Nats Component

Available as of Camel version 2.17

NATS is a fast and reliable messaging platform.

Maven users will need to add the following dependency to their pom.xml for this component.

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-nats</artifactId>
    <!-- use the same version as your Camel core version -->
    <version>x.y.z</version>
</dependency>

URI format

nats:servers[?options]

Where servers represents the list of NATS servers.

Options

The Nats component supports 2 options, which are listed below.

Name Description Default Type

useGlobalSslContext Parameters (security)

Enable usage of global SSL context parameters.

false

boolean

resolveProperty Placeholders (advanced)

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

boolean

The Nats endpoint is configured using URI syntax:

nats:servers

with the following path and query parameters:

Path Parameters (1 parameters):

Name Description Default Type

servers

Required URLs to one or more NAT servers. Use comma to separate URLs when specifying multiple servers.

String

Query Parameters (25 parameters):

Name Description Default Type

connection (common)

Reference an already instantiated connection to Nats server

Connection

connectionTimeout (common)

Timeout for connection attempts. (in milliseconds)

2000

int

flushConnection (common)

Define if we want to flush connection or not

false

boolean

flushTimeout (common)

Set the flush timeout (in milliseconds)

1000

int

maxPingsOut (common)

maximum number of pings have not received a response allowed by the client

2

int

maxReconnectAttempts (common)

Max reconnection attempts

60

int

noEcho (common)

Turn off echo. If supported by the gnatsd version you are connecting to this flag will prevent the server from echoing messages back to the connection if it has subscriptions on the subject being published to.

false

boolean

noRandomizeServers (common)

Whether or not randomizing the order of servers for the connection attempts

false

boolean

pedantic (common)

Whether or not running in pedantic mode (this affects performace)

false

boolean

pingInterval (common)

Ping interval to be aware if connection is still alive (in milliseconds)

120000

int

reconnect (common)

Whether or not using reconnection feature

true

boolean

reconnectTimeWait (common)

Waiting time before attempts reconnection (in milliseconds)

2000

int

requestCleanupInterval (common)

Interval to clean up cancelled/timed out requests.

5000

int

topic (common)

Required The name of topic we want to use

String

verbose (common)

Whether or not running in verbose mode

false

boolean

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

maxMessages (consumer)

Stop receiving messages from a topic we are subscribing to after maxMessages

String

poolSize (consumer)

Consumer pool size

10

int

queueName (consumer)

The Queue name if we are using nats for a queue configuration

String

exceptionHandler (consumer)

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

ExceptionHandler

exchangePattern (consumer)

Sets the exchange pattern when the consumer creates an exchange.

ExchangePattern

replySubject (producer)

the subject to which subscribers should send response

String

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

secure (security)

Set secure option indicating TLS is required

false

boolean

sslContextParameters (security)

To configure security using SSLContextParameters

SSLContextParameters

Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-nats-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 3 options, which are listed below.

Name Description Default Type

camel.component.nats.enabled

Enable nats component

true

Boolean

camel.component.nats.resolve-property-placeholders

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

Boolean

camel.component.nats.use-global-ssl-context-parameters

Enable usage of global SSL context parameters.

false

Boolean

Headers

Name Type Description

CamelNatsMessageTimestamp

long

The timestamp of a consumed message.

Producer example:

from("direct:send").to("nats://localhost:4222?topic=test");

In case of using Authorization you can directly specify your credentials in the server URL

from("direct:send").to("nats://username:password@localhost:4222?topic=test");

or your token

from("direct:send").to("nats://token@localhost:4222?topic=test");

Consumer example:

from("nats://localhost:4222?topic=test&maxMessages=5&queueName=test").to("mock:result");