NatsConnection

NATS connection using the default driver.

Inherits: IMessageQueueConnection, IReferenceable, IConfigurable, IOpenable

Description

The NatsConnection class is used to define NATS connections using the default driver.

Important points

  • By defining a connection and sharing it through multiple message queues, you can reduce the number of used database connections.

Configuration parameters

  • client_id: (optional) name of the client id
  • connection(s):
    • discovery_key: (optional) key to retrieve the connection from IDiscovery
    • host: host name or IP address
    • port: port number (default: 27017)
    • uri: resource URI or connection string with all parameters in it
  • credential(s):
    • store_key: (optional) key to retrieve the credentials from ICredentialStore
    • username: username
    • password: user’s password
  • options:
    • retry_connect: (optional) turns on/off automated reconnect when the connection is lost (default: true)
    • max_reconnect: (optional) maximum number of reconnection attempts (default: 3)
    • reconnect_timeout: (optional) number of milliseconds to wait on each reconnection attempt (default: 3000)
    • flush_timeout: (optional) number of milliseconds to wait on flushing messages (default: 3000)

References

  • *:logger:*:*:1.0 - (optional) ILogger components to pass log messages
  • *:discovery:*:*:1.0 - (optional) IDiscovery services
  • *:credential-store:*:*:1.0 (optional) credential stores to resolve credentials

Constructors

Creates a new instance of the connection component.

public NatsConnection()

Fields

_clientId

Hostname as client id.

private _clientId: string

_connection

NATS connection pool object.

protected _connection: IConnection

_connectionResolver

Connection resolver.

protected _connectionResolver: NatsConnectionResolver = new NatsConnectionResolver()

_flushTimeout

Number of milliseconds to wait on flushing messages (default: 3000)

private _flushTimeout: int = 3000

_logger

Logger

protected _logger: CompositeLogger = new CompositeLogger()

_maxReconnect

Maximum number of reconnection attempts (default: 3)

protected _maxReconnect: number = 3

_options

Connection options

protected _options: ConfigParams = new ConfigParams()

_reconnectTimeout

Number of milliseconds to wait on each reconnection attempt (default: 3000)

private _reconnectTimeout: int = 3000

_retryConnect

Retry to connect option

protected _retryConnect: bool = true

_subscriptions

Topic subscriptions

protected _subscriptions: List<NatsSubscription> = new List<NatsSubscription>()

Instance methods

CheckOpen

Checks if the connection is open.
Raises an error if the connection is closed.

private void CheckOpen()

CloseAsync

Closes a component and frees used resources.

public Task CloseAsync(IContext context)

  • context: IContext - (optional) a context to trace execution through a call chain.

Configure

Configures the component by passing its configuration parameters.

public void Configure(ConfigParams config)

  • config: ConfigParams - configuration parameters to be set.

CreateQueueAsync

Creates a message queue. If the connection doesn’t support this function, it exists without error.

public Task CreateQueueAsync(string name)

  • name: string - name of the queue to be created.

DeleteQueueAsync

Deletes a message queue. If the connection doesn’t support this function, it exists without error.

public Task DeleteQueueAsync(string name)

  • name: string - name of the queue to be deleted.

GetConnection

Gets the connection.

public IConnection GetConnection()

  • returns: IConnection - connection to NATS

IsOpen

Checks if the component is open.

public bool IsOpen()

  • returns: bool - true if the component is open and false otherwise.

OpenAsync

Opens the component.

public Task OpenAsync(IContext context)

  • context: IContext - (optional) a context to trace execution through a call chain.

PublishAsync

Publishes a message to a specified topic.

public Task PublishAsync(string subject, Msg message)

  • subject: string - subject (topic) where the message will be placed
  • message: Msg - message to be published

ReadQueueNames

Reads a list of registered queue names. If the connection doesn’t support this function, it returns an empty list.

public Task<List<string>> ReadQueueNamesAsync()

  • returns: Task<List<string>> - queue names.

SetReferences

Sets references to dependent components.

public void SetReferences(IReferences references)

  • references: IReferences - references to locate the component’s dependencies.

SubscribeAsync

Subscribes to a topic.

public Task SubscribeAsync(string subject, string queue, INatsMessageListener listener)

  • subject: string - subject (topic) name
  • options: string - subscription options
  • listener: INatsMessageListener - message listener

UnsubsUnsubscribeAsynccribe

Unsubscribes from a previously subscribed topic.

public Task UnsubscribeAsync(string subject, string queue, INatsMessageListener listener)

  • subject: string - subject (topic) name
  • queue: string - subscription queue
  • listener: INatsMessageListener - message listener