Within distributed client/server systems, each client that is supported adds overhead to system resources (such as memory). Responsiveness is improved and system resource overhead is reduced by using TP monitor technology to multiplex many clients onto a much smaller set of application service routines. TP monitor technology provides a highly active system that includes services for delivery order processing, terminal and forms management, data management, network access, authorization, and security.
TP monitor technology supports a number of program-to-program communication
models, such as store-and-forward, asynchronous, Remote Procedure Call (RPC), and conversational. This
improves interactions among application components. TP monitor technology
provides the ability to construct complex business applications from modular,
well-defined functional components. Because this technology is well-known and
well-defined it should reduce program risk and associated costs
[Dickman 95,
Hudson 94].
TP monitor technology has been used successfully in the field for 25 years. TP
monitor technology is used for delivery order processing, hotel and airline
reservations, electronic fund transfers, security trading, and manufacturing
resource planning and control. It improves batch and time-sharing application
effectiveness by creating online support to share application services and
information resources
[Dickman 95,
Hudson 94].
TP monitor technology makes database processing cost-effective for online
applications. Spending relatively little money on TP monitor technology can
result in significant savings compared to the resources required to improve
database or platform resources to provide the same functionality
[Dickman 95].
A limitation to TP technology is that the implementation code is usually
written in a lower-level language (such as COBOL), and is not yet widely
available in the popular visual toolsets
[Schussel 96].
A variation of TP monitor technology is
session based technology. In the TP monitor technology, transactions from the client are treated as messages. In the session based technology, a single server provides both database and transaction services. In session based technology, the server must be aware of clients in advance to maintain each client's processing thread. The session server must constantly send messages to the client (even when work is not being done in the client) to ensure that the client is still alive. Session based architectures are not as scalable because of the adverse effect on network performance as the number of clients grow.
Another alternative to TP monitor technology is
remote data access (RDA). The
RDA centers the application in a client computer, communicating with back-end
database servers. Clients can be network-intensive, but scalability is limited.
A third alternative to TP monitor technology is the database server approach,
which provides functions (usually specific to the database) and is
architecturally locked to the specific database system
[Dickman 95,
Hudson 94].
Complementary technologies include mainframe client/server software
architectures (see Mainframe Server Software
Architectures) and Three Tier Software Architectures; in both cases the TP monitor technology could server as the middle tier.
This technology is classified under the following categories. Select a
category for a list of related topics.
