Availability Guide for Application Design

Designing Applications for Change
Availability Guide for Application Design—525637-004
10-13
Considering Portability Requirements
In addition to the mapping of call and reply syntax, a framework might need to
provide other services to standardize such things as transfer of control, error
reporting, and statistic recording.
By redeveloping the framework rather than the valuable business logic, a core
business service can be transferred from one transaction processing monitor to
another, to a queue-based environment, or even to the body of a method in an
object class.
This engineering model is particularly well suited to object-oriented analysis and design
using business objects. You can use either of the following approaches:
•
Use the overall Object Management Group (OMG) model in which an object
represents a set of related but externally independent transitions. These transitions
must be hosted in a Distributed Object Management Object Request Broker
(DOM/ORB), which must in turn provide the invocation framework and other
commonly required functionality, including that defined in the CORBA standard
services specifications.
•
Implement the business objects resulting from the object-oriented application
development phase as portable object classes in an appropriate object-oriented
programming language such as C
++
or Java. The resulting object class library can
then be wrapped in the invocation function of a chosen middleware product, such
as NonStop Tuxedo services. The object class with its business rules should
remain easily accessible for transfer to alternative environments through
alternative framework and service wrappings.
Preserving NonStop Operating System to Windows NT Server Portability
The rise of the Windows NT Server platform, with its support for clustering, has created
tremendous interest in portability between the NonStop operating system and Windows
NT Server platforms. HP’s development of cluster-aware middleware assures
portability between the two environments. This subsection details specific
considerations for portability between the NonStop operating system and Windows NT
Server environments.
Windows NT Server is the only new commercial-grade solution for large-scale server
processing that has become available since the introduction of HP NonStop systems
more than 20 years ago, and its design targets a broader range of capabilities than the
NonStop operating system. For example, Windows NT Server is designed to support
uniprocessor and SMP systems as well as the more scalable, higher-availability
clustered platforms.
Two important long-term challenges exist for developers who wish to adopt Windows
NT Server as the basis for enterprise applications:
•
Ensuring scalability to meet the expanding size of applications
•
Avoiding the creation of a generation of legacy applications dependent upon
subsequently outdated technology