Hands-on NoSQL MongoDB & Spring Integration

http://automateddeveloper.blogspot.com

I’m a professional Software Engineer based in the UK.

Neither I, nor this presentation, are in any way affiliated with SpringSource or MongoDB

Still want more?– http://automateddeveloper.blogspot.com– http://www.thirdmindmedia.co.uk– info@thirdmindmedia.co.uk

What is NoSQL?

NoSQL means “Not Only SQL”The NoSQL umbrella covers a range of non-

relational databases, including key-value, document , wide column store and graph based databases

NoSQL

Document

MongoDB CouchDB

Graph

Neo4J InfoGrid

Wide Column

Cassandra Hadoop

Why NoSQL?

NoSQL’s recent increase in popularity being largely driven by the explosion in amount of data that is now being created/captured on the web

Many leading web 2.0 sites now use NoSQL implementations:– Facebook – Cassandra (originally developed in-house

and later open-sourced– Twitter – Hadoop & Cassandra– Google – BigTable– Digg – Cassandra– FourSquare - MongoDB

In the News

$14millionAmount raised in Series C Funding last week by CouchBase for further investment in to NoSQL solutions(Aug2011)

4,850%Percent increase in NoSQL jobs since November 2009 as reported by SimplyHired.com

8TBAmount of data generated everyday in Twitter, and needs to be supported by their NoSQL solution (figure from 2010)

MongoDB

An Open Source Document oriented database

Dynamic schemas, storing data in JSON style documents that allows for addition of data on the fly

Supports indexing of documentsAuto-sharding supported, providing full

horizontal scaling

MongoDB & Spring

Core Spring and the SpringMVC framework areenterprise standard Javalibraries for building professional web sites

As more and more web sites need to be able to handle huge amounts of data, there will be an increased need to be able to build professional sites incorporating NoSQL solutions

How Spring & MongoDB Fit Together

Servlet Engine (e.g. Tomcat)

Controller Layer

Front Controller (Spring

Dispatcher)

Controller

Request/Response

Service Layer DAO Layer

Mongo Repository

iRepository

Mongo DB

Spring enables complete configuration of the Controller, Service, DAO Layer and facilitates connection to Mongo DB

Getting Started

This overview does not cover details of setting up a Spring MVC app, and will assume a working knowledge of the framework

Only the configuration to connect an existing Spring MVC app will be covered in detail

Before proceeding, install MongoDB – full details are available: http://www.mongodb.org/display/DOCS/Quickstart

If you plan to follow the walkthrough with the source code, it is provided as an Eclipse/Maven project and uses the M2Eclipse plugin

Domain Objects

Similar to using JPA(Hibernate, etc) the first step is to model the underlying Domain objects you want to use to model the applications underlying meta-data.

Using Spring Data we can model ourdomain using POJOsand annotations.

Domain Objects

@Document annotation on the root Document object

@Id on any member variable to be used as an identifier for the object (must be String/int/long)

The @Id field must either be named “id”, or the annotation used in combination with a MappingConverter

Domain Objects Unlike traditional JPA models, Document based models will often

have a root object, and will often contain nested objects, which do not need to be annotated

In our Resume example, only our top level “Resume” object needs to be annotated and we will only be persisting/retrieving at this level (Document based DB makes sense for this model, as a “ResumePage” only makes sense within the context of a “Resume” and not as an object in itself)

Using JPA, all three objects would be annotated “@Entity” and all could be queried as independent objects

@Document public class Resume

@Idprivate String id;

public class ResumePage

public class PageSection

Data Access – The Repository

Core CRUD functionality can be achieved out-of-the-box by extending the “MongoRepository” class

This provides save(), findAll(), findOne() and delete() methods that can be used on our @Document object (in our case “Resume.java”)

Data Access – The Repository

Our Repository interface can easily be extended to include custom methods, and the MongoTemplate class provides an API to create custom queries:

mongoTemplate.find(“COLLECTION_NAME”, new Query(Criteria.where(“name”).is(searchTerm)), Resume.class);

Criteria allows querying by any field name in a MongoDB Document

Service Layer

The majority of the MongoDB implementation is abstracted to the Data Access layer through the MongoRepository

There is no real change in the Service or Controller Layers to the normal Spring MVC approach

In the Service class we can just auto-wire the Repository Interface in to the class just like we would normally with the DAOs

Configuration

<!-- Mongo Configuration --><mongo:repositories base-package="com.tmm.nosql.mongodb.repo" />

<bean id="mongoTemplate" class="org.springframework.data.document.mongodb.MongoTemplate"> <constructor-arg ref="mongoDbFactory" /></bean>

<!-- local config --><mongo:db-factory id="mongoDbFactory" dbname="resume_db“ host="localhost" port="27017"/>

1. Define package location for the Repository

2. Define MongoTemplate bean

3. Define the Mongo DB Factory with the host name, port, dbname (can also provide username and password if needed)

Deploying to CloudFoundry

Sign up for your free CloudFoundry account (currently in Beta, so it may take time for your account details) at http://www.cloudfoundry.com/

Install the latest STS Eclipse build and CloudFoundry extensions (full details here: http://blog.springsource.com/2011/04/13/using-cloud-foundry-from-sts/

App Config for CloudFoundry

A change to your application config is needed to support access to CloudFoundry MongoDB service

Notice the only change is the “mongoDbFactory” bean is being instantiated with no constructor arguments – this will all be injected by Cloud Foundry

Configuring CloudFoundryIn the Servers tab, double-click the deployed application to open the Applications tab

In the Services section of the Applications tab, select the “Add Service” button, select MongoDB and name the service appropriately

Once the MongoDB service has been created, click and drag it in to the “Application Services” tab

Thoughts

NoSQL is growing in popularity but is not intended to be a replacement for RDBMS

NoSQL should be considered as another tool in the arsenal – RDBMS is not going anywhere!

Database technology choice should be driven by the requirements of the problem – Document oriented have specific applications

Appendix

Full source code for the application is available from http://automateddeveloper.blogspot.com

Feel free to drop me an email or come by to the blog and leave a comment if you have any questions or feedback