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The ESB profile of WSO2 Enterprise Integrator(WSO2 EI) supports standard XPath functions and variables through its underlying XPath engine. The ESB profile also provides custom XPath functions and variables for accessing message properties.

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The  get-property()  function allows any XPath expression used in a configuration to look up information from the current message context. Using the Property mediator, you can retrieve properties from the message context and header.

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If you provide only the property name without the scope, the default synapse scope will be used.

Info

When the result of an XPath evaluation results in a single XML node, the evaluator will return the text content of this node by default (equivalent of doing /root/body/node/text()). If you want to retrieve the node itself, you can configure the Enrich mediator as shown in the following example.

Code Block
languagexml
<inSequence>
<log level="custom">
<property name="WHERE" value="before doing stuff"/>
</log>
<enrich>
<source type="body" clone="true"/>
<target type="property" property="ENRICH_PROPERTY"/>
</enrich>
<property name="PROPERTY_PROPERTY"
expression="$body/child::node()"
scope="default"/>
<log level="custom">
<property name="WHERE" value="before doing stuff"/>
<property name="ENRICH_PROPERTY" expression="get-property('ENRICH_PROPERTY')"/>
<property name="PROPERTY_PROPERTY" expression="get-property('PROPERTY_PROPERTY')"/>
</log>
<enrich>
<source type="property" clone="true" property="ENRICH_PROPERTY"/>
<target type="body" action="sibling"/>
</enrich>
<log level="full"/>
</inSequence>
Synapse scope

When the scope of a property mediator is synapse, its value is available throughout both the in sequence and the out sequence. In addition to the user-defined properties, you can retrieve the following special properties from the synapse scope.

NameReturn Value
ToIncoming URL as a String, or empty string («») if a To address is not defined.
FromFrom address as a String, or empty string («») if a From address is not defined.
ActionSOAP Addressing Action header value as a String, or empty string («») if an Action is not defined.
FaultToSOAP FaultTo header value as a String, or empty string («») if a FaultTo address is not defined.
ReplyToReplyTo header value as a String, or empty string («») if a ReplyTo address is not defined.
MessageIDA unique identifier (UUID) for the message as a String, or empty string («») if a MessageID is not defined. This ID is guaranteed to be unique.
FAULTTRUE if the message has a fault, or empty string if the message does not have a fault.
MESSAGE_FORMATReturns pox, get, soap11, or soap12 depending on the message. If a message type is unknown this returns soap12
OperationNameOperation name corresponding to the message. A proxy service with a WSDL can have different operations. If the WSDL is not defined, ESB defines fixed operations.


To access a property with the synapses cope inside the mediate() method of a mediator, you can include the following configuration in a custom mediator created using the Class mediator:

Code Block
languagejava
public boolean mediate(org.apache.synapse.MessageContext mc) {  
// Available in both in-sequence and out-sequenc  
String propValue = (String) mc.getProperty("PropName");  
System.out.println("SCOPE_SYNAPSE : " + propValue);  
return true;  
}
axis2 scope

When the scope of a property mediator is axis2, its value is available only throughout the sequence for which the property is defined (e.g., if you add the property to an in sequence, its value will be available only throughout the in sequence). You can retrieve message context properties within the axis2 scope using the following syntax.
Syntax:
get-property('axis2', String propertyName)

To access a property with the axis2  scope inside the mediate() method of a mediator, you can include the following configuration in a custom mediator created using the Class mediator:

Code Block
languagejava
public boolean mediate(org.apache.synapse.MessageContext mc) {  
org.apache.axis2.context.MessageContext axis2MsgContext;  
axis2MsgContext = ((Axis2MessageContext) mc).getAxis2MessageContext();  
  
// Available only in the sequence the property is defined.  
String propValue = (String) axis2MsgContext.getProperty("PropName");  
System.out.println("SCOPE_AXIS2 : " + propValue);  
return true;  
}
axis2-client

This is similar to the synapse  scope. The difference is that it can be accessed inside the  mediate()  method of a mediator by including one of the following configurations in a custom mediator, created using the Class mediator :

Code Block
languagejava
public boolean mediate(org.apache.synapse.MessageContext mc) {  
org.apache.axis2.context.MessageContext axis2MsgContext;  
axis2MsgContext = ((Axis2MessageContext) mc).getAxis2MessageContext();  
String propValue = (String) axis2MsgContext.getProperty("PropName");  
System.out.println("SCOPE_AXIS2_CLIENT - 1 : " + propValue);

...

