Chapter 5: Technical Summary of Middleware Textbook IT Architectures and Middleware, Second Edition Chris Britton and Peter Bye AIT 600 Jeff Schmitt October 13, 2008

Middleware Elements ● Communications link ● The Protocol ● Programmatic Interface ● Data Presentation – Common data format ● Server Control ● Naming and directory services ● Security ● Systems management

Vendor Architectures ● Vendor Platform Architecture ● Vendor-distributed Architecture ● Using Vendor Architectures ● Positioning ● Strawman for user target audience ● Marketing ● Implicit architectures

Middleware Interoperability

Summary ● Middleware products classified  Technology: Client/server, peer-to-peer, push  Integrity: message integrity (delivery guarantee), transaction integrity  Differences among products: Huge variety in API ● SOAP dictates basic message transfer facility  but allows enhancement by headers or protocol layered on top of SOAP  No standard API, and some API’s restrict the Web services functionality ● Vendor products  Moving from tightly coupled to loosely coupled middleware .NET (more PL) and J2EE (more platforms) are remarkably similar, same basic notions of tiering and just-in-time compilation

Summary ● Middleware interoperability  Possible and often important  Important technical issue is integrity, not to lose integrity when moving from one middleware technology to another  Message and transaction integrity can be implemented by two-phase commit transactions on the middleware hub  Applications can check on integrity, checking to see if last transaction was done, reversal transactions to undo previous work if needed