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1. Interface: Classname of the Java interface which defines the plugin, including package name. e.g. org.dspace.app.mediafilter.FormatFilter
2. Implementation Class: Classname of the implementation class, including package. e.g. org.dspace.app.mediafilter.PDFFilter
3. Names: (Named plugins only) There are two ways to bind names to plugins: listing them in the value of a plugin.named.interface key, or configuring a class in plugin.selfnamed.interface which extends the SelfNamedPlugin class.
4. Reusable option: (Optional) This is declared in a plugin.reusable configuration line. Plugins are reusable by default, so you only need to configure the non-reusable ones.

Configuring Singleton (Single) Plugins

This entry configures a Single Plugin for use with getSinglePlugin():

plugin.single.interface = classname

For example, this configures the class org.dspace.checker.SimpleDispatcher as the plugin for interface org.dspace.checker.BitstreamDispatcher:

plugin.single.org.dspace.checker.BitstreamDispatcher=org.dspace.checker.SimpleDispatcher

Configuring Sequence of Plugins

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Plugins are assumed to be reusable by default, so you only need to configure the ones which you would prefer not to be reusable. The format is as follows:

plugin.reusable.classname = ( true | false )

For example, this marks the PDF plugin from the example above as non-reusable:

plugin.reusable.org.dspace.app.mediafilter.PDFFilter = false

Validating the Configuration

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Which fields are indexed by DSIndexer? These fields are defined in dspace.cfg in the section "Fields to index for search" as name-value-pairs. The name must be unique in the form search.index.i (i is an arbitrary positive number). The value on the right side has a unique value again, which can be referenced in search-form (e.g. title, author). Then comes the metadata element which is indexed. '*' is a wildcard which includes all sub elements. For example:

search.index.4 = keyword:dc.subject.*

tells the indexer to create a keyword index containing all dc.subject element values. Since the wildcard ('*') character was used in place of a qualifier, all subject metadata fields will be indexed (e.g. dc.subject.other, dc.subject.lcsh, etc)

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The browse API maintains indexes of dates, authors, titles and subjects, and allows callers to extract parts of these:

• *Title: Values of the Dublin Core element *title (unqualified) are indexed. These are sorted in a case-insensitive fashion, with any leading article removed. For example: _"The DSpace System_Appears " would appear under 'D' rather than 'T'.
• *Author: Values of the *contributor (any qualifier or unqualified) element are indexed. Since contributor values typically are in the form 'last name, first name', a simple case-insensitive alphanumeric sort is used which orders authors in last name order.Note that this is an index of authors, and not items by author. If four items have the same author, that author will appear in the index only once. Hence, the index of authors may be greater or smaller than the index of titles; items often have more than one author, though the same author may have authored several items.The author indexing in the browse API does have limitations:
  • Ideally, a name that appears as an author for more than one item would appear in the author index only once. For example, 'Doe, John' may be the author of tens of items. However, in practice, author's names often appear in slightly differently forms, for example:

    Code Block
    Doe, John Doe, John Stewart Doe, John S.

    Currently, the above three names would all appear as separate entries in the author index even though they may refer to the same author. In order for an author of several papers to be correctly appear once in the index, each item must specify exactly the same form of their name, which doesn't always happen in practice.
  • Another issue is that two authors may have the same name, even within a single institution. If this is the case they may appear as one author in the index.These issues are typically resolved in libraries with authority control records, in which are kept a 'preferred' form of the author's name, with extra information (such as date of birth/death) in order to distinguish between authors of the same name. Maintaining such records is a huge task with many issues, particularly when metadata is received from faculty directly rather than trained library catalogers.
• *Date of Issue: Items are indexed by date of issue. This may be different from the date that an item appeared in DSpace; many items may have been originally published elsewhere beforehand. The Dublin Core field used is *date.issued. The ordering of this index may be reversed so 'earliest first' and 'most recent first' orderings are possible.Note that the index is of items by date, as opposed to an index of dates. If 30 items have the same issue date (say 2002), then those 30 items all appear in the index adjacent to each other, as opposed to a single 2002 entry.Since dates in DSpace Dublin Core are in ISO8601, all in the UTC time zone, a simple alphanumeric sort is sufficient to sort by date, including dealing with varying granularities of date reasonably. For example:

  Code Block
  2001-12-10 2002 2002-04 2002-04-05 2002-04-09T15:34:12Z 2002-04-09T19:21:12Z 2002-04-10

