Availability Guide for Application Design

Designing Applications for Change
Availability Guide for Application Design—525637-004
10-10
Considering Portability Requirements
Process Pools
For clustered systems, the preferable model would be the requester/server class
model provided by NonStop TS/MP on HP NonStop servers. This model allows
scalability by adding instances to the server class and executing the instances
across all the available processors of the system. The instances are shared
between users, with one instance being allocated for the duration of each request.
This model reduces the number of processes required for a given user population
and thus simplifies management and reduces the demand for system resources
such as file opens.
The optimum model combines multiple multithreaded client handlers with context-
free server class pools of application logic servers. This model underlies the
transaction processing manager and object request broker (ORB) middleware that
is offered on the NonStop operating system and Windows NT Server as part of the
NonStop Software product set.
Application Engineering
Engineering deals with how an application is constructed, as opposed to how it will
function. Three basic approaches are available for developing portable applications:
•
Use a complete multiplatform application definition, generation, and execution
product
•
Use a multiplatform middleware product such as NonStop Tuxedo with
development tool that targets that product
•
Use a portable language in association with multiplatform, international-standard
APIs adhering to ISO, ANSI, and X/Open specifications and with development
practices explicitly defined to ensure awareness of portability issues. This becomes
even easier if you use language-based development tools with carefully
engineered isolation of any platform-specific APIs.
All three techniques can be used in the joint environment of the NonStop operating
system and Windows NT Server. The following considerations apply to each of these
approaches:
•
Using Integrated Products on page 10-10
•
Isolating the Unportable on page 10-12
•
Worrying About the Bits on page 10-12
•
Preserving Investments Through Services and Frameworks on page 10-12
•
Preserving NonStop Operating System to Windows NT Server Portability on
page 13
•
Easier Targeting of NonStop Operating System and Windows NT Server Platforms
on page 10-14
Using Integrated Products
The following products provide the needed functionality: