Editing Download Metrics (section)

==Exposing Usage==

Eprints 3 includes a script that can expose access logs through an [http://www.openarchives.org/ OAI-PMH] interface. This interface is located at <tt>/cgi/oai_accesslogs</tt>. The interface contains an <code>EPrints::abort</code> at the top that prevents all access - this is because usage logs are potentially sensitive data: a repository will want to implement some kind of access restriction before providing access to their logs.

The OAI interface uses Eprints export plugins to convert access log objects (as read from the Eprints database) into XML suitable to be embedded in the OAI output. From an Eprints architecture perspective the mechanism to expose access log records is nearly identical to the exposure of eprint records (they are both ''datasets'' in Eprints).

{| border=1 class="wikitable"
|+eprint/access OAI comparison
!
!eprint
!access
|-
|identifier
|oai:<archive name>:<item id>
|oai:<archive name>:<item id>
|-
|export plugins
|(predefined list in cfg.d/oai.pl)
|can_accept => "list/access"
|-
|from/until
|last_mod field
|datestamp field
|-
|OAI sets
|arbitrary fields defined in cfg.d/oai.pl
|not-supported
|}

An OAI ListRecords request may contain date and set filters, although sets aren't yet supported for access logs. OAI date filters consist of optional ''from'' and ''until'' arguments that restrict the resulting data to only those accesses that occurred between the two dates.

Using the Eprints search API a result set of records is generated that matches the OAI arguments e.g. all access log records made after a certain time. Each record is converted into XML using the export plugin requested (via a mapping of the metadataPrefix OAI argument to plugin identifier) and the result output as an OAI response.

Currently Eprints supports exporting access log records in OpenURL ContextObject format. To be OAI-compliant an interface should also support Dublin Core (but access logs don't make a lot of sense in DC). The following is our example request, exposed as an XML ContextObject in an OAI response:

<pre>
<ctx:context-object timestamp="2007-05-25T13:07:19Z" >
<ctx:referent>
<ctx:identifier>oai:eprints.ecs.soton.ac.uk:12614</ctx:identifier>
</ctx:referent>
<ctx:referring-entity>
<ctx:identifier>http://www.w3.org/2001/sw/</ctx:identifier>
</ctx:referring-entity>
<ctx:requester>
<ctx:identifier>urn:ip:127.0.0.1</ctx:identifier>
<ctx:private-data>Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)</ctx:private-data>
</ctx:requester>
<ctx:service-type>
<ctx:metadata-by-val>
<ctx:format>info:ofi/fmt:xml:xsd:sch_svc</ctx:format>
<sv:svc-list>
<sv:fulltext>yes</sv:fulltext>
</sv:svc-list>
</ctx:metadata-by-val>
</ctx:service-type>
</ctx:context-object>
</pre>