The document introduces the book Enterprise Integration Patterns by Gregor Hohpe and Bobby Woolf. It discusses how enterprise integration often involves messaging as an alternative to remote procedure invocation, file transfer, and shared databases. Messaging involves program-to-program communication through asynchronous messages sent over channels. Messaging systems support store and forward capabilities and can be language/platform independent. Reasons for using messaging include integration, asynchronous communication, disconnected operation, improved thread utilization, reliability, and throttling. Challenges include complex programming, sequence issues, performance, limited platform support, and vendor lock-in. An example order processing system is described using messaging between different systems. The book covers various messaging patterns.

1. Enterprise Integration Patterns Introduction to Gregor Hohpe and Bobby Woolf’s book. David Kemp, Jan 2006

2. Enterprise Integration Usually Involves Messaging

3. Alternatives to Messaging Remote Procedure Invocation File Transfer Shared Database

4. Messaging The book (and this talk) focuses on messaging. What is messaging? Program-to-program communication. Asynchronous. Information exchanged as messages on channels . Optional features: Reliable (durable) Transactional

5. Messaging Systems Support Store and Forward Language and/or platform independent. Computer 1 Sending application 1. Create 2. Send Receiving application 5. Process 4. Receive 3. Deliver Computer 2 Channel

6. Why use messaging Platform/Language integration Asynchronous communication Allow disconnected operation Improve thread utilization Reliability Throttling

7. Challenges Complex programming model Sequence issues Synchronous scenarios Performance Limited platform support Vendor lock-in

8. An Example: Widgets & Gadgets R’ Us Web Interface Call Centre Inbound Fax Outbound Email Billing/Accounting Shipping Widget Inventory Widget Catalog Gadget Inventory Gadget Catalog

9. Taking Orders Call Centre Inbound fax Web Interface Channel Adapter Channel Adapter Gateway Point to point channel New Order Message Point to point channel Point to point channel Publish-Subscribe Channel Message translator Message translator Message translator

10. Order Processing New Order Message Publish-Subscribe Channel Billing/ Accounting Inventory Point to point channel Aggregator Content- Based Router Invalid Order Publish-Subscribe Channel Billing/ Accounting Shipping

11. Messaging Patterns Messaging System Patterns Messaging Channel Patterns Message Construction Patterns Message Routing Patterns Message Transformation Patterns Messaging Endpoint Patterns System Management Patterns