Spring - MongoDB (Document Oriented Database)

We often hear following terms viz high scalability, elasticity , high availability..
In addition to this, we do face performance issues with humongous data , which brings our critical applications to deadly halt.

I have experienced such performance problems numerous times in my professional carrier (almost 6 years til now), we usually solved these problems with trade offs like minimizing data fetched / even gone ahead and moved on to more cores and disks etc or tuning and other stuff.

Having such a experience , I was always looking to try out thing called NOSQL databases, recently I got chance & time to try out MongoDB .

My first reaction to Mongo was ..."Its Kool !!".

I tried MongoDB along with spring , (spring-data mongodb), as always spring provides nice abstraction and spring style templates to interact with mongo.

 Setting up MongoDB is very simple,
1. Download zip from http://www.mongodb.org/downloads appropriate for your platform.For me its mongodb-win32-i386-1.8.1.zip
2. Unzip the zip the downloaded zip to a directory, it will have a bin directory with mongo executables.
3. To get mongo working create "C:\data\db\"  ,as mongo uses this location as default to store file system.
4. You are almost done, now go to bin directory and run mongod.exe , this will start up database server.
5. "help' command will help you after that, to explore more functions like creating database, switching, adding users, adding updating/ removing collections.

Now, will move to spring -mongo part,

Spring comes with MongoTemplate, 
sample configurations , that I tried are as follows

<br /> <bean id="mongo" class="com.mongodb.Mongo"><br /> <constructor-arg value="localhost" /> <constructor-arg value="27017" /> </bean> <bean id="thinkerPersister" class="com.dhananjay.ithinker.persister.MongoRepository"> <constructor-arg index="0" ref="mongo" /> <constructor-arg index="1" value="myDB" /> </bean>

The class MongoRepository is a implementation of below interface with mongotemplate instance injected in it

public interface Repository <T extends Entity> { void saveEntity(String collectionName,T object,Mode mode); void saveAll(String collectionName,List<T> objects,Mode mode); T getEntityById(String collectionName,long id,Class<T> clazz); List<T> getEntitiesById(String collectionName,long id,Class<T> clazz); T getEntityByColumn(String column,String value, String collection,Class<T> clazz); enum Mode{ INSERT, UPDATE, DELETE } }

Constructor of MongoRepository initializes a mongoTemplate instance as follows

public MongoRepository(Mongo mongo, String dbName){ this.mongoTemplate = new MongoTemplate(mongo,dbName); }

 It works very smoothly..

 @Override
    public void saveEntity(String collectionName, Entity object,com.dhananjay.ithinker.persister.Repository.Mode mode) {
        log.info("Saving record for in Collection Name "+collectionName);
        switch(mode){
            case INSERT:
                this.mongoTemplate.insert(collectionName,object);
                break;
            case UPDATE:
            { 
                Map objectMap;
                try {
                    objectMap = org.apache.commons.beanutils.BeanUtils.describe(object);
                    Update update = new Update();
                    if(objectMap != null && !objectMap.isEmpty()){
                      
                        for(Map.Entry entry : objectMap.entrySet()){
                            if(entry.getValue() != null)
                                //update.addToSet(entry.getKey(), entry.getValue());
                                update = update.set(entry.getKey(), entry.getValue());
                            this.mongoTemplate.updateFirst(collectionName,new Query(where("_id").is(object.getId())), update);
                        }
                    }
                  
                } catch (IllegalAccessException e) {
                    throw new RuntimeException("Error while update ",e);
                } catch (InvocationTargetException e) {
                    throw new RuntimeException("Error while update ",e);
                } catch (NoSuchMethodException e) {
                    throw new RuntimeException("Error while update ",e);
                }
                break;
            }
            case DELETE:
                this.mongoTemplate.remove(collectionName,new Query(where("_id").is(object.getId())));
                break;
            default :
                throw new UnsupportedOperationException("This mode for DB operation is not yet supported "+mode);
      
        }
      
        log.info("Saving record for in Collection Name is completed"+collectionName);
    }

@Override
    public T getEntityByColumn(String column, String value,String collection, Class clazz) {
        return this.mongoTemplate.findOne(collection, new Query(where(column).is(value)),clazz);
    }

    @Override
    public T getEntityById(String collectionName, long id,Class clazz) {
        log.info("Fetching single record for id "+id +" Collection Name "+collectionName);
        return this.mongoTemplate.findOne(collectionName, new Query(where("_id").is(id)),clazz);
    }

MongoRepository

 HUMONGOUS  :)
Thanks,
Dhananjay