| Oracle® Transparent Gateway for DRDA Installation and User's Guide 10g Release 2 (10.2) for Microsoft Windows Part Number B16218-01 |
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View PDF |
| Oracle® Transparent Gateway for DRDA Installation and User's Guide 10g Release 2 (10.2) for Microsoft Windows Part Number B16218-01 |
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|
View PDF |
The Oracle Transparent Gateway for DRDA enables you to:
Integrate heterogeneous database management systems so that they appear as a single homogeneous database system
Read and write data from Oracle applications to data in DB2/OS390, DB2/400, DB2 Universal Database, DB2/VM, and IBM SQL/DS on VM databases in addition to any Oracle database server data.
Read this chapter for information about the architecture, uses, and features of the Oracle Transparent Gateway for DRDA. It contains the following sections:
In today's global economy, information is a company's most valuable resource. Whether you need to analyze new markets, tailor your products to meet local demands, increase your ability to handle complex customer information, or streamline operations, your company requires instant access to current and complete information
Company growth and diversification often mean functioning with a collage of applications and geographically scattered data that may be using incompatible networks, platforms, and storage formats. Diverse application standards and storage formats can make integration of information difficult. Oracle offers integration technologies to overcome these technical barriers. Oracle Enterprise Integration Gateways simplify complex systems and remove obstacles to information, thereby providing your company the opportunity to focus on business.
Oracle Transparent Gateway for DRDA gives your company the ability to develop its information systems without forfeiting its investments in current data and applications. The gateway gives you access to the Oracle and DB2 data with a single set of applications while you continue to use existing IBM applications to access your DB2 data. You can also use more productive database tools and move to a distributed database technology without giving up access to the current data.
If you choose to migrate to Oracle Database technology and productivity, then the gateway enables you to control the pace of your migration. As you transfer applications from your previous technology to the Oracle Database, you can use the gateway to move the DB2 data into Oracle databases.
Oracle Database 10g provides the foundation for the next generation of the Oracle Enterprise Integration Gateways Release 10g, which will deliver enhanced integration capabilities by exploiting Oracle Database 10g Heterogeneous Services. Heterogeneous Services is a component of the Oracle Database 10g server. The Oracle Database 10g server provides the common architecture for future generations of the gateways. For detailed information on Oracle Heterogeneous Services, refer to Oracle Database Heterogeneous Connectivity Administrator's Guide.
The version 10 gateways are even more tightly integrated with the Oracle Database 10g server than previous versions, enabling improved performance and enhanced functionality while still providing transparent integration of Oracle and non-Oracle data. For example, connection initialization information is available in the local Oracle Database 10g server, reducing the number of round trips and the amount of data sent over the network. SQL processing is also faster, because statements that are run by an application are parsed and translated once and can then be reused by multiple applications.
Release 10g gateways leverage any enhancements in the Oracle Database 10g server, and you can quickly extend those benefits to the non-Oracle data.
Oracle Transparent Gateway for DRDA enables Oracle applications to access the DRDA Application Servers, such as DB2 for OS/390 (MVS), through Structured Query Language (SQL). The gateway and the Oracle Database 10g server together create the appearance that all data resides on a local Oracle Database 10g server, though data might be widely distributed. If data is moved from a DRDA Application Server database to an Oracle Database server, then no changes in application design or function are needed. The gateway handles all differences in both data types and SQL functions between the application and the database.
Oracle Transparent Gateway for DRDA gives you the power to integrate your heterogeneous systems into a single, seamless environment. This integration enables you to make full use of existing hardware and applications throughout your corporatewide environment. You can eliminate the need to rewrite applications for each configuration, and you can avoid the tedious, error-prone process of manual data transfer. Together with the Oracle tools, networking, and data server technology, the Oracle Transparent Gateway for DRDA sets a high standard for seamless, enterprise wide information access.
Oracle Transparent Gateway for DRDA enables applications to read and update DB2 data and Oracle data as if all of the data were stored in a single database. As a result, users and application programmers are not required to know either the physical location or the storage characteristics of the data. This transparency not only permits you to integrate heterogeneous data seamlessly, but also simplifies your gateway implementation, application development, and maintenance.
The Oracle Transparent Gateway for DRDA gives you transparency at every level within your enterprise.
Users can access tables by name without needing to understand the physical location of the tables.
The gateways exploit Oracle Net technology to enable users to access data across multiple networks without concern for the network architecture or protocols. TCP/IP protocol is supported.
You can access data that is stored under multiple operating systems without being aware of the operating systems that hold the data.
Data can be accessed regardless of the database or file format.
