1. System Integration (Cont.) Week 7 – Lecture 2

2. Approaches • Information transfer • Interface • Database replication • Data federation • Business process integration

3. Interface approach • Fixed format – any minor changes requires changes to both systems • Comma separated – bit more flexible, but still changes are usually required at both ends • Operations have to manage the timing System 2 System 1 Interface files System 3

4. Database replication • Uses the DBMS facilities to replicate data as changes occur System 1 System 2

5. Two current methods • Proprietary hub & spoke based middleware • Mercator • MQSeries Integrator • Publish and Subscribe middleware and XML using a Message broker bus • Java Messaging Service (JMS) part of J2EE • MSMQ – from Microsoft • These approaches may well merge, but closer to the Publish & subscribe approach

6. Hub based Publish & Subscribe

7. Proprietary Hub based middleware • EAI originated in the MOM market • The connector is often provided by the application supplier but may have to be coded for legacy systems • The EAI provides • translation for data heterogeneity, • rules engine that can process or trigger an event • transport mechanism – usually IBM’s MQ Series, • and is usually asynchronous • transaction queue

8. EAI is fast developing • Richer application servers (hub) • Facilities for interface definition • Business rules for converting data • Fail over protection • Database access • Different transport models • Use of XML as a data definition standard • Closer to real time integration with publish and subscribe model

9. Document definition language • SGML developed by ISO prior to the Web, but is considered too complex for everyday use • HTML developed as a presentation language for the Web is a subset of SGML • XML has been developed by W3C to better describe the internal structure of a document. It is also a subset of SGML • Because it does “self describe” the content of a document it has become accepted as the standard for the definition of data being transferred between applications. • ANSI’s EDI was also considered too complex for general use

10. XML • Is not a single pre-defined language but a language for describing other customised languages • It allows the creation of DTDs (Document Type Descriptions) now replaced by Schemas • A DTD consists of a DOCTYPE and ELEMENT definitions • These allow a program to validate the syntax of a document

11. A simple XML example <product><model>P266 Laptop</model><dealer>Friendly Computer Shop</dealer><price>$1438</price></product>

12. XML • The data is all ANSII/Unicode text thus can be read by any machine • Parsers can be written in any language • Tags can be created for the definition, transmission, validation and interpretation of data • However XML by itself does not provide all of the elements needed

13. XML (continued) • XML documents can contain other documents, thus XML schemas are being defined to act as an envelope as part of a transport protocol. SOAP is an example. • W3C is also developing a XML schema. These will make it easier to define links between applications.

14. Specific uses of XML • Various industry groups are defining XML architectures for specific purposes: • OASIS Organisation for Advancement of Structured Information Standards • W3C – OASIS & W3C are cataloging XML specifications, and products http://www.w3.org/XML/ • RosettaNet is an industry consortium advocating open e-Business standards • There are Finance and other Industry specific XML transaction definitions • IBM have added XML support to MQ Series • Microsoft include XML and SOAP in their BizTalk

15. There is a down side • It is verbose • & thus costs bandwidth