Client API

The OrientDBClient is the entry point of the driver. Once connected it provides APIs for databases manipulation and sessions creation

Connecting

Use the method OrientDBClient.connect to establish a connection to one OrientDB server/cluster. The methods return a Promise. Below an example of a connection to a single OrientDB server.

const OrientDBClient = require("orientjs").OrientDBClient;

OrientDBClient.connect({
  host: "localhost",
  port: 2424
}).then(client => {
  return client.close();
}).then(()=> {
   console.log("Client closed");
});

or with async/await

const OrientDBClient = require("orientjs").OrientDBClient;

(async function() {
  let client;
  try {
    client = await OrientDBClient.connect({ host: "localhost" });
    console.log("Connected");
  } catch (e) {
    console.log(e);
  }

  if (client) {
    await client.close();
    console.log("Disconnected");
  }
})();

Configuration with OrientDB Cluster

To do so, define the servers configuration parameter when you initialize the server connection. OrientJS uses these as alternate hosts in the event that it encounters an error while connecting to the primary host.

When using this method, the only requisite is that at least one of these servers must be online when the application attempts to establish its first connection. Below an example of a connection with two servers.


const OrientDBClient = require("orientjs").OrientDBClient;

OrientDBClient.connect({
  host: "localhost",
  port: 2424,
  servers : [{host : "localhost", port : 2425}]
}).then(client => {
  return client.close();
}).then(()=> {
   console.log("Client closed");
});

The only prerequisite when executing this code is that at least one of the hosts, primary or secondary, be online at the time that it first runs. Once it has established this initial connection, OrientJS keeps the list up to date with those servers in the cluster that are currently online. It manages this through the push notifications that OrientDB sends to connected clients when changes occur in cluster membership.

Connection Pooling

By default OrientJS create a connection pool of 5 sockets. Use the paramenter pool in order to change the default configuration.

const OrientDBClient = require("orientjs").OrientDBClient;

OrientDBClient.connect({
  host: "localhost",
  port: 2424,
  pool : { max : 10}
}).then(client => {
  return client.close();
}).then(()=> {
   console.log("Client closed");
});

Databases Manipulation

Once you have initialized the client variable in your application, you can use it to work with the OrientDB Server, such as creating new databases on the server. It also provides methods to initialize the OrientJS Sessions API, which are covered in more detail below.

Create a database

In the event that you need to create a database on OrientDB, you can do so through the OrientDBClient API using the client.createDatabase method.

client.createDatabase({
    name: "test",
    username: "root",
    password: "root"
})
.then(() => {
    console.log("Database created");
})
.catch(err => {
    console.log("Error creating database");
});

Check existence of a databases

client.existsDatabase({
    name: "test",
    username: "root",
    password: "root"
})
.then(result => {
    console.log(result);
})
.catch(err => {
    console.log("Error checking for database");
});

List Databases

client.listDatabases({
    username: "root",
    password: "root"
})
.then(results => {
    console.log(results);
})
.catch(err => {
    console.log("Error listing databases");
});

Drop a database

client.dropDatabase({
    name: "test",
    username: "root",
    password: "root"
})
.then(() => {
    console.log("Database dropped");
})
.catch(err => {
    console.log("Error dropping the database");
});

Sessions

Once you have initialized the client variable in your application, you can use it to open sessions on OrientDB Server. You can either open a single session with the API client.session or request a pool of sessions with the API client.sessions. Then use the Session API to interact with the database.

Single Session

To open a new standalone session use the client.session api. This api will create a new stateful session associated with the given database and credentials. Once done, call session.close in order to release the session on the server. Session are stateful since OrientJS 3.0 as they can execute server side transactions.

client.session({ name: "demodb", username: "admin", password: "admin" })
.then(session => {
    // use the session
    ... 
    // close the session
    return session.close();
});

Pool of Sessions

Opening and closing sessions everytime can be expensive, since open and close require a network request to the server. Use the API client.sessions to create a pool of sessions with a given database and credentials. To get a session from the pool call the api pool.acquire. Once done with the session you can return the session to the pool by calling session.close.

By default the pool size is is 5 sessions. Use the pool parameter to change this default configuration.

// Create a sessions Pool
client.sessions({ name: "demodb", username: "admin", password: "admin", pool: { max: 10} })
  .then(pool => {
    // acquire a session
    return pool.acquire()
      .then(session => {
        // use the session
        ...
        // release the session
        return session.close();
      })
      .then(() => {
           // close the pool
        return pool.close();
      });
  });
});

results matching ""

    No results matching ""