# PageBody aboutToRead(RequestContext, PageHeader)

This method is called before a service retrieves information.

Input

- `RequestContext` - Contains session parameters, such as language cd, user id, and so on.

Input/Output

- `PageHeader` - The data describing the information that should be read.

Return value

- `PageBody` or `null` - If a page body is returned, this is considered the result of the service and the underlying service will not be invoked. If null is returned, the underlying service will be invoked normally.

Throws

`InterceptorError` - Throw this exception when an error occurs.

`InterceptorWarning` - Throw this exception to signal an application warning.

Parent topic: IReadInterceptor Interface