EaI is one of those newer terms used to describe a process we have always known as integration.
EaI uses modern programming techniques and protocols to achieve a consolidated system via tight coupling.
Typically operated at an application-level, it consists of integrating legacy applications and operational systems with modern ERP and CRM applications.
Entering the EaI picture is this year's hot integration solution, SOA. It brings a new approach to integration, providing application architecture in which all functions, or services, are loosely coupled using web-services' SOAP and XML. This architecture has evocable interfaces that are called to perform business processes. Each interaction is independent of each other and the infrastructure components that determine the communication system does not affect the interfaces. Because these interfaces are platform-independent, a client from any device using any operating system in any language can use the service. This means better integration capabilities between disparate systems and simpler maintenance of that integration.
Looking at traditional EaI and SOA, an organisation could then wonder which technology to use as their integration solution. SOA actually complements traditional EaI. End to end applications with an SOA vision and compliance is the ultimate solution. You can reduce the total cost of ownership by implementing solutions that are integrated with each other out of the box, such as an ERP, and use SOA to integrate to operational and legacy systems that do not form part of ERP.
When having to choose your integration solution, understand what the vendor has in its portfolio first. It must be made clear how end to end their applications can be. It is crucial to perform an in-depth analysis of each component that is expected to be used and rolled out in the future. Once this has satisfied the needs of the organisation, consider the integration and convergence technologies that may be employed. A solid vendor should give you a full choice of coupling including XML, WSDL, ODBC, ADO or COM.