EclipseLink: From NoSQL to HTML5 by Shaun Smith

1 Beyond Relational and NoSQL to Polyglot and HTML5 | © 2013 Oracle and AGETO; Licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License1 EclipseLink: From NoSQL to HTML5 | © 2013 Oracle and AGETO; Licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License
EclipseLink: From NoSQL to HTML5
Shaun Smith
shaun.smith@oracle.com
@shaunMsmith

About Me
§  Shaun Smith
–  Eclipse committer on EclipseLink and related projects
–  Oracle TopLink Product Manager
–  OO developer since 1987
§  “Old guy who knows Smalltalk” ;-)

Agenda—Database to Browser (and back again)
Browser
HTTP / REST
Binding Persistence
XML/JSON
Java
Database Persistence
Relational/NoSQL
Relational DB | NoSQL DB

Agenda
Browser
HTTP / REST
Binding Persistence
XML/JSON
Java
Relational/NoSQL

NoSQL Databases
§  EclipseLink is best known for relational persistence but…
§  NoSQL databases are increasingly popular
§  No common definition (document, graph, columnar)
–  Differing feature sets
–  Some offer query language/API—some not
§  No standards
§  Every database offers a unique API
–  Cost in terms of learning each database
–  Zero portability across databases

EclipseLink NoSQL
§  Support JPA-style access to NoSQL databases
–  Leverage non-relational database support for JCA (and JDBC when
available)
§  Define annotations and XML to identify NoSQL stored entities (e.g.,
@NoSQL)
§  Support JPQL subset for each
–  Key principal: leverage what’s available
§  Initial support for MongoDB and Oracle NoSQL

Applicability of JPA to NoSQL
§  Core JPA concepts apply to NoSQL:
–  Persistent Entities, Embeddables, ElementCollection, OneToOne,
OneToMany, ManyToOne, Version, etc.
§  Some concepts apply with some databases:
–  JPQL, NamedNativeQuery
§  Pure relational concepts don’t apply:
–  CollectionTable, Column, SecondaryTable,
SequenceGenerator, TableGenerator, etc.

Querying NoSQL with JPA
§  Two kinds of queries
–  JQPL—portable query language defined by the spec
–  Native query—lets you leverage database specific features
–  Dynamic or static @NamedQuery
§  JPQL translated to underlying database query framework.

Example MongoDB Mapped Entity

MongoDB Query Examples
§ JPQL

Select o from Order o
where o.totalCost > 1000
Select o from Order o
join o.orderLines l where l.cost > :cost
§ Native Queries

query = em.createNativeQuery(
"db.ORDER.findOne({"_id":"" +
oid + ""})", Order.class);
Order order =
(Order) query.getSingleResult();

Demo EclipseLink NoSQL

“…we are gearing up for a shift to polyglot persistence - where any
decent sized enterprise will have a variety of different data storage
technologies for different kinds of data…we'll be first asking how
we want to manipulate the data and only then figuring out what
technology is the best bet for it..”
Martin Fowler
ThoughtWorks

Composite Persistence Unit
Composite PU
Relational PU NoSQL PU

Demo Polyglot Persistence

Agenda
Browser
HTTP / REST
Binding Persistence
XML/JSON
Java
Relational/NoSQL

Binding Persistence
§  EclipseLink implements
–  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 Binding

XML 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/JSON
•  Bidirectional/Cyclical Relationships
•  Composite Keys/Embedded Key Classes
•  Byte Code Weaving
<customer>
<phone-numbers>
<phone-number>
<id>1</id>
...
<type>mobile</type>
</phone-number>
</phone-numbers>
</customer>
JPAJAXB

Bidirectional Relationship
@Entity
public class Customer{
...
@OneToMany(mappedBy="owner")
private List<Phone> phones;
}
@Entity
public class Phone{
...
@ManyToOne
private Customer owner;
}

Bidirectional Relationships in JAXB
§  JAXB specification does not support bidirectional relationships. One
side must be marked @XmlTransient.
§  But that loses the relationship!
Customer Phone
<customer>
<phone-numbers>
<phone-number>
<id>1</id>
...
<type>mobile</type>
</phone-number>
</phone-numbers>
</customer>
Marshall
Customer Phone
Unmarshall
X
owner
phones phones

EclipseLink XmlInverseReference
@Entity
public class Customer{
...
@OneToMany(mappedBy=“owner")
private List<Phone> phones;
}
@Entity
public class Phone{
...
@ManyToOne
@XmlInverseReference(mappedBy=“phones")
private Customer owner;
}

EclipseLink XmlInverseReference
§  EclipseLink restores relationships on unmarshall!
<customer>
<phone-numbers>
<phone-number>
<id>1</id>
...
<type>mobile</type>
</phone-number>
</phone-numbers>
</customer>
Marshall
Customer Phone
owner
phones
Unmarshall
Customer Phone
owner
project

Demo
JAXB/JPA Fidelity
JSON Binding

Agenda
Browser
HTTP / REST
Binding Persistence
XML/JSON
Java
Relational/NoSQL

JPA-RS
Browser
JAX-RS / JPA-RS
Binding Persistence
XML/JSON
Java
Relational/NoSQL
HTTP

JPA-RS
JPA-RS
JAX-RS
Accounting PU Human Resources PUContracting PU
...
JPA
GET http://.../persistence/Accounting/Invoice/...
JPA-RS maps URI http://.../persistence/Accounting/
Invoice/...
to Accounting PU and Invoice entity
JAX-RS http://.../persistence/Accounting/Invoice/...
mapped to JPA-RS service

JPA-RS Features
§  Access relational data through REST with JSON or XML
§  Provides REST operations for entities in persistence unit (GET, PUT,
POST, DELETE)
§  Automatic generation of XML and JSON bindings
§  Supports invocation of named queries via HTTP
§  Server Caching—EclipseLink clustered cache
§  Dynamic Persistence also supported
–  Entities defined via metadata—no Java classes required
–  Enables persistence services for HTML 5/JavaScript applications

Resource Model
JPA Entity Model
Resource
Model

Resource Model & Links
{
"firstName": "Frank",
"gender": "Male",
"id": 1,
"lastName": "Smith",
"responsibilities": [],
"salary": 1,
"version": 13,
"address": {
"_link": {
"href": "http://localhost:7001/employee.web-js/persistence/employee/entity/Address/18",
"method": "GET",
"rel": "self"
}
},
…

Demo EclipseLink JPA-RS

EclipseLink Roadmap
EclipseLink 2.3
Indigo
•  Tenant Isolation
•  SINGLE_TABLE
•  Extensible
•  External
Metadata
•  Multiple DBs
•  Data Partitioning
2010 2011 2012 2013
EclipseLink 2.1
Helios
•  Query Extensions
•  TREAT AS
•  FUNC
•  Batch IN and
EXISTS
•  Attribute Group
•  Load
•  Fetch
•  Copy
•  Merge
•  eclispelink-
oxm.xml
•  Dynamic MOXy
EclipseLink 2.4
Juno
•  JSON Binding
•  JPA-RS
•  Tenant Isolation
•  Tenant per
Table/Schema
•  ALTER Schema
•  NoSQL
EclipseLink 2.5
Kepler
•  JPA 2.1
•  JPA-RS++…

Summary
§  Java application needs are changing—and EclipseLink is evolving too!
§  Support for NoSQL and Polyglot Persistence
§  Support for building apps that go from Database to Browser
–  JSON Binding
–  JAXB/JPA Fidelity
–  JPA-RS automating RESTful persistence service

EclipseLink: From NoSQL to HTML5 by Shaun Smith

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