The VSAM Redirector Connector enables VSE programs to
work with:
VSAM data that is synchronized with a remote database or file system.
VSAM files, all of whose data has been moved to a remote platform.
Using the VSAM Redirector Connector:
VSAM data can be migrated to other file systems or databases.
Data can be synchronized on different systems with VSE VSAM data.
VSE programs can work transparently with data on other file systems or
databases.
Changes made to VSAM data can be captured and temporarily stored on your z/VSE system for further
processing.
Your existing z/VSE host programs that are:
written in any language (COBOL, PL/I, ASSEMBLER)
batch or CICS® programs
can work with migrated VSAM data without the need to amend and recompile these z/VSE host programs. The VSAM Redirector Connector manages all connections
and data conversions.
The VSAM Redirector Connector consists of:
The VSAM Redirector Client for
synchronous redirection, which is installed on your z/VSE host. It is
responsible for communication and redirection of VSAM requests.
The VSAM Capture Exit for
asynchronous redirection, which is installed on your z/VSE host. It captures
changes made to a specific VSAM file, and then stores them in:
Another VSAM file (the VSAM delta cluster).
A WebSphere® MQ queue.
The VSAM Redirector Server which is
installed on each remote Java™ platform, as shown in
Figure 1. It is a Java program that:
Is responsible for connection-handling.
Is responsible for data conversion.
Builds the interface to the different file system VSAM Redirector Handlers (referred to
simply as redirector handlers.
Generates error messages that are the same as those generated before VSAM datasets were
migrated. Therefore, your application programs do not need to be amended for changes in
error-message handling.
VSAM Redirector Loaders (referred to simply as redirector
loaders), which are Java programs on the remote platform which are
used for loading and processing VSAM data. The following redirector loaders
are supplied by IBM®:
A basic redirector loader, which is used to load data from
a given VSAM file and process it via a specified redirector
handler (for example, to store the data in a database).
A delta redirector loader, which is used to load captured
data from a VSAM delta cluster and
process it via a specified redirector handler.
An MQ redirector loader, which is called from WebSphere MQ on a
workstation as an MQ trigger, to process captured data via
a specified redirector handler.
A graphical user interface, which you can use to configure the data
mapping used for the DBHandler redirector handler either
manually, or by importing COBOL copybooks. You can also use the graphical
user interface to create the corresponding database tables.
Redirector handlers are also stored on the Java platform, and have a common interface. They
are specific to the file system with which they work. For all connections,
information about the file and the request are sent to the redirector handler.
Using synchronous data redirection, you can migrate or synchronize your VSAM
data for example with DB2® tables residing on a remote system, and your VSE
programs will then work with this data, without requiring any changes to these VSE
programs. On the remote system, a Java handler provides access to the specific file
system or database on the remote system. For example, you can migrate your VSAM data
into Db2 tables residing on a remote system, and your VSE
programs will then work with this data, without requiring any changes to these VSE
programs.
Figure 1 provides an overview of how the VSAM Redirector Connector can be used to synchronously redirect
VSAM requests from an application running on the z/VSE host to a Db2
database stored on a Java platform. It can use any of these
IBM-supplied redirector handlers on the Java platform:
Each handler can decide at each of the above requests, which processing is required for the
remote data.
Figure 1. How Synchronous Data Redirection Is Used
The general processing shown in Figure 1 is as
follows:
1
An application running on the z/VSE host issues a
VSAM command (for example, to open a VSAM file). The request is passed to the generic exit
(IKQVEX01.PHASE).
2
The generic exit checks whether the VSAM file has been set up to be redirected. To do so, it
checks the configuration phase (IESRDCFG.PHASE).
3
If the VSAM file has not been redirected to another Java
platform (and is therefore still stored as a VSAM record on the z/VSE host), the generic exit returns and indicates that the
VSAM file has not been redirected. It also indicates that the generic exit should not be called
again for any request against this VSAM file. Normal VSAM processing then continues.
4
If the VSAM file has been redirected to another Java platform, the generic exit (IESREDIR.PHASE) calls the VSAM Redirector Client.
5
The VSAM Redirector Client establishes a connection to
the VSAM Redirector Server running on the Java platform, and forwards the VSAM file request, together with any data
(such as a VSAM record contents) to the VSAM Redirector Server.
6
The VSAM Redirector Server uses the redirector handler
that is specified in the configuration phase, to perform access to the target file system or
database. In Figure 1, the specified redirector handler
is DB2Handler (which is supplied by IBM during the
installation of the VSAM Redirector Server).
DB2Handler implements access to a Db2 database.
Asynchronous redirection of VSAM data is provided by the VSAM Capture Exit, which allows
you to:
Capture changes made to a particular VSAM file.
Store these changes for further processing.
There are two options you can use:
Save changes in a VSAM cluster (the VSAM delta cluster).
Save changes in an WebSphere MQ queue.
Captured changes are written as delta records or messages. They contain:
The data of the changed record.
Information about when (the timestamp) and by whom (the
partition, phase name, origin value, and so on) the record was
changed.
The saved changes can later be accessed via the Java-based connector by Java programs running on the remote platform. Loader
programs are also provided to load and process the captured data from the VSAM delta cluster (for example, to apply
the changes to a database).
The VSAM Redirector Connector is used to
capture changes in a specific VSAM file on your z/VSE host.
A redirector loader program running on a Java workstation then processes this captured
data via the Java-based connector.
Figure 2. How Asynchronous Data Redirection Is Used
The general processing shown in Figure 2 is as follows:
1
An application running on the z/VSE host issues a
VSAM command (for example, to open a VSAM file). The request is passed to the generic exit
(IKQVEX01.PHASE).
2
The generic exit checks whether the VSAM file has been set up to be redirected. To do so, it
checks the configuration phase (IESRDCFG.PHASE).
3
If the VSAM file has not been redirected to another Java
platform, the generic exit returns and indicates that the VSAM file has not been redirected. It also
indicates that the generic exit should not be called again for any request against this VSAM
file. Normal VSAM processing then continues.
4
Changes (UPDATE, INSERT, or DELETE) made to the VSAM file are captured via the VSAM Capture Exit (IESVSCAP.PHASE).
5
The changes are written to the VSAM delta cluster.
6
The redirector loader reads the VSAM delta cluster.
7
The redirector loader calls the redirector handler, so that it can apply the delta-file changes
to the database or file system.
8
When completed, the redirector loader deletes the processed records from the VSAM delta cluster.
9
(Optional). The redirector loader copies the contents of the VSAM file to the remote data base
or file system (for example, for initial loading).
