CICS® applications
written in Java™ can use a variety of methods to access data. The
methods available depend on the type of data to be accessed.
- Accessing relational data
-
To access relational data, a CICS application written in Java can
use any of the following methods:
- A JCICS LINK command, or the CCI Connector for CICS TS, to
link to a program that uses Structured Query Language (SQL) commands to access
the data. For information about using the CCI Connector for CICS TS, see The CCI Connector for CICS TS.
- Where a suitable driver is available, use Java Data Base Connectivity
(JDBC) or Structured Query Language for Java (SQLJ) calls to access the data
directly. Suitable JDBC drivers are available for DB2®. TheCICS DB2 Guide tells
you how to use the JDBC and SQLJ application programming interfaces and the
DB2-supplied JDBC drivers to access data held in a DB2 database.
Note: To
use JDBC or SQLJ from a Java program or enterprise bean with a Java 2 security
policy mechanism active, you must use the JDBC 2.0 driver provided by DB2
Version 7. The JDBC 1.2 driver provided by DB2 does not support Java 2 security,
and will fail with a security exception.
CICS DB2 Guide tells
you how to grant permissions to the JDBC driver in your Java 2 security policy.
- Data Access beans developed using Visual Age for Java. Data Access
beans give you a fast, easy, non-programming way of building SQL queries.
They might have a higher overhead than plain JDBC or SQLJ calls, as you cannot
tailor them so precisely for your application. However, if you are not experienced
in JDBC or SQLJ programming, Data Access beans reduce application development
time and are more convenient to use. Data Access beans are described in Using Data Access beans.
- JavaBeans that use JDBC or SQLJ as the underlying access
mechanism. You can use any suitable Java integrated development environment
(IDE) to develop such JavaBeans.
- Entity beans. CICS does not support entity beans running under CICS but
does support access to entity beans running on other EJB servers. A CICS enterprise
bean could, for example, use an entity bean running on WebSphere® Application Server to
access DB2 on z/OS.
- Accessing DL/I data
-
To access DLI data, a CICS application written in Java can use a JCICS
LINK command, or the CCI Connector for CICS TS, to link to a program that issues
EXEC DLI commands to access the data. For information about using the CCI
Connector for CICS TS, see The CCI Connector for CICS TS.
- Accessing VSAM data
-
To access VSAM data, a CICS application written in Java can use either
of the following methods:
- Use a JCICS LINK command, or the CCI Connector for CICS TS, to link
to a program that issues CICS File Control commands to access the data. For
information about using the CCI Connector for CICS TS, see The CCI Connector for CICS TS.
- Use the JCICS File Control classes to access VSAM directly.
Note: - All the above techniques can be used by both CICS enterprise beans and
CICS Java programs.
- The same data can be accessed by CICS enterprise beans, CICS Java programs,
and (excluding CICS VSAM data) by non-CICS entity beans.
- For all the above techniques except the use of entity beans, data integrity
is maintained by the CICS recovery manager. When entity beans are used, you
can use CICS and, for example, WebSphere Application Server's
global transactional support, to maintain data integrity.
- You can encapsulate JCICS commands in a JavaBean. This makes it easier
to program the enterprise beans that use JCICS to access data.