DSpace REST API - Bojan Suzic

Integration, testing, documentation and further development of DSpace REST services for 1.x and 2.0 versions. - Bojan Suzic

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Details

Project Title:	DSpace REST API
Student:	Bojan Suzic, University of Technology Graz
Mentors:	Aaron Zeckoski, Mark Diggory
Contacting author:	bojan AT student . tugraz DOT at - using subject line DSpace
SCM Location for Project:	http://scm.dspace.org/svn/repo/modules/rest

Project description

The REST approach promotes simplification and decoupling of software architecture, enabling further scalability, portability, granularity and simplified interaction of software systems and components.
The aim of this project is to provide DSpace with REST capable API and underlying component, which will enable developers and end-users to exploit the advantages of such approach.

Some of uses this module is intended to provide could be, for instance:

interaction between DSpace systems and/or other repositories
automation of different activities, e.g. submission of packages
integrating repositories in process workflows of other applications or systems
interaction with many kinds of systems or web applications, such as CMS, LMS, LCMS, VLS, AMS etc
providing of other approaches to UI, such as client based/run UI
crawling of repositories, exposing information in structural way

This project is continuation of last year's activities, supported by Google as part of GSoC 2009. In the first stage the basic support for REST for DSpace is provided, exposing many parts of DSpace functionality to the clients.

In this year's GSoC the following activities should be primarily addressed:

integration of existing code in the system
alignment of REST API with currently available DSpace features/functionality, e.g. adding of new features
extending of existing code, in order to provide better handling of management and injection functions
providing more detailed documentation and examples for end users
testing activities, e.g. cooperation/coordination with other GSoC 10 project Unit testing
promotion of DSpace REST interaction (by taking part in integration with other systems)

Detailed activities

In the following sections main activities are elaborated in detail.

REST API Methods

Changes in comparison to existing support are marked with red color. Please note that changes may appear as:

introduction of new method
extending of existing method, by implementing new functionality (e.g. GET/PUT/DELETE)
extending of existing method, by changing its parameters, output etc

Naming convention for endpoints
DSpace 1.x and 2.x are treating the resources on different way. 2.x is more generalized, suggesting the use of RDF-like interrelation notations.

