NFRs

Description

Availability

Potentially there is a minor improvement in availability. If the common persistent store fails, some data is still available in the local cache. However, only a subset of functionality is likely to remain available; functions such as ordering require access to the persistent store, not merely to a cache.

Performance

Performance is improved by the local availability of data or assets that would otherwise have to be retrieved from a remote store.

Scalability

Not affected.

Security

We need to consider the type of information being held in the local cache. If the information is sensitive, the introduction of the cache has an adverse impact on security as we have to protect the cache as well as the persistent store.

Manageability

There is a negative impact on manageability as we have to manage the cache and any caching parameters that can be 'tuned'.

Maintainability

Not affected.

Flexibility

Not affected.

Portability

Not affected.

Cost

The cost of implementing a local cache depends on its sophistication. It is relatively easy to build and maintain a very simple cache, and the cost is minimal. However, an adaptive cache that holds frequently updated information is harder to build and products that perform this function can be expensive to buy.