= Credit statistics web sites and services =

'''Statistics data''' is the number of [CreditSystem Cobblestones] (credit units) granted to hosts, participants and teams by the various BOINC projects. This can be used for various purposes, such as:
 * Web sites that show statistics and leaderboards for one or more BOINC projects. Examples are listed at [http://boinc.berkeley.edu/stats_sites.php here].
 * Dynamically-generated images (typically used as message-board signatures) that show user and/or team credit, possible across projects. Examples are listed at [http://boinc.berkeley.edu/stats_sites.php here].
 * Displays of current credit on cell phones and PDAs.

Displays that use colors to distinguish BOINC projects should use [http://boinc.netsoft-online.com/project_colors.html these colors].

BOINC provides a flexible architecture for distributing statistics data, with the goal of enabling new display applications.

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[[Image(http://boinc.berkeley.edu/stats.png)]]
'''The BOINC statistics data architecture'''
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== Project-specific data ==
Each BOINC project provides data in two forms:

 * As [XmlStats a set of downloadable files] (in a compressed XML format) that contain the project's complete current statistics. These files are typically updated once every 24 hours.
 * As [WebRpc a set of Web RPCs] that return an XML-format description of a given participant's credit, based on that participant's database ID.

Applications should access these data sources as infrequently as possible, to avoid imposing unnecessary load on project servers. For example, a Web RPCs to get a particular participant's data should made at most once per hour.

== Aggregate data ==
A '''data aggregator''' is a service that collects XML files from several projects, and computes the totals for participants and hosts (based on [CrossProjectId cross-project IDs]) across these projects. This aggregate data is then exported in two ways:

 * As [StatsXml a set of downloadable files] (in a compressed XML format). An example is at  http://boinc.netsoft-online.com/stats/.
 * As [StatsXml#WebRPCs a set of Web RPCs] that return an XML-format description of a given participant or host's credit, based on the cross-project ID. Example: http://boinc.netsoft-online.com/get_host.php?cpid=???? and http://boinc.netsoft-online.com/get_host_tot.php?cpid=????

Application developers are encouraged to concentrate on aggregate rather than per-project data. This will encourage participants to join multiple projects, and will make it possible for new projects to quickly get many participants.