# Web Services Support

## Web Services Support

This chapter describes Spring Integration’s support for web services, including:

* [Outbound Web Service Gateways](#webservices-outbound)

* [Inbound Web Service Gateways](#webservices-inbound)

* [Web Service Namespace Support](#webservices-namespace)

* [Outbound URI Configuration](#outbound-uri)

* [WS Message Headers](#ws-message-headers)

* [MTOM Support](#mtom-support)

You need to include this dependency into your project:

Maven

```
<dependency>
    <groupId>org.springframework.integration</groupId>
    <artifactId>spring-integration-ws</artifactId>
    <version>5.5.9</version>
</dependency>
```

Gradle

```
compile "org.springframework.integration:spring-integration-ws:5.5.9"
```

### Outbound Web Service Gateways

To invoke a web service when you send a message to a channel, you have two options, both of which build upon the [Spring Web Services](https://projects.spring.io/spring-ws/) project: `SimpleWebServiceOutboundGateway` and `MarshallingWebServiceOutboundGateway`.
The former accepts either a `String` or `javax.xml.transform.Source` as the message payload.
The latter supports any implementation of the `Marshaller` and `Unmarshaller` interfaces.
Both require a Spring Web Services `DestinationProvider`, to determine the URI of the web service to be called.
The following example shows both options for invoking a web service:

```
 simpleGateway = new SimpleWebServiceOutboundGateway(destinationProvider);

 marshallingGateway = new MarshallingWebServiceOutboundGateway(destinationProvider, marshaller);
```

|   |When using the namespace support ([described later](#webservices-namespace)), you need only set a URI.<br/>Internally, the parser configures a fixed URI `DestinationProvider` implementation.<br/>If you need dynamic resolution of the URI at runtime, however, then the `DestinationProvider` can provide such behavior as looking up the URI from a registry.<br/>See the Spring Web Services [`DestinationProvider`](https://docs.spring.io/spring-ws/docs/current/api/org/springframework/ws/client/support/destination/DestinationProvider.html) Javadoc for more information about this strategy.|
|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

Starting with version 5.0, you can supply the `SimpleWebServiceOutboundGateway` and `MarshallingWebServiceOutboundGateway` with an external `WebServiceTemplate` instance, which you can configure for any custom properties, including `checkConnectionForFault` (which allows your application to deal with non-conforming services).

For more detail on the inner workings, see the Spring Web Services reference guide’s chapter covering [client access](https://docs.spring.io/spring-ws/docs/current/reference/#client) and the chapter covering [Object/XML mapping](https://docs.spring.io/spring/docs/current/spring-framework-reference/data-access.html#oxm).

### Inbound Web Service Gateways

To send a message to a channel upon receiving a web service invocation, you again have two options: `SimpleWebServiceInboundGateway` and `MarshallingWebServiceInboundGateway`.
The former extracts a `javax.xml.transform.Source` from the `WebServiceMessage` and sets it as the message payload.
The latter supports implementation of the `Marshaller` and `Unmarshaller` interfaces.
If the incoming web service message is a SOAP message, the SOAP action header is added to the headers of the `Message` that is forwarded onto the request channel.
The following example shows both options:

```
 simpleGateway = new SimpleWebServiceInboundGateway();
 simpleGateway.setRequestChannel(forwardOntoThisChannel);
 simpleGateway.setReplyChannel(listenForResponseHere); //Optional

 marshallingGateway = new MarshallingWebServiceInboundGateway(marshaller);
 //set request and optionally reply channel
```

Both gateways implement the Spring Web Services `MessageEndpoint` interface, so they can be configured with a `MessageDispatcherServlet` as per standard Spring Web Services configuration.

For more detail on how to use these components, see the Spring Web Services reference guide’s chapter covering [creating a web service](https://docs.spring.io/spring-ws/docs/current/reference/#server).
The chapter covering [Object/XML mapping](https://docs.spring.io/spring/docs/current/spring-framework-reference/data-access.html#oxm) is also applicable again.

To add the `SimpleWebServiceInboundGateway` and `MarshallingWebServiceInboundGateway` configurations to the Spring WS infrastructure, you should add the `EndpointMapping` definition between `MessageDispatcherServlet` and the target `MessageEndpoint` implementations, as you would for a normal Spring WS application.
For this purpose (from the Spring Integration perspective), Spring WS provides the following convenient `EndpointMapping` implementations:

* `o.s.ws.server.endpoint.mapping.UriEndpointMapping`

* `o.s.ws.server.endpoint.mapping.PayloadRootQNameEndpointMapping`

* `o.s.ws.soap.server.endpoint.mapping.SoapActionEndpointMapping`

* `o.s.ws.server.endpoint.mapping.XPathPayloadEndpointMapping`

You must specify the beans for these classes in the application context and reference the `SimpleWebServiceInboundGateway` and/or `MarshallingWebServiceInboundGateway` bean definitions according to the WS mapping algorithm.

