Editing Enterprise application integration (section)

=== Patterns ===
This section describes common design patterns for implementing EAI, including integration, access and lifetime patterns.  These are abstract patterns and can be implemented in many different ways. There are many other patterns commonly used in the industry, ranging from high-level abstract design patterns to highly specific implementation patterns.<ref name="Enterprise Integration Patterns">{{cite web | url=http://www.enterpriseintegrationpatterns.com/patterns/messaging/ | title=Messaging Patterns Overview | publisher=Enterpriseintergationpatterns.com and Addison-Wesley | date=2015 | access-date=2016-05-19 |author1=Hohpe, Gregor |author2=Woolf, Bobby }}</ref>

==== Integration patterns ====
EAI systems implement two patterns:<ref>MSquare Systems (2014-05-21). "Types of EAI". Archived on 2014-05-21 at https://web.archive.org/web/20140521124430/http://www.msquaresystems.com/enterprise-application-2/eai. ''[[MSquare Systems]]'' Retrieved on 2014-05-28 from http://www.msquaresystems.com/enterprise-application-2/eai.</ref>

;[[Data mediation|Mediation]] (intra-communication):Here, the EAI system acts as the go-between or broker between multiple applications. Whenever an interesting event occurs in an application (for instance, new information is created or a new transaction completed) an integration module in the EAI system is notified. The module then propagates the changes to other relevant applications.
;[[Federation (information technology)|Federation]] (inter-communication):In this case, the EAI system acts as the overarching facade across multiple applications. All event calls from the 'outside world' to any of the applications are front-ended by the EAI system. The EAI system is configured to expose only the relevant information and interfaces of the underlying applications to the outside world, and performs all interactions with the underlying applications on behalf of the requester.

Both patterns are often used concurrently. The same EAI system could be keeping multiple applications in sync (mediation), while servicing requests from external users against these applications (federation).{{citation needed|date=February 2020}}

==== Access patterns ====
EAI supports both asynchronous (fire and forget) and synchronous access patterns, the former being typical in the mediation case and the latter in the federation case.{{Citation needed|reason=Reliable source needed for the whole section|date=May 2016}}

==== Lifetime patterns ====
An integration operation could be short-lived (e.g., keeping data in sync across two applications could be completed within a second) or long-lived (e.g., one of the steps could involve the EAI system interacting with a human [[work flow]] application for approval of a loan that takes hours or days to complete).{{Citation needed|reason=Reliable source needed for the whole section|date=May 2016}}