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__TOC__
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[http://www.eclipse.org/eclipselink/documentation/2.4/solutions/restful_jpa003.htm#CHDEGJIG JPA-RS API Documentation version 2.4.0]
= JAX-RS: A RESTful API for JPA=
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'''History'''
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Date
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Author
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Description
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01/10/11
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dclarke
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Initial Version
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{|{{BMTableStyle}}
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|-{{BMTHStyle}}
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! Date
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! Author
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! Description
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|-
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| Oct 1, 2011 || dclarke || Initial Version
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|-
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| Nov 9, 2011 || dclarke || Moved to wiki for community review and feedback.
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|-
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| Jan-Mar, 2012 || tware || updates and additions to REST API descriptions
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|}
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==Overview==
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This specification will define a RESTful API for dealing with JPA. The intent is to simplify how JPA persistence units can be accessed using REST with JSON or XML formatted messages. A JPA-RS runtime will provide access to all persistence units packaged in the same application that it is running in as well as any dynamic persistence unit that is provisioned within it.
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==Using JPA-RS==
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JPA-RS comes in two parts and is available starting with our 2.4.0 release.
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# Server side - The majority of code is written in EclipseLink and should be run server-side there are two ways you can get this functionality
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## If you are on a server that distributes with the full EclipseLink jar or on our 2.4.0 or 2.4.1 release, no changes are needed
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## If you are on our 2.4.2 or a later release and on a server that uses our OSGi bundles, you will have to ensure that you have the org.eclipse.persistence.dbws bundle (e.g. GlassFish ships with the OSGi bundles.  You will need to ensure our org.eclipse.persistence.dbws bundle is available to GlassFish)
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# Client Side - A small web-fragment called org.eclipse.persistence.jpars is used to enable JPA-RS.  This web-fragment should be included with your application.
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Although there is no reason the web service cannot be enabled on any fairly recent container that contains Jersey, initial development and testing was done on GlassFish 3.1.2 and this description will assume you are using GlassFish 3.1.2 or better.
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JPA-RS uses "/persistence" as its path.  (i.e. The base URL for JPA-RS for a particular application is: http://<server>:<port>/<applicationName>/persistence)
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== Persistence Unit Operations==
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The JPA-RS URI structure then requires a persistence unit name: '''/persistence/{unit-name}'''. Assuming this is a valid persistence unit in the given JPA-RS application context the following high level operations are available.
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* BASE /persistence/{unit-name}
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* ENTITY: /persistence/{unit-name}/entity
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* QUERY: /persistence/{unit-name}/query
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* SINGLE_RESULT_QUERY: /persistence/{unit-name}/singleResultQuery
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* METADATA: /persistence/{unit-name}/metadata
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===Data Formats: JSON or XML===
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This REST interface deals with XML and JSON representations of the data equally well. The caller is responsible for using the HTTP header values to indicate the format of the content it is sending (Content-Type = application/json or application/xml) as well as indicating the format of the result it expects (Accept = application/json or application/xml).
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NOTE: In many REST utilities the accept value is defaulted to application/xml making it the users responsibility to configure this value explicitly.
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===HTTP Header Fields ===
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'''Standard HTTP'''
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* If-Match - conditional
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* Warning
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'''EclipseLink JPA-RS'''
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* Refresh
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=== Multi-Tenancy ===
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When using EclipseLink's multi-tenancy features developers can choose to isolate their tenant's data by schema/table (@Multitenant(TABLE_PER_TENANT) - EclipseLink 2.4) or within a shared table (@Multitenant(SINGLE_TABLE) - EclipseLink 2.3). In order to access a persistence unit that supports concurrent access by multiple tenants the persistence context must specify tenant discriminator values within its properties. To support this usage within JPA-RS the tenant identifier values will be supplied using matrix parameters within the persistence unit portion of the URI.
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<pre>
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/persistence/{unit-name};mysports.league=HTHL/
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</pre>
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=== Logging ===
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Messages related to JPA-RS operations are logged to a logger called org.eclipse.persistence.jpars.  Most messages are logged at the FINE level.  Exception stacks are logged at FINER.