Repository browsing

Earlier Implementation Description - GSoC09

C	Verb	URL	Description	Mandatory parameters	Optional parameters	Sorting fields	Response Data	Formats	Response codes
	`GET`	`/communities`	Returns a list of all communities on the system or return just top level communities.	-	`topLevelOnly=true` `idOnly=false`	`id` name `countitems`	`countitems` - number of items under community `handle` - handle of the community (unique persistent resource identifier) `id` - entity identifier, internal to the system `name` - entity name `type` - entity type (object type in the system) `collections` - collections contained in the community, ordered by id `ancestors` - ancestors of the community, ordered by id `children` - subcommunities, ordered by id `admins` - group administrators, ordered by id `metadata` - community metadata `administrators` - default group of administrators Response code details: `204` - if there are no communities on the system	`json` `xml`	200, 204, 400, 500
•	`GET`	`/communities/{id`}	Return information about `id` community.	`id`	`idOnly=false`	-	`countitems` - number of items under community `handle` - handle of the community (unique persistent resource identifier) `id` - entity identifier, internal to the system `name` - entity name `type` - entity type (object type in the system) `collections` - collections contained in the community, ordered by id `ancestors` - ancestors of the community, ordered by id `children` - subcommunities, ordered by id `admins` - group administrators, ordered by id `metadata` - community metadata `administrators` - default group of administrators	`json` `xml`	200, 400, 404, 500
•	`GET`	`/communities/{id}/ancestors`	Return a list of all ancestor communities of the `id` community.	`id`	`idOnly=false` `immediateOnly=true`	`id` `name` `countitems`	`countitems` - number of items under community `handle` - handle of the community (unique persistent resource identifier) `id` - entity identifier, internal to the system `name` - entity name `type` - entity type (object type in the system) `collections` - collections contained in the community, ordered by id `ancestors` - ancestors of the community, ordered by id `children` - subcommunities, ordered by id `admins` - group administrators, ordered by id `metadata` - community metadata	`json` `xml`	200, 204, 400, 500
•	`GET`	`/communities/{id}/children`	Returns a list of immediate sub-communities (children) of the `id` community.	`id`	`idOnly=false`	`id` `name` `countitems`	`countitems` - number of items under community `handle` - handle of the community (unique persistent resource identifier) `id` - entity identifier, internal to the system `name` - entity name `type` - entity type (object type in the system) `collections` - collections contained in the community, ordered by id `ancestors` - ancestors of the community, ordered by id `children` - subcommunities, ordered by id `admins` - group administrators, ordered by id `metadata` - community metadata `administrators` - default group of administrators	`json` `xml`	200, 204, 400, 500
•	`GET`	`/communities/{id}/collections`	Return a list of collections in the `id` community.	`id`	`idOnly=false`	id `name` `countitems`	`countitems` - number of items under collection `handle` - handle of the collection `id` - entity identifier, internal to the system `name` - entity name `type` - entity type (object type in the system) `items` - items contained in the collection, ordered by id `communities` - owners of the collection, ordered by id `admins` - group administrators, ordered by id `licence` - collection licence `templateItem` - template item Response code details: `204` - if there are no collections	`json` `xml`	200, 204, 400, 500
•	`GET`	`/communities/{id}/recent`	Return a list of recent submissions to a community.	`id`	`idOnly=false`	`id` `name` `lastmodified` `submitterId` `submitterName`	`id` - entity (item) identifier, internal to the system `handle` - handle of the item `isArchived` - archival status of the item `isWithdrawn` - withdrawal status of the item `lastModified` - timestamp of last modification `metadata` - item metadata `name` - item name `submitter` - submiter entity `type` - entity type (object type in the system, item in this case) `bitstreams` - bitstreams related to the item `bundles` - bundles related to the item `collections` - collections related item appear in `communities` - communities related item appear in Response details: `204` - if there are no recently submitted items	`json` `xml`	200, 204, 400, 500
•	`GET`	`/communities/{id}/logo`	Return a community logo	`id`	-	-	Contains community logo (bitstream)	`binary`	200, 400
•	`GET`	`/collections`	Return a list of all collections in the system.	-	`idOnly=false` `isAuthorized=false`	`id` `name` `countitems`	Contains item count, identifiers, name and handle of collections, or 204 if there are none of them. In the case idOnly=true is used, returns only identifiers of collections.	`json` `xml`	200, 204, 400, 500
•	`GET`	`/collections/{id`}	Return information about `id` collection	`id`	`idOnly=false`	`id` `name` `countitems`	`countitems` - number of items under collection `items` - items present in the collection `id` - entity (collection) identifier, internal to the system `handle` - handle of the collection `licence` - collection licence `name` - collection name `type` - entity type (object type in the system, item in this case) `communities` - communities related collection appear in `submiters` - default group of submitters, if there is one `administrators` - default group of administrators, if there is one `templateitem` - template item for collection, if there is one	`json` `xml`	200, 204, 400, 500
•	`GET`	`/collections/{id}/ancestors`	Return a list of all ancestor communities a collection with `id` belongs to.	`id`	`idOnly=false` `immediateOnly=true`	`id` `name` `countitems`	`countitems` - number of items under community `handle` - handle of the community (unique persistent resource identifier) `id` - entity identifier, internal to the system `name` - entity name `type` - entity type (object type in the system) `collections` - collections contained in the community, ordered by id `ancestors` - ancestors of the community, ordered by id `children` - subcommunities, ordered by id `admins` - group administrators, ordered by id `metadata` - community metadata `administrators` - default group of administrators	`json` `xml`	200, 204, 400, 500
•	`GET`	`/collections/{id}/items`	Returns a list of all items from the collection `id`.	`id`	`idOnly=false` `inArchive=false`	`id` `name` `lastmodified` `submitterId` `submitterName`	`id` - entity (item) identifier, internal to the system `handle` - handle of the item `isArchived` - archival status of the item `isWithdrawn` - withdrawal status of the item `lastModified` - timestamp of last modification `metadata` - item metadata `name` - item name `submitter` - submiter entity `type` - entity type (object type in the system, item in this case) `bitstreams` - bitstreams related to the item `bundles` - bundles related to the item `collections` - collections related item appear in `communities` - communities related item appear in Response details: `204` - if there are no items	`json` `xml`	200, 204, 400, 500
•	`GET`	`/collections/{id}/logo`	Return a collection logo	`id`	-	-	Contains collection logo (bitstream)	`binary`	200, 400

