Practical RESTful Persistence

@shaunMsmith#DV13 #JPARS

Practical RESTful Persistencewith EclipseLink JPA-RS

Shaun SmithOracle


• JPA 2.0 (EE 6) and 2.1 (EE 7) reference implementation

• JPA provider in GlassFish and Oracle WebLogic

• Project founded on mature Oracle TopLink codebase

• EPL and EDL licensed open source JPA and JAXB implementation


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EclipseLink JPA

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JAX-RS

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EclipseLink JPA


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JAX-RS

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EclipseLink JPA

EclipseLink JAXB / JSON Binding


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JAX-RS

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EclipseLink JPA

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{ id: 5, …}


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{ id: 5, …}


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Binding PersistenceXML / JSON

Java PersistenceRelational / NoSQL

JAX-RS

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EclipseLink MOXyEclipseLink MOXy

• JAXB for Java/XML binding—covert Java to/from XML

• Java/JSON binding—convert Java to/from JSON

• Currently no Java/JSON binding standard• Java API for JSON Processing (JSR 535) is parsing, not

binding

• EclipseLink interprets JAXB XML bindings for JSON• Content-type selectable by setting property on

Marshaller/Unmarshaller


XML and JSON from JAXB MappingsXML and JSON from JAXB Mappings

{ "phone-numbers" : [ { "id" : 2, "num" : "512-555-9999", "type" : "mobile" } ], "address" : { "city" : "New York", "id" : 1, "street" : "Central Park East" }, "firstName" : "Woody", "id" : 1, "lastName" : “Allen"}

<?xml version="1.0" encoding="UTF-8"?><customer> <phone-numbers> <phone-number> <id>2</id> <num>512-555-1234</num> <type>home</type> </phone-number> </phone-numbers> <address> <city>New York</city> <id>1</id> <street>Central Park East</street> </address> <firstName>Bill</firstName> <id>1</id> <lastName>Allen</lastName></customer>


Challenges – Binding JPA Entities to XML/JSONChallenges – Binding JPA Entities to XML/JSON

• Composite Keys/Embedded Key Classes

• Byte Code Weaving

• Bidirectional/Cyclical Relationships

<customer> <phone-numbers> <phone-number> <id>1</id> ... <type>mobile</type> </phone-number></phone-numbers></customer>

JPAJAXB


Bidirectional RelationshipBidirectional Relationship@Entitypublic class Customer{

...@OneToMany(mappedBy="owner")private List<Phone> phones;

}

@Entitypublic class Phone{

...@ManyToOneprivate Customer owner;

}


What about @XmlTransient?What about @XmlTransient?@Entitypublic class Customer{

...@OneToMany(mappedBy=“owner")private List<Phone> phones;

}


...@ManyToOne@XmlTransientprivate Customer owner;

}


With @XmlTransientWith @XmlTransient

Loses the relationship! <customer> <phone-numbers> <phone-number> <id>1</id> ... <type>mobile</type> </phone-number></phone-numbers></customer>

MarshallMarshall

Customer

Phone

UnmarshallUnmarshall

X

Customer

Phone

owner

phones phones


EclipseLink XmlInverseReferenceEclipseLink XmlInverseReference@Entitypublic class Customer{

...@OneToMany(mappedBy=“owner")private List<Phone> phones;

}


...@ManyToOne@XmlInverseReference(mappedBy=“phones")private Customer owner;

}


With @XmlInverseReferenceWith @XmlInverseReference

EclipseLink restores relationships on unmarshall!<customer> <phone-numbers> <phone-number> <id>1</id> ... <type>mobile</type> </phone-number></phone-numbers></customer>

MarshallMarshall

Customer

Phone

UnmarshallUnmarshall

Customer

Phone

owner

phones phones

owner

Demo



Binding PersistenceXML / JSON

Java PersistenceRelational / NoSQL

EclipseLink MOXy

EclipseLink JPA

Database

Java

Browser

JAX-RSJAX-RS


JAX-RS with JPA ExampleJAX-RS with JPA Example

public class InvoiceService {...

public Invoice read(int id) {

return null;

}

...