You can use a single dialect of SQL for any data store, eliminating the need to code for database-specific access methods or SQL implementations.
Following are some of the more sophisticated Oracle Database 10g server services that are available through the gateway.
Your application can access all of your data using Oracle SQL, which is rich in features. Advanced Oracle Database 10g server functions, such as outer joins, are available even if the target data stores do not support them in a native environment. The method by which the gateways are integrated with the Oracle Database 10g server ensures that the newest features of each database release are always available immediately to the gateway.
Heterogeneous data can be integrated seamlessly because Oracle Database distributed capabilities, such as JOIN and UNION, can be applied to non-Oracle data without any special programming or mapping.
Distributed query optimization
The Oracle Database 10g server can use its advanced query optimization techniques to ensure that SQL statements are run efficiently against any of your data. The data distribution and storage characteristics of local and remote data are equally considered.
The Oracle server two-phase commit mechanism provides consistency across data stores by ensuring that a transaction that spans data stores is still treated as a single unit of work. Changes are not committed (or permanently stored) in any data store unless the changes can be committed in all data stores that will be affected.
Stored procedures and database triggers
The same Oracle stored procedures and database triggers can be used to access all of the data, thereby ensuring uniform enforcement of business rules across the enterprise.
The gateway integration with the Oracle Database 10g server extends (to non-Oracle data) the benefits of the Oracle Internet software, and Oracle Net software and extends the benefits of the Oracle client/server and server/server connectivity software. These powerful features include:
Any Internet or intranet application that can access data in Oracle database can also incorporate information from data stores that are accessible through the gateways. Web browsers can connect to Oracle database using any application server product that supports Oracle software.
Oracle Database and Oracle Net can work together as a protocol converter, enabling applications to transparently access other data stores on platforms that do not support the network protocol of the client. An Oracle Database 10g server can use TCP/IP to communicate with the gateway and another data store.
Non-Oracle data can be protected from unauthorized access or tampering during transmission to the client. This is done by using the hardware-independent and protocol-independent encryption and CHECKSUM services of Advanced Security.
Oracle Mobile Agents, an industry-leading Oracle mobile technology, enables wireless communication to Oracle Database 10g servers or to any databases that are accessible through the gateways. This gives your field personnel direct access to enterprise data from mobile laptop computers.
The simple setup of the gateway does not require any additional mapping. Before an application can access any information, the application must be told the structure of the data, such as the columns of a table and their lengths. Many products require administrators to manually define that information in a separate data dictionary stored in a hub. Applications then access the information using the hub dictionary instead of the native dictionaries of each database. This approach requires a great deal of manual configuration and maintenance on your part. As administrators, you must update the data dictionary in the hub whenever the structure of a remote table is changed.
Inefficient duplication is not necessary with Oracle Transparent Gateway for DRDA. The gateway uses the existing native dictionaries of each database. The applications access data using the dictionaries that are designed specifically for each database, which means that no redundant dictionary ever needs to be created or maintained.
Oracle Transparent Gateways ease application development and maintenance by enabling you to access any data using a uniform set of SQL queries. Changes to the location, storage characteristics, or table structure do not require any changes to the applications. ANSI and ISO standard SQL are supported, along with powerful Oracle extensions.
Oracle applications can create tables in target data stores by using native data definition language (DDL) statements.
You can run native data control language (DCL) statements from an Oracle environment, enabling central administration of user privileges and access levels for heterogeneous data stores.
Running of native DB2 SQL can be passed through the gateway for processing directly against DB2. This enables applications to send statements, such as a DB2 CREATE TABLE, to the gateway for running on a target DB2 system.
The gateway enables you to exploit both Oracle and non-Oracle stored procedures, leveraging your investments in a distributed, multi database environment. Oracle stored procedures can access multiple data stores easily, without any special coding for heterogeneous data access.
Oracle stored procedures enable you to access and update DB2 data by using centralized business rules that are stored in the Oracle Database 10g server. Using Oracle stored procedures can increase database performance by minimizing network traffic. Instead of sending individual SQL statements across the network, an application can send a single EXECUTE command to begin an entire PL/SQL routine.
Any application or tool that supports the Oracle Database 10g server can access over thirty different data sources through the Oracle gateways. A wide variety of open system tools from Oracle and third-party vendors can be used, even if the data is stored in legacy, proprietary formats. Hundreds of tools are supported, including ad hoc query tools, Web browsers, turnkey applications, and application development tools.
