Replication Server distributes database operations from a primary database to destination Replication Servers as functions that consist of a name and a set of data parameters. The destination Replication Server then uses function strings to map functions to the commands recognized by the destination data server. These commands represent transaction-control directives (begin transaction or commit transaction) or data-manipulation instructions (insert, update, or delete). The function string serves as a template or meta-command that transforms a function to a data-server-specific command. The use of function strings makes it possible for a primary site to replicate data to multiple heterogeneous data servers. Function strings are categorized into function-string classes according to data server type.
For example, a primary Replication Server transmits the rs_insert function to a destination Replication Server, which uses the appropriate function string to translate the function into the insert command specific for the data server in use at that site, whether the database is Adaptive Server, DB2, or another database.
There are two types of functions:
System functions – represent data-server operations with function strings supplied by Replication Server or available when you install a new database to the replication system.
User-defined functions – allow you to customize Replication Server applications to distribute stored procedures.
See Chapter 2, “Customizing Database Operations” in the Replication Server Administration Guide Volume 2 for details.
