Availability Guide for Application Design

Increasing the Availability of Tuxedo Applications
Availability Guide for Application Design—525637-004
5-4
How Does NonStop Tuxedo Work?
program that uses the Application Transaction Monitor Interface (ATMI) or TX standard
interface can do this.
This subsection introduces the NonStop Tuxedo product and its availability features.
First, it establishes how the components that make up this product normally function
and includes a skeletal work session. It goes on to describe how availability is
maintained even if critical components fail and how a typical work session is affected.
Finally, it includes a checklist of issues that the application designer or developer
should consider to take full advantage of these features and run an application with the
highest-possible level of availability.
This subsection does not provide information on how to write NonStop Tuxedo
applications. For that level of detail, refer to the NonStop Tuxedo System Application
Development Guide.
How Does NonStop Tuxedo Work?
The following discussion provides a brief overview of the components of the NonStop
Tuxedo transaction-processing environment. Refer to the Introduction to NonStop
Transaction Processing for a complete overview of the NonStop Tuxedo product.
NonStop Tuxedo Components
Figure 5-2 on page 5-5 shows the components in a typical NonStop Tuxedo
application. For clarity, this figure shows only one HP NonStop server. NonStop Tuxedo
applications can, however, span multiple servers connected by an Expand network and
can span multiple server types using the System /Domain feature.
The application is made up of support for remote client processes, bulletin board
facilities, server process management and linkage provided by NonStop TS/MP, and
transaction management provided by TMF.
Support for remote client processes includes:
•
Tuxedo/WS facilities on the client workstation. These interfaces support ATMI or
TX interface calls to establish connections and sessions with the transaction
monitor (System /T) on the server.
•
A workstation listener (WSL) process that executes on the server system and
listens for connection requests from remote client processes. When it receives a
request, the WSL process assigns a workstation handler (WSH) to handle all
requests between the client process on the workstation and server processes on
the HP server. If no WSH process can handle the session, the WSL process
creates one.
•
A workstation handler (WSH) process to act as the gateway between the
workstation client and the server process. The WSH is a multithreaded process
Note. In Tuxedo terminology, the system in which a Tuxedo application or part of a Tuxedo
application runs is known as a machine. This section uses this term in this context.