The gateway is integrated into the Oracle Database server technology, which provides global query optimization, transaction coordination for multisite transactions, support for all Oracle Net configurations, and so on. Tools and applications that support the Oracle Database server can be used to access heterogeneous data through the gateway.
You can use SQL*Plus for moving data between databases. This product gives you the ability to copy data from your department databases to corporate Oracle databases.
The gateway can participate as a partner in multisite transactions and two-phase commit. How this occurs depends on the capabilities of the underlying data source, meaning that the gateway can be implemented as any one of the following:
A full two-phase commit partner
A commit point site
A single-site update partner
A read-only partner
The deciding factors for the implementation of the gateway are the locking and transaction-handling capabilities of the target database.
Oracle Transparent Gateway for DRDA, by default, is configured as a commit point site (that is, commit confirm protocol). Optionally, you can configure the gateway as read-only if you choose to enforce read-only capability through the gateway. Other protocols are not supported. Refer to "Read-Only Gateway" in Chapter 11, "Using the Gateway".
All Oracle Database server products, including gateways, supply site autonomy. For example, administration of a data source remains the responsibility of the original system administrator. Site autonomy also functions so that gateway products do not override the security measures that are established by the data source or the operating environment.
The integration of a data source through the gateway does not require any changes to be made to applications at the data source. The result is that the Oracle Database server technology is nonintrusive, providing coexistence and an easy migration path.
The gateway does not bypass existing security mechanisms. Gateway security coexists with the security mechanisms that are already used in the operating environment of the data source.
Functionally, gateway security is identical to that of an Oracle Database server, as described in the Oracle Database Administrator's Guide. Oracle Database security is mapped to the data dictionary of the data source.
The terms that are used in this guide do not necessarily conform to IBM terminology. The following table presents several terms and their meanings as used within this guide:
| Terms | Meaning |
|---|---|
| DRDA data | Any database data that is accessed through DRDA |
| DRDA database | The collection of data that belongs to a DRDA Server |
| DRDA Server | A database server that can be accessed through DRDA. IBM terminology for a DRDA Server is a DRDA Application Server, or AS. |
| DRDA server type | A specific database product or program that can act as a DRDA server |
| Oracle integrating server | Any Oracle Database 10g server instance that communicates with the Oracle Transparent Gateway for DRDA to distribute database access operations to a DRDA Server. The Oracle integrating server can also be used for non-gateway applications. |
| DB2 Universal Database | A generic name for the UNIX-based implementations of DB2. DB2/UDB is frequently used as an abbreviation for DB2 Universal Database. |
The Oracle Transparent Gateway for DRDA works with the Oracle Database 10g server to shield most of the differences of the non-Oracle database from Oracle applications. This means that the Oracle applications can access the Oracle Database 10g server data and also can access the DRDA database data as if it were Oracle data located at the Oracle integrating server.
The architecture consists of the following main components:
Client
The Oracle integrating server is an Oracle Database instance that is accessed by an Oracle Database 10g server with procedural and distributed options. Usually, the Oracle integrating server is installed on the same host as the gateway, but this is not a requirement. The Oracle integrating server and the gateway communicate in the normal Oracle server-to-server manner.
If the Oracle integrating server is not on the host where the gateway resides, then you must install the correct Oracle networking software on the platform where the server resides. For Oracle Database 10g, you must install Oracle Net on the Oracle Database 10g server system.
Oracle Transparent Gateway for DRDA
The gateway must be installed on hosts that are running the appropriate operating system.
If the Oracle integrating server is not on the same host, then you must also install Oracle Net so that the gateway and Oracle Database 10g server can communicate.
The DRDA Server must be a DB2/OS390, DB2/400, DB2 Universal Database, or DB2 server for VM database on a system that is accessible to the host using either the SNA or TCP/IP protocol.
Multiple Oracle Database 10g servers can access the same gateway. A single host gateway installation can be configured to access more than one DRDA Server.
Figure 1-1 illustrates the gateway architecture that was just described.
When the gateway is installed on your host, it has some of the same components as an Oracle Database instance on Microsoft Windows. The gateway has the following components:
A base file directory, similar to the one that is associated with the ORACLE_HOME environment variable of an Oracle Database instance
A gateway system identifier (SID), comparable to the ORACLE_SID of an Oracle Database instance
Oracle Net to support communication between the Oracle integrating server and the Oracle Transparent Gateway for DRDA
The gateway does not have:
Control, redo log, or database files
The full set of subdirectories and ancillary files that are associated with an installed Oracle Database 10g server
Because the gateway does not have background processes and does not need a management utility such as Oracle Enterprise Manager, you do not need to start the gateway product. Each Oracle Database 10g server user session that accesses a particular gateway creates an independent process on the host. This process runs the gateway session and runs SNA or TCP/IP functions to communicate with a DRDA Server.