Note: modifier idOnly is referred only to first layer of the results. For all other layers (e.g. nested results) only ids are returned in some cases, due to possible loops. Example: for community containing collections, on second level the response contains only ids for some elements where multiple loops may be created (community->has_collection->has_community....). Other data is modified according to idOnly flag.

Optional parameters

Parameter	Description
`topLevelOnly`	returns only top level communities
`idOnly`	if true return only the identifiers for the record
`immediateOnly`	return only direct parent community
`isAuthorized`	return only collections user has permission to work on
`inArchive`	return archived items for respective collection

Sorting fields:

Parameter	Description	Ordering supported
`id`	sort results by entity id	`asc` \| `ascending` `desc` \| `descending`
`name`	sort results by entity name	`asc` \| `ascending` `desc` \| `descending`
`countitems`	sort results by number of items contained	`asc` \| `ascending` `desc` \| `descending`
`lastmodified`	sort results by date of last item modification	`asc` \| `ascending` `desc` \| `descending`
`submitterName`	sort results by submitter name	`asc` \| `ascending` `desc` \| `descending`
`submitterId`	sort results by submitter id	`asc` \| `ascending` `desc` \| `descending`

Controlling results

Parameter	Description	Default	Example
`_start`	position of the first entity to return	0 (first)	`_start=5` to list 6th item and onwards
`_page`	page of data to display	0 (first)	`_page=2`, to display second page with query results
`_perpage`	number of results to show on each page	0 (all)	`_perpage=10` to display 10 results per page
`_limit`	maximum number of entities to return	0 (all)	`_limit=50`
`_sort`		the sort order to return entities in should be comma separated list of field names suffix determines ordering suffixes: `_asc`, `_ascending`, `_desc`, `_descending` ascending default	`sort=name` `_sort=name,email_desc,lastname_desc`

Response codes

Code	Description
200	OK
201	Created
204	No content
400	Bad request
401	Unauthorized
403	Forbidden
404	Not found
405	Method not allowed
500	Internal server error
503	Service unavailable

