![]() If an instantiation representing the same underlying archival entity already exists, the find method can simply return that same instantiation to avoid multiple copies and any inconsistencies which might result.Ĭollection, Bundle and Bitstream do not have create methods rather, one has to create an object using the relevant method on the container. ![]() A null return value from a static method can in general be dealt with more simply in code. A constructor would have to throw an exception in this case. To construct a brand new item in the system, rather than simply instantiating an in-memory instance of an object in the system.įind methods may often be called with invalid IDs, and return null in such a case. "Constructing" an object may be misconstrued as the action of creating an object in the DSpace system, for example one might expect something like: You can also commit a context, which means that any changes are written to the database, and the context is kept active for further use. You should always abort a context if any error happens during its lifespan otherwise the data in the system may be left in an inconsistent state. If anything has gone wrong, abort is called to roll back any changes and free up the resources. If all goes well, complete is called to commit the changes and free up any resources used by the context. Several operations may be performed using the context object. Typical use of the context object will involve constructing one, and setting the current user if one is authenticated. For example, when first installing the system, there are no authorized administrators who would be able to create an administrator account!Īs noted above, the public API is trusted, so it is up to applications in the application layer to use this flag responsibly. This should only be used in rare, specific circumstances. For example, the Web UI adds a session ID, so that when the logs are analysed the actions of a particular user in a particular session can be tracked.Ī flag indicating whether authorization should be circumvented. Such a group is called a 'special group'.Īny extra information from the application layer that should be added to log messages that are written within this context. For example, a user might automatically be part of a particular group based on the IP address they are accessing DSpace from, even though they don't have an e-person record. Checksum checkerĪny 'special groups' the user is a member of. Support for Other Metadata Schemas 10.2.6. The Configuration Manager (ConfigurationManager) 10.1.2. Web sites, though, are the most common users of Dublin Core.Table of Contents 10.1. So, while Dublin Core targets electronic resources, it aims to be flexible enough to help in searches for more traditional formats of data too. Dublin Core has always held that resource discovery should be independent from the medium of the resource. It has since become international in scope and has representatives from more than 20 countries now contributing. The Dublin Core Metadata Initiative began in 1995, taking its name from the location of the original workshop, Dublin, Ohio. HTML, XML, RDF, and relational databases are among the more common methods. While enabling searches to be more specific, qualifiers are also more complex and can pose challenges to interoperability.Įach method of recording or transferring Dublin Core metadata has its plusses and minuses. Qualified Dublin Core increases the specificity of metadata by adding information about encoding schemes, enumerated lists of values, or other processing clues. Simple Dublin Core expresses elements as attribute-value pairs using just the 15 metadata elements from the Dublin Core Metadata Element Set. Two forms of Dublin Core exist: Simple Dublin Core and Qualified Dublin Core. The 15 metadata elements used by Dublin Core are: title (the name given the resource), creator (the person or organization responsible for the content), subject (the topic covered), description (a textual outline of the content), publisher (those responsible for making the resource available), contributor (those who added to the content), date (when the resource was made available), type (a category for the content), format (how the resource is presented), identifier (numerical identifier for the content such as a URL), source (where the content originally derived from), language (in what language the content is written), relation (how the content relates to other resources, for instance, if it is a chapter in a book), coverage (where the resource is physically located), and rights (a link to a copyright notice). Dublin Core is made up of 15 metadata (data that describes data) elements that offer expanded cataloging information and improved document indexing for search engine programs. Dublin Core is an initiative to create a digital "library card catalog" for the Web.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |