Legacy Data Server

The Legacy Data Server appears as a relational DBMS to the ViaSQL Access Server, and provides the SQL access to legacy data sources like VSAM, IMS, DL/I, sequential disk, and sequential tape. The result sets and datatypes that are returned to the ViaSQL Access Server are consistent with the result sets and datatypes of DB2 and SQL/DS.

In order to use SQL to access a non-relational data source, for example VSAM or IMS, the data must first be mapped into a relational format. The mapping is typically done by the database administrator, and must be done once for each file that is to be accessed. The mapping is performed using the Legacy Data Manager, a Windows-based, GUI application that uses your existing COBOL copybooks to perform the mapping automatically. The Legacy Data Manager stores the mapping information in a mainframe-resident catalog.

At runtime, when the Legacy Data Server receives an SQL request from the Access Server, it checks the user's privileges on the referenced data, performs SQL parsing and syntax checking, optimizes the query, manages the data access, and produces a relational result set that will ultimately be returned to the client or web application that issued the SQL statement.

The Legacy Data Server supports SELECT, INSERT, UPDATE, and DELETE statements. Supported query functions include multi-table joins, and heterogeneous joins between any combination of VSAM, IMS (or DL/I), and sequential files, plus search conditions, unions, and ordering of results. ODBC catalog stored procedure functions are also supported.

In order to optimize query performance, the Legacy Data Server will utilize existing VSAM primary, alternate, and user indexes as appropriate. All System 370/390 datatypes are supported, as are complex VSAM structures like multiple record types and repeating fields.

The Legacy Data Server resides in its own address space (static or dynamic) and communicates with the ViaSQL Access Server via Cross Memory Services ( the z/OS cross-partition communication mechanism), or XPCC (the VSE cross-partition communication mechanism).

View the system requirements.