Repository manipulation

C	Verb	URL	Description	Mandatory parameters	Optional parameters	Response Data	Formats	Response codes
•	`PUT`	`/communities/{id`}	Change description of `id` community	`id`	`name` `metadata` `logo`	Response code	`json` `xml`	200, 400, 401, 403, 500
•	`POST`	`/communities`	Add community to the system	`name`	`logo` `parent` other metadata	`Id` of newly created community	`json` `xml`	200, 400, 401, 403, 500
•	`DELETE`	`/communities/{id`}	Delete community from the system	`id`	-	Response code	`json` `xml`	200, 400, 401, 403, 500
•	`DELETE`	`/communities/{id}/administrators`	Remove the administrators group from the community	`id`	-	Response code	`json` `xml`
•	`DELETE`	`/communities/{id}/collections/{cid`}	Remove collection `cid` from community `id`	`id`	`cid`	Response code
•	`DELETE`	`/communities/{id}/children/{cid`}	Remove subcommunity `cid` from community `id`	`id`	`cid`	Response code
•	`POST`	`/communities/{id}/administrators`	Create a default administrators group if one does not already exists	`id`	-	`Id` of newly created group
•	`POST`	`/communities/{id}/collections`	Create a new collection within community `id`	`id`	-	`Id` of newly created collection
•	`PUT`	`/communities/{id}/collections/{cid`}	Add an existing collection `cid` to community `id`	`id` `cid`	--	Response code
•	`POST`	`/communities/{id}/children`	Create a new subcommunity within community `id`	`id`	-	`Id` of newly created subcommunity
•	`PUT`	`/communities/{id}/children/{cid`}	Add an existing community `cid` as a subcommunity of community `id`	`id` `cid`	-	Response code
	`PUT`	`/communities/{id}/metadata`	Set metadata value	`id`	`metadataField` `metadataValue`	Response code
•	`PUT`	`/collections/{id`}	Change description of `id` collection	`id`		Response code	`json` `xml`	200, 400, 401, 403, 500
•	`POST`	`/collections`	Add collection to the system	`name` `communityId`		`Id` of newly created collection	`json` `xml`	200, 400, 401, 403, 500
•	`DELETE`	`/collections/{id`}	Delete collection from the system	-	-	Response code	`json` `xml`	200, 400, 401, 403, 500
	`DELETE`	`/collections/{id}/items/{cid`}	Delete item `cid` from collection `id`	`id`	`cid`	Response code	`json` `xml`
	`PUT`	`/collections/{id}/logo`	Set the logo for collection `id`	`id`		Response code
	`POST`	`/collections/{id}/administrators`	Create a default administrators group if one does not already exists	`id`	-	Response code
	`DELETE`	`/collections/{id}/administrators`	Remove the administrators group from the collection	`id`	-	Response code
	`PUT`	`/collections/{id}/submitters`	Create a default submitters group if one does not already exists	`id`	-	Response code
	`DELETE`	`/collections/{id}/submitters`	Remove the submitters group	`id`	-	Response code
	`PUT`	`/collections/{id}/templateitem`	Create an empty template item for this collection	`id`	-	Response code
	`DELETE`	`/collections/{id}/templateitem`	Remove the template item from the collection	`id`	-	Response code
	`POST`	`/collections/{id}/items`	Add an item to the collection	`id`	`itemId`	Response code
	`PUT`	`/collections/{id}/metadata`	Set metadata value	`id`	`metadataField` `metadataValue`	Response code
	`PUT`	`/collections/{\id}/licence`	Set collection licence	`id`	`licence`	Response code

Content searching

C	Verb	URL	Description	Mandatory parameters	Optional parameters	Sorting fields	Response Data	Formats	Response codes
	`GET`	`/search`	Return a list of all objects found by searching criteria. Notice: community and collection are mutually exclusive options.	-	TBD modifiers{{query=`query`}}&(community=`id` or `collection={{id`}} `idOnly=false`	`id` `name` `lastmodified` `submitter`	Item info with basic metadata for the search results. Additionally return only identifiers when `idOnly=true` is used.	`json` `xml`	200, 204, 400, 500
	`GET`	`/harvest`	Return a list of all objects that have been created, modified or withdrawn within specified time range.	-	`startdate` {enddate}} `community` `collection` `idOnly=false` `withdrawn=false` Notice: community and collection are mutually exclusive options	-	Contains item info including id, name, handle, metadata, bitstreams according to the defined requirements. Additionally when idOnly=true only identifiers of results are returned. If the date is in incompatible format, error 400 is returned.	`json` `xml`	200, 204, 400, 500

