Dynamic Screen Manager APIs

The Dynamic Screen Manager (DSM) APIs are a set of screen I/O interfaces that provide a dynamic way to create and manage screens for the Integrated Language Environment (ILE) high-level languages. Because the DSM interfaces are bindable, they are accessible to ILE programs only.

The DSM APIs provide an alternative to the existing way of defining screen appearance outside a program by coding in DDS or UIM, for example. Instead, programmers can use a series of calls to DSM within their programs to dynamically specify and control screen appearance for their applications. Unlike static definition methods, the DSM interfaces provide the flexibility needed for those applications requiring more dynamic screen control. The DSM support provided varies from low-level interfaces for direct screen manipulation to windowing support.

The DSM APIs fall into the following functional groups:

• Low-level services provide a direct interface to the 5250 data stream commands. These APIs are used to query and manipulate the state of the screen; to create, query, and manipulate input and command buffers used to interact with the screen; and to define fields and write data to the screen.

• Window services are used to create, delete, move, and resize windows, and to manage multiple windows during a session.

• Session services provide a general scrolling interface that can be used to create, query, and manipulate sessions, and to perform input and output operations to sessions.

Data Structures for DSM APIs

Data structures for use with ILE C, ILE COBOL, and ILE RPG/400 are available in the QSYSINC library in member QSNAPI for service program QSNAPI.

Omitting Parameters with Associated Lengths

To omit a parameter with an associated length parameter, that length parameter should be omitted or specified as 0. If the length parameter is specified with a value greater than 0, the parameter with which it is associated is required.

For example, to omit the user extension information on the low-level environment, specify either a NULL pointer by value, or 0 by reference for the length. The extension information structure is ignored. If the length is greater than 0, the extension information structure cannot be NULL. If it is, then a Required parameter omitted error is generated.