Connecting to a :py:class:`Cluster<aiogremlin.driver.cluster.Cluster>`
To take advantage of the higher level features of the :py:mod:`driver<goblin.driver>`, :py:mod:`~goblin.app.Goblin` provides the :py:class:`Cluster<aiogremlin.driver.cluster.Cluster>` object. :py:class:`Cluster<aiogremlin.driver.cluster.Cluster>` is used to create multi-host clients that leverage connection pooling and sharing. Its interface is based on the TinkerPop Java driver:
>>> async def print_results(gremlin='1+1'):
... # opens a cluster with default config
... cluster = await driver.Cluster.open('')
... client = await cluster.connect()
... # round robin requests to available hosts
... resp = await client.submit(gremlin=gremlin)
... async for msg in resp:
... print(msg)
... await cluster.close() # Close all connections to all hosts
And that is it. While :py:class:`Cluster<aiogremlin.driver.cluster.Cluster>` is simple to learn and use, it provides a wide variety of configuration options.
Configuration options can be set on :py:class:`Cluster<aiogremlin.driver.cluster.Cluster>` in one of two ways, either passed as keyword arguments to :py:meth:`open<aiogremlin.driver.cluster.Cluster.open>`, or stored in a configuration file and passed to the :py:meth:`open<aiogremlin.driver.cluster.Cluster.open>` using the kwarg configfile. Configuration files can be either YAML or JSON format. Currently, :py:class:`Cluster<aiogremlin.driver.cluster.Cluster>` uses the following configuration:
| Key | Description | Default |
|---|---|---|
| scheme | URI scheme, typically 'ws' or 'wss' for secure websockets | 'ws' |
| hosts | A list of hosts the cluster will connect to | ['localhost'] |
| port | The port of the Gremlin Server to connect to, same for all hosts | 8182 |
| ssl_certfile | File containing ssl certificate | '' |
| ssl_keyfile | File containing ssl key | '' |
| ssl_password | File containing password for ssl keyfile | '' |
| username | Username for Gremlin Server authentication | '' |
| password | Password for Gremlin Server authentication | '' |
| response_timeout | Timeout for reading responses from the stream | None |
| max_conns | The maximum number of connections open at any time to this host | 4 |
| min_conns | The minimum number of connection open at any time to this host | 1 |
| max_times_acquired | The maximum number of times a single pool connection can be acquired and shared | 16 |
| max_inflight | The maximum number of unresolved messages that may be pending on any one connection | 64 |
| message_serializer | String denoting the class used for message serialization, currently only supports basic GraphSONMessageSerializer | 'classpath' |
For information related to improving driver performance, please refer to the :doc:`performance section <performance>`.