Host Application Software
System Host in the same chassis. In order for a host application to be capable of maintaining the system’s serviceability, these redundant applications should maintain some level of synchronization. The level of synchronization and the level of sophistication of the system’s peripherals determine the failover characteristics of your system. Synchronization issues, in addition to other implementation concerns, are covered in the Section 3.3, “Development Issues” on page 23.
3.2Division of Labor
Historically, embedded application developers have integrated the management of the system with the host application. This tight integration meant it was unlikely that much of the host application could be ported when the application was rehosted on a new platform. This topic presents a possible architecture that allows the host application to remain aware of system performance and degradation while maintaining a loose coupling with the system management aspects of the architecture.
One of the keys to portability in application design is to maintain a modular design. This goal is often complicated by routines used for system management that place particular requirements upon the implementation of the application. One way to reduce the awareness of the application on a particular implementation is to take a layered approach to the design of the application. In this way you can reduce specific implementation features without unnecessarily isolating the application from the underlying performance of the system. See the “Layered Host Application Diagram” below.
Figure 5. Layered Host Application Diagram
Host Application
Platform Interface
System Management
Modules
22 | High Availability Software for the Intel® NetStructureTM ZT 4901 Technical Product Specification |