See the [endpoint mappings](https://docs.spring.io/spring-ws/docs/current/reference/#server-endpoint-mapping) for more information.

### Web Service Namespace Support

To configure an outbound web service gateway, use the `outbound-gateway` element from the `ws` namespace, as the following example shows:

```
<int-ws:outbound-gateway id="simpleGateway"
                     request-channel="inputChannel"
                     uri="https://example.org"/>
```

|   |This example does not provide a 'reply-channel'.<br/>If the web service returns a non-empty response, the `Message` containing that response is sent to the reply channel defined in the request message’s `REPLY_CHANNEL` header.<br/>If that is not available, a channel resolution exception is thrown.<br/>If you want to send the reply to another channel instead, provide a 'reply-channel' attribute on the 'outbound-gateway' element.|
|---|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   |By default, when you invoke a web service that returns an empty response after using a String payload for the request `Message`, no reply `Message` is sent.<br/>Therefore, you need not set a 'reply-channel' or have a `REPLY_CHANNEL` header in the request `Message`.<br/>If you actually do want to receive the empty response as a `Message`, you can set the 'ignore-empty-responses' attribute to `false`.<br/>Doing so works only for `String` objects, because using a `Source` or a `Document` object leads to a null response and consequently never generates a reply `Message`.|
|---|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

To set up an inbound Web Service Gateway, use the `inbound-gateway` element, as the following example shows:

```
<int-ws:inbound-gateway id="simpleGateway"
                    request-channel="inputChannel"/>
```

To use Spring OXM marshallers or unmarshallers, you must provide bean references.
The following example shows how to provide a bean reference for an outbound marshalling gateway:

```
<int-ws:outbound-gateway id="marshallingGateway"
                     request-channel="requestChannel"
                     uri="https://example.org"
                     marshaller="someMarshaller"
                     unmarshaller="someUnmarshaller"/>
```

The following example shows how to provide a bean reference for an inbound marshalling gateway:

```
<int-ws:inbound-gateway id="marshallingGateway"
                    request-channel="requestChannel"
                    marshaller="someMarshaller"
                    unmarshaller="someUnmarshaller"/>
```

|   |Most `Marshaller` implementations also implement the `Unmarshaller` interface.<br/>When using such a `Marshaller`, only the `marshaller` attribute is necessary.<br/>Even when using a `Marshaller`, you may also provide a reference for the `request-callback` on the outbound gateways.|
|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

For either outbound gateway type, you can specify a `destination-provider` attribute instead of the `uri` (exactly one of them is required).
You can then reference any Spring Web Services `DestinationProvider` implementation (for example, to lookup the URI from a registry at runtime).

For either outbound gateway type, the `message-factory` attribute can also be configured with a reference to any Spring Web Services `WebServiceMessageFactory` implementation.

For the simple inbound gateway type, you can set the `extract-payload` attribute to `false` to forward the entire `WebServiceMessage` instead of just its payload as a `Message` to the request channel.
Doing so might be useful, for example, when a custom transformer works against the `WebServiceMessage` directly.

Starting with version 5.0, the `web-service-template` reference attribute lets you inject a `WebServiceTemplate` with any possible custom properties.

### Web Service Java DSL Support

The equivalent configuration for the gateways shown in [Web Service Namespace Support](#webservices-namespace) are shown in the following snippets:

```
@Bean
IntegrationFlow inbound() {
    return IntegrationFlows.from(Ws.simpleInboundGateway()
                .id("simpleGateway"))
        ...
        .get();
}
```

```
@Bean
IntegrationFlow outboundMarshalled() {
    return f -> f.handle(Ws.marshallingOutboundGateway()
                    .id("marshallingGateway")
                    .marshaller(someMarshaller())
                    .unmarshaller(someUnmarshalller()))
        ...
}
```

```
@Bean
IntegrationFlow inboundMarshalled() {
    return IntegrationFlows.from(Ws.marshallingInboundGateway()
                .marshaller(someMarshaller())
                .unmarshaller(someUnmarshalller())
                .id("marshallingGateway"))
        ...
        .get();
}
```