• *Date Accessioned: In order to determine which items most recently appeared, rather than using the date of issue, an item's accession date is used. This is the Dublin Core field *date.accessioned. In other aspects this index is identical to the date of issue index.
• *Items by a Particular Author*: The browse API can perform is to extract items by a particular author. They do not have to be primary author of an item for that item to be extracted. You can specify a scope, too; that is, you can ask for items by author X in collection Y, for example.This particular flavor of browse is slightly simpler than the others. You cannot presently specify a particular subset of results to be returned. The API call will simply return all of the items by a particular author within a certain scope.Note that the author of the item must exactly match the author passed in to the API; see the explanation about the caveats of the author index browsing to see why this is the case.
• *Subject: Values of the Dublin Core element *subject (both unqualified and with any qualifier) are indexed. These are sorted in a case-insensitive fashion.

Using the API

The API is generally invoked by creating a BrowseScope object, and setting the parameters for which particular part of an index you want to extract. This is then passed to the relevant Browse method call, which returns a BrowseInfo object which contains the results of the operation. The parameters set in the BrowseScope object are:

• How many entries from the index you want
• Whether you only want entries from a particular community or collection, or from the whole of DSpace
• Which part of the index to start from (called the focus of the browse). If you don't specify this, the start of the index is used
• How many entries to include before the focus entry

To illustrate, here is an example:

• We want 7 entries in total
• We want entries from collection x
• We want the focus to be 'Really'
• We want 2 entries included before the focus.

The results of invoking Browse.getItemsByTitle with the above parameters might look like this:

        Rabble-Rousing Rabbis From Sardinia
        Reality TV: Love It or Hate It?
FOCUS>  The Really Exciting Research Video
        Recreational Housework Addicts: Please Visit My House
        Regional Television Variation Studies
        Revenue Streams
        Ridiculous Example Titles:  I'm Out of Ideas

Note that in the case of title and date browses, Item objects are returned as opposed to actual titles. In these cases, you can specify the 'focus' to be a specific item, or a partial or full literal value. In the case of a literal value, if no entry in the index matches exactly, the closest match is used as the focus. It's quite reasonable to specify a focus of a single letter, for example.

Being able to specify a specific item to start at is particularly important with dates, since many items may have the save issue date. Say 30 items in a collection have the issue date 2002. To be able to page through the index 20 items at a time, you need to be able to specify exactly which item's 2002 is the focus of the browse, otherwise each time you invoked the browse code, the results would start at the first item with the issue date 2002.

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Checksum checker is used to verify every item within DSpace. While DSpace calculates and records the checksum of every file submitted to it, the checker can determine whether the file has been changed. The idea being that the earlier you can identify a file has changed, the more likely you would be able to record it (assuming it was not a wanted change).

org.dspace.checker.CheckerCommand class, is the class for the checksum checker tool, which calculates checksums for each bitstream whose ID is in the most_recent_checksum table, and compares it against the last calculated checksum for that bitstream.

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• Browser IntegrationMany recent browsers (IE7+, FF2+) can detect, or 'autodiscover', links to the document describing the search engine. Thus you can easily add your or other DSpace instances to the drop-down list of search engines in your browser. This list typically appears in the upper right corner of the browser, with a search box. In Firefox, for example, when you visit a site supporting OpenSearch, the color of the drop-down list widget changes color, and if you open it to show the list of search engines, you are offered an opportunity to add the site to the list. IE works nearly the same way but instead labels the web sites 'search providers'. When you select a DSpace instance as the search engine and enter a search, you are simply sent to the regular search results page of the instance.
• Flexible, interesting RSS FeedsBecause one of the formats that OpenSearch specifies for its results is RSS (or Atom), you can turn any search query into an RSS feed. So if there are keywords highly discriminative of content in a collection or repository, these can be turned into a URL that a feed reader can subscribe to. Taken to the extreme, one could take any search a user makes, and dynamically compose an RSS feed URL for it in the page of returned results. To see an example, if you have a DSpace with OpenSearch enabled, try:http://dspace.mysite.edu/open-search/?query-<your query>The default format returned is Atom 1.0, so you should see an Atom document containing your search results.
• You can extend the syntax with a few other parameters, as follows: |

  Parameter

  |

  	Values

  |

  format	atom, rss, html
  scope	<handle>—search is restricted to a collection or community with the indicated handle.
  rpp	number indicating the number of results per page (i.e. per request)
  start	number of page to start with (if paginating results)
  sort_by	number indicating sorting criteria (same as DSpace advanced search values