Code Block
languagejava
propValue = (String) axis2MsgContext.getOptions().getProperty("PropName");  
System.out.println("SCOPE_AXIS2_CLIENT - 2: " + propValue);  
return true;  
}
transport scope

When the scope of a property mediator is transport, it will be added to the transport header of the outgoing message from the ESB profile. You can retrieve message context properties within the transport scope using the following syntax.

Syntax:
get-property('transport', String propertyName)

registry scope

You can retrieve properties within the registry using the following syntax.

Syntax:
get-property('registry', String registryPath@propertyName)
get-property('registry', String registryPath)

system scope

You can retrieve Java System properties using the following syntax.

Syntax:
get-property('system', String propertyName)

...

You can retrieve a property in the operation context level from the operation scope. The properties within iterated/cloned message with the operation scope are preserved in the in sequence even if you have configured your API resources to be sent through the fault sequence when faults exist. A given property with the operation scope only exists in a single request and can be accessed by a single resource. The properties in this scope are passed to the error handler when the FORCE_ERROR_ON_SOAP_FAULT property is set to true. See FORCE_ERROR_ON_SOAP_FAULT section in Generic Properties for more information.

Syntax:
get-property('operation', String propertyName)  

url-encode() function

The url-encode function returns the URL-encoded value of the specified string.

...

  • url-encode(string value)
  • url-encode(string value, string charset)

Synapse XPath Variables

There is a set of predefined XPath variables that you can directly use to write XPaths in the Synapse configuration, instead of using the synapse:get-property() function. These XPath variables get properties of various scopes as follows:

Table of Contents
maxLevel3
minLevel3

...

  1. Deploy the following proxy service using instructions in Creating a Proxy Service .

    Note the property, <property xmlns:m0=" http://services.samples " name="stockprop" expression="$body//m0:getQuote"/> in the configuration. It is used to log the first <m0:getQuote> element of the request SOAP body.

    Code Block
    languagehtml/xml
    <proxy xmlns="http://ws.apache.org/ns/synapse" name="StockQuoteProxy" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">
   <target>
      <inSequence>
         <log>
            <property xmlns:m0="http://services.samples" name="stockprop" expression="$body//m0:getQuote"/>
         </log>
         <send>
            <endpoint>
               <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <description></description>
</proxy>

  2. Send the following StockQuote request using the sample StockQuote client. For information on working with the sample client, see Using the Sample Clients/wiki/spaces/EI6xx/pages/49611458.

    Code Block
    languagexml
    ant stockquote -Daddurl=http://localhost:8280/services/StockQuoteProxy

  3. Note the following message in the log.

    Code Block
    [2013-03-18 14:04:41,019] INFO - LogMediator To: /services/StockQuoteProxy, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:930f68f5-199a-4eff-90d2-ea679c2362ab, Direction: request, stockprop = <m0:getQuotexmlns:m0="http://services.samples"><m0:request><m0:symbol>IBM</m0:symbol></m0:request></m0:getQuote>

...

  1. Deploy the following proxy service using instructions in Creating a Proxy Service.

    Note the property, <property xmlns:wsa=" http://www.w3.org/2005/08/addressing " name="stockprop" expression="$header/wsa:To"/> in the configuration. It is used to log the value of wsa:To header of the SOAP request. 

    Code Block
    languagehtml/xml
    <proxy xmlns="http://ws.apache.org/ns/synapse" name="StockQuoteProxy" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">
   <target>
      <inSequence>
         <log>
            <property xmlns:wsa="http://www.w3.org/2005/08/addressing" name="stockprop" expression="$header/wsa:To"/>
         </log>
         <send>
            <endpoint>
               <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <description></description>
</proxy>

  2. Send the following StockQuote request using the sample StockQuote client. For information on working with the sample client, see Using the Sample Clients/wiki/spaces/EI6xx/pages/49611458.

    Code Block
    languagexml
    ant stockquote -Daddurl=http://localhost:8280/services/StockQuoteProxy

  3. Note the following message in the log.

    Code Block
    [2013-03-18 14:14:16,356] INFO - LogMediator To: http://localhost:9000/services/SimpleStockQuoteService, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:8a64c9cb-b82f-4d6f-a45d-bef37f8b664a, Direction: request,
stockprop = http://localhost:9000/services/SimpleStockQuoteService

...

