Special-Purpose Engines


Character Variable Padding (CVP) Engine

The character variable padding (CVP) engine expands character variable lengths, using a specified expansion amount, so that character data truncation does not occur when a file requires transcoding. Character data truncation can occur when the number of bytes for a character in one encoding is different from the number of bytes for the same character in another encoding, such as when a single byte character set (SBCS) is transcoded to a double byte character set (DBCS) or a multibyte character set (MBCS).

The CVP engine is a read-only engine for SAS data files only. You can request character variable expansion by either of the following methods :

  • You can explicitly specify the CVP engine, for example, with the LIBNAME statement, and using the default expansion of 1.5 times the variable lengths.

  • You can implicitly specify the CVP engine with the LIBNAME statement options CVPBYTES= or CVPMULTIPLIER=. The options specify the expansion amount. In addition, you can use the CVPENGINE= option to specify the primary engine to use for processing the SAS file; the default is the default Base SAS engine.

For more information about using the CVP engine to avoid character data truncation and for details on the CVP engine options on the LIBNAME statement, see SAS National Language Support (NLS): User's Guide .

SAS Metadata LIBNAME Engine

The metadata engine accesses metadata that is stored on the SAS Metadata Server within a specific SAS Metadata Repository. The metadata is information about the structure and content of data, and about the applications that process and manipulate that data. The metadata contains details such as the location of the data and the SAS engine that is used to process the data.

The metadata engine works in a similar way to other SAS engines. That is, you execute a LIBNAME statement in order to assign a libref and specify an engine. You then use that libref throughout the SAS session where a libref is valid. However, instead of the libref being associated with the physical location of a SAS data library, the metadata libref is associated with specific metadata objects that are stored in a specific repository on the metadata server. The metadata objects define the SAS engine and options that are necessary to process a SAS data library and its members .

When you execute the LIBNAME statement for the metadata engine, the metadata engine retrieves information about the target SAS data library from the metadata. The metadata engine uses this information in order to construct a LIBNAME statement for the underlying engine and assigns it with the appropriate options. Then, when the metadata engine needs to access your data, the metadata engine uses the underlying engine to process the data.

You invoke the metadata engine by explicitly specifying the engine name META, along with specific arguments and options for the metadata engine, for example, in the LIBNAME statement or in the New Library window.

For information about how to use the metadata engine, see SAS Metadata LIBNAME Engine: User's Guide .

SAS XML LIBNAME Engine

The SAS XML engine imports an XML document as one or more SAS data sets and exports a SAS data set as an XML document.

  • The engine imports (reads from an input file) an external XML document by translating the XML markup into SAS proprietary format.

  • The engine exports ( writes to an output file) an XML document from a SAS data set by translating SAS proprietary format to XML markup.

To use the XML engine, you must explicitly specify XML as the engine name, along with specific arguments and options, for example, in the LIBNAME statement or in the New Library window.

For information about how to use the XML engine, see SAS XML LIBNAME Engine User's Guide .




SAS 9.1.3 Language Reference. Concepts
SAS 9.1.3 Language Reference: Concepts, Third Edition, Volumes 1 and 2
ISBN: 1590478401
EAN: 2147483647
Year: 2004
Pages: 258

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