Node.js NAN C++ NuoDB Driver

The nuodb driver add-on for Node.js powers high performance NuoDB Database applications.

Use nuodb driver to connect Node.js to a NuoDB Database.

nuodb driver supports basic features of the NuoDB Database and NuoDB C++ client.

Dependencies

Node 16.13.2

Installation

If you have NuoDB installed locally, skip to step 4

1. Download the nuodb client package. The client package releases can be found here: https://github.com/nuodb/nuodb-client/releases

2. Extract the client package. tar -xzf nuodb-client-version.lin64.tar.gz

3. Set the NUODB_CLIENT_PACKAGE environment variable. export NUODB_CLIENT_PACKAGE=/path/to/nuodb-client-version.lin64

4. Clone the nuodb node.js driver from the git repo. git clone https://github.com/nuodb/node-nuodb

5. Install the driver. cd node-nuodb && npm i

6. Ensure the driver is working as intended (requires NuoDB database running named test with user dba and a password dba). npm test

7. Import the driver into your node.js project. var Driver = require('/path/to/driver/repo/nuodb');

Documentation

Documentation is Available Online!

Connection Pool

The NuoDB Node.js driver comes with a built in connection pool available.

Arguments

connectionConfig: the configuration that will be used to create the connection in the pool, required argument.

minAvailable: initial size of the pool and the number of connections the pool will aim to maintain, default of 10 is used if no argument is provided.

maxAge: Amount of time from connection creation until it will age out, default of 300000ms (5 minutes) is used if no argument is provided.

checkTime: how often the pool will run an internal liveliness check on free connections, default of 120000ms(2 minutes) is used if no argument is provided. If 0 is provided, the liveliness check will be disabled.

maxLimit: hard cap on the amount of live connection the pool can maintain, default of 200 is used if no argument is provided. If 0, the pool will have no hard cap.

connectionRetryLimit: amount of times a pool will attempt to create a connection, default of 5 is used if no argument is provided.

id: optional argument to give the pool an id. As default the pool will be provided the “new Date().getTime()” at the time of its creation as its id.

skipCheckLivelinessOnRelease: turns off liveliness checks on connections when they are released back to the pool, which is different than the checkTime that is used for aging purposes. The default is false, meaning we will perform a liveliness check when a connection is returned to the pool.

livelinessCheck: indicates the type of liveliness check to be performed. By default, the value is set to 'query', which means a query to test the connection. If set to any value (quoted string) other than 'query', it will only look to see if the NuoDB API isConnected returns true and we have not trapped a connection related exception previously.

Arguments should be provided to the pool as an object. Please refer to the Usage section for an example.

Usage

const myPool = new Pool({
    minAvailable: <arg>,
    connectionConfig: <connection config obj>,
    maxAge: <arg>,
    checkTime: <arg>,
    maxLimit: <arg>,
    connectionRetryLimit: <arg>,
    id: <arg>,
    skipCheckLivelinessOnRelease: false|true,
    livelinessCheck: query|<arg>
})

Methods

After a pool is created the user must initialize it using the init method:

await Pool.init()

This will populate the pool. The pool is unavailable until this completes.

Once the pool has been successfully initialized it is ready for use. The user calls:

const newConnection = await Pool.requestConnection()

to get a connection, this method will return a connection ready for use.

Once the user has finished using a connection, it can be returned to the pool with:

await Pool.releaseConnection(<connection>)

Connections that have been released back to the connection pool should not be used anymore. Connections that have failed in any way should be returned to the pool where they will dealt with and replaced.

A pool should be shutdown by calling:

await Pool.closePool()

This will close all of the connections in the pool regardless of whether or not they are in use.

Users cannot manually close connections provided by the pool, and calling: connection.close() on a connection provided by the pool will have the same effect as calling: Pool.releaseConnection(connection)

Related Links

• NuoDB Multiplexer
• NuoDB Node.js Driver Documentation
• NuoDB Node.js Driver Docker Sample Express Application

Examples (EXPERIMENTAL)

See branch examples.

Best Practices

Any try catch block in which NuoDB resources are created must be followed by a finally block in which NuoDB resources are then cleaned up. Attempting to clean up NuoDB resources in a try block can lead to NuoDB resources being created and never cleaned up.

Good Example

 let conn
 let results
 try {
    conn = await pool.requestConnection();
    results = await conn.execute(query);
    const rows = await results?.getRows();
    rows?.should.be.ok();
  } catch (e) {
    console.error(e);
    should.not.exist(e);
  } finally {
      await results?.close();
      await pool.releaseConnection(conn);
  }

Bad Example

 try {
    const conn = await pool.requestConnection();
    const results = await conn.execute(query); // if we get an error here we will never clean up our connection
    const rows = await results?.getRows();
    rows?.should.be.ok();
    await results?.close();
    await pool.releaseConnection(conn);
  } catch (e) {
    console.error(e);
    should.not.exist(e);
  }

Help

Issues and questions about nuodb driver can be posted on GitHub.

License

This module is released under the BSD 3-Clause License.