Managing Information Access to an Enterprise Information System Using J2EE and Services Oriented Architecture

58 Managing Information Access to an EIS Using J2EE and Services Oriented Architecture

2.3 Key technologies

The architecture discussion up to now has focussed mainly on architectural

issues, patterns, components, services, and processes for creating an EIS

integration architecture.

Of course, any architecture that you create must have a detailed design and

must be implementable. Otherwise, what would be the purpose of creating an

architecture that cannot be implemented?

Some of the discussions in the architecture chapter have mentioned

technologies or specifications, most notably J2C and JMS. You would also have

noticed the architecture chapter suggesting a services-based style of

architecture, commonly referred to as SOA. Of course, SOA is not an

implementation architecture but rather a style of architecture.

You can assert that calling CICS / COBOL routines on your EIS from your

desktop C/C++ application is a services-based architecture. The fact that you

could have used proprietary technologies, such SNA / APPC, and your own

proprietary protocol does not suggest that you do not have a services-based

architecture. Your services (in this example scenario, your CICS / COBOL

routines) might not pass an interoperability test. However, that is another

discussion and technical challenge.

Our architecture discussion mentions a lot of catchy phrases used by software

architects like interoperability, components, loose coupling, adaptability, scalable

flexible on demand solutions, services, and so on. The following sections discuss

some of the key technologies that you can use to implement this architecture.

J2EE

Java 2 Platform, Enterprise Edition (J2EE) is a set of coordinated specifications

and practices that together enable the development, deployment, and

management of multi-tier, server-centric applications. J2EE builds on top of the

Java 2 Platform, Standard Edition (J2SE) platform with additional capabilities

that are necessary to provide a complete, stable, and secure environment for an

enterprise level application.

The J2EE platform provides a reusable component model, using a suite of

technologies, such as Enterprise JavaBeans, JavaServer Pages (JSP), Java

Servlets and so on, to allow application developers to build and deploy multi-tier

J2EE applications that are platform and vendor-independent. The J2EE platform

shares the "Write Once, Run Anywhere" approach of the Java platform and has

gained significant industry support.

Chapter 2. Architecture 59

More information of J2EE can be found at:

http://java.sun.com/j2ee/index.jsp

Web services

The W3C Web Services Architecture Working Group has provided the following

definition for Web services:

A Web service is a software application identified by a URI, whose interfaces

and bindings are capable of being defined, described, and discovered as

XML artifacts. A Web service supports direct interactions with other software

agents using XML-based messages exchanged via Internet-based protocols.

The primary technologies that make up Web services consist of:

򐂰 Extensible Markup Language (XML)

A specification developed by W3C that provides a generic language for

describing content in a structured way to facilitate data interchange between

computer applications.

򐂰 SOAP

A XML-based protocol that is used to facilitate exchange of information in a

decentralized, distributed environment. It is used in combination with a variety

of other standard Internet technologies such as SMTP, HTTP, and FTP.

򐂰 Web Service Description Language (WSDL)

A XML-based language that provides a standardized way of describing the

interface of a Web service.

򐂰 Universal Description, Discovery, and Integration (UDDI)

A worldwide registry of Web services to facilitate advertisement, discovery

and integration.

The following is a list of key characteristics of Web services:

򐂰 Web services are language independent and interoperable.

The core technologies of Web services, such as XML, SOAP, WSDL, and

UDDI , are built using open source projects, promoting vendor independence

and interoperability. In addition, the use of technologies allows the service

provider and service requester to communicate without knowing the platforms

and languages that the other is using. This language and platform

independence in turn facilitates interoperability.

򐂰 Web services are loosely coupled

Traditionally, application design depended on tight interconnections at both

ends. In Web services, a consumer of a Web service is not tied to the service

provider directly. Instead, the service provider can change its interface over