Datasheet

Server Reports
❘
25
intermediate report generated from a report request is cached for some period of time and used to
render reports for other users until the cached copy expires.
With both report session and report execution caching, the end-user requests a report, and the Report
Processor checks for a cached copy. If none exists, the Report Processor must assemble the intermediate
format report, store it in a cache for subsequent requests, and then render the requested final report.
While later requests may take advantage of the cached copy, the first request does not have this option.
This can lead to an inconsistent end-user experience.
To address this, snapshots may be scheduled to populate the cache in advance of an end-user request.
Snapshots are recorded in the same intermediate format and have the same security requirements as
report execution caching.
The HTML Rendering Extension
HTML is highly accessible and a generally good format for interactive reports. For these reasons,
HTML 4.0 is the default rendering format for Reporting Services reports.
The downside to HTML is that web pages have never been very good for printing. The HTML Viewer,
a JavaScript-based application embedded in most HTML-rendered reports discussed earlier in this
chapter, provides client-side printing that overcomes some of the challenges experienced when printing
from a web browser. (Client-side printing is accessed through the HTML Viewer toolbar.)
The HTML rendering extension can be instructed to return MIME-HTML (MHTML) as an alternative
to the HTML 4.0 default. With MHTML, images, style sheets, and other referenced items are embed-
ded in the HTML document. This allows a report to be delivered without dependencies on external
resources. That can be very useful in certain scenarios such as the e-mail delivery of a report to a user.
(Not all e-mail products support MHTML, so check with your user community before selecting this
format for e-mail delivery.)
The CSV-Rendering Extension
The comma-separated values (CSV)–rendering extension renders the data portion of a report to a
comma-delimited flat-file format accessible by spreadsheets and other applications. With the 2008
release of Reporting Services, this extension has been improved to keep formatting elements out of the
resulting data file.
The 2008 CSV-rendering extension operates in two modes. In the default, Excel-optimized mode,
each data region of the report is rendered as a separate block of comma-delimited values. In CSV-
compliant mode, the extension produces a single, uniform block of data accessible to a wider range of
applications.
The XML-Rendering Extension
XML is another format commonly used for rendering reports. The XML-rendering extension incorpo-
rates both data and layout information in the XML it generates.
One of the most powerful features of the XML-rendering extension is its capability to accept an XSLT
document. XSLT documents provide instructions for converting XML to other text-based formats.