5.6.1 Highlights -
New integration technologies have enabled exposing legacy system functionality on a mainframe to be reusable as Web Services. Architects and developers can enjoy faster implementation and easier interoperability using Open Standards. This becomes attractive to many customers because Web Services can leverage on legacy systems without rewriting them. -
Existing mainframe integration design approaches include using CICS Transaction Gateway, CICS Web Support, Java technology (such as EJB Server for CICS), and SOAP proxy to enable legacy CICS applications as Web Services. A server-side SOAP component can be created to invoke the remote CICS transactions via any of these mainframe integration components . Different design approaches have certain architecture implications, and architects need to make conscious design decisions based on the cost-benefits. -
The alternative to wrapping legacy system functionality as Web Services is to migrate legacy code to Java and enable them as Web Services later. This is a more flexible strategy that brings long- term benefits. At present, architects and developers can transcode, re-compile, rehost, or refront legacy application code. Examples of success stories include the U.S. Air Force (using RescueWare) and Access International's Global Product Suite for Straight-through Processing (using BluePhoenix's AppBuilder). 5.6.2 Best Practices and Pitfalls -
Prerequisites of Enabling Web Services on Legacy Mainframe. Implementing Web Services on a legacy mainframe platform may require hardware and software upgrades on the legacy mainframe to z/OS, which may be extremely expensive. Architects and developers may wish to check out the prerequisites of each integration option to the hardware and software, as well as the architecture implications. -
Coarse-Grained Web Services. Do not create a Web Services call for each individual legacy system functionality. This is because there will be scalability and maintainability issues to support too many Web Services calls on the legacy mainframe systems. Architects and developers can also consider passing parameters to coarse-grained Web Services. -
Mainframe Interoperability When to Use. Architects and developers may not need to integrate with all legacy mainframe functionality. Some of the legacy functionality may be available via existing messaging. Some of them are dead codes and thus deserve re-engineering. Therefore, it will not be sensible to wrap them as Web Services. Architects and developers may wish to consider the cost-benefits of building Web Services, such as the costs associated with internal implementation, external consultancy, or mentoring service. -
Using Web Services Mentoring Service. Some case studies show that architects and developers can jumpstart a Web Services implementation if experienced Web Services consultants are brought in. Architects and developers may wish to consider piloting a Web Services architecture workshop to define a pilot scenario, develop a Proof of Concept, and pilot a small system. This will enable transfer of skills and lessons learned about implementation pitfalls. 5.6.3 References -
OS/390 or z/OS IBM Redbook. S/390 Partners in Development: Thinkpad Enabled for S/390 . http://publib-b.boulder.ibm.com/Redbooks.nsf/RedbookAbstracts/sg246507.html OpenJava on S/390 resources. http://www.s390java.com/ OS/390 resource portal. http://ronmas.virtualave.net/ S./390 Mainframe Emulation on Notebook - FLEX-ES. http://www.funsoft.com/index-technical.html -
Mainframe Integration Eugene Deborin, Anita Ekstedt, Jim Hollingsworth, Takeo Machida, Antonius Inggil Paripurnanto, and Norbert Verbestel. CICS Transaction Server for OS/390 Version 1 Release 3: Web Support and 3270 Bridge . San Jose: IBM Redbooks, November, 1999. http://www.redbooks.ibm.com/pubs/ pdfs /redbooks/sg245480.pdf Chris Smith. "CICS Transaction Server for VSE/ESA: CICS Web Support Technical Overview." London: IBM UK, July 2001. http://www-3.ibm.com/software/ts/cics/pdfs/cictsvse_cwsovw.pdf Sun Microsystems. Using Forte 4GL for OS/390: Release 3.5 of Forte 4GL . Palo Alto: Sun Microsystems, October 2000. http://docs.sun.com/db?p=/doc/806-6665-01 (under Sun ONE Integration Server EAI Edition). Phil Wakelin, Antonio C. Benedete, Jr., Phil Cartwright, John Holland, Jim Hollingsworth, Daniel McGinnes, Satish Tanna, and Bart Verboven. Revealed! Architecting Web Access to CICS . San Jose: IBM Redbooks, 2002. http://publib-b.boulder.ibm.com/Redbooks.nsf/RedbookAbstracts/sg245466.html Phil Wakelin, Martin Keen, Richard Johnson, and Daniel Cerecedo Diaz. Java Connectors for CICS: Featuring the J2EE Connector Architecture . San Jose: IBM Redbooks, March 2002. http://publib-b.boulder.ibm.com/Redbooks.nsf/RedbookAbstracts/sg246401.html -
Case Studies Tim Hilgenberg and John A. Hansen. " Building a Highly Robust, Secure Web Services Architecture to Process Four Million Transactions per Day " IBM developerWorks Live! 2002 conference. -
Mainframe Integration Vendors Blue Phoenix . http://www.bluephoenixsolutions.com/index.cfm Jacada. http://www.jacada.com LegacyJ. http://www.legacyj.com/ Sun Microsystems. http://www.sun.com A list of J2EE Connectors vendors. http://java.sun.com/j2ee/connector/industry.html -
Other Alur Deepak, John Crupi, and Dan Malks. Core J2EE Patterns . Prentice Hall, 2001.  |
