1） Versant数据库可以直接支持复杂的业务模型：

public class Person {

String firstName;

String lastName;

String gender;

String ethnicity;

String language;

// 新增的节点

int index = 5;

Contact info;

Location location;

public String primaryCountry;

public String primaryAreaCode;

HashSet<Person> friends = new HashSet<Person>();

HashSet<Person> colleagues = new HashSet<Person>();

HashSet<Person> family = new HashSet<Person>();

HashSet<Person> relations = new HashSet<Person>();

}

Versant数据库可以直接支持包括HashSet、LinkedList在内的复杂数据结构。

 

2）Versant数据库可以直接支持复杂的对象间的关系

如下的代码中展示了一个两层的关系结构。

public void addFriend( Person p ){

friends.add(p);

addRelation(p);

p.getFriends().add(this);

}

 

3）Versant数据库可以很容易的建立和数据库之间的连接：

Iterator<DatabaseLoginHelper> ite = this.dblist.iterator();

DatabaseLoginHelper helper = (DatabaseLoginHelper)ite.next();

session = new TransSession(helper.getDatabaseNodeProperty());

session.setSchemaOption(TransSession.SCHEMA_ADD_DROP_ATTRIBUTES);

// System.out.println("Define Logical database:");

session.newLogicalDatabase(HPC_DEMO_NETWORK_NAME);

// System.out.println("Add to logical database:"+dbList[0]);

session.addToLogicalDatabase(HPC_DEMO_NETWORK_NAME, helper.databaseName);

System.out.println("Add to logical database:" + helper.databaseName);

 

4）Versant数据库可以很容易地创建对象，并保存到数据库中。

TransSession session = DistributedDatabaseManager.getInstance()

.createNewSession();

session.setDefaultDatabase("dbnodeb");

// TransSession session = new TransSession("dbnodea");

/**

* generate 500 random objects

*/

for (int i = 0; i < 1500; i++) {

Person person = new Person();

person.setFirstName("TFistName" + i);

person.setLastName("TListName" + i);

// set storage schema

DistributedDatabaseManager.getInstance()

.setRoundRonPersistentSchema();

session.makePersistent(person);

session.commit();

}

System.out.println("Demo data generated.");

session.commit();

上面的例子中，可以实现自动将数据对象配载到分布式数据库的不同节点中。

 

5）创建复杂的对象关联，在Versant数据库中也非常容易，可以直接理解为内存对象的操作。

public void createKnownPerson() {

TransSession session = DistributedDatabaseManager.getInstance()

.createNewSession();

session.setDefaultDatabase("dbnodeb");

Person personA = new Person();

personA.setFirstName("AAF1");

personA.setLastName("AAL1");

Person personB = new Person();

personB.setFirstName("BBF1");

personB.setLastName("BBL1");

personB.addFriend(personA);

Person personC = new Person();

personC.setFirstName("CCF1");

personC.setLastName("CCL1");

personC.addFriend(personB);

Person personD = new Person();

personD.setFirstName("DDF1");

personD.setLastName("DDL1");

personD.addFriend(personC);

session.makePersistent(personA, "dbnodea");

session.makePersistent(personB, "dbnodeb");

session.makePersistent(personC, "dbnodea");

session.makePersistent(personD, "dbnodeb");

System.out.println("Special Test Data created.");

session.commit();

}

 

6）Versant数据库的对象查询

Versant数据库可以支持SQL查询和NOSQL查询两种模式，以下为SQL查询的例子：

TransSession session = DistributedDatabaseManager.getInstance()

.createNewSession();

VQLQuery q = new VQLQuery(

session,

DistributedDatabaseManager.getInstance().HPC_DEMO_NETWORK_NAME,

"select selfoid from com.versant.domain.Person where firstName='AAF1' and lastName='AAL1'");

//"select * from com.versant.domain.Person");

System.out.println("About to execute query, and load root object.");

VEnumeration results = q.execute();

// 创建已经走过的朋友路径，避免回环

System.out

.println("--------------------------------------------------------------------------");

 

7）Versant数据库的对象查询

Versant数据库可以支持SQL查询和NOSQL查询两种模式，以下为在查到第一个目标对象，之后采用NOSQL方式，自动执行朋友圈子遍历的例子：

VQLQuery q = new VQLQuery(

session,

DistributedDatabaseManager.getInstance().HPC_DEMO_NETWORK_NAME,

"select selfoid from com.versant.domain.Person where firstName='AAF1' and lastName='AAL1'");

//"select * from com.versant.domain.Person");

System.out.println("About to execute query, and load root object.");

VEnumeration results = q.execute();

// 创建已经走过的朋友路径，避免回环

System.out

.println("--------------------------------------------------------------------------");

long middleTime = System.currentTimeMillis();

HashSet<Person> friendSet = new HashSet<Person>();

if (results.hasMoreElements()) {

Person person = (Person) results.nextElement();

friendSet.add(person);

System.out.println("Start Person found:" + person.getFirstName()

+ "/" + person.getLastName()

+ ", about to print friend path.");

Iterator ite = person.getFriends().iterator();

System.out.print("<<<  -> " + person.getFirstName() + "/"

+ person.getLastName());

while (ite.hasNext()) {

Person aFriend = (Person) ite.next();

if (!inFriendCircle(aFriend, friendSet)) {

System.out.print("--> " + aFriend.getFirstName() + "/"

+ aFriend.getLastName());

printFriendPath("--> ", aFriend, friendSet);

}

}

System.out.println("  >>>");

} else {

System.out.println("No root person found.");

}

long endTime = System.currentTimeMillis();