DB2 Universal Database™ for i5/OS™ provides all the database management functions for i5/OS. Distributed relational database support on the system is an integral part of the operating system, just as is support for communications, work management, security functions and other functions.
The i5/OS operating system can be part of a distributed relational database network with other servers that support a Distributed Relational Database Architecture™ (DRDA®) implementation. The i5/OS operating system can be an application requester (AR) or an application server (AS) in either like or unlike environments. Distributed relational database implementation on the iSeries™ system supports remote unit of work (RUW) and distributed unit of work (DUW). RUW allows you to submit multiple requests to a single database within a single unit of work, and DUW allows requests to multiple databases to be included within a single unit of work.
For example, using DUW support you can decrement the inventory count of a part on one server and increment the inventory count of a part on another server within a unit of work, and then commit changes to these remote databases at the conclusion of a single unit of work using a two-phase commit process. DB2 Universal Database™ for iSeries does not support distributed requests, so you can only access one database with each SQL statement. The level of support provided in an application program depends on the level of support available on the application server (AS) and the order in which connections and updates are made. See Connect to a distributed relational database for more information.
In addition to DRDA access, application requester driver (ARD) programs can be used to access databases that do not support DRDA. Connections to relational databases accessed through ARD programs are treated like connections to unlike servers. Such connections can coexist with connections to DRDA application servers, connections to the local relational database, and connections which access other ARD programs.
On the iSeries server, the distribution functions of snapshots and replication are not automatically performed by the server. You can install and configure the DataPropagator™ for iSeries, V8.1 product on iSeries servers to perform these functions. Also, you can use these functions in user-written application programs. More information about how you can organize these functions in a distributed relational database is discussed in Data availability and protection for a distributed relational database.
On the iSeries server, the distributed request function is not directly supported. However, the DataJoiner® product can perform distributed queries, joining tables from a variety of data sources. DataJoiner works synergistically with DataGuide, a comprehensive information catalog in the IBM® Information Warehouse family of products. DataGuide provides a graphical user interface to complete information listings about a company's data resources.
The i5/OS licensed program includes runtime support for SQL. You do not need the DB2® UDB for iSeries Query Manager and SQL Development Kit licensed program installed on a DB2 UDB for iSeries application requester or application server to process distributed relational database requests or to create an SQL collection on an iSeries server. However, you do need the DB2 Universal Database for iSeries Query Manager and SQL Development Kit program to precompile programs with SQL statements, run Interactive SQL, or run DB2 Universal Database for iSeries Query Manager.
Communications support for the DRDA implementation on the iSeries is
provided under either TCP/IP or the IBM Systems Network Architecture (SNA) through
the Advanced Program-to-Program Communication (APPC) protocol, with or without Advanced
Peer-to-Peer Networking® (APPN).