The gateway has no database functions of its own. Instead, it provides an interface by which an Oracle Database 10g server can direct part or all of a SQL operation to a DRDA database.
The gateway that is supporting the DRDA Server is identified to the Oracle integrating server by using a database link. The database link is the same construct that is used to identify other Oracle Database 10g server databases. Tables on the DRDA Server are referenced in SQL as:
table_name@dblink_name
or
owner.table_name@dblink_name
If you create synonyms or views in the Oracle integrating server database, then you can refer to tables on the DRDA Server by using simple names as though the table were local to the Oracle integrating server.
When the Oracle integrating server encounters a reference to a table that is on the DRDA Server, the applicable portion of the SQL statement is sent to the gateway for processing. Any host variables that are associated with the SQL statement are bound to the gateway and, therefore, to the DRDA Server.
The gateway is responsible for sending these SQL statements to the DRDA Server for processing and for fielding and is also responsible for returning responses. The responses are either data or messages. Any conversions between Oracle data types and DRDA data types are performed by the gateway. The Oracle integrating server and the application read and process only Oracle data types.
Not all SQL implementations are the same. The Oracle Database 10g server supports a larger set of built-in functions than the databases that are currently accessed through the gateway. The Oracle integrating server and the gateway work together to convert SQL to a form that is compatible with the specific DRDA Server.
During this conversion, an Oracle Database 10g server function can be converted to a function that is recognizable to the specific DRDA Server. For example, the Oracle Database 10g server NVL function is converted to the DB2 VALUE function.
Alternatively, the Oracle integrating server withholds functions that are not executable by the DRDA Server, and it performs them after rows are fetched from the DRDA database. This processing generally applies to SELECT statements. The Oracle integrating server and the gateway cannot perform this kind of manipulation on UPDATE, INSERT, or DELETE statements because doing so changes transaction semantics.
Use the gateway to run applications, such as Oracle tools, that read and write data that is stored in DRDA databases.
Although the Oracle Transparent Gateway for DRDA provides no new application or development facilities, it extends the reach of existing Oracle tools to include data in non-Oracle databases that support DRDA.
Using the Oracle Transparent Gateway for DRDA with other Oracle products can greatly extend the capabilities of the standalone gateway. The following examples demonstrate how powerful the gateway is with other Oracle tools.
Use SQL*Plus and the Oracle Transparent Gateway for DRDA to create a distributed database system, providing an easy-to-use transfer facility for moving data between the distributed databases. One possible use is to distribute the data in your corporate Oracle Database to departmental DRDA databases. You can also distribute data in your corporate DRDA database to departmental Oracle Databases.
Following is a list of important features that characterize this release of the gateway.
This release of the Oracle Transparent Gateway for DRDA uses the Oracle Heterogeneous Services component within the Oracle Database 10g server. Heterogeneous Services is the building block for the next generation of Oracle Enterprise Integration Gateways.
For detailed information about Heterogeneous Services, refer to the Oracle Database Heterogeneous Connectivity Administrator's Guide.
Oracle Transparent Gateway for DRDA contains several internal performance enhancements. This product has shown major improvements in response time and CPU utilization for all relevant address spaces for a variety of workloads compared to version 9 gateways. The actual performance improvement at your site might vary, depending on your installation type and workload.
The array size of the application for SELECT is effective between the application and the Oracle integrating server. However, the array block size and the block fetch between the Oracle integrating server and the gateway are controlled by two Heterogeneous Services initialization parameters, HS_RPC_FETCH_SIZE and HS_RPC_FETCH_REBLOCKING. These parameters are specified in the gateway initialization file. Refer to the Oracle Database Heterogeneous Connectivity Administrator's Guide for more information.
You can use the Oracle Database 10g DBMS_HS_PASSTHROUGH.EXECUTE_IMMEDIATE feature to pass commands or statements (that are available in the DRDA database) through the gateway.
Oracle Transparent Gateway for DRDA provides a facility to retrieve result sets from a select SQL statement that is run with passthrough. Refer to "Retrieving Result Sets Through Passthrough" for additional information.
This release of the gateway supports the TCP/IP communication protocol between the gateway and the DRDA Server. Refer to Chapter 8, "Configuring TCP/IP" for further information.
This release of the gateway supports the ability to selectively enable or disable post-processing of various SQL functions by the DRDA Server. Refer to "Native Semantics" for further information.
