PDF of this tutorialWith the increasing reliability of standard computer systems, the focus of the communication industry is shifting increasingly to software fault tolerance and software replication to ensure continuous availability of communication services.
As this tutorial demonstrates, continuous service availability must be addressed at many different levels:
- providing a persistent store for application data
- ensuring reliable network connectivity
- detecting and isolating service level faults
- addressing on-line upgradability of both the platform and the application
- offering protection against site failures, through the multisite distribution of service logic and service data
A software framework that aims to ensure continuous service availability must address all of these issues.
Some companies now offer solutions that can address the software reliability issue and that can ensure continuous availability of revenue-generating services.
By focusing on software replication and software upgradability, these solutions significantly increase service availability beyond the level that can be achieved through simple hardware fault tolerance.
