REST OpenApi :: Apache Camel

URI format

rest-openapi:[specificationPath#]operationId

Where operationId is the ID of the operation in the OpenApi specification, and specificationPath is the path to the specification. If the specificationPath is not specified it defaults to openapi.json. The lookup mechanism uses Camels ResourceHelper to load the resource, which means that you can use CLASSPATH resources (classpath:my-specification.json), files (file:/some/path.json), the web (http://api.example.com/openapi.json) or reference a bean (ref:nameOfBean) or use a method of a bean (bean:nameOfBean.methodName) to get the specification resource, failing that OpenApi’s own resource loading support.

This component does not act as a HTTP client, it delegates that to another component mentioned above. The lookup mechanism searches for a single component that implements the RestProducerFactory interface and uses that. If the CLASSPATH contains more than one, then the property componentName should be set to indicate which component to delegate to.

Most of the configuration is taken from the OpenApi specification but the option exists to override those by specifying them on the component or on the endpoint. Typically you would just need to override the host or basePath if those differ from the specification.

The host parameter should contain the absolute URI containing scheme, hostname and port number, for instance: https://api.example.com

With componentName you specify what component is used to perform the requests, this named component needs to be present in the Camel context and implement the required RestProducerFactory interface — as do the components listed at the top.

If you do not specify the componentName at either component or endpoint level, CLASSPATH is searched for a suitable delegate. There should be only one component present on the CLASSPATH that implements the RestProducerFactory interface for this to work.

This component’s endpoint URI is lenient which means that in addition to message headers you can specify REST operation’s parameters as endpoint parameters, these will be constant for all subsequent invocations so it makes sense to use this feature only for parameters that are indeed constant for all invocations — for example API version in path such as /api/{version}/users/{id}.

Options

The REST OpenApi component supports 10 options, which are listed below.

Name	Description	Default	Type
basePath (producer)	API basePath, for example /v2. Default is unset, if set overrides the value present in OpenApi specification.		String
componentName (producer)	Name of the Camel component that will perform the requests. The component must be present in Camel registry and it must implement RestProducerFactory service provider interface. If not set CLASSPATH is searched for single component that implements RestProducerFactory SPI. Can be overridden in endpoint configuration.		String
consumes (producer)	What payload type this component capable of consuming. Could be one type, like application/json or multiple types as application/json, application/xml; q=0.5 according to the RFC7231. This equates to the value of Accept HTTP header. If set overrides any value found in the OpenApi specification. Can be overridden in endpoint configuration		String
host (producer)	Scheme hostname and port to direct the HTTP requests to in the form of https://hostname:port. Can be configured at the endpoint, component or in the corresponding REST configuration in the Camel Context. If you give this component a name (e.g. petstore) that REST configuration is consulted first, rest-openapi next, and global configuration last. If set overrides any value found in the OpenApi specification, RestConfiguration. Can be overridden in endpoint configuration.		String
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
produces (producer)	What payload type this component is producing. For example application/json according to the RFC7231. This equates to the value of Content-Type HTTP header. If set overrides any value present in the OpenApi specification. Can be overridden in endpoint configuration.		String
specificationUri (producer)	Path to the OpenApi specification file. The scheme, host base path are taken from this specification, but these can be overridden with properties on the component or endpoint level. If not given the component tries to load openapi.json resource. Note that the host defined on the component and endpoint of this Component should contain the scheme, hostname and optionally the port in the URI syntax (i.e. https://api.example.com:8080). Can be overridden in endpoint configuration.	openapi.json	URI
basicPropertyBinding (advanced)	Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities	false	boolean
sslContextParameters (security)	Customize TLS parameters used by the component. If not set defaults to the TLS parameters set in the Camel context		SSLContextParameters
useGlobalSslContextParameters (security)	Enable usage of global SSL context parameters.	false	boolean

Name

Description

Default

Type

basePath (producer)

API basePath, for example /v2. Default is unset, if set overrides the value present in OpenApi specification.

String

componentName (producer)

Name of the Camel component that will perform the requests. The component must be present in Camel registry and it must implement RestProducerFactory service provider interface. If not set CLASSPATH is searched for single component that implements RestProducerFactory SPI. Can be overridden in endpoint configuration.