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Messages related to operations withing EntityManagers, EntityManagerFactories and JAXBContexts are logged in the same manner as other EclipseLink logging.
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=== Deployment Requirements ===
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Weaving is required for several features to work (providing relationships as links, editing relationships, dealing with LAZY x-1 relationships).  You should either deploy to a Java EE compliant server or statically weave you classes.
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Note: Lazy x-1 relationships are only supported when using JPA RS's default mapping strategy which returns those mappings as links by using read-only mappings for the JSON/XML support and providing the links through a weaved attribute.
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== Entity Operations: /persistence/{unit-name}/entity/* ==
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Entity operations are those performed against a specific entity type within the persistence unit. The {type} value refers to the type name (descriptor alias).
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=== FIND ===
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* GET /persistence/{unit-name}/entity/{type}/{id}
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** Refresh = GET + Header(Refresh)
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** {id} is currently defined as a string
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** e.g. http://localhost:8080/persistence/ExamplePU/entity/Foo/1
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* Produces: JSON or XML
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* Response
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** OK, Payload: Entity
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** NOT_FOUND if Entity does not exist
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'''EntityManager.find API:'''
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<pre>
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public <T> T find(Class<T> entityClass, Object primaryKey);
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public <T> T find(Class<T> entityClass, Object primaryKey, Map<String, Object> properties);
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</pre>
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==== Composite Key ====
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Composite keys are supported.  In the initial implementation, the character '+' will be reserved and not available for use in fields that represent keys.  Composite keys will be separated using the '+' character and should be specified in an order cooresponding to java default sorting of the attribute names.
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Imagine this entity:
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* Foo
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** idB=1
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** idA=2
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The URL to find this entity would be as follows:
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http://localhost:8080/persistence/ExamplePU/entity/Foo/2+1
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Notice that the '2' comes before the '1' because "idA" comes before "idB" when sorted in java.
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==== Result Caching ====
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Default EclipseLink and HTTP caching will be enabled and configured through standard means.
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==== REFRESH ====
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The EntityManager.refresh operation can be invoked using the find with the query hint for Refresh.  See the Query section of the document for how to use hints.
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==== Attributes ====
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Navigating into the attributes of an Entity (e.g. get the Address entity associated with a particular employee in a single URL) is initially only supported to one level:
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e.g. /persistence/{unit-name}/entity/{type}/{id}/{relationship} will work
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/persistence/{unit-name}/entity/{type}/{id}/{relationship}/{index}/{relationship2} will not
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==== Relationships ====
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To make use of Entities with relationships, the persistence unit classes MUST be weaved.  JPA-RS relies on Fetch groups to implement its relationships maintenance. PUT/POST operations on relationships for non-weaved classes is an error condition
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Relationships are, by default, represented as links.  Reading and writing to relationships is done through that link.  See the Relationships section below.
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Private-Owned(orphan removal in JPA) relationships are inlined and hence an object model with only Private-Owned relationships does not need to be weaved.
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=== PERSIST ===
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* PUT /persistence/{unit-name}/entity/{type}
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** e.g. PUT http://localhost:8080/persistence/ExamplePU/entity/Foo
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* Consumes: JSON or XML
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* Payload: Entity
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* Produces: JSON or XML
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* Response:
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** Payload: Entity returned by Persist
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PUT is required to be itempotent.  As a result, it will fail if called with an object that expects the server to provide an ID field.  Typically this will occur if the metadata specifies a generated key and the field that contains that key is unpopulated.
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=== MERGE ===
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* POST /persistence/{unit-name}/entity/{type}
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** e.g. POST http://localhost:8080/persistence/ExamplePU/entity/Foo
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* Consumes: JSON or XML
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* Payload: Entity
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* Produces: JSON or XML
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* Response:
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** Payload: Entity returned by Merge
+
 
