Migrating from WebSphere Application Server Community Edition to WebSphere Application Server

24 Migrating from WebSphere Application Server Community Edition to WebSphere Application Server

difficult to make generic, one-size-fits-all recommendation as to the

interoperability option to be used.

In some cases, a complete migration can take several months; in other cases,

parts of applications will never be migrated. There are also clients who decide to

perform all new development and deployment with IBM software, but keep their

existing applications intact. It is likely that these existing applications need to

communicate with the new ones, as in the case of a phased migration. This leads

us into the interoperability discussion.

3.2 Application servers interoperability

In recent years, the concept of universal interoperability became widely

accepted. It is called Enterprise Service Bus (ESB). IBM and many other vendors

see ESB as an architectural pattern that can be implemented in different ways

using different protocols and products.

In Table 3-1 on page 26, we have tried to summarize some of these

considerations as they apply to J2EE application servers. The following list

provides a description of each protocol that you can use to interoperate between

different application server instances as well as between different vendor

products:

 JMS over WebSphere MQ

WebSphere MQ provides JMS as one of its programming APIs. You can use

WebSphere MQ as a JMS provider from within any J2EE application server,

C, or COBOL, and it supports over 40 platforms. WebSphere MQ provides

great quality of service for its messages and is one of the fastest messaging

engines with 80% market share in the message-oriented middleware market.

Note that the performance of this protocol is heavily dependent on the quality

of services configured in the messaging engine. Because of the persistence

and assured delivery options, we did not give it the highest mark for

performance, because we compared it to low latency synchronous protocols

that do not have high quality of service. If you need very high performance

and do not require full crash recovery, you can configure non-durable

in-memory messaging and achieve very high performance levels comparable

to those of synchronous protocols. JMS over WebSphere MQ is a very

popular choice for interoperability between WebSphere and other application

servers.

 Simple Object Access Protocol

Simple Object Access Protocol is a popular Web services communication

protocol. most often used over HTTP, although it can also use JMS, SMTP or

other lower level protocols. Recent developments in Web services have