Configuring JAX-RS 2.0 client

For Java™ API for XML RESTful Web Services 2.0, you can configure the client to access REST endpoints. JAX-RS 2.0 introduces a new and standardized Client API so that you can make http requests to your remote RESTful web services.

About this task

An instance of Client is required to access a Web resource using the Client API. The default instance of Client can be obtained by calling newClient or build on ClientBuilder. After you create the client, you can configure it at the server level or within the client application.

Procedure

Enable the jaxrsClient-2.0 or jaxrs-2.0 feature in your server.xml file:

<featureManager>
    <feature>jaxrs-2.0</feature>// If you only need the JAX-RS 2.0 client feature, you can enable jaxrsClient-2.0 instead of  jaxrs-2.0
</featureManager>

Create a JAX-RS 2.0 client and send request to server:

javax.ws.rs.client.ClientBuilder cb = ClientBuilder.newBuilder();

javax.ws.rs.client.Client c = cb.build();
String res = null;

try {
	res = c.target("<Resource_URL>")
             .path("<PATH>")
             .request()
             .get(String.class);
	} catch (Exception e) {
      	res = "[Error]:" + e.toString();
      } finally {
            c.close();
      }

For more information about async JAX-RS 2.0 client, you can see Asynchronous processing.

What to do next

After you create the JAX-RS 2.0 client, you can configure it either by defining webTarget elements in the server.xml file or by programmatically configuring properties in the client application.

To configure properties in the server.xml file with the webTarget XML element:

<webTarget URI="value" property="value" property="value".../>

When a webTarget object is instantiated and its URI matches the URI value in this element, the properties are applied to the webTarget object. Consider the following configuration information when you define the webTarget element:

The URI can be exact, such as http://foo, or end with a trailing *, such as http://foo*. When you use a trailing *, the properties are applied to any webTarget object with a URI that begins with http://foo.
If more than one webTarget element in the server.xml file matches the URI, exact matches are applied first, then wildcard matches, in sorted order by URI.
Property name matching is case-insensitive.
Any provided JAX-RS property name and value can be used. To find the shortened names for configuration properties, see webTarget JAX-RS Client Properties.

To programmatically configure properties in the JAX-RS 2.0 application:

Use the com.ibm.ws.jaxrs.client.connection.timeout client property and the com.ibm.ws.jaxrs.client.receive.timeout client property to set the timeout value.

com.ibm.ws.jaxrs.client.connection.timeout

javax.ws.rs.client.ClientBuilder cb = ClientBuilder.newBuilder();
        cb.property("com.ibm.ws.jaxrs.client.connection.timeout", "1000");
        Client c = cb.build();

com.ibm.ws.jaxrs.client.receive.timeout

javax.ws.rs.client.ClientBuilder cb = ClientBuilder.newBuilder();
        cb.property("com.ibm.ws.jaxrs.client.receive.timeout", "1000");
        Client c = cb.build();

Tip: The value of the timeout property is millisecond, and the type must be long or int. If the type of the value is invalid, the following message is displayed:

CWWKW0700E: The timeout value {0} that you specified in the property com.ibm.ws.jaxrs.client.receive.timeout on the JAX-RS Client side is invalid. The value is set to default 30000. {3}

Use the com.ibm.ws.jaxrs.client.keepalive.connection property to set the desired persistent connection behavior.

. keep-alive (default) - specifies that the connections should persist across multiple requests
        javax.ws.rs.client.ClientBuilder cb = ClientBuilder.newBuilder();
        cb.property("com.ibm.ws.jaxrs.client.keepalive.connection", "keep-alive");
        Client c = cb.build();

. close - specifies that the connections should closed following each request
        javax.ws.rs.client.ClientBuilder cb = ClientBuilder.newBuilder();
        cb.property("com.ibm.ws.jaxrs.client.keepalive.connection", "close");
        Client c = cb.build();

Use the following client properties for client proxy support:

ClientBuilder cb = ClientBuilder.newBuilder();
cb.property("com.ibm.ws.jaxrs.client.proxy.host", "hostname");
cb.property("com.ibm.ws.jaxrs.client.proxy.port", "8888";);
cb.property("com.ibm.ws.jaxrs.client.proxy.type", "HTTP");

Client c = cb.build();

com.ibm.ws.jaxrs.client.proxy.host

com.ibm.ws.jaxrs.client.proxy.port

Tip: The type of the proxy server port value must be int. The default value is 80. If the value type is invalid, the following message is displayed:

