1. iSeries Interface Green screen Web browser Web service Transport 5250
WebFacing
Presentation and
navigation
Display file
Struts/JSF
Connectors
JDBC, MQ, etc.
Application logic
RPG or COBOL program
Session bean
There are 2 slides, firstly an iSeries version and secondly a Unix version.
The red arrows indicate the ‘legacy’ setup. In the iSeries environment I would count WebFacing as ‘legacy’.
The blue arrows indicate first steps towards a J2EE deployment using either Struts or Java ServerFaces. The need arises at this stage to decouple the 5250 interface from its accompanying back end logic, but this work should require no new skills. Navigation and presentation are taken over by Struts or JSF, interfacing with the back end logic via appropriate connector technology (JDBC+stored procedures, MQ, etc.). This is the point at which IDE (e.g. Eclipse) and Java skills start to be acquired. There is little requirement at this stage for detailed OO understanding, since the vast majority of the code is either generated automatically by the Java IDE or remains within the legacy code base (‘thin layer of Java, fat layer of RPG’).
The green arrows indicate J2EE Enterprise JavaBeans deployment. Here the logic has been migrated to session beans, and the data is held as entity beans, persistence involving storage within the existing relational database. At this stage there is a need for detailed OO understanding and extensive Java skills.
Physical or logical file
Entity bean
Interface to data store
Database
DB2/400

2. Unix Interface Web browser Client/server Web service Green screen
Transport
Telnet
Presentation
and navigation
Struts/JSF
Programs written in
COBOL, C, etc.
Connectors
JDBC,
MQ, etc.
Application
logic
Session bean
I have looked up Powerhouse & it appears to be able to generate 3 types of application: straight green screen, client/server and Web. Thus I have allowed for all of these in the diagram.
For clarity the diagram does not show the ‘fat client’ client/server model where the Unix box is used only as a database server and the database client API (or ODBC) runs on the client PC. I don’t think Powerhouse generates this sort of application anyway.
The red arrows indicate the ‘legacy’ setup.
The blue arrows indicate first steps towards a J2EE deployment using either Struts or Java ServerFaces. The need arises at this stage to decouple the 5250 interface from its accompanying back end logic, but this work should require no new skills. Navigation and presentation are taken over by Struts or JSF, interfacing with the back end logic via appropriate connector technology (JDBC+stored procedures, MQ, etc.). This is the point at which IDE (e.g. Eclipse) and Java skills start to be acquired. There is little requirement at this stage for detailed OO understanding, since the vast majority of the code is either generated automatically by the Java IDE or remains within the legacy code base.
The green arrows indicate J2EE Enterprise JavaBeans deployment. Here the logic has been migrated to session beans, and the data is held as entity beans, persistence involving storage within the existing relational database. At this stage there is a need for detailed OO understanding and extensive Java skills.
Database client APIs
Entity bean
Interface to data store
Database
Relational database (Oracle, DB2, etc.)