CoAP

Since Camel 2.16

Both producer and consumer are supported

Camel-CoAP is an Apache Camel component that allows you to work with CoAP, a lightweight REST-type protocol for machine-to-machine operation. CoAP, Constrained Application Protocol is a specialized web transfer protocol for use with constrained nodes and constrained networks and it is based on RFC 7252.

Camel supports the DTLS, TCP and TLS protocols via the following URI schemes:

Scheme Protocol

coap

UDP

coaps

UDP + DTLS

coap+tcp

TCP

coaps+tcp

TCP + TLS

There are a number of different configuration options to configure TLS. For both DTLS (the "coaps" uri scheme) and TCP + TLS (the "coaps+tcp" uri scheme), it is possible to use a "sslContextParameters" parameter, from which the camel-coap component will extract the required truststore / keystores etc to set up TLS. In addition, the DTLS protocol supports two alternative configuration mechanisms. To use a pre-shared key, configure a pskStore, and to work with raw public keys, configure privateKey + publicKey objects.

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

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

Options

The CoAP component supports 3 options, which are listed below.

Name Description Default Type

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

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

basicPropertyBinding (advanced)

Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities

false

boolean

The CoAP endpoint is configured using URI syntax:

coap:uri

with the following path and query parameters:

Path Parameters (1 parameters):

Name Description Default Type

uri

The URI for the CoAP endpoint

URI

Query Parameters (16 parameters):

Name Description Default Type

alias (common)

Sets the alias used to query the KeyStore for the private key and certificate. This parameter is used when we are enabling TLS with certificates on the service side, and similarly on the client side when TLS is used with certificates and client authentication. If the parameter is not specified then the default behavior is to use the first alias in the keystore that contains a key entry. This configuration parameter does not apply to configuring TLS via a Raw Public Key or a Pre-Shared Key.

String

cipherSuites (common)

Sets the cipherSuites String. This is a comma separated String of ciphersuites to configure. If it is not specified, then it falls back to getting the ciphersuites from the sslContextParameters object.

String

clientAuthentication (common)

Sets the configuration options for server-side client-authentication requirements. The value must be one of NONE, WANT, REQUIRE. If this value is not specified, then it falls back to checking the sslContextParameters.getServerParameters().getClientAuthentication() value.

String

privateKey (common)

Set the configured private key for use with Raw Public Key.

PrivateKey

pskStore (common)

Set the PskStore to use for pre-shared key.

PskStore

publicKey (common)

Set the configured public key for use with Raw Public Key.

PublicKey

recommendedCipherSuitesOnly (common)

The CBC cipher suites are not recommended. If you want to use them, you first need to set the recommendedCipherSuitesOnly option to false.

true

boolean

sslContextParameters (common)

Set the SSLContextParameters object for setting up TLS. This is required for coapstcp, and for coaps when we are using certificates for TLS (as opposed to RPK or PKS).

SSLContextParameters

trustedRpkStore (common)

Set the TrustedRpkStore to use to determine trust in raw public keys.

TrustedRpkStore

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

coapMethodRestrict (consumer)

Comma separated list of methods that the CoAP consumer will bind to. The default is to bind to all methods (DELETE, GET, POST, PUT).

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. The value can be one of: InOnly, InOut, InOptionalOut

ExchangePattern

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

basicPropertyBinding (advanced)

Whether the endpoint should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities

false

boolean

synchronous (advanced)

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

false

boolean

Message Headers

Name Type Description

CamelCoapMethod

String

The request method that the CoAP producer should use when calling the target CoAP server URI. Valid options are DELETE, GET, PING, POST & PUT.

CamelCoapResponseCode

String

The CoAP response code sent by the external server. See RFC 7252 for details of what each code means.

CamelCoapUri

String

The URI of a CoAP server to call. Will override any existing URI configured directly on the endpoint.

Configuring the CoAP producer request method

The following rules determine which request method the CoAP producer will use to invoke the target URI:

  1. The value of the CamelCoapMethod header

  2. GET if a query string is provided on the target CoAP server URI.

  3. POST if the message exchange body is not null.

  4. GET otherwise.

Spring Boot Auto-Configuration

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

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

The component supports 4 options, which are listed below.

Name Description Default Type

camel.component.coap.basic-property-binding

Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities

false

Boolean

camel.component.coap.bridge-error-handler

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

camel.component.coap.enabled

Whether to enable auto configuration of the coap component. This is enabled by default.

Boolean

camel.component.coap.lazy-start-producer

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

Boolean
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