JAX-RS with JPA ExampleJAX-RS with JPA Example

@Stateless



return entityManager.find(Invoice.class, id);

}

...


JAX-RS with JPA ExampleJAX-RS with JPA Example@Path("/invoice")

@Stateless




}

... http://[machine]:[port]/[web-context]/invoice http://[machine]:[port]/[web-context]/invoice



@Stateless


@Path("{id}”)

public Invoice read(@PathParam("id") int id) {


}

... http://[machine]:[port]/[web-context]/invoice/4 http://[machine]:[port]/[web-context]/invoice/4



@Stateless


@GET

@Path("{id}”)



}

... GET http://[machine]:[port]/[web-context]/invoice/4GET http://[machine]:[port]/[web-context]/invoice/4



@Stateless


@Produces({"application/xml"})

@GET

@Path("{id}")

public Invoice read(@PathParam("id") int id) {


}

... GET http://[machine]:[port]/[web-context]/invoice/4GET http://[machine]:[port]/[web-context]/invoice/4


Invoice Bean

JAX-RSJAX-RS

JAX-RS with JPAJAX-RS with JPA GET http://.../invoice/4GET http://.../invoice/4

http://.../invoice/4 mapped to beanhttp://.../invoice/4 mapped to bean

JPA

Accounting PUBean uses JPABean uses JPA

GETGET

GET http://.../invoice/4 mapped to methodGET http://.../invoice/4 mapped to methodContract Bean Payment Bean

...GETGETGETGETGETGET GETGETGETGETGETGETGETGETGETGETGETGET


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EclipseLink JPA-RSEclipseLink JPA-RS

• Automatically provides REST operations for entities in persistence unit (GET, PUT, POST, DELETE)

• Automatic generation of XML and JSON bindings• Leverages EclipseLink’s JAXB/JPA fidelity features to

avoid lossy transformations

• Automatic publication of REST API metadata


EclipseLink JPA-RSEclipseLink JPA-RS

• Supports invocation of named queries via HTTP

• Server side caching—EclipseLink clustered cache

• Automatic injection of links for entity relationships• Default Resource Model generation


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11 22

{ "id": 1, "lastName": "Smith", … "address": { "_link": { "href": "http:/…/Address/2", "method": "GET", "rel": "self" } }

{ "id": 2, "city": ”Toronto", …}

...

...


Configuring JPA-RSConfiguring JPA-RS

• Add JPA-RS web fragment jar to WEB-INF/lib!


JPA

JPA-RS

JAX-RSJAX-RS

JPA-RSJPA-RS

Accounting

GET http://.../persistence/Accounting/Invoice/4GET http://.../persistence/Accounting/Invoice/4

JPA-RS maps URI http://.../persistence/Accounting/Invoice/4 to Accounting PU and Invoice entity

JPA-RS maps URI http://.../persistence/Accounting/Invoice/4 to Accounting PU and Invoice entity

JAX-RS http://.../persistence/Accounting/Invoice/4mapped to JPA-RS serviceJAX-RS http://.../persistence/Accounting/Invoice/4mapped to JPA-RS service

Human Resources

Benefits

...

Demo



Demo ModelDemo Model


EclipseLink JPA-RS RoadmapEclipseLink JPA-RS Roadmap

• Resource Model• Scope of resource• Entity format• partial entities/projections

• Configuration• URL mapping/customization• Manage Entity exposure

• Meta-data• JSON Schema? Swagger? ...


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SummarySummary

• Java EE stack has (most of) what you need to build Thin Server Architecture applications

• You have to be aware of various impedance mismatches

• EclipseLink JPA-RS • Integrates JAX-RS / JAXB / JPA• Eliminates JAX-RS boilerplate for data access• Simplifies Java EE Thin Server Architecture applications

☛ www.eclipse.org/eclipselink


The preceding is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.

Practical RESTful Persistence

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