With the framework used in Pyrounakis and Nikolaidou’s article, Omeka’s functionalities or capabilities are described below. My preliminary impression is Omeka has struck a good balance between ease-to-use and flexibility. The interfaces for both managing and visiting a site are friendly while a rich set of customizations can be achieved through theme mechanism, plug-ins, or even API.
1. Object model
The basic entity in Omeka is item. Each item contains a variety of metadata including keywords (or tags). Omeka supports twelve pre-defined item types to categorize items.
The next concept in its object model is metadata schema. In Omeka’s term, it is called element set and defined as “a set of related elements that are available to all items.” For example, at the installation, the “Dublin Core Metadata” element set is automatically imported to be used for describing the fifteen DC properties of an element. Each organization can add pre-defined element sets or make application-specific element sets. For example, libraries may want to add am METS element set, which is to describe descriptive, administrative, and structural metadata.
2. Collections and relations support
Omeka provides the mechanism of collection for modeling an object hierarchy. A collection is a group of items. Collections can be nested. Making or publishing collections is straightforward. Moreover, users can define their own types of “collection” to meet application-specific needs.
3. Metadata and digital content storage
Omeka adopts a flexible approach to metadata representation. Dublin Core is used as the default metadata set. Users can import other metadata sets of choice. Furthermore, Omeka users are encouraged to create customized item type (i.e., element set).
Individual items can be authored in a tabbed template that contains six categories of metadata including Dublin Core, tags, etc.
4. Search and browse
Omeka’s site-wide search capabilities include Boolean, keyword, and exact match options for admin and public queries.
5. Object management
Omeka provides friendly interfaces to support collection-building and metadata-creation workflows. It is easy to add or delete objects of different levels. However, Omeka does not yet offer a feature of item validation.
6. User interfaces
Site Visitors are given several options for exploring: (1) “Featured Collection” for casual browsers (2) “Recently Added” for visitors to look for “what’s new” (3) “Search Box” for simple or advanced search (4) “Browse Tab” for browsing a directory or collections.
Omeka facilitates easy sharing of content via clean and simple URLs generated by Omeka and bookmarking plug-in.
7. Access control
Omeka employs user access list to control accesses to various resources. User accounts can be easily created for different levels of access. In addition, Omeka allows integrating CAPTCHA service to reduce spam.
8. Multiple languages support
As of Omeka version 1.5.2, twenty one choices of localization are available, though some of which are still partial complete.
9. Interoperability features
It is easy to create standards-based, interoperable online exhibits in Omeka. Omeka items are compatible with bibliographic research tools like Zotero because of embedded bibliographic metadata. Besides, a variety of plug-ins can be installed to import or export CSV files, OAI-PMH records, and so on.
10. Level of customization
Omeka allows the customization of an application’s visual presentation through configurable themes; for example, the web site’s style, logo, font, etc.
Users can also expand or modify the default site functionality by using plug-ins. More than forty plug-ins are downloadable for use. For example, the “Contribution” plug-in offers a way to collect contributions from the public and manage them in the Omeka archive as items. Shipped plug-ins can even be modified or new plug-ins can be developed for further sophisticated customizations.
For web administrators, Omeka publishes an API for the customization of the deployment.