dLibra software is a professional digital repository which can be used to build systems such as:
- digital libraries,
- institutional digital repositories,
- digital archives.
dLibra system stores digital objects in any format (e.g. multifile HTML pages, PDF documents, audio and video recordings, etc.). Every stored digital object can be described using metadata schema defined by the concrete repository. Digital objects can be made available to the readers on the Internet throught repository’s web pages. dLibra repositories can also cooperate with other IT systems using well known communication standards such as OAI-PMH protocol or RSS feeds. The following illustration presents architecture of the digital repository based on the dLibra software:
On the illustration we can point out three basic elements of the dLibra system:
- Digital repository server (in the middle of the illustration) – responsible for the realization of all repository’s functions, running on a dedicated computer (or several computers), unavailable directly to the end-users.
- Editor’s and Administrator’s application – allows ursers which create digital repository (submit digital objects, describe digital objects etc.) and administrate it to use repository’s functions.
- Reader’s application – available throught web pages, allows users („readers”) to use the digital objects stored in the repository.
Basis on the scope of used functions we can divide dLibra users into three basic groups:
- Administrators – responsible for dLibra system configuration, adjustment to specific needs of concrete institution, management of the whole repository (e.g. users management).
- Editors – users which submit and describe digital objects, responsible for the content and the metadata of digital objects stored in the repository.
- Readers – users which use digital objects stored in dLibra repository, browse repository’s web pages, search and download or view on-line digital objects of their interest.
One of the most important functions of the dLibra system is the storage and the presentation of digital objects. Among many features in the field of storage and presentation, the most important are:
- Hierachical repository structure – structure of directories and publications created by the editors and available only for them. This is the structure where the digital objects are placed.
- Collections – lists of objects which are available to the readers. Collections are usually used to divide thematically stored digital objects, but it is of course possible to divide digital objects in other way. The structure of the collections is hierarchical – collections may be divided into subcollections, e.g. with narrower thematical scope. Every digital object stored in the repository may be assigned to one or more collections.
- Groups of digital objects – dLibra software allows editors to create groups of digital objects which have common features. Groups simplify the management (e.g. modification of common properties of all objects in a group, such as: assignment to collections or metadata) and the presentation of the digital objects in a group.
- Planned digital objects – dLibra software allows editors to create planned digital objects. These kind of objects informs users about digital content which is planned to be stored in a repository. Planned digital objects contain only metadata (do not contain content).
- Content versioning – dLibra system allows editors to update the content of a digital object and keep all earlier versions of the content in the system. As a result dLibra system stores all versions of the digital object’s content.
As mentioned earlier, every digital object in the dLibra repository has associated metadata. The metadata can be divided into three basic categories:
- Technical metadata – contain infromation about the structure of an object, types, sizes and control sums of particular files, etc.
- Administrative metadata – contain information about the location of an object in the repository’s structure, rights of users to specific objects, the state of an object, etc.
- Descriptive metadata – contain assignment of a digital object to collection and description of the digital content it contains. By default, the descriptive metadata schema is based on the Dublin Core standard. It is possible to modify (adjust) the descriptive metadata schema by the system administrator. Descriptive metadata can be imported from other, external metadata formats such as XML (e.g. MASTER, MARCXML, RDF), MARC 21, BibTeX.
Digital objects stored in dLibra repository are available to the readers throught the web pages. Readers have also various functions available on the web pages such as:
- Local search – dLibra repository allows its users to search for stored digital objects using simple or advanced search. Simple search can be performed in specific elements of metadata (e.g. in titles), in the whole metadata and in the text of the digital objects if the format of the object allows for text extraction (currently it is possible for MS Office documents, OpenOffice documents, documents in HTML, TXT, PDF, DjVu, etc.). Advanced search mechanism extends simple search by adding possibility to combine simple search queries using logical operators. In addition simple and advanced search can be narrowed to the scope of a specific collection.
- Distributed search – each dLibra repository can provide descriptive metadata of all stored digital objects throught the OAI-PMH protocol. Each repository can harvest metadata from other OAI-PMH based repositories. Thanks to these functions it is possible to search for digital objects in the dLibra repositories network in which each repository exchanges metadata with others. Search in the scope of repositories network is possible both on all metadata level and specific field of metadata scheme level.
- Values indexes – besides local and distributed search it is possible to browse indexes of values. Values of each element of metadata (e.g. titile, author) are browsable on the dLibra repository web pages in form of alphabetically sorted indexes of values.
- Collections of objects – reader may browse repository using collections of objects defined by the editors. In the scope of a specific collection it is possible to search and browse the list of objects in this collection.
- Readers accounts – readers may create an account in dLibra repository which among other things allows user to subscribe for bulletins with news send by e-mail.
dLibra repositories may communicate with other, external IT systems using among other things:
- RSS feeds – many information (such as lately added digital objects, planned digital objects, news) available on dLibra repository web pages are also available in form of RSS feeds. It is also possible to search dLibra repository using RSS feeds.
- OAI-PMH protocol – each dLibra repository may communicate with other repositories which support OAI-PMH protocol. This protocol allows to exchange metadata between different IT systems. As a result it is possible among other things to create distributed search mechanism. Moreover, each dLibra repository provides metadata of stored digital objects in Dublin Core format and in specific format of the concrete repository. OAI-PMH support in dLibra allows other IT systems to easily use metadata from dLibra repositories.
- SSO – dLibra repository may be configured to cooperate with Single Sign-On system, therefore it may be easily integrated with existing web portals and IT systems which use Single Sign-On system. Currently SSO mechanism is based on the CAS system.
- LDAP protocol – dLibra system users may be authenticated basis on external LDAP system. In addition it is possible to create dynamic groups of users based on the LDAP attributes and use these groups to authorize access to digital objects.
dLibra repository web pages are specially prepared for communication with Internet search engines, therefore digital objects stored in dLibra repositories are better exposed on the Internet and it is easier to find them in different search engines. dLibra repository provides administrators with expanded rights management system. Rights are granted on many levels, starting from rights on administrative level and ending on rights to particular digital objects. In addition, access to dLibra repository may be controlled basis on IP addresses (or range of addresses) – e.g. for comupers located in reading room grant access to all digital objects in repository, for other computers grant access only to part of the digital objects.