Integrating the ArsDigita Community System with Mainframe Data

part of the ArsDigita Community System by Philip Greenspun
At most large companies, the most useful information is held by transaction systems running on an IBM mainframe of some sort, e.g., an S/390. The ACS-backed Web service per se isn't as interesting to an end-user as the access to data or transaction opportunities. For example, consider What users value is the ability to find out the current location of their package, not interaction with other users or any pure Web service.

Approach 1: have AOLserver talk to the mainframe

AOLserver comes with drivers for a bunch of RDBMSes, including a driver for the Solid RDBMS, whose C library is basically the same as ODBC (and therefore libraries from companies like and (used to be InterSolv) will work). AOL publishes a document entitled "Developing Database Drivers for AOLserver" at

It takes a good C programmer only a few days to write a database driver for AOLserver and the result is typically 500-1000 lines of code. Remarkably, there is nothing in the AOLserver database pooling system that says the database has to be relational or interpret SQL. The database management system to which you're talking ought to return a cursor and then you page through row-by-row and/or just grab one row at a time. It ought to have some kind of ASCII query language. It ought to be running on the same machine as AOLserver or have some facility to be queried over TCP/IP.

Making AOLserver talk directly to an RDBMS or other DBMS on the mainframe works great if all you want to do is display pages of information from the mainframe or send user data back to the mainframe. However, if you want to combine queries or transactions with a local Oracle RDBMS and some kind of DBMS on the mainframe, it might be better to take the next approach.

Approach 2: have Oracle talk to the mainframe

AOLserver knows how to talk to Oracle. Oracle knows how to talk to virtually any database management system in the world, via the Oracle Procedural Gateways (see If you need to query from your local Oracle and include or exclude rows depending on what's in the mainframe, an Oracle Procedural Gateway is a convenience. If you want to do an atomic transaction where you are guaranteed that a local operation and a mainframe operation will either both commit or both rollback, the Procedural Gateway is essential.
Note: AOLserver is free and open-source. It runs on any computer with a C compiler. Oracle runs on most mainframes. So you could just move everything to the mainframe and serve all the Web pages from there. Not too many companies would choose to do this, however.