Metadaten- & Content-Austausch mit externen Servern

Make external content available to your users

For your users, content from connected source systems appears in the search and browse functions. Depending on the connection level, the content can also be used within your applications connected to edu-sharing (e.g. learning platforms). In addition, you can make developed sources available to other external education servers or e-learning repositories or departments via interfaces.

The metadata of the external content is obtained via interfaces and protocols such as OAI and REST. These interfaces are either queried live or used to import external metadata. For this purpose, the source systems (libraries, educational servers, other content repositories) must in turn provide appropriate interfaces.

If the external source does not offer an OAI or REST interface, but a queryable, structured database (e.g. MySQL), a specific connector for edu-sharing can be implemented. This way, a classic content database (for example, the database of a web CMS) can be upgraded to a fully-fledged content or OER referatorium or repository.

If a CSV or Excel export is possible for the external source, the metadata can be transferred to edu-sharing via CSV import. This usually requires import adaptations.

Via such connectors and the above-mentioned OAI/REST interfaces, the source metadata (and possibly the content itself) is usually imported nightly into the edu-sharing metadata management. From here, the functions of an e-learning or OER repository or repository are then available.

When importing, either only the metadata or the content itself can be imported.

• If only the metadata is imported, then edu-sharing is used as a referatorium:

  The external contents can be found with edu-sharing, the files themselves are only referenced, i.e. linked.

• If metadata and content are managed in edu-sharing, then it is called a repository:

  All edu-sharing functions, including rendering (the playback service), are then available for the use of external content.

If neither metadata nor contents are imported, but are queried live at the time of the search, this is referred to as a federated search across the connected sources. In this case, usually only the metadata provided by the source can be displayed, as live mapping would cause unfavourable runtime behaviour. In addition, the search results of several sources cannot be ranked in a search result list.

1st level of integration: edu-sharing as a federated search engine

If edu-sharing is used as a federated search, the source metadata is retrieved live at the time of the user's search. For each source, the best search results are displayed in a column or tab. This is the simplest level of integration, but it does not provide an optimal user experience:

• The relevance of search results cannot be calculated across all sources. Therefore, less relevant search results may displace the more relevant ones.

Example: A search results page can display 10 hits (before scrolling).

The 1st source offers the best 10 search results and the 2nd source only places 11-20.

Nevertheless, 5 search results are displayed for each source.

The 5 hits of the less relevant source displace the 5 more relevant places 6-10 of the 1st source.

• At this connection level, the content object is only linked, i.e. the user is redirected to the website of the source (media break).
• The playback function (edu-sharing rendering) cannot be used because the edu-sharing rendering service has no access to the content.
• The content object cannot be embedded in the WYSIWYG fields of connected learning platforms unless the edu-sharing rendering service has been extended for this purpose (e.g. YouTube and vimeo).
• Links to the external objects can be provided.

The federated search is used:

• when sources are to be indexed with little effort,
• if the owners of the source do not allow replication (copy making) of the metadata,
• if the source contains too many objects and the edu-sharing operator does not want to import this quantity.

2nd level of integration: edu-sharing imports metadata from the external source

The next connection level offers more convenience for the user. For this, the metadata of the external source is imported (e.g. in nightly synchronisation processes). In the search and browse functions, the contents of the external sources appear like contents from your own system. The origin of the objects can be made recognisable via metadata or a logo on the object.

• The most relevant results for the respective search query can be determined from all sources and displayed with the correct ranking.
• But even with this connection level, the content object is only linked, i.e. the user is redirected to the website of the source (media break).
• The playback function (edu-sharing rendering) cannot be used either.
• The content object cannot be embedded in the WYSIWYG fields of connected learning platforms unless the edu-sharing rendering service has been extended for this purpose (e.g. YouTube and vimeo).
• Links to the external objects can be provided.

Example: From external sources, e.g. education servers of other countries

metadata is readily taken from external sources, e.g. education servers in other countries, in order to translate it

metadata and curricula ("mapping").

