Difference between revisions of "Basic Concepts"

Revision as of 10:27, 4 December 2007

Virtual Research Environments and Community Portals

Communities of scientists and research use the gCube middleware and Grid resources to setup Virtual Research Environments (VRE) for Content exchange and collaboration. The gCube empowered VRE provides a framework of applications, services and resources to support the underlying processes of research. The purpose of a VRE is to help researchers in all disciplines by managing the increasingly complex range of tasks involved in carrying out research.

Portals provide the required tools for content search, browsing, annotation, metadata management and other value added capabilities.

Content, Information Objects, and Collections

The Content concept encompasses the data and information that the VRE handles and makes available to its users.It is an umbrella concept used to aggregate all forms of information objects that a VRE collects, manages, and delivers, including such objects as annotations, and metadata.

Content is composed of a set of information objects organized into collections.

The notion of Information Object represents the main entity populating the Content of a Virtual Research Environment. An Information Object can be a complex, multimedia and multi-type object with parts, such as a sound recording associated with a set of slides, a music score, political and economic data associated with interactive simulations, a Ph.D. thesis which includes a representation of a performance, or a simulation experiment and the experimental data set adopted, a data stream representing the pool of data continuously measured by a sensor.

Collections represent the “classic” mechanism to organize Information Objects and to provide focused views of the VRE Content. They are sets of Information Objects aggregated for some management purposes, e.g. behave as a single entity for access rights management. Another typical role assigned to collections is organizing the search space into restricted and/or topic-based sub-sets of it, thus allowing improving the search results.

Communities exploit any VRE collection through the features offered by the Web Portals.

Content Annotation

As a definition of annotation we could say that it is a written explanation or criticism or illustration that is added to an information object. Informally, annotations are comments or notes made by users in order to expose their ideas about a document. The annotations’ role in a digital library is very important since they promote collaboration between the users of the library. Through annotations, new ideas and concepts can be discussed, something which may help the understanding of an annotated object and the advance of knowledge about it.

In gCube a number of different types of annotations are provided. The first distinction has to do with the content of the annotation. So, there are text annotations and associations. By adding a text annotation a user may add a comment or a note about a gCube information object. On the other hand, associations are used in order to create conceptual links between two or more information objects.

Annotations can be applied to the whole document or just to a part of it. In the first occasion text annotations or associations are denoted as generic or non-anchored annotations and in the second as anchored ones.

Generic annotations should be used when the comment or the association is referred to the whole entity. General comments, notes and additional information about an information object belong to that category.

Anchored annotations introduce a more interesting concept of annotating an object. Now, the author is able to bring in information about a specific part/ fragment of an information object. Presumably, this extends the capabilities of users as they may indicate in a visual and descriptive way which part of the information object their comment refer to.

Metadata

The “classic” definition of metadata is “data about data”. Metadata are used for describing different aspects of data, such as the semantics, provenance, constraints, parameters, content, quality, condition, and other characteristic. These data can be used in different contexts and for a diversity of purposes; usually, they are associated with an Information Object as a means for facilitating the effective discovery, retrieval, use and management of the object. There are a number of schemes for classifying metadata. One of them consists in classifying metadata according to the specific role they play:

Descriptive metadata 

metadata that provide a mechanism for representing attributes describing and identifying an information object, such as its creator, title, publisher, date, format, list of keywords characterising its contents. The term “descriptive” is used here in a consistent, but broader sense than in “descriptive cataloguing”.

Administrative metadata 

metadata for managing an information object. This category of metadata may include metadata detailing: (i) technical characteristics of the information object, (ii) the history of the operations performed on the information object since its creation/ingest, (iii) means of access, (iv) how the authenticity and integrity of the information object can be verified.

Preservation metadata 

metadata designed to support the long term accessibility of an information object by providing information about its content, technical attributes, dependencies, management, designated community(ies) and change history. Preservation Metadata have been identified as essential for the long-term management of digital objects. The Reference Model for an Open Archival Information System (OAIS) provides an excellent overview of the role of preservation metadata in the management overtime of digital resources.