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White Paper:
InterPlex
Enterprise Gateway
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Page 3
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2, 3, 4,
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The
illustration contains 3 different types of computer systems. The first system is the Unisys ClearPath IX or 2200 mainframe
that contains the DMS databases. The
DMS databases embodied are both the InterPlex SQL internal or support
database and the customer’s applications database(s).
The installed mainframe portion of the InterPlex Enterprise product
is the InterPlex SQL, which consists of four principal pieces.
The InterPlex SQL DDP Generalized Front End, the InterPlex SQL DMS
Access, the InterPlex SQL DDP UPDriver, and the InterPlex NET.
The
next system is designated as the DataServer Node, which can be a UNIX
system, Microsoft server, or any computer system that supports the
DataServer. This node
contains InterPlex Enterprise gateway and the DataServer software.
The gateway node handles all network and database connectivity
requests between the DataServer and the Unisys ClearPath IX or 2200 data
sources.
The
final system is a Microsoft Client computer within the network. This node
contains the InterPlex ODBC driver and one of many Microsoft ODBC client
software packages. The
InterPlex Administration software also resides on the Microsoft computer.
InterPlex SQL DDP Generalized Front
End
The
InterPlex SQL DDP Generalized Front End handles the initialization of SQL
cursors and sessions, as well as the termination of the same. This generalized front end is multiplexed and controls the
requests and subsequent data delivery to the InterPlex Enterprise gateway
processes. There are
configuration options and systems techniques to change and enhance the
performance of the generalized front end.
The use of the max-rows
parameter allows for controlling how much data each sessions receives
within each fetch request. By
controlling the number of rows of data returned, the actual CPU usage and
DMS I/O usage of the InterPlex SQL DMS access module is controlled.
Also the ECL run card can be set to various batch priorities to
enhance or tune the front end. Other
features available in the generalized front end are the capability to turn
tracing on or off and informational consoles messages.
By turning off the informational console message and tracing, this
eliminates disk and console I/O. These
features are available for problem analysis and should not be left on
during normal operation. When
running with tracing off, the InterPlex SQL DDP Generalized Front End
works within local banks in memory and the InterPlex SQL Common Banks. Therefore there is no disk I/O.
Also, when there are no active sessions or the front end is waiting
for DMS data to be retrieved by the InterPlex SQL DMS access module, there
is little or no CPU usage. This
is accomplished by using test and set cells within the InterPlex SQL
common banks and DDP Wait-For-Connection logic.
InterPlex SQL DMS Access
The
InterPlex SQL DMS Access module handles the login, the retrieval of the
user catalog, the parsing and verification of the SQL statement, and the
initiation of the Work
Transaction that
accesses the customer’s DMS application database.
This is a batch run that can be set, via the ECL run card, to run
at any priority.
Query
processing, within InterPlex SQL, consists of parsing the SQL statement,
retrieving description information about the view and it’s columns, and
converting it into DMS Data Manipulation Language (DML) for execution
against the hierarchical database records.
At this point, the InterPlex DMS access module will start the
access transaction to begin the DMS fetch processing.
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UNISYS Integrators