Host Integration Solutions

For host-integration, there are multiple products available in the market, which are based on different integration pattern (screen-scrapping, proxy, peer-to-peer etc.) for application & data integration. Saying that, let’s review the types of products available in the market at present:

1. Upgrading CICS TS: In CICS Transaction Server 3.1 & 3.2, IBM has given facility to expose CICS transactions as web-service. However, I think some amount of configuration or coding may be required. I have not done a detail-study on this.
   
   
   1. Advantage: No additional tool is required and it is well supported by IBM.
   2. Disadvantage: The enterprise may have an older version of transaction servers. This approach would require upgrading all transaction servers to the latest version (which may be costly & time-taking exercise).

1. Upgrading CICS TS + SOLA: The research team of Meryll Lynch developed an add-on tool on top of CICS TS 3.1, which is now sold to SOA Software. This tool provides complements CICS TS 3.1, and provides support to other standards of WS-* standards. Also, it reduces the development and deployment cycle. In production, this tool is installed on Mainframe with a small footprint.
   
   
   1. Links: http://www.soa.com/index.php/section/company_press_detail/soa_software_acquires_mainframe_web_services_product_from_merrill_lynch/
   2. Link-SOLA Overview: http://www.soa.com/index.php/section/sola/sola_mainframe_web_services/
   3. Advantage: Get all benefits of CICS TS 3.1 with additional facilities provided by the tool. Reduction in development & administration cycle may justify for SOLA tool.
   4. Disadvantage: If the enterprise has an older version of transaction, this approach would require upgrade of transaction server to version 3.1.

1. Using tools deployed on Mainframe: There are products like IBM's HATS, Ivory, HostBridge, which are installed on Mainframe and exposes the CICS transactions, 3270 programs, IMS transactions as web-services over http or MQ. This requires a small footprint on mainframe. No other tool is required.
   
   
   1. Links: http://www.hostbridge.com/
   2. Advantage: No change in existing code is required. All existing CICS transactions are exposed as web-service.
   3. Disadvantage: The product installed on Mainframe would consume additional Mainframe resources in terms of memory and CPU cycle. If current usage of mainframe resources is near its peak, additional budget would be required to upgrade the mainframe resources.

1. Using Middleware (adapters) like (DataDirect’s Shadow, LegaSuite, Microsoft's Host-Integration Server): There are few middleware products available, which sit between mainframe and the client application. It intercepts the SOAP requests, translates into COMMAREA message and invokes CICS transaction over TCP/IP or SNP.
   
   
   1. Link: DataDirect- http://www.datadirect.com/products/mainframe-integration/shadow-rte/index.ssp
   2. Link: LegaSuite- http://www.seagullsoftware.com/products/legasuite.html
   3. Link: Microsoft’s HIS- http://www.microsoft.com/hiserver/evaluation/overview/default.mspx
   4. Advantage: No change in existing application.
   5. Disadvantage: One more layer (middleware) is introduced in the system. This layer has its own landscape in terms of application and hardware.

Other than that, there are few other products available based on screen-scrapping or to provide access to data-sets/IMS/DB2 database on mainframe. These solutions are not complete solutions to access CICS & IMS transactions.

In my opinion, all the above options should be evaluated for the current and long-term vision. Evaluation would require participation from multiple vendors and creating a comparison-matrix. As of now, there is no clear-cut mandate on which one is the best product or the best integration pattern. The decision varies from one company to another company on the basis of requirements of volume, transaction etc. as well as the size of the company. A small size company may go for different solution/product than a huge enterprise depending upon various factors like budget, extend of reuse of mainframe resources, future landscape etc.