SOA - Service Characteristics - Abstract

Services must be abstract in the sense that they offer a functional interface that is not tied to any particular underlying implementation of that interface. In other words they should hide implementation details such as programming language, operating system platform, database structure, internal object model, etc. Abstraction supports other service characteristics such as reusability, extensibility and reduces coupling between producer and consumer.

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