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Classes and Interfaces for Streams

The classes and interfaces of streams are in the SABP_STREAMS_AND_LOCATORS package. Interfaces and classes that have been released for use are exposed in their package interface SABP_STREAMS_AND_LOCATORS. The following figure shows the hierarchy of the most important interfaces and classes for streams.

Mapping

Other versions: 7.31 | 7.40 | 7.54

Classes for Data Streams and Filter Streams

The classes for data streams and filter streams are the templates for data stream objects and filter stream objects.

The classes for the "data stream" stream kind start with "CL_ABAP_", followed by

  • an identification resource, for the resource, which is used as a data source or a data drain. At the moment, data streams are supported for the following resources:
    • LOBs in database tables; the associated resource ID is "DB".
  • an identification type for the stream type. Here the identifications "C" and "X" are possible for the binary streams and character streams.
  • an identification direction for the stream direction. Here the identifications "READER" and "WRITER" are possible for reader streams or writer streams.

    • The classes for the "filter stream" stream kind start with "CL_ABAP_FILTER_", followed by the identifications type and direction with the same meanings as for data stream classes. At present, no filter streams have been implemented.

    Interfaces and Superclasses

    All public methods of the data stream and filter stream classes are declared in interfaces which allow general access to the classes.

    • The IF_ABAP_direction interface enables general access to all reader and writer streams.
    • The IF_ABAP_type_direction interface enables a type-dependent access to reader and writer streams.
    • The IF_ABAP_resource_direction interface enables resource-dependent access to reader and writer streams.
    • The IF_ABAP_CLOSE_RESOURCE interface contains the CLOSE method, which is required by all stream kinds in order to close an open resource. This also applies for filter streams, since these are usually connected to data streams and the resource can then only be closed using the filter stream.

    Data stream classes inherit CL_ABAP_type_direction from abstract superclasses. In these, methods are implemented, which are dependent on stream type and stream direction but independent of the resource.

    Important Methods

    In the case of data streams, the following methods are implemented as kernel methods. This means that access to the data source or data drain is completed by the ABAP runtime environment.

    Methods for Reader Streams

    Methods from the IF_ABAP_READER interface:

    • DATA_AVAILABLE returns "X", if there is still data in the reader stream.
    • IS_X_READER returns "X", if it is a binary stream.
    • READ returns a string with a predefined number of bytes or characters from the reader stream.
    • SKIP skips a predefined number of bytes or characters from the reader stream.

    Methods for Writer Streams

    Methods from the IF_ABAP_WRITER interface:

    • WRITE writes the content of a specified string to a writer stream.

    Methods for Both Stream Kinds

    Methods from the IF_ABAP_CLOSE_RESOURCE interface:

    • CLOSE closes the stream.
    • IS_CLOSED returns "X" if the stream is closed.