Lecture 6 - Enterprise Application Integration (EAI) Flashcards
What are the two aspects of Enterprise Application Integration?
- Process Integration
2. Data integration
What is meant by interoperatbility?
The ability of two or more applications to pass data and services to each other.
Important impediment for developing cross enterprise applications.
Achieved by setting common protocols and standard processes
What are the 4 characteristics of Enterprise Application Integration?
- Focus: achieving intra-enterprise integration and driving operational efficiency.
- Provides infrastructure to reuse, rapidly connect, interface AND unify information between internal applications.
- Represents both products and processes of integration of applications with data files and databases
- Non-intrusive –> apps don’t change or the changes required are insignificant.
What two types of messaging exists between systems?
- Synchronous messaging
2. Asynchronous messaging
What is synchronous messaging?
When a message is transmitted between systems, the whole elaboration is stopped until a response is received.
-> Not per see bad or good, sometimes it is necessary in a process (Purchase order)
-> Leads to tight coupling of interfaces and applications
What is asynchronous messaging?
Response is not required for continuance of the activity/process. This means more/multiple messages can be send at the same time.
-> leads to loose coupling of interfaces and applications.
What is meant by loose coupling?
When an application does not need to know the intimate details of how to reach and interface with other applications. They can just send and receive messages - only concern per application is that it can send a message to the messaging system.
-> Means there is a messaging backbone (intermediate) between systems.
What is the messaging concept used for asynchronous messaging?
- The publish/subscribe Interaction Model.
- Applications communicate by exchanging messages, but senders do not specify the recipients - they just publish a topic of interest that is put on the message server within the message backbone
- Receivers have to subscribe with the middleware for topics of interest
- The middleware retrieves a list of subscribers and delivers the message.
What is MOM?
- > Message-Oriented Middleware
- The backbone infrastructure that is responsible for relaying data from one application to another by putting in a uniform message format.
- It includes a MOM message broker, dealing with the retrieval, storage and sending of the messages AND a function in the applications to publish and retrieve the messages.
Why is using a MOM compared to point to poin attractive?
- Allows for prioritization of requests
- It can balance the load on the server and on the applications
- It allows for synchronous and asynchronous messaging.
What are three typical EAI topologies?
- Point-to-point
- Publish/Subscribe
- Hub and Spoke
What is the Point-to-point topology?
Applications are linked through custom-build connectivity systems, through which data is interchanged directly between any two systems.
-> So each system is independently linked to each other.
What are the disadvantages of the point-to-point topology?
- It is not scalable (complexity increases)
- Hard to manage
- Inherently static and expensive
What is the Publish/Subscribe topology?
- All the systems are linked to a shared bus, the MOM.
- The publisher produces messages on a subject or topic, which are sent and stored in the MOM.
- Subscribers can subscribe on specific subjects or topics. The MOM then sends the relevant messages.
- Each system has an adapter that is connected to the MOM through which it sends or receives the messages
What is the multi-cast model in publish/subscribe topology?
A model used by modern publish/subscribe tools. It makes it possible that messages are published by being sent once and they are received simultaneously by all subscribers.