+
 
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=== DELETE ===
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* DELETE /persistence/{unit-name}/entity/{type}{id}
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** {id} is currently defined using HTTP query parameters
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** e.g. http://localhost:8080/persistence/ExamplePU/entity/Foo?id=1
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* Response
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** OK
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== Relationships: /persistence/{unit-name}/entity/{entity}/{id}/{relationship} ==
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=== READ ===
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To get the values of a relationship
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* GET /persistence/{unit-name}/entity/{type}/{id}/{relationship}
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** {id} is currently defined as a string
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** {relationship} is the JPA name of the relationship
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** e.g. http://localhost:8080/persistence/ExamplePU/entity/Foo/1/myRelationship
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* Produces: JSON or XML
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* Response
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** OK, Payload: Entity or List of Entities
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** NOT_FOUND if Entity does not exist
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=== ADD ===
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To add to a list or replace the value of a X-1 Relationship
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* POST /persistence/{unit-name}/entity/{type}/{id}/{relationship}{partner}
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** For unidirectional relationships {partner} is not required
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*** e.g. POST http://localhost:8080/persistence/ExamplePU/entity/Foo/1/myRelationship
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** For bi-directional relationships, you must provide the name of the attribute that makes up the opposite side of the relationship.
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*** e.g. To update an Auction.bid where the opposite side of the relationship is Bid.auction use the following:
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**** e.g. POST http://localhost:8080/persistence/ExamplePU/entity/Foo/1/myRelationship;partner=bid
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* Consumes: JSON or XML
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* Payload: Entity with the new value
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* Produces: JSON or XML
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* Response:
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** Payload: Entity with added element
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=== REMOVE ===
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To remove a specific entity from the list or null on an X-1 Relationship
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* DELETE /persistence/{unit-name}/entity/{type}/{id}/{relationship}
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** e.g. DELETE http://localhost:8080/persistence/ExamplePU/entity/Foo/1/myRelationship
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* Consumes: JSON or XML
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* Payload: Entity to be removed
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* Response
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** OK
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** Payload: Entity with added element
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== Query Operations ==
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* Named Query: GET /persistence/{unit-name}/query/{name}{params}
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=== Named Query ===
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Named queries doing reads can be run two ways in JPA.  Both are supported in the REST API.
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==== List of Results ====
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* GET /persistence/{unit-name}/query/{name}<parameters><hints>
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** <parameters> are specified using HTTP matrix parameters
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** <hints> are specified using HTTP query parameters and with the key being the name of the EclipseLink query hint
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** e.g. http://localhost:8080/persistence/ExamplePU/query/Foo.findByName;name=myname
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** e.g. http://localhost:8080/persistence/ExamplePU/query/Foo.findByName;name=myname?eclipselink.jdbc.max-results=500
+
* Produces: JSON or XML
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* Response
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** Payload: List of Entities
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==== Single Result ====
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* GET /persistence/{unit-name}/querySingleResult/{name}<parameters><hints>
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** <parameters> are specified using HTTP matrix parameters
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** <hints> are specified using HTTP query parameters and with the key being the name of the EclipseLink query hint
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** e.g. http://localhost:8080/persistence/ExamplePU/querySingleResult/Foo.findByName;name=myname
+
* Produces: JSON or XML
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* Response
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** Payload: Entity
+
 
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==== Update/Delete Query ====
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* POST /persistence/{unit-name}/query/{name}<parameters><hints>
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** <parameters> are specified using HTTP matrix parameters
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** <hints> are specified using HTTP query parameters and with the key being the name of the EclipseLink query hint
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** e.g. http://localhost:8080/persistence/ExamplePU/query/Foo.deleteAllByName;name=myname
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** e.g. http://localhost:8080/persistence/ExamplePU/query/Foo.updateName;name=myname?eclipselink.jdbc.max-results=500
+
* Produces: application/octet-stream
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* Response
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** Payload:  Number of entities updated or deleted in
+
 
+
== Session Beans ==
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+
A restful API is provided to make a call into a SessionBean
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* POST /persistence
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** payload: A SessionBeanCall JSON or XML object containing the following information:
+
*** jndiName: The JNDI name of the SessionBean
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*** methodName: The name of the SessionBean method to call
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*** context: (optional) The JPA RS context to use to unmarshall parameters and marshall return values.  If not provided, return values are returned as is
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*** parameters: A list of parameter Object with the following information
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**** typeName: The name of the java class of the parameter, or the name of the entity type in JPA RS
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**** value: The value of the parameter
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* Produces: */*
+
* Response
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** NOT_FOUND is the context is not found or the Session bean cannot be found on lookup
+
** OK on succes with:
+
*** Payload: Return value of SessionBean method
+
 
+
== Metadata Operations ==
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+
* GET /persistence
+
* GET /persistence/{unit-name}/metadata
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* GET /persistence/{unit-name}/metadata/entity/{type}
+
* GET /persistence/{unit-name}/metadata/query
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+
=== List Existing Persistence Units ===
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* GET /persistence
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** e.g. http://localhost:8080/persistence/
+
* Produces: JSON
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* Response
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** Payload: List of Persistence Unit Names and links to metadata about them
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+
Example:
+
<pre>
+
[
+
  {
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    "rel": "auction",
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    "type": "application/json",
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    "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/metadata"
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  },
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  {
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    "rel": "DataAppLibraryPU",
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    "type": "application/json",
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    "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/DataAppLibraryPU/metadata"
+
  }
+
]
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</pre>
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=== List Types in a Persistence Unit ===
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* GET /persistence/{unit-name}/metadata
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** e.g. http://localhost:8080/persistence/ExamplePU/metadata
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* Produces: JSON
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* Response
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** OK, Payload: List of Types with links to more detailed metadata
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** NOT_FOUND if persistence unit is not found
+
 
