CoAP

Since Camel 2.16

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.

From Camel 3.0.0, 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

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 has no options.

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

Name

Description

Default

Type

uri

The URI for the CoAP endpoint

URI

Query Parameters (13 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
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.		ExchangePattern
synchronous (advanced)	Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).	false	boolean

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

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.

ExchangePattern

synchronous (advanced)

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

false

boolean

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-coap-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 2 options, which are listed below.

Name	Description	Default	Type
camel.component.coap.enabled	Enable coap component	true	Boolean
camel.component.coap.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

Name

Description

Default

Type

camel.component.coap.enabled

Enable coap component

true

Boolean

camel.component.coap.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

Message Headers

Name Type Description

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.

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:

The value of the CamelCoapMethod header
GET if a query string is provided on the target CoAP server URI.
POST if the message exchange body is not null.
GET otherwise.