String

consumes (producer)

What payload type this component capable of consuming. Could be one type, like application/json or multiple types as application/json, application/xml; q=0.5 according to the RFC7231. This equates to the value of Accept HTTP header. If set overrides any value found in the OpenApi specification. Can be overridden in endpoint configuration

String

host (producer)

Scheme hostname and port to direct the HTTP requests to in the form of https://hostname:port. Can be configured at the endpoint, component or in the corresponding REST configuration in the Camel Context. If you give this component a name (e.g. petstore) that REST configuration is consulted first, rest-openapi next, and global configuration last. If set overrides any value found in the OpenApi specification, RestConfiguration. Can be overridden in endpoint configuration.

String

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

produces (producer)

What payload type this component is producing. For example application/json according to the RFC7231. This equates to the value of Content-Type HTTP header. If set overrides any value present in the OpenApi specification. Can be overridden in endpoint configuration.

String

specificationUri (producer)

Path to the OpenApi specification file. The scheme, host base path are taken from this specification, but these can be overridden with properties on the component or endpoint level. If not given the component tries to load openapi.json resource. Note that the host defined on the component and endpoint of this Component should contain the scheme, hostname and optionally the port in the URI syntax (i.e. https://api.example.com:8080). Can be overridden in endpoint configuration.

openapi.json

URI

basicPropertyBinding (advanced)

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

false

boolean

sslContextParameters (security)

Customize TLS parameters used by the component. If not set defaults to the TLS parameters set in the Camel context

SSLContextParameters

useGlobalSslContextParameters (security)

Enable usage of global SSL context parameters.

false

boolean

The REST OpenApi endpoint is configured using URI syntax:

rest-openapi:specificationUri#operationId

with the following path and query parameters:

Path Parameters (2 parameters):

Name	Description	Default	Type
specificationUri	Path to the OpenApi specification file. The scheme, host base path are taken from this specification, but these can be overridden with properties on the component or endpoint level. If not given the component tries to load openapi.json resource from the classpath. Note that the host defined on the component and endpoint of this Component should contain the scheme, hostname and optionally the port in the URI syntax (i.e. http://api.example.com:8080). Overrides component configuration. The OpenApi specification can be loaded from different sources by prefixing with file: classpath: http: https:. Support for https is limited to using the JDK installed UrlHandler, and as such it can be cumbersome to setup TLS/SSL certificates for https (such as setting a number of javax.net.ssl JVM system properties). How to do that consult the JDK documentation for UrlHandler. Default value notice: By default loads openapi.json file	openapi.json	URI
operationId	Required ID of the operation from the OpenApi specification.		String

Name

Description

Default

Type

specificationUri

Path to the OpenApi specification file. The scheme, host base path are taken from this specification, but these can be overridden with properties on the component or endpoint level. If not given the component tries to load openapi.json resource from the classpath. Note that the host defined on the component and endpoint of this Component should contain the scheme, hostname and optionally the port in the URI syntax (i.e. http://api.example.com:8080). Overrides component configuration. The OpenApi specification can be loaded from different sources by prefixing with file: classpath: http: https:. Support for https is limited to using the JDK installed UrlHandler, and as such it can be cumbersome to setup TLS/SSL certificates for https (such as setting a number of javax.net.ssl JVM system properties). How to do that consult the JDK documentation for UrlHandler. Default value notice: By default loads openapi.json file

openapi.json

URI

operationId

Required ID of the operation from the OpenApi specification.

String

Query Parameters (8 parameters):

