System Integration (Cont.)

Week 7 – Lecture 2

Approaches

• Information transfer– Interface– Database replication– Data federation

• Business process integration

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 1

System 2

System 3

Interface files

Database replication

• Uses the DBMS facilities to replicate data as changes occur

System 1 System 2

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

Hub based

Publish & Subscribe

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

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

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

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

<product><model>P266 Laptop</model><dealer>Friendly Computer Shop</dealer><price>$1438</price></product>

A simple XML example

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

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.

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

There is a down side

• It is verbose

• & thus costs bandwidth