The sources often require that the content may only be viewed or downloaded from their own websites.

viewed or downloaded only on their own websites.

3rd level of integration: edu-sharing imports metadata and content from the source.

The most recommended and best solution for users is a metadata and content import.

• As in stage 2, a correctly ranked search result list is possible.
• The object can also be used, played and edited directly (provided the user has the rights to do so).
• The source content can be embedded in the pages of connected e-learning applications (e.g. Moodle).
  i.e. a video can be played directly in the LMS course, for example.

Avoiding media discontinuity despite low connection levels

At low connection levels, the edu-sharing delivery and rendering system can be adapted to "fetch" the object at the time of use. The source operator must allow this "live access".

Alternatively, the source system can be extended to include an edu-sharing rendering. The two rendering services must be configured to work together. This option is suitable, for example, for publishers or other commercial content providers who want to monitor access to their content (e.g. counting accesses per user group or delivery according to membership of certain media centres).

YouTube video - embedded in a Moodle course via edu-sharing

Making your own metadata and content available via interfaces

If you operate edu-sharing as a referatorium or as a repository, you can make your metadata - or - metadata & contents available to external partners.

Provision using the edu-sharing OAI interface

Using the edu-sharing OAI interface you can allow partners to retrieve metadata for import into your own system. For this purpose, the partners usually agree on times with little user activity (e.g. at night). The metadata are "fetched" in subsets (e.g. in increments of thousands).

Providing access via edu-sharing REST interface

1. As with the OAI interface, your partners can query metadata for nightly transfers. In contrast to the OAI interface, the REST interface is intended for targeted search queries, not for complete transfers in partial steps.
2. Main use: For a current search in the partner system, suitable content objects can be requested "live" from your edu-sharing system. In this case, your edu-sharing is used as the source for a federated search of the partner.
3. The REST interface is also used by edu-sharing developers to retrieve content data for display in user interfaces.
4. In addition, the REST interface allows interactions such as writing back metadata or collecting statistical usage information.

Mapping between metadata formats & catalogues

Often the source and recipient do not have the same metadata formats or use different catalogues.

The metadata format determines which "form fields" an editor can fill in when entering metadata. It also determines in which structure the metadata can be queried via an interface. Such form templates are defined in metadata standards. Since libraries, educational servers and other users have different requirements for the scope and type of descriptions, several standards have been established. edu-sharing supports the formats LOM, LOM-DE and ELEXIER so far. The internal metadata structure of edu-sharing is based on LOM. When importing or exporting, other metadata formats are translated to the internal metadata format ("mapping"). The internal metadata format of edu-sharing can be adapted by configuring an XML file. The mapping for import and export can also be configured by an administrator.

Catalogues determine which values can be entered in the "form fields". Typical examples are subject area or curriculum assignment. Subject areas differ between the school and university sectors, and curriculum assignment differs between individual federal states. Catalogues are usually coordinated and adapted before an edu-sharing instance goes live.

• For the subject metadata, the Dewey Decimal Classification (DCC) is usually used and
• for keywords the Gemeinsame Normdatei (GND) of the German National Library is used.
• Curriculum assignment catalogues are available for several German states and can be represented in a metadata chain (state > school type > subject area > year > subject).
• For the content type, a catalogue with the learning resource type is used and usually adapted.
• All of these metadata can of course be adapted to your domestic specifications.

When importing and exporting, metadata format and catalogues can be translated from or into external formats. The edu-sharing mapping service must be configured for this purpose. Mappings are available for the following formats:

• LOM
• LOM-DE
• ELEXIER

Adaptation support from IT professionals

To connect to external sources or recipients, you need IT professionals who are familiar with the edu-sharing architecture and the technologies and standards mentioned here.
You can find trained professionals in the edu-sharing.com service partner network:

• OAI, REST
• LRMI
• OAuth2, BasicAuth
• LOM, LOM-DE, DC, ELEXIER
• JSON, XML, XSD
• edu-sharing mapping service
• edu-sharing rendering service
• edu-sharing API and interface