boinc/doc/result.html

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<h2>Compute model: results</h2>
<p>
A <b>result</b> describes an instance of a computation,
either to be performed, in progress, or completed.
Results are stored in the <b>result</b> table of the BOINC DB.
The attributes of a result include:
<ul>
<li> The name of the result (unique across all results in the project).
<li> The name of the associated workunit.
<li> An XML document listing the names of its output files; see below.
<li> An XML document giving the sizes and checksums of its output files
(this is filled in after the result is completed).
<li> The stderr output of the result.
<li> The host that computed the result.
<li> The times when the result was dispatched and received.
<li> The exit status of the application.
<li> The reported CPU time.
<li> Its <b>state</b>. Values include:
<ul>
<li> Inactive (not ready to dispatch)
<li> Unsent (ready to dispatch, but not dispatched)
<li> In progress (dispatched, not done)
<li> Done successfully
<li> Timed out
<li> Done with error
</ul>
</ul>
The XML document listing the output files has the form:
<pre>
&lt;file_info>...&lt;/file_info>
[ ... ]
&lt;result>
&lt;name>foobar&lt;/name>
&lt;wu_name>blah&lt;/wu_name>
&lt;file_ref>...&lt;/file_ref>
[ ... ]
&lt;/result>
</pre>
The components are:
<ul>
<li> The <b>&lt;name></b> element is the result name.
<li> The <b>&lt;wu_name></b> element is the workunit name.
<li> Each <b>&lt;file_ref></b> element is an association
to an output file, described by a corresponding
<b>&lt;file_info></b> element.
</ul>
<p>
The XML document describing the sizes and checksums
of the output files is just a list of
<b>&lt;file_info></b> elements, with the
<b>nbytes</b> and <b>md5_cksum</b> fields present.
The project back end must parse this field to
find the locations and checksums of output files.
<p>
Several results may be associated with a single workunit.
Results may be generated in either of two ways
(selected as part of the application):
<ul>
<li> <b>Advance generation</b> of results.
One or more result records are stored in the database
when the workunit is produced.
The scheduling server dispatches each result to a single participant host.
When all result records have been dispatched,
participants hosts are "turned away".
<li> <b>On-demand generation</b> of results.
The application specifies a "result template",
which has place-holder tokens for the output filenames.
The scheduling server, in response to a host request,
generates a new result record and sends the result template.
The host generates unique output filenames,
and returns them along when it the computation is done.
</ul>