Other properties can be set on the endpoint specs in a fluent manner (with the properties depending on whether or not an external `WebServiceTemplate` has been provided for outbound gateways).
Examples:

```
.from(Ws.simpleInboundGateway()
                .extractPayload(false))
```

```
.handle(Ws.simpleOutboundGateway(template)
            .uri(uri)
            .sourceExtractor(sourceExtractor)
            .encodingMode(DefaultUriBuilderFactory.EncodingMode.NONE)
            .headerMapper(headerMapper)
            .ignoreEmptyResponses(true)
            .requestCallback(requestCallback)
            .uriVariableExpressions(uriVariableExpressions)
            .extractPayload(false))
)
```

```
.handle(Ws.marshallingOutboundGateway()
            .destinationProvider(destinationProvider)
            .marshaller(marshaller)
            .unmarshaller(unmarshaller)
            .messageFactory(messageFactory)
            .encodingMode(DefaultUriBuilderFactory.EncodingMode.VALUES_ONLY)
            .faultMessageResolver(faultMessageResolver)
            .headerMapper(headerMapper)
            .ignoreEmptyResponses(true)
            .interceptors(interceptor)
            .messageSenders(messageSender)
            .requestCallback(requestCallback)
            .uriVariableExpressions(uriVariableExpressions))
```

```
.handle(Ws.marshallingOutboundGateway(template)
            .uri(uri)
            .encodingMode(DefaultUriBuilderFactory.EncodingMode.URI_COMPONENT)
            .headerMapper(headerMapper)
            .ignoreEmptyResponses(true)
            .requestCallback(requestCallback)
            .uriVariableExpressions(uriVariableExpressions))
)
```

### Outbound URI Configuration

For all URI schemes supported by Spring Web Services (see [URIs and Transports](https://docs.spring.io/spring-ws/docs/current/reference/#client-transports)) `<uri-variable/>` substitution is provided.
The following example shows how to define it:

```
<ws:outbound-gateway id="gateway" request-channel="input"
        uri="https://springsource.org/{thing1}-{thing2}">
    <ws:uri-variable name="thing1" expression="payload.substring(1,7)"/>
    <ws:uri-variable name="thing2" expression="headers.x"/>
</ws:outbound-gateway>

<ws:outbound-gateway request-channel="inputJms"
        uri="jms:{destination}?deliveryMode={deliveryMode}&amp;priority={priority}"
        message-sender="jmsMessageSender">
    <ws:uri-variable name="destination" expression="headers.jmsQueue"/>
    <ws:uri-variable name="deliveryMode" expression="headers.deliveryMode"/>
    <ws:uri-variable name="priority" expression="headers.jms_priority"/>
</ws:outbound-gateway>
```

If you supply a `DestinationProvider`, variable substitution is not supported and a configuration error occurs if you provide variables.

#### Controlling URI Encoding

By default, the URL string is encoded (see [`UriComponentsBuilder`](https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/util/UriComponentsBuilder.html)) to the URI object before sending the request.
In some scenarios with a non-standard URI, it is undesirable to perform the encoding.
The `<ws:outbound-gateway/>` element provides an `encoding-mode` attribute.
To disable encoding the URL, set this attribute to `NONE` (by default, it is `TEMPLATE_AND_VALUES`).
If you wish to partially encode some of the URL, you can do so by using an `expression` within a `<uri-variable/>`, as the following example shows:

```
<ws:outbound-gateway url="https://somehost/%2f/fooApps?bar={param}" encoding-mode="NONE">
          <http:uri-variable name="param"
            expression="T(org.apache.commons.httpclient.util.URIUtil)
                                             .encodeWithinQuery('Hello World!')"/>
</ws:outbound-gateway>
```

|   |If you set `DestinationProvider`, `encoding-mode` is ignored.|
|---|-------------------------------------------------------------|

### WS Message Headers

The Spring Integration web service gateways automatically map the SOAP action header.
By default, it is copied to and from Spring Integration `MessageHeaders` by using the [`DefaultSoapHeaderMapper`](https://docs.spring.io/spring-integration/api/org/springframework/integration/ws/DefaultSoapHeaderMapper.html).

You can pass in your own implementation of SOAP-specific header mappers, as the gateways have properties to support doing so.

Unless explicitly specified by the `requestHeaderNames` or `replyHeaderNames` properties of the `DefaultSoapHeaderMapper`, any user-defined SOAP headers are not copied to or from a SOAP Message.

