Enterprise Application Integration (EAI) - Guide to Cloud Computing for Business and Technology Managers - page 97

As EAI enables enterprise-wide integration of diverse applications across
various products and divisions, it provides the enterprise with a 360° view
of its customer relationships across multiple channels of interaction. Every
customer perceives the enterprise as a whole and also expects to be recog-
nized and valued by the enterprise as a whole; familiarity with customers'
earlier interactions and purchases helps frontline members of the enterprise
to create opportunities for selling other products or additional add-ons and
services to the earlier purchases.
One of the important objectives of application integration is to
achieve the integration between applications with as reduced a
level of coupling or interdependency as possible so that the
impact of changes in one application does not affect the other
application(s).
4.2.1 Basics of Integration
The basic concepts related with EAI are described here. A robust and flex-
ible EAI provides a combination of the methods of integration and modes
of communication that are embodied into the various models of integration
that are deployed within the EAI architecture as discussed next.
4.2.1.1 Methods of Integration
Methods of integration are the approaches used to guide a request from a
sender to a receiver. The two primary methods of integration are as follows:
a. Messaging—In this approach, the sender constructs a message
that contains information on the actions desired as well as the data
required to perform these actions—the message contains both the
control information and data. Messages provide a lot of flexibility
because the control information can be easily changed and extended;
they are independent of any of the applications. However, to func-
tion correctly, the integration messages must be predefined precisely
so that the messages can be coded and decoded in exactly the same
way by all senders and receivers.
b. Interface—In this approach, the sender communicates through an
interface, which defines explicitly the actions that can be invoked
by an application; the interface is self-describing in terms of the
actions that can be taken. Interfaces make the application look
like a procedure, or a method, or an object. Interfaces are diffi-
cult to change and extend; they are associated with a particular
application.