CWWKW0701E: The proxy server port value {0} that you specified in the property com.ibm.ws.jaxrs.client.proxy.port on the JAX-RS Client side is invalid. The value is set to default 80. {3}

com.ibm.ws.jaxrs.client.proxy.type
Tip: The value of the proxy server type must be HTTP or SOCKS. The default value is HTTP. If the type of the proxy server is invalid, the following message is displayed:
```
CWWKW0702E: The proxy server type value {0} that you specified in the property com.ibm.ws.jaxrs.client.proxy.type on the JAX-RS Client side is invalid. The value is set to default HTTP. {3}
```

Use the com.ibm.ws.jaxrs.client.ltpa.handler client property to set SSO cookie and set the value to true.
```
ClientBuilder cb = ClientBuilder.newBuilder();
        Client c = cb.build();
        c.property("com.ibm.ws.jaxrs.client.ltpa.handler", "true");
```
If you want to use the Secure Sockets Layer (SSL) function in JAX-RS 2.0, you need to enable the transportSecurity-1.0 or appSecurity-2.0 feature. For the LTPA token function, the appSecurity-2.0 feature is required.
For more information about how to configure the environment to have JAX-RS 2.0 client to run with SSL through IHS, see Configuring IBM® HTTP server SSL support.

Note: The transportSecurity-1.0 feature is a subfeature of the appSecurity-2.0 feature. If you enable the jaxrsClient-2.0 feature and the transportSecurity-1.0 feature, the appSecurity-2.0 feature is enabled automatically.
Use the com.ibm.ws.jaxrs.client.ssl.config client property to set the SSL reference ID of server.xml.
```
ClientBuilder cb = ClientBuilder.newBuilder();
        cb.property("com.ibm.ws.jaxrs.client.ssl.config", "mySSLRefId");
        Client c = cb.build();
```
For more information about establishing trust by extracting certificate from IHS key file and add it to the Liberty JKS file, see Create a key database file and certificates needed to authenticate the Web server during an SSL handshake.
Note: The configuration in server.xml shows as follows:
```
<ssl id="mySSLRefId" keyStoreRef="clientKeyStore" trustStoreRef="clientTrustStore" />
```
Instead of programmatically setting the com.ibm.ws.jaxrs.client.ssl.config client property, configure outbound SSL so that the JAX-RS 2.0 client can rely on the SSL configuration to identify the outbound SSL to use.
To configure outbound SSL, you can configure both the outbound SSL filters and the outbound SSL default, or you can configure either one of the two options. No matter which combination of options you implement, you must enable the transportSecurity-1.0 feature.
- Enable the transportSecurity-1.0 feature in your server.xml file:
```
<featureManager>
    <feature>transportSecurity-1.0</feature>
</featureManager>
```
- Configure outbound SSL filters so that they specify the SSL configuration for a destination host, or both a destination host and a destination port.
  The configuration in the server.xml file that you are to update is as follows:
```
<ssl id="mySSLRefId" keyStoreRef="clientKeyStore"
trustStoreRef="clientTrustStore">
   <outboundConnection host="myhost.atdomain.com" port="9443" />
   <outboundConnection host="theotherhost.atdomain.com" port="8020"
/>
</ssl>
<ssl id="defaultSSLConfig" keyStoreRef="defaultKeyStore" >
   <outboundConnection host="defaulthost.domain.com" />
</ssl>
```
  For more information about outbound SSL filters, see Outbound filters for SSL configurations.
- Configure the outbound SSL default.
  If no SSL filter exists to match the outbound connection, the JAX-RS client uses the outbound SSL default.
  The configuration in the server.xml file that you are to update is as follows:
```
<sslDefault outboundSSLRef="mySSLRefId" />

<ssl id="mySSLRefId" keyStoreRef="clientKeyStore"
trustStoreRef="clientTrustStore"/>

<ssl id="defaultSSLConfig" keyStoreRef="defaultKeyStore" />
```
  For more information about the SSL outbound default, see Configuring SSL Settings for outbound communications.

Use the com.ibm.ws.jaxrs.client.disableCNCheck client property to disable the common name check.

ClientBuilder cb = ClientBuilder.newBuilder();
cb.property("com.ibm.ws.jaxrs.client.disableCNCheck", true);