TS/MP Pathsend and Server Programming Manual (H06.05+, J06.03+)

Besides process pairs and server classes, fault tolerance in a Pathway application is ensured by
the PATHMON process, the TCP, and the TMF subsystem. Using information stored in the PATHMON
configuration file, the PATHMON process automatically restarts processes at their initialization
level after a failure, allowing these processes to resume work immediately.
Other NonStop Fundamentals
Besides data integrity and fault tolerance, the Pathway environment also provides the high
performance and low cost, system security, scalability, and distributed processing of NonStop
systems.
High Performance and Low Cost
The more transactions your system can process (preferably without degrading response time), the
lower the cost of each transaction. The Pathway environment supports fast response time and high
system throughput by allowing:
• Component processes in a Pathway application (for example, requester and server processes)
to reside and execute concurrently in different processors of a multi-processor system or even
a network. This is called multiprocessing.
• More than one Pathway application to run in a NonStop system.
TS/MP also supports fast response time and high system throughput by allowing the replication of
processes and programs and the distribution of processes. For example:
• The PATHMON process can dynamically create additional copies of server processes at times
of peak demand and delete the additional servers when activity slows again.
• You can add copies of requester and server programs to your Pathway application to maintain
fast response time when the number of users or terminals increases.
• You can distribute processes such as requesters and servers close to the resources they manage,
reducing interprocess communication time within a network.
• You can distribute requesters and servers to less active processors if peak activity on a particular
processor is affecting throughput or response time.
System Security
The Guardian operating environment includes basic mechanisms for controlling access to files,
whether they are data files or program files. Because TS/MP runs in the Guardian operating
environment, Guardian system security parameters also apply to Pathway users and processes. In
addition, you can supplement the security features of the Guardian environment with the Safeguard
product, which provides authentication, authorization, and auditing capabilities for Guardian files.
Scalability
Your organization must be able to expand its transaction processing system as its operations evolve
and its technical requirements change. NonStop systems are expressly designed to support
incremental, modular expansion, allowing you to increase the size and processing power of your
transaction processing system by:
• Adding hardware and application resources to your existing system
• Linking individual Pathway applications into a single network or adding more Pathway
applications to an existing network
• Supporting an open systems architecture in which standards-based networks as well as devices
and systems from other vendors can be connected to your NonStop system
Distributed Processing
Data communications technology allows organizations to extend their online operations over long
distances to form global networks and to support distributed processing. The Pathway environment,
20 Introduction to Pathway Application Programming