+
Example:
+
<pre>
+
{
+
  "persistence-unit-name": "auction",
+
  "types": [
+
    {
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      "rel": "User",
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      "type": "application/json",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/metadata/entity/User"
+
    },
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    {
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      "rel": "Auction",
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      "type": "application/json",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/metadata/entity/Auction"
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    },
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    {
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      "rel": "Bid",
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      "type": "application/json",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/metadata/entity/Bid"
+
    }
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  ]
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}
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</pre>
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=== List Queries in a Persistence Unit ===
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* GET /persistence/{unit-name}/metadata/query
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** e.g. http://localhost:8080/persistence/ExamplePU/metadata/query
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* Produces: JSON
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* Response
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** OK, Payload: List of all available queries
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** NOT_FOUND if persistence unit is not found
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Example:
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<pre>
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[
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  {
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    "query-name": "User.all",
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    "reference-type": "jpars.app.auction.model.User",
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    "jpql": "SELECT u from User u",
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    "link-template": {
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      "rel": "execute",
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      "method": "get",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/query/User.all/{parameters}"
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    }
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  },
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  {
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    "query-name": "User.updateName",
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    "reference-type": "jpars.app.auction.model.User",
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    "jpql": "UPDATE User u SET u.name = :name WHERE u.id = :id",
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    "link-template": {
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      "rel": "execute",
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      "method": "post",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/query/User.updateName/{parameters}"
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    }
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  }
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]
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</pre>
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=== Describe a specific entity ===
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* GET /persistence/{unit-name}/metadata/entity/<type>
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** e.g. http://localhost:8080/persistence/ExamplePU/metadata/entity/MyEntity
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* Produces: JSON
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* Response
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** OK, Payload: Details about the entity and available operations on it
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** NOT_FOUND if persistence unit is not found
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Example:
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<pre>
+
{
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  "name": "User",
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  "type": "jpars.app.auction.model.User",
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  "link-templates": [
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    {
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      "rel": "find",
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      "type": "application/json",
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      "method": "get",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/entity/Bid/{primaryKey}"
+
    },
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    {
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      "rel": "persist",
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      "type": "application/json",
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      "method": "put",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/entity/Bid"
+
    },
+
    {
+
      "rel": "update",
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      "type": "application/json",
+
      "method": "post",
+
      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/entity/Bid"
+
    },
+
    {
+
      "rel": "delete",
+
      "type": "application/json",
+
      "method": "delete",
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      "href": "http://localhost:8080/HenleyAvatarModel/jpa-rs/auction/entity/Bid/{primaryKey}"
+
    }
+
  ],
+
  "attributes": [
+
    {
+
      "name": "id",
+
      "type": "java.lang.Integer"
+
    },
+
    {
+
      "name": "name",
+
      "type": "java.lang.String"
+
    }
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  ],
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  "queries": [
+
    {
+
      "query-name": "User.all",
+
      "reference-type": "jpars.app.auction.model.User",
+
      "jpql": "SELECT u from User u"
+
    },
+
    {
+
      "query-name": "User.updateName",
+
      "reference-type": "jpars.app.auction.model.User",
+
      "jpql": "UPDATE User u SET u.name = :name WHERE u.id = :id"
+
    }
+
  ]
+
}
+
</pre>
+
 
+
== Entity Representation ==
+
 
+
Interaction in REST is done through XML and JSON and makes use of EclipseLink's MOXy functionality which provides a JAXB implementation and also leverages that implementation to produce JSON based on the JAXB mappings.  Objects are mapped to XML using standard JAXB mapping rules including JAXB defaults and use of a JAXB mappings file.  Since all the configuration is in the JPA persistence unit, the JAXB mappings file can be named in the Persistence Unit property called: "eclipselink.jpa-rs.oxm".
+
 
+
=== Relationships ===
+
 
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=== Sample JSON ===
+
 
+
The following provides some sample JSON with some regular-expression-like notation.
+
 
+
<pre>
+
<code>
+
{
+
  numericAttribute: 1
+
  stringAttribute: "auction1"
+
  dateAttribute: 12-09-16
+
  singleRelatedItem: RELATED_ITEM?
+
    listRelatedItem:
+
    {
+
        RELATED_ITEM*
+
    }
+
}
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+
 
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RELATED_ITEM =
+
 
+
    {
+
      numericAttribute: 11
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      stringAttribute: "myName"
+
    }
+
 
+
OR
+
 
+
    {
+
      rel="self",
+
      href=LINK_HREF,
+
      method="GET"
+
    }
+
</pre>
+
 
+
Notice: When an entity is the target of a relationship, it can either be completely represented in the JSON, or it can be represented as a Link.
+
 
+
As a rule, JPA RS will marshal relationships using links from GET calls unless they are private-owned in which case the object will be embedded
+
 
+
When using PUT/POST new objects should be embedded and existing object should be supplied using links.
+
 
+
'''Bidirectional Relationships and Cycles'''
+
 
+
in progress
+
 
+
=== XML ===
+
 
+
in progress
+
 
+
== Future Development ==
+
 
+
http://wiki.eclipse.org/EclipseLink/Development/JPA-RS
+

Latest revision as of 09:22, 9 April 2013

JPA-RS API Documentation version 2.4.0