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Technical documentation

Technical data

For pedocs the document server software DIDoRe is used. That software is technically based on the Opus software system, version no. 3.1, but it has also been customised to the specific requirements of the DIPF | Leibniz Institute for Research and Information in Education and is subject to continual further development.
DIDoRe is a web application using PHP5 as a server-based programming language. From the client perspective, activated Javascript is being expected.
DIDoRe is run by a SUSE Linux 13.1 operating system, on a Dell Power Edge with 32 GB RAM and a 4 TB hard disk. The database is implemented in MySQL 5.

Data storage and backup

The database (metadata) and respective document files and documentations as well as the DIDoRe software as such are daily stored on a backup server. Such backups are available for six weeks to the day. Daily backups of a previous month are deleted during the latter ten days of a month, apart from the very first one, so that a full backup is available for each month of a past year.

Independent from this, monthly full backups are created and permanently stored on DVDs.


The system is designed to be redundant to ensure operation despite a fault. By applying autonomous monitoring and alarm functions, we assert that we can react appropriately upon disruptions that occur during the regular office hours common in public service.


Three check sums, i.e. CRC32, MD5 and SHA-1, are calculated for each data file in the process of its clearing. Once a document has been cleared for publication, these check sums can also be viewed in the full display of the respective data record.


Since July 2007, we have documented access rates to pedocs. To this end, server logs are assessed daily, access rates are counted for full displays of records as well as accounting for downloads of pertinent documents. Automated access rates (bots, crawlers etc.) are filtered out.
The download statistics of each document can be viewed from the full display of each respective document. The figure relates to the absolute download frequency of a document since it went online and further access figures are given for a selected month and a selected year. The average download rate of all documents that have been uploaded onto pedocs by the end of the given period is also listed.

The assessments is entirely based on our own statistics. The access rates listed here are not suitable for comparison with other document servers. But they merely allow for comparing the statistical relevance of a particular document on pedocs with other documents also provided by this server.

OAI interface

All of the metadata are made available to other service providers via a standardised interface according to the “Protocol for Metadata Harvesting” of the Open Archive Initiative (OAI-PMH 2.0) (Basic URL for pedocs: peDOCS is listed as a Data Provider in the Open Archive Initiative. Except for the abstracts, pedocs metadata are subject to the Creative Commons Licence CC0 1.0. Therefore, they can be freely used by third parties without naming the source.

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