Name	Description	Default	Type
basePath (producer)	API basePath, for example /v2. Default is unset, if set overrides the value present in OpenApi specification and in the component configuration.		String
componentName (producer)	Name of the Camel component that will perform the requests. The component must be present in Camel registry and it must implement RestProducerFactory service provider interface. If not set CLASSPATH is searched for single component that implements RestProducerFactory SPI. Overrides component configuration.		String
consumes (producer)	What payload type this component capable of consuming. Could be one type, like application/json or multiple types as application/json, application/xml; q=0.5 according to the RFC7231. This equates to the value of Accept HTTP header. If set overrides any value found in the OpenApi specification and. in the component configuration		String
host (producer)	Scheme hostname and port to direct the HTTP requests to in the form of https://hostname:port. Can be configured at the endpoint, component or in the corresponding REST configuration in the Camel Context. If you give this component a name (e.g. petstore) that REST configuration is consulted first, rest-openapi next, and global configuration last. If set overrides any value found in the OpenApi specification, RestConfiguration. Overrides all other configuration.		String
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
produces (producer)	What payload type this component is producing. For example application/json according to the RFC7231. This equates to the value of Content-Type HTTP header. If set overrides any value present in the OpenApi specification. Overrides all other configuration.		String
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

Name

Description

Default

Type

basePath (producer)

API basePath, for example /v2. Default is unset, if set overrides the value present in OpenApi specification and in the component configuration.

String

componentName (producer)

Name of the Camel component that will perform the requests. The component must be present in Camel registry and it must implement RestProducerFactory service provider interface. If not set CLASSPATH is searched for single component that implements RestProducerFactory SPI. Overrides component configuration.

String

consumes (producer)

What payload type this component capable of consuming. Could be one type, like application/json or multiple types as application/json, application/xml; q=0.5 according to the RFC7231. This equates to the value of Accept HTTP header. If set overrides any value found in the OpenApi specification and. in the component configuration

String

host (producer)

Scheme hostname and port to direct the HTTP requests to in the form of https://hostname:port. Can be configured at the endpoint, component or in the corresponding REST configuration in the Camel Context. If you give this component a name (e.g. petstore) that REST configuration is consulted first, rest-openapi next, and global configuration last. If set overrides any value found in the OpenApi specification, RestConfiguration. Overrides all other configuration.

String

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

produces (producer)

What payload type this component is producing. For example application/json according to the RFC7231. This equates to the value of Content-Type HTTP header. If set overrides any value present in the OpenApi specification. Overrides all other configuration.

String

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

Example: PetStore

Checkout the example in the camel-example-rest-openapi project in the examples directory.

For example if you wanted to use the PetStore provided REST API simply reference the specification URI and desired operation id from the OpenApi specification or download the specification and store it as openapi.json (in the root) of CLASSPATH that way it will be automaticaly used. Let’s use the Undertow component to perform all the requests and Camels excelent support for Spring Boot.

Here are our dependencies defined in Maven POM file:

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-undertow-starter</artifactId>
</dependency>

<dependency>
  <groupId>org.apache.camel.springboot</groupId>
  <artifactId>camel-rest-openapi-starter</artifactId>
</dependency>

Start by defining the Undertow component and the RestOpenApiComponent:

@Bean
public Component petstore(CamelContext camelContext, UndertowComponent undertow) {
    RestOpenApiComponent petstore = new RestOpenApiComponent(camelContext);
    petstore.setSpecificationUri("https://petstore3.swagger.io/api/v3/openapi.json");
    petstore.setDelegate(undertow);

    return petstore;
}

Support in Camel for Spring Boot will auto create the UndertowComponent Spring bean, and you can configure it using application.properties (or application.yml) using prefix camel.component.undertow.. We are defining the petstore component here in order to have a named component in the Camel context that we can use to interact with the PetStore REST API, if this is the only rest-openapi component used we might configure it in the same manner (using application.properties).

Now in our application we can simply use the ProducerTemplate to invoke PetStore REST methods:

@Autowired
ProducerTemplate template;

String getPetJsonById(int petId) {
    return template.requestBodyAndHeaders("petstore:getPetById", null, "petId", petId);
}

Spring Boot Auto-Configuration

When using rest-openapi 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-rest-openapi-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 11 options, which are listed below.

