In this blog you’ll get the basic idea of Integration and its evolution
The first question that should arise when you wanted to learn Integration is What’s Integration in first place and What exactly we do ?
The basic meaning of Integration is to establish communication between two different systems that wanted to interact with each other. If a “System A” wants to interact with “System B” what integration does is establish a communication by taking the message from “System A” and passing it to “System B” and then passing the reply from “System B” to “System A”. This is very simple scenario of Integration. There is a whole ltot Integration can do like Authentication, Authorization, Virtualization etc..
In the above scenario why can’t the “System A” and “System B” interact with each other directly? Can they interact directly without Integration layer? The answer is YES they can. To do so “System A” need to interpret message in a format that is understandable to “System B” and “System B” should reply with a message in a format that is understandable to “System A”. For this “System A” should have a adapter for “System B”( An adapter is a program that takes care of message conversion/transformation) and “System B” should have an adapter for “System A”. The same is shown in below image.
The adapters are required to setup the communication in the above scenario as “System A” and “System B” might have been implemented on different platforms. Communication with adaptors seems simple when there are only two systems trying to interact. Assume if we have two more systems in the interaction, then the number of adapters to install would increase and this would make the application/system heavy.
In the above scenario we have four systems that wants to interact. For “System A” to interact with other systems it should install one adaptor for every system that it wants to connect, making the systems heavy thereby risking the performace. And in near future if any of the system is replaced with another system, there will a huge changes within the adapters and connectivity. This problem can be resolved with implementation of Enterprise Application Integration(EAI) which is an Integration framework.
What is EAI : Enterprise Application Integration is a framework that makes use of software and computer systems to enable data integration across applications within a single organization, while also simplifying business processes among connected applications and data sources. EAI aims at integrating different enterprise applications. SOA is one of the implementation of EAI. The below image depicts the high level architecture of EAI.
What is SOA: Service Oriented Architecture is an approach to establish communication between different independent services available/discoverable to achieve a business functionality. The main aim of SOA is to implement “loose coupling” between the services so that services can interact with each other irrespective of the service type. In SOA architecture, everything is a service. IN SOA some one has a service which some one else wants to consume it. SOA defines a way to make software components reusable via service interfaces.
What is ESB: Enterprise Service Bus provides a messaging platform to facilitate SOA architecture. The core concept of the ESB architecture is that you integrate different applications by putting a communication bus between them and then enable each application to talk to the bus. This decouples systems from each other, allowing them to communicate without dependency on or knowledge of other systems on the bus.
Link1
EAI VS SOA VS ESB: Here are some of the links that might be helpful to map the exact differences between EAI VS SOA VS ESB.
Integration Consultant 