Using the DirectConnect interface

The DirectConnect interface uses SAP's Open Client CT-Library (CT-Lib) API to access a database through SAP middleware data access products such as the DirectConnect for OS/390 component of Mainframe Connect and Open ServerConnect.

Accessing Unicode data

PowerBuilder can connect, save, and retrieve data in both ANSI/DBCS and Unicode databases. When character data or command text is sent to the database, PowerBuilder sends a DBCS string if the UTF8 database parameter is set to 0 (the default). If UTF8 is set to 1, PowerBuilder sends a UTF-8 string.

The database server must have the UTF-8 character set installed. See the description of the UTF-8 database parameter in the section called “UTF8” in Connection Reference.

A Unicode database is a database whose character set is set to a Unicode format, such as UTF-8, UTF-16, UCS-2, or UCS-4. All data must be in Unicode format, and any data saved to the database must be converted to Unicode data implicitly or explicitly.

A database that uses ANSI (or DBCS) as its character set might use special datatypes to store Unicode data. Columns with these datatypes can store only Unicode data. Any data saved into such a column must be converted to Unicode explicitly. This conversion must be handled by the database server or client.

Connecting through the DirectConnect middleware product

SAP DirectConnect is a data access server that provides a standardized middleware interface between your applications and your enterprise data sources. Data access services to a particular database are defined in a DirectConnect server. Since a DirectConnect server can support multiple access services, you can access multiple databases through a single server.

When you use the DirectConnect interface to connect to a particular database, your connection is routed through the access service for that database. An access service consists of a named set of configuration properties and a specific access service library.

To access DB2 data on an IBM mainframe through a DirectConnect server, you can use the DirectConnect interface to connect through either a DirectConnect for MVS access service or a DirectConnect Transaction Router Service (TRS).

TRS provides fast access to a DB2/MVS database by using remote stored procedures. The DirectConnect interface supports both versions of the TRS library: TRSLU62 and TRSTCP.

The DirectConnect server operates in two modes: SQL transformation and passthrough. The DirectConnect interface for DB2/MVS uses passthrough mode, which allows your PowerBuilder application to have direct access to the capabilities of the DB2/MVS data source.

Connecting through the Open ServerConnect middleware product

SAP's Open ServerConnect supports mainframe applications that retrieve and update data stored on the mainframe that SAP client applications can execute. Client applications can connect directly to a DB2/MVS database through an Open ServerConnect application residing on the mainframe, eliminating the need for an intermediate gateway like DirectConnect. (This type of connection is also known as a gateway-less connection.) In addition, an Open ServerConnect application presents mainframe Remote Procedure Calls (RPCs) as database stored procedures to the client application.

To access DB2 data on an IBM mainframe through Open ServerConnect, you can use the DirectConnect interface to connect through Open ServerConnect for IMS and MVS.

Selecting the type of connection

To select how PowerBuilder accesses the database, use the Choose Gateway drop-down list on the Connection tab of the DirectConnect Database Profile Setup dialog box and select one of the following:

  • Access Service

  • Gatewayless

  • TRS

All the DBParm parameters defined for the DirectConnect interface are applicable to all three connections except the following:

  • HostReqOwner applies to Access Service and Gatewayless only

  • Request, ShowWarnings, and SystemOwner apply to Access Service only

  • UseProcSyntax applies to Gatewayless only

See Database Parameters in Connection Reference for the complete list of DBParm parameters applicable to the DirectConnect interface.