Name	Description	Default	Type
camel.component.rest-openapi.base-path	API basePath, for example /v2. Default is unset, if set overrides the value present in OpenApi specification.		String
camel.component.rest-openapi.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.rest-openapi.component-name	Name of the Camel component that will perform the requests. The component must be present in Camel registry and it must implement RestProducerFactory service provider interface. If not set CLASSPATH is searched for single component that implements RestProducerFactory SPI. Can be overridden in endpoint configuration.		String
camel.component.rest-openapi.consumes	What payload type this component capable of consuming. Could be one type, like application/json or multiple types as application/json, application/xml; q=0.5 according to the RFC7231. This equates to the value of Accept HTTP header. If set overrides any value found in the OpenApi specification. Can be overridden in endpoint configuration		String
camel.component.rest-openapi.enabled	Whether to enable auto configuration of the rest-openapi component. This is enabled by default.		Boolean
camel.component.rest-openapi.host	Scheme hostname and port to direct the HTTP requests to in the form of https://hostname:port. Can be configured at the endpoint, component or in the corresponding REST configuration in the Camel Context. If you give this component a name (e.g. petstore) that REST configuration is consulted first, rest-openapi next, and global configuration last. If set overrides any value found in the OpenApi specification, RestConfiguration. Can be overridden in endpoint configuration.		String
camel.component.rest-openapi.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
camel.component.rest-openapi.produces	What payload type this component is producing. For example application/json according to the RFC7231. This equates to the value of Content-Type HTTP header. If set overrides any value present in the OpenApi specification. Can be overridden in endpoint configuration.		String
camel.component.rest-openapi.specification-uri	Path to the OpenApi specification file. The scheme, host base path are taken from this specification, but these can be overridden with properties on the component or endpoint level. If not given the component tries to load openapi.json resource. Note that the host defined on the component and endpoint of this Component should contain the scheme, hostname and optionally the port in the URI syntax (i.e. https://api.example.com:8080). Can be overridden in endpoint configuration.		URI
camel.component.rest-openapi.ssl-context-parameters	Customize TLS parameters used by the component. If not set defaults to the TLS parameters set in the Camel context. The option is a org.apache.camel.support.jsse.SSLContextParameters type.		String
camel.component.rest-openapi.use-global-ssl-context-parameters	Enable usage of global SSL context parameters.	false	Boolean

Name

Description

Default

Type

camel.component.rest-openapi.base-path

API basePath, for example /v2. Default is unset, if set overrides the value present in OpenApi specification.

String

camel.component.rest-openapi.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.rest-openapi.component-name

Name of the Camel component that will perform the requests. The component must be present in Camel registry and it must implement RestProducerFactory service provider interface. If not set CLASSPATH is searched for single component that implements RestProducerFactory SPI. Can be overridden in endpoint configuration.

String

camel.component.rest-openapi.consumes

What payload type this component capable of consuming. Could be one type, like application/json or multiple types as application/json, application/xml; q=0.5 according to the RFC7231. This equates to the value of Accept HTTP header. If set overrides any value found in the OpenApi specification. Can be overridden in endpoint configuration

String

camel.component.rest-openapi.enabled

Whether to enable auto configuration of the rest-openapi component. This is enabled by default.

Boolean

camel.component.rest-openapi.host

Scheme hostname and port to direct the HTTP requests to in the form of https://hostname:port. Can be configured at the endpoint, component or in the corresponding REST configuration in the Camel Context. If you give this component a name (e.g. petstore) that REST configuration is consulted first, rest-openapi next, and global configuration last. If set overrides any value found in the OpenApi specification, RestConfiguration. Can be overridden in endpoint configuration.

String

camel.component.rest-openapi.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

camel.component.rest-openapi.produces

What payload type this component is producing. For example application/json according to the RFC7231. This equates to the value of Content-Type HTTP header. If set overrides any value present in the OpenApi specification. Can be overridden in endpoint configuration.

String

camel.component.rest-openapi.specification-uri

Path to the OpenApi specification file. The scheme, host base path are taken from this specification, but these can be overridden with properties on the component or endpoint level. If not given the component tries to load openapi.json resource. Note that the host defined on the component and endpoint of this Component should contain the scheme, hostname and optionally the port in the URI syntax (i.e. https://api.example.com:8080). Can be overridden in endpoint configuration.

URI

camel.component.rest-openapi.ssl-context-parameters

Customize TLS parameters used by the component. If not set defaults to the TLS parameters set in the Camel context. The option is a org.apache.camel.support.jsse.SSLContextParameters type.

String

camel.component.rest-openapi.use-global-ssl-context-parameters

Enable usage of global SSL context parameters.

false

Boolean