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Functionally, the embargo system allows you to attach 'terms' to an item before it is placed into the repository, which express how the embargo should be applied. What do 'we mean by terms' here? They are really any expression that the system is capable of turning into (1) the time the embargo expires, and (2) a concrete set of access restrictions. Some examples:
"2020-09-12" - an absolute date (i.e. the date embargo will be lifted)"6 months" - a time relative to when the item is accessioned"forever" - an indefinite, or open-ended embargo"local only until 2015" - both a time and an exception (public has no access until 2015, local users OK immediately)"Nature Publishing Group standard" - look-up to a policy somewhere (typically 6 months)
These terms are 'interpreted' by the embargo system to yield a specific date on which the embargo can be removed or 'lifted', and a specific set of access policies. Obviously, some terms are easier to interpret than others (the absolute date really requires none at all), and the 'default' embargo logic understands only the most basic terms (the first and third examples above). But as we will see below, the embargo system provides you with the ability to add in your own 'interpreters' to cope with any terms expressions you wish to have. This date that is the result of the interpretation is stored with the item and the embargo system detects when that date has passed, and removes the embargo ("lifts it"), so the item bitstreams become available. Here is a more detailed life-cycle for an embargoed item:

1. Terms Assignment. The first step in placing an embargo on an item is to attach (assign) 'terms' to it. If these terms are missing, no embargo will be imposed. As we will see below, terms are carried in a configurable DSpace metadata field, so assigning terms just means assigning a value to a metadata field. This can be done in a web submission user interface form, in a SWORD deposit package, a batch import, etc. - anywhere metadata is passed to DSpace. The terms are not immediately acted upon, and may be revised, corrected, removed, etc, up until the next stage of the life-cycle. Thus a submitter could enter one value, and a collection editor replace it, and only the last value will be used. Since metadata fields are multivalued, theoretically there can be multiple terms values, but in the default implementation only one is recognized.
2. Terms interpretation/imposition. In DSpace terminology, when an item has exited the last of any workflow steps (or if none have been defined for it), it is said to be 'installed' into the repository. At this precise time, the 'interpretation' of the terms occurs, and a computed 'lift date' is assigned, which like the terms is recorded in a configurable metadata field. It is important to understand that this interpretation happens only once, (just like the installation), and cannot be revisited later. Thus, although an administrator can assign a new value to the metadata field holding the terms after the item has been installed, this will have no effect on the embargo, whose 'force' now resides entirely in the 'lift date' value. For this reason, you cannot embargo content already in your repository (at least using standard tools). The other action taken at installation time is the actual imposition of the embargo. The default behavior here is simply to remove the read policies on all the bundles and bitstreams except for the "LICENSE" or "METADATA" bundles. See the section on Extending Embargo Functionality for how to alter this behavior. Also note that since these policy changes occur before installation, there is no time during which embargoed content is 'exposed' (accessible by non-administrators). The terms interpretation and imposition together are called 'setting' the embargo, and the component that performs them both is called the embargo 'setter'.
3. Embargo Period. After an embargoed item has been installed, the policy restrictions remain in effect until removed. This is not an automatic process, however: a 'lifter' must be run periodically to look for items whose 'lift date' is past. Note that this means the effective removal of an embargo is not the lift date, but the earliest date after the lift date that the lifter is run. Typically, a nightly cron-scheduled invocation of the lifter is more than adequate, given the granularity of embargo terms. Also note that during the embargo period, all metadata of the item remains visible. This default behavior can be changed. One final point to note is that the 'lift date', although it was computed and assigned during the previous stage, is in the end a regular metadata field. That means, if there are extraordinary circumstances that require an administrator (or collection editor—anyone with edit permissions on metadata) to change the lift date, they can do so. Thus, they can 'revise' the lift date without reference to the original terms. This date will be checked the next time the 'lifter' is run. One could immediately lift the embargo by setting the lift date to the current day, or change it to 'forever' to indefinitely postpone lifting.
4. Embargo Lift. When the lifter discovers an item whose lift date is in the past, it removes (lifts) the embargo. The default behavior of the lifter is to add the resource policies that would have been added had the embargo not been imposed. That is, it replicates the standard DSpace behavior, in which an item inherits it's policies from its owning collection. As with all other parts of the embargo system, you may replace or extend the default behavior of the lifter (see section V. below). You may wish, e.g. to send an email to an administrator or other interested parties, when an embargoed item becomes available.
5. Post Embargo. After the embargo has been lifted, the item ceases to respond to any of the embargo life-cycle events. The values of the metadata fields reflect essentially historical or provenance values. With the exception of the additional metadata fields, they are indistinguishable from items that were never subject to embargo.