Oracle Transparent Gateway for DRDA supports up to 1000 columns in a result set.
The EXPLAIN_PLAN table contains the actual SQL statements passed to the DRDA Server from the Oracle Database 10g server through the gateway.
The gateway support for ANSI-standard SQL enables read/write access to DRDA databases. Even if your data exists on different platforms in different applications, new applications can use all data, regardless of location.
The gateway does not require installation of additional Oracle software on your OS/390 (MVS), AS/400, VM, UNIX or Microsoft Windows target system. The database interface that it uses is provided by IBM and is built into the DRDA database products and SNA or TCP/IP facilities that already exist on these platforms.
Configuring an IBM system for DRDA access typically consists of defining the SNA or TCP/IP resources involved and establishing access security definitions specific to the target database.
DRDA Application Server Function is supported by most IBM DB2 database products.
The ability of the gateway to interface with heterogeneous databases makes it possible to develop a single set of portable applications that can be used against both Oracle and IBM databases, and any other databases for which Oracle Corporation provides gateways.
Location flexibility is maximized because the gateway architecture permits network connections between each of the components. The application can use the Oracle client-server capability to connect to a remote Oracle integrating server through Oracle Net. The Oracle integrating server can connect to a remote gateway using a database link. The gateway connects to DRDA Servers through SNA or TCP/IP network facilities.
The benefits of remote access are that it:
Provides a means to allocate the suitable resource to a given task
You can, for example, move application development off expensive processors and onto cost-efficient workstations or microcomputers.
Expands the number of available data sources
Without remote access, you are limited to the data that is available in the local environment. With remote access, your data sources are limited only by your networks.
Provides a means to tailor an application environment to a given user
For example, some users prefer a block-mode terminal environment, while others prefer a bit-mapped, graphics-driven terminal environment. Remote access can satisfy both because you are not constrained by the interface environment that is imposed by the location of your data.
Because the gateway gives your application direct access to DRDA data, you eliminate the need to upload and download large quantities of database data to other processors. Instead, you can access data where it is, when you want it, without having to move the data between systems and thus risk unsynchronized and inconsistent data. Avoiding massive data replication can also reduce aggregate disk storage requirements over all of your systems.
However, if your system design requires moving data among the systems in a network, SQL*Plus and the gateway can simplify the data transfer. With a single SQL*Plus command, you can move entire sets of data from one node of the network to another and from one database to another.
You can pass commands and statements that are specific to your DRDA database through the gateway to be run by the DRDA database. For example, you can pass DB2/OS390 commands through the gateway for DB2 to run. You can also run stored procedures defined in non-Oracle databases.
Through the gateway, Oracle extends the range of application development and user tools that you can use to access the IBM databases. These tools increase application development and user productivity by reducing prototype, development, and maintenance time. Current Oracle users do not have to learn a new set of tools to access data that is stored in DRDA databases. Instead, they can access Oracle and DRDA data with a single set of tools.
With the gateway and the application development tools that are available from Oracle, you can develop a single set of applications to access Oracle data and DRDA data. Users can use the decision support tools that are available from Oracle to access Oracle data and DRDA data. These tools can run on remote systems that are connected through Oracle Net to the Oracle integrating server.
When designing applications, keep in mind that the gateway is designed for retrieval and relatively light transaction loads. The gateway is not currently designed to be a heavy transaction processing system.
This release of the gateway includes a utility to support encryption of plain-text passwords in the gateway initialization file. Refer to Chapter 13, "Security Considerations" for details.
This release of the gateway supports the native stored procedure catalogs in DB2 V6, V7, and V8 (SYSIBM.SYSROUTINES and SYSIBM.SYSPARMS).
This release of the gateway supports external mapping of IBM CCSIDs to Oracle character sets. Refer to "Gateway Codepage Map Facility" in Appendix D, "National Language Support".
IBM DB2 version 5.1 supports ASCII and EBCDIC character sets. The character set selection is defined during table creation. The Oracle Transparent Gateway for DRDA supports access to EBCDIC tables and ASCII tables. Refer to Appendix D, "National Language Support".
This release enables the gateway to be configured as a read-only gateway. In this mode, no modifying of user data is permitted. For more information, refer to "DRDA_READ_ONLY".
This release of the gateway adds support for DB2 GRAPHIC and VARGRAPHIC data types. Refer to Chapter 12, "Developing Applications".
This release of the gateway adds support for DRDA Servers running on Microsoft Windows and Linux on Intel hardware.
This release of the gateway adds Oracle data dictionary support for DB2 UDB V7. Refer to " for more information.