Item status and retrieval

Verb	URL	Description	Mandatory parameters	Optional parameters	Sorting fields	Response Data	Formats	Response codes
`GET`	`/items/{id`}	Return detailed information about an item.	`id`	-	`id` `name` `lastmodified` `submitter`	`id` - entity (item) identifier, internal to the system `handle` - handle of the item `isArchived` - archival status of the item `isWithdrawn` - withdrawal status of the item `lastModified` - timestamp of last modification `metadata` - item metadata `name` - item name `submitter` - submiter entity `type` - entity type (object type in the system, item in this case) `bitstreams` - bitstreams related to the item `bundles` - bundles related to the item `collections` - collections related item appear in `owningCollection` - get the owning collection of the item `communities` - communities related item appear in	`json` `xml`	200, 204, 400, 500
`GET`	`/items/{id}/permissions`	Return status of user permissions on this item.	`id`	-	-	Boolean variable, stating can user edit the listed item.	`json` `xml`	200, 400, 500
`GET`	`/items/{id}/communities`	Return communities this item is part of.	`id`	idOnly=false	`id` `name` `countitems`	`countitems` - number of items under community `handle` - handle of the community (unique persistent resource identifier) `id` - entity identifier, internal to the system `name` - entity name `type` - entity type (object type in the system) `collections` - collections contained in the community, ordered by id `ancestors` - ancestors of the community, ordered by id `children` - subcommunities, ordered by id `admins` - group administrators, ordered by id `metadata` - community metadata `administrators` - default group of administrators	`json` `xml`	200, 400, 500
`GET`	`/items/{id}/collections`	Return collections this item is part of.	`id`	idOnly=false	`id` `name` `countitems`	`countitems` - number of items under collection `items` - items present in the collection `id` - entity (collection) identifier, internal to the system `handle` - handle of the collection `licence` - collection licence `name` - collection name `type` - entity type (object type in the system, item in this case) `communities` - communities related collection appear in `submiters` - default group of submitters, if there is one `administrators` - default group of administrators, if there is one `templateitem` - template item for collection, if there is one	`json` `xml`	200, 400, 500
`GET`	`/bitstream/{id`}	Return bitstream object - usually the library item file.	`id`	-	-	`id` - id of bitstream `name` - name of the bitstream `bundles` - bundles the related bitstream appears in `checksum` - checksum of bitstream `checksumAlgorithm` - checksum algorithm used `description` - bitstream description `formatDescription` - format description of bitstream `handle` - bitstream handle `mimeType` - mime type of bitstream `sequenceId` - sequence id `size` - bitstream size in bytes `source` - bitstream source, local `storeNumber` - store number `type` - object type `userFormatDescription` - description of user format	`json` `xml`	200, 400, 401, 403, 404, 500
`GET`	`/bitstream/{id}/receive`	Return bitstream	`id`	-	-	Return bitstream	`binary`	200, 400, 401, 403, 404, 500

Item manipulation

C	Verb	URL	Description	Mandatory parameters	Optional parameters	Response Data	Formats	Response codes
•	`POST`	`/items/{id}/action`	Change parameters of item `id`	`id`	`addBundle` `addMetadata` `createBundle` `createSingleBitstream` `removeBundle` `removeLicenses` `setArchived` `setOwningCollection` `setSubmitter` `withdraw`	Response code	`json` `xml`	200, 400, 401, 403, 500
	`PUT`	`/items/{id}/bundle/{{bid`}}	Add an existing bundle `bid` to item `id`	`id` `bid`
	`DELETE`	`/items/{id}/bundle/{{bid`}}	Remove bundle `bid` from item `id`	`id` `bid`
	`PUT`	`/items/{id}/metadata`	Add a single metadata field	`id` `element` `value` `schema` `qualifier` `lang`
	`DELETE`	`/items/{id}metadata`	Remove a single metadata field	`schema` `element` `qualifier` `lang`
	`DELETE`	`/items/{id}/metadata`
•	`POST`	`/communities`	Add community to the system	`name`	`logo` `parent` other metadata	`Id` of newly created community	`json` `xml`	200, 400, 401, 403, 500
•	`DELETE`	`/communities/{id}{`}	Delete community from the system	`id`	-	Response code	`json` `xml`	200, 400, 401, 403, 500
•	`PUT`	`/collections/{id}{`}	Change description of `id` collection	`id`		Response code	`json` `xml`	200, 400, 401, 403, 500
•	`POST`	`/collections`	Add collection to the system	`name` `communityId`		`Id` of newly created collection	`json` `xml`	200, 400, 401, 403, 500
•	`DELETE`	`/collections/{id}{`}	Delete collection from the system	-	-	Response code	`json` `xml`	200, 400, 401, 403, 500

User oriented functions

C	Verb	URL	Description	Mandatory parameters	Optional parameters	Sorting fields	Response Data	Formats	Response codes
	`GET`	`/users`	Return a list containing id, name and email of persons.	-	`query` `idOnly=false`	`id` `name` `lastname` `fullname` `language`	List with information on particular user. Additionaly only identifiers are sent if idOnly is true.	`json` `xml`	200, 204, 400, 500

