DB2 Middleware and Connectivity

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	DB2 Universal Database for OS/390 v7.1 Application Certification Guide By Susan Lawson
	Table of Contents
	Chapter 1.  Product Overview

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DB2 Middleware and Connectivity

DB2 is a very open database and provides a variety of options for connecting to DB2 and non-DB2 databases.

• DB2 Clients . Client code is required on workstations for remote users to access a DB2 database.

• DB2 Connect. This product provides support for applications executing on UNIX and Intel platforms to transparently access DB2 databases on the OS/400, VSE/VM, OS/390, and Linux on S/390 environments. Note that DB2 Connect is not required to access DB2 for any of the UNIX or Intel platforms.

• DB2 Net.Data. Provides the ability for a Web browser to access relational or nonrelational data. This middleware provides an easy way to embed database calls into a macrolanguage.

• DB2 DataJoiner. This product allows DB2 clients to access, join, and update tables from heterogeneous databases, such as Sybase, Informix, and Microsoft SQL Server.

• IBM Classic Connect. This product is a separately orderable component of DataJoiner that provides read-only access to nonrelational data stored in information management system (IMS) databases and virtual storage access method (VSAM) datasets on multiple virtual systems ( MVSs).

• DB2 Relational Connect. This product allows DB2 clients to access and join tables from DB2 and Oracle databases.

• WebSphere Application Server. This application server is shipped with DB2 Enterprise Edition and allows developers to use Java as a platform in a transaction processing environment.

DB2 Universal Database Clients

DB2 supports a variety of clients. These clients include

• Windows (2000, NT, 98, 95, and 3.x)

• OS/2

• AIX

• HP-UX

• SGI-IRIX

• Linux

• Solaris Operating Environment

• Web browsers

DB2 Connect

The DB2 Connect product allows clients to access data stored on data servers that implement the Distributed Relational Database Architecture (DRDA). The target database server for a DB2 Connect installation is known as a DRDA Application Server (see Figure 1-10).

Figure 1-10. DRDA application flow.

NOTE

The most commonly accessed DRDA application server is DB2 for OS/390 and z/OS.

DB2 Connect supports both the TCP/IP and APPC DRDA communication protocols. The protocol supported depends on the DRDA application server being connected to and the version of the host software being run. For instance, a DB2 Connect server acting as a DRDA Application Requester to a host DRDA Application Server can connect to DB2 for OS/390 at version 5.1 and higher. Any of the supported network protocols can be used for a DB2 client to establish a connection to the DB2 Connect Server. Some of the major capabilities provided by DB2 Connect include

• Support for open database connectivity (ODBC), object linking and embedding database (OLE DB), command-line interface (CLI), Java database connectivity (JDBC), and Structured Query Language for Java (SQLJ) applications.

• Distributed Join across all DB2 databases.

• Distributed Join with Oracle (via Relational Connect).

• Connection pooling.

• S/390 Sysplex Exploitation for failover and load balancing.

Some of the common uses of DB2 Connect are

• Web-enabling DB2 OS/390 by providing browsers direct access.

• Leveraging Microsoft applications written using ADO, ODBC, or OLE DB to transparently access DB2 on mainframe platforms.

• Offloading mainframe development cycles.

The database application must request the data from a DRDA Application Server through a DRDA Application Requester.

NOTE

The DB2 Connect product provides the DRDA Application Requestor functionality.

The DRDA Application Server accessed using DB2 Connect could be any DB2 server on OS/390, VM, VSE, or OS/400. If TCP/IP is the protocol of choice, then the following are prerequisites:

• DB2 for OS/390. Only version DB2 5.1 or higher supports TCP/IP in a DRDA environment.

• DB2 for OS/400. Only OS/400 version 4.3 or higher supports TCP/IP.

• DB2 Server for VSE/VM. Only version DB2 6.1 or higher for VM supports TCP/IP.

DB2 Connect is available as a server (Enterprise Edition) and as a single- user package (Personal Edition). The DB2 Connect Enterprise Edition product allows multiple clients to access host data. A DB2 Connect server routes the ability for multiple clients to access host data. A DB2 Connect server routs each database request from the DB2 clients to the appropriate DRDA Application Server. The remote client communicates with the DB2 Connect server using any of the supported communication protocols. DB2 Connect Personal Edition is available on Windows, OS/2, and Linux platforms. It provides access to the host database from the system where it is installed.

DB2 Net.Data

Net.Data provides high-performance Web applications with robust application development functions (see Figure 1-11). Net.Data exploits Web server interfaces (APIs), providing higher performance than common gateway interface (CGI) applications. Net.Data supports client-side processing as well as server-side processing with languages such as Java, REXX, Perl, and C++. Net.Data provides conditional logic, a rich macrolanguage, and support for Java, JavaScripts, and XML.

Figure 1-11. DB2 Net.Data.

In a Net.Data environment, users connected to the Internet or an intranet can access database applications. Users can either select automated queries or define new ones that retrieve specified information directly from a variety of data sources. The results are returned to the Web browser in HTML format. Net.Data not only allows access to DB2 data, but also offers native access to Oracle and Sybase, flat files, and other data sources that support ODBC.

DB2 DataJoiner

DB2 DataJoiner (see Figure 1-12) provides application access to both DB2 and multivendor relational databases such as Microsoft, Sybase, and Informix. It acts as middleware for access to heterogeneous data sources. With a single SQL statement, an application can transparently access, join, and update data located across multiple data sources. The access can be done without needing to know the location of the data or the specifics of the SQL dialects for the data source. DataJoiner can run on Windows NT, Windows 2000, AIX, Solaris, or HP-UX.

Figure 1-12. DB2 DataJoiner.

DB2 Relational Connect

DB2 Relational Connect provides applications access to both DB2 and Oracle (see Figure 1-13). This is particularly useful if there is a heterogeneous database environment where DB2 and Oracle coexist, and need to share data.

Figure 1-13. DB2 Relational Connect.

IBM WebSphere Application Server

IBM WebSphere Application Server is built on an open Java-based platform that enables applications to leverage existing application resources and access various databases, including DB2. It is part of the WebSphere family of products that help you develop and manage high-performance Web sites and to integrate those Web sites with new or existing non-Web business systems. Some of the capabilities of WebSphere Application Server include use of

• Java servlets

• Java Server Pages

• XML

With these capabilities, you can quickly transform static Web sites into vital sources of dynamic Web content. Enterprise Java Beans (EJB) can also be used for implementing EJB components that incorporate business logic. WebSphere Application Server is packaged with DB2.

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