Report Management - Professional SQL Server 2005 Reporting Services - page 428

On-demand Report Generation
After a report is deployed to the Report Server, its definition is stored in the ReportServer Database.
Before the final rendered report is created, an image of the report and its data is produced on the server
in an intermediate report format . The intermediate report describes the placement of the report elements
before it is rendered to a specific output format. Figure 10-18 provides an example of the result of when
a user has initiated the report generation process.

Data Retrieval Intermediate Generation Report Rendering

Source
DB

Report User

Report
Server DB

Web Service Host

Report
Server
TempDB

Figure 10-18

The Report Server connects to the databases to retrieve the source data and report definition and
then creates the intermediate version of the report. A copy of the intermediate report is written to the
ReportServerTempDB database for that user, defined as a browser session. If that same user goes back
to the folder in Report Manager and clicks the report link again, he or she will get the cached version
of the report, saving database connections and processing time. Each user gets his or her own cached
version. For reports that take parameters, a different intermediate report is cached for different
parameter combinations.

The intermediate rendering format is the foundation of report caching. When a report is cached, the
intermediate format image is written to disk in the ReportServerTempDB database (one of the two
databases that compose the Report Server). This enables the report data and definition to be retrieved
with one connection and then output in different formats (or multiple times in the same format). A sin-
gle cached instance can produce different outputs based on report parameters that filter data on the
cached data. The final rendering is performed against the intermediate format using a designated ren-
dering extension.

Working with Cached Instances
Data sources used by cached reports (either cached instances or report snapshots) must use stored cre-
dentials. This information is stored in encrypted form with the shared data source or the report defini-
tion in the ReportServer database.