Difference between SOA and ESB

Question

I am confused in these web service terminologies SOA, ESB.

Anybody please explain.

Answer 1

SOA is service oriented architecture. In SOA services are decoupled and can interact with each other irrespective of the service type. Meaning a particular service can be platform or protocol specific but SOA enables such services to interact and exchange data. This data is essentially exchanged via ESB (Enterprise service bus) which forms the backbone of any SOA architecture.

Let me go ahead and give specific example to help understand this better. One way ESB could be implemented us by using JMS servers and using XML/XSD as means of transferring data between various services. So various service will register or connect to these JMS servers and exchange data using XML format. Generally SOA suite comes bundles with so called adapters that help transforming messages to and from format understood by service and XML.

For example consider shares trading system. Messages from stock exchange come in FIX protocol. You may have build an application that expects JSON. To make these both systems work you will use SOA - FIX Adapter will convert FIX message to XML, then this xml will be transferred to JSON Adapter over ESB which will then convert to JSON as required by your system endpoint.

Finally hoping following picture makes it very clear.

Answer 2

SOA is an architectural approach where you expose and encapsulate 'services' in a coarse-grained manner. It does not prescribe any technical mechanism or implementation. SOA is more related to boundary / integration interaction between systems. So if system A exposes services using a SOA I can interact with those services from system B.

An ESB on the other hand is a technical implementation that aids in delivering a SOA.

Answer 3

SOA :- Basically In SOA, On one side we have the Producer/Provider and on the other side we have the Consumer, separated by a Bridge(which is network) where the two sides communicate. So focus is on how two parties interact(produce/consume) services

ESB:- ESB is architectural pattern which how multiple applications/components/system can communicate/interact with each other following SOA principles, though here there is no direct producer/consumer. HSo here we focus how multiple heterogeneous application going to interact with each other and achieve business objective.

Also,ESB gives API which can be used to develop services and makes services interact with each other reliably. Technically ESB is a messaging broker which does protocol conversion, message format transformation, routing, accept and deliver messages from various services and application which are linked to ESB.