Statistical info

C	Verb	URL	Description	Mandatory parameters	Optional parameters	Sorting fields	Response Data	Formats	Response codes
	`GET`	`/stats`	Return general statistics.	-	-	-	Cummulative list of statistics data for the system currently available.	`json` `xml`	200, 400, 500

Administrative tasks

Workflow related tasks

Relationships interface

C	Verb	URL	Description	Mandatory parameters	Optional parameters	Sorting fields	Response Data	Formats	Response codes
•	GET	/resource/{handle}/relations	Return entities according to relation and parameters specified	`handle` `property`	`rtype` rfield	-	ontains entities selected and sorted in conformance to request parameters. For more details see description of `rtype` and`rfield`.	`json` `xml`	200, 204, 400, 401, 403, 500

Mandatory parameters

Parameter	Description	Values	Example
`property`	Return entities satisfying requested property relation	Structural properties `ds:isPartOfSite` `ds:isPartOfCommunity` `ds:isPartOfCollection` `ds:isPartOfItem` `ds:isPartOfBundle` `ds:hasCommunity` `ds:hasCollection` `ds:hasItem` `ds:hasBundle` `ds:hasBitstream` `ds:hasBitstreamFormat` Communities and collections `ds:logo` Bistream format `ds:support` `ds:fileExtension` `ds:mimeType` Bitstream `ds:messageDigest` `ds:messageDigestAlgorithm` `ds:messageDigestOriginator` `ds:size` Eperson `ds:language`	`property=ds:hasCommunity` - return subcommunities of a community `property=ds:isPartOfCommunity` - return communities current community is part of (children) `property=ds:hasCollection` - return collections belonging to community `property=ds:hasItem` - return Items belonging to community
`rtype`	restriction on type - only entity with specifed type(s) would be returned	`ds:Bitstream` `ds:Bundle` `ds:Collection` `ds:Community` `ds:EPerson` `ds:Group` `ds:Item` `ds:DSpaceObject` `ds:Policy` `ds:Site` `ds:BitstreamFormat`\|	`rtype=ds:Collection` - return entities of Collection type
rfield	restriction on fields - return only selected fields; by default all fields are returned	id name countitems metadata subcommunities ancestors owner other (depending on object type, will be documented later)	rfield=id,name - return only entity id and name in response

Note: incomplete/orientative properties, for more info check [Vocabularies|http://code.google.com/p/dspace-sandbox/source/browse/#svn/modules/dspace-rdf/tags/dspace-rdf-1.5.1/src/main/java/org/dspace/adapters/rdf/vocabularies].

Visitors' suggestions or wishes

Here the visitors and stakeholders can insert their suggestions or describe the needs for their applications in detail.

Comment: In this case it is not clear how to treat recent part of endpoint. If we stick to semantic mapping, then it should look like /resource/id/mapping, but recent in this case obviously do not represent a mapping, but the property.

Comment #2: Semantic mapping presented in this case should be probably hardcoded for 1.x branch, but on abstraction level which enables easy replacement with some auto-discovery method prepared for 2.x and eventually backported to 1.x. This way we would be able to call something similar to /communities/id or communities/id/capabilities in order to get supported mappings (amongst other data).

Integration in the system

It is planned to consult two external subjects for cooperation and the assistance during integration process (LMS and national library internal automation process). More information coming soon - awaiting approval of other parties.

Documentation tasks

Although provided software module exposes basic documentation automatically to the end user, in order to make it easier for other developers and users the documentation in the following forms is additionaly to be provided:

Confluence pages, current location
integrated documentation in PDF form (manual)
short slides containing technology overview, advocacy/facts, configuration and usage guideliens and examples
code will be additionally commented

Example of usage

At the end of the current stage of this project as a bonus task (if time constraints allow) the examples of usage will be provided for several languages, the use-cases will be presented (example of integration in other software, e.g. LMS) and optionally simple client system demonstrating UI customization will be demonstrated (e.g. Flex or JavaFX like).

Page tree

GSOC10 - DSpace REST API