Terms and Concepts

Metadata

This is a generic term referring to a connector's data definition. The data definition includes the names of data elements, their data types, and implies the order of the elements. For example, Notes® uses Forms to describe both the names of data fields as well as the data type of each field. Sybase metadata describes a Table. See the Connector Properties appendix for information specific to each connector metadata.

Alternate Metadata

Available through some connectors, this is an alternate source for the data definition. For example, DB2® metadata is in the form of a 'table', while its alternate metadata form is a SQL view. See the Connector Properties appendix for information on whether a specific connector supports alternate metadata.

Result Set

The return from an information request through a connection produces a result set. Each connection can have a single active result set. The LCConnection methods Execute, Select, Call and Catalog each generate a result set, replacing any existing result set. The result set describes the collection of data or information from the connection, which matched the input criteria. It does not return the actual data until fetched. If desired, these methods will build a fieldlist representing the metadata as part of generating the result set.

When using other connection methods which read or write data of a result set, the implied order of the metadata may be suspended by using the connection's OrderByName property to indicate that, regardless of the order of the data elements within the metadata, match the names in the metadata to the names in the external system.

Writeback Result Set

A writeback result set is an optimized form of result set supported by some connectors. A writeback result set provides both sequential read and write operations on the data, and may be used for efficient Update and Remove operations by directly operating on the most recently fetched record in the result set, rather than having to locate the information in the external system a second time. Some connectors may implement locking in the external system for writeback result sets.

Token

A token is an integer used to identify a property of a connection. All connection properties have a token value. Common properties have predefined tokens represented by constants. Connection-specific properties do not have predefined tokens.

For a list of property tokens and names for each connection, see the appendix.

Connection properties may be accessed by token or by name. The token method may be used when testing if a property is supported. The name may be used when it is known that a given property exists.