About Caching Contents

When designing your application, you can set specific elements to have their content cached and this way improve your application's runtime performance: the execution of cached elements is faster since when their resulting content is already stored in the cache and it is immediately returned.

This functionality is only available for the .NET stack. If the Application Server eSpace property is set to J2EE, the Cache in Minutes property will be ignored at runtime.

Where is the Cache?

There is a cache in the memory of each Front-end Server. Whenever memory space is required, elements are removed from the cache using the least recently used algorithm.

Setting an Element for Caching

To start caching an element content simply set its Cache in Minutes property to a value grater than zero.

The elements that can be cached are the following:

1. • Web Screens : Web Screens and all elements they contain are cached;

   • Web Blocks : Web Blocks and all elements they contain are cached;

   • Aggregates and SQL : list returned by the Query is cached;

   • User-defined Actions : output parameter values of User-defined Actions are cached;

   • Consumed SOAP Methods : output parameter values of methods consumed from SOAP Web Services are cached.

Cached elements cannot have input parameters of the following types: Record, List, and Binary Data.

Cache in Multi-tenant Applications

In Multi-tenant applications, there is a specific cache for each tenant, which only stores data specific to it. In this case: Web Screens, Web Blocks, Aggregates and SQl, User-defined Actions and methods output of consumed SOAP Web Services will be stored on the tenant's cache.

Learn more about Using Cache in Multi-Tenant Applications .

Behavior of Cached Elements

A cached element behaves as follows:

• On the first usage : the element is evaluated and the resulting content is stored in the cache;
• On the following usages : the stored content is returned by the server, thus skipping the evaluation.

However, any cached element is evaluated again whenever:

• The elapsed time since the element content was last cached exceeds the element's Cache in Minutes value: the cached content is no longer valid, it is evaluated again, and the resulting content is updated in the cache;
• The element has input parameters and there's no cached content for their new values: the element is evaluated and the resulting content is stored in a new entry in the cache;
• The cache is invalidated : if the element content is invalidated by this operation, it is evaluated again, and the resulting content is updated in the cache.

Web Screens and Web Blocks cache the content of all elements they contain. However, if the content of any of these elements changes, it won't be automatically updated in the Web Screen or Web Block cached content. This will only happen when the whole Web Screen or Web Block is evaluated again.

Electing Elements for Caching

You should consider caching the contents of:

• Elements with an execution time which impacts on the end-user experience;
• Elements that overload your system resources (database, CPU, memory, ...)
• Elements that fetch data from databases or external systems;
• Elements for which the returned results rarely change or change in a controlled way for the same input parameters.

Following are some concrete examples of these situations:

• A Web Block containing a list of categories stored in the database;
• A method of a consumed SOAP Web Service that fetches job opportunities from an external system;
• A method consumed from a SOAP Web Service that returns the list of employees.

See Also

Invalidating the Cache