When you use the XML namespace for configuration, you can set these properties by using the `mapped-request-headers` and `mapped-reply-headers` attributes, you can provide a custom mapper by setting the `header-mapper` attribute.

|   |When mapping user-defined headers, the values can also contain simple wildcard patterns (such `myheader*` or `**myheader**`**).<br/>For example, if you need to copy all user-defined headers, you can use the wildcard character: ``**.|
|---|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

Starting with version 4.1, the `AbstractHeaderMapper` (a `DefaultSoapHeaderMapper` superclass) lets the `NON_STANDARD_HEADERS` token be configured for the `requestHeaderNames` and `replyHeaderNames` properties (in addition to existing `STANDARD_REQUEST_HEADERS` and `STANDARD_REPLY_HEADERS`) to map all user-defined headers.

|   |Rather than using the wildcard (`*`), we recommend using the following combination : `STANDARD_REPLY_HEADERS, NON_STANDARD_HEADERS`.<br/>Doing so avoids mapping `request` headers to the reply.|
|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

Starting with version 4.3, you can negate patterns in the header mappings by preceding the pattern with `!`.
Negated patterns get priority, so a list such as `STANDARD_REQUEST_HEADERS,thing1,thing*,!thing2,!thing3,qux,!thing1` does not map `thing1`, `thing2`, or `thing3`.
It does map the standard headers, `thing4`, and `qux`.
(Note that `thing1` is included in both non-negated and negated forms.
Because negated values take precedence, `thing1` is not mapped.)

|   |If you have a user-defined header that begins with `!` that you do wish to map, you can escape it with `\`, as follows: `STANDARD_REQUEST_HEADERS,\!myBangHeader`.<br/>A `!myBangHeader` is then mapped.|
|---|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

Inbound SOAP headers (request headers for the inbound gateway and reply headers for the outbound gateway) are mapped as `SoapHeaderElement` objects.
You can explore the contents by accessing the `Source`:

```
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soapenv:Header>
        <auth>
            <username>user</username>
            <password>pass</password>
        </auth>
        <bar>BAR</bar>
        <baz>BAZ</baz>
        <qux>qux</qux>
    </soapenv:Header>
    <soapenv:Body>
        ...
    </soapenv:Body>
</soapenv:Envelope>
```

If `mapped-request-headers` is `auth, ca*`, the `auth`, `cat`, and `can` headers are mapped, but `qux` is not mapped.

The following example shows how to get a value named `user` from a header named `auth`:

```
...
SoapHeaderElement header = (SoapHeaderElement) headers.get("auth");
DOMSource source = (DOMSource) header.getSource();
NodeList nodeList = source.getNode().getChildNodes();
assertEquals("username", nodeList.item(0).getNodeName());
assertEquals("user", nodeList.item(0).getFirstChild().getNodeValue());
...
```

Starting with version 5.0, the `DefaultSoapHeaderMapper` supports user-defined headers of type `javax.xml.transform.Source` and populates them as child nodes of the `<soapenv:Header>`.
The following example shows how to do so:

```
Map<String, Object> headers = new HashMap<>();

String authXml =
     "<auth xmlns='http://test.auth.org'>"
           + "<username>user</username>"
           + "<password>pass</password>"
           + "</auth>";
headers.put("auth", new StringSource(authXml));
...
DefaultSoapHeaderMapper mapper = new DefaultSoapHeaderMapper();
mapper.setRequestHeaderNames("auth");
```

The result of the preceding examples is the following SOAP envelope:

```
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soapenv:Header>
        <auth xmlns="http://test.auth.org">
            <username>user</username>
            <password>pass</password>
        </auth>
    </soapenv:Header>
    <soapenv:Body>
        ...
    </soapenv:Body>
</soapenv:Envelope>
```

### MTOM Support

The marshalling inbound and outbound web service gateways support attachments directly through built-in functionality of the marshaller (for example, `Jaxb2Marshaller` provides the `mtomEnabled` option).
Starting with version 5.0, the simple web service gateways can directly operate with inbound and outbound `MimeMessage` instances, which have an API to manipulate attachments.
When you need to send web service message with attachments (either a reply from a server or a client request) you should use the `WebServiceMessageFactory` directly and send a `WebServiceMessage` with attachments as a `payload` to the request or reply channel of the gateway.
The following example shows how to do so:

```
WebServiceMessageFactory messageFactory = new SaajSoapMessageFactory(MessageFactory.newInstance());
MimeMessage webServiceMessage = (MimeMessage) messageFactory.createWebServiceMessage();

String request = "<test>foo</test>";

TransformerFactory transformerFactory = TransformerFactory.newInstance();
Transformer transformer = transformerFactory.newTransformer();
transformer.transform(new StringSource(request), webServiceMessage.getPayloadResult());

webServiceMessage.addAttachment("myAttachment", new ByteArrayResource("my_data".getBytes()), "plain/text");

this.webServiceChannel.send(new GenericMessage<>(webServiceMessage));
```