  1. Deploy the following proxy service. For instructions, see Creating a Proxy Service .

    Note the property, <property name="stockprop" expression="$axis2:REST_URL_POSTFIX"/> in the configuration which is used to log the REST_URL_POSTFIX value of the request message. 

    Code Block
    languagehtml/xml
    <proxy xmlns="http://ws.apache.org/ns/synapse" name="StockQuoteProxy" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">
   <target>
      <inSequence>
         <log>
            <property name="stockprop" expression="$axis2:REST_URL_POSTFIX"/>
         </log>
         <send>
            <endpoint>
              <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <description></description>
</proxy>

  2. Send the following StockQuote request using the sample StockQuote client. For information on working with the sample client, see Using the Sample Clients/wiki/spaces/EI6xx/pages/49611458.

    Code Block
    languagexml
    ant stockquote -Daddurl=http://localhost:8280/services/StockQuoteProxy/test/prefix

  3. Note the following message in the log.

    Code Block
    INFO - LogMediator To: http://localhost:8280/services/StockQuoteProxy/test/prefix, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:ecd228c5-106a-4448-9c83-3b1e957e2fe5, Direction: request, stockprop = /test/prefix

...

  1. Deploy the following proxy service. For instructions, see Creating a Proxy Service .

    Note the property, <property name="stockerrorprop" expression="$ctx:ERROR_MESSAGE"/> in the fault sequence configuration. It is used to log the error message that occurs due to a  mediation fault. 

    Code Block
    languagehtml/xml
    <proxy xmlns="http://ws.apache.org/ns/synapse" name="StockQuoteProxy" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">
   <target>
      <inSequence>
        <send>
            <endpoint key="ep2"/>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
      <faultSequence>
         <log>
            <property name="stockerrorprop" expression="$ctx:ERROR_MESSAGE"/>
            <property name="Cause" expression="get-property('ERROR_MESSAGE')"/>
         </log>
      </faultSequence>
   </target>
   <description></description>
</proxy>

  2. Send the following StockQuote request using the sample StockQuote client. For information on working with the sample client, see Using the Sample Clients /wiki/spaces/EI6xx/pages/49611458.

    Code Block
    languagexml
    ant stockquote -Dtrpurl=http://localhost:8280/services/StockQuoteProxy

  3. Note the following message in the log.

    Code Block
    INFO - LogMediator To: /services/StockQuoteProxy, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:54205f7d-359b-4e82-9099-0f8e3bf9d014, Direction: request, stockerrorprop = Couldn't find the endpoint with the key : ep2

In this example, the property definition, <property name="stockerrorprop" expression="$ctx:ERROR_MESSAGE"/> is equivalent to <property name="stockerrorprop" expression="get-property('ERROR_MESSAGE')"/>.

Similarly, you can use $ctx prefix with Generic Properties .

$trp

Prefix used to get the transport headers. For example, to get the transport header named Content-Type of the current message, use the XPath expression $trp:Content-Type. HTTP transport headers are not case sensitive. Therefore, $trp:Content-Type and $trp:CONTENT-TYPE are regarded as the same. We have discussed an example below.

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  1. Deploy the following proxy service. For instructions, see Creating a Proxy Service .

    Note the property, <property name="stockprop" expression="$trp:Content-Type"/> in the configuration, which is used to log the Content-Type HTTP header of the request message.

    Code Block
    languagehtml/xml
    <proxy xmlns="http://ws.apache.org/ns/synapse" name="StockQuoteProxy" transports="https,http" statistics="disable" trace="disable" startOnLoad="true">
   <target>
      <inSequence>
         <log>
             <property name="stockprop" expression="$trp:Content-Type"/>
         </log>
         <send>
            <endpoint>
               <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
            </endpoint>
         </send>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
   </target>
   <description></description>
</proxy>

     

  2. Send the following StockQuote request using the sample StockQuote client. For information on working with the sample client, see Using the Sample Clients/wiki/spaces/EI6xx/pages/49611458.

    Code Block
    languagexml
    ant stockquote -Daddurl=http://localhost:8280/services/StockQuoteProxy

     

  3. Note the following message in the log.

    Code Block
    [2013-03-18 12:23:14,101] INFO - LogMediator To: http://localhost:8280/services/StockQuoteProxy, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:25a3143a-5b18-4cbb-b8e4-27d4dd1895d2, Direction: request, stockprop = text/xml; charset=UTF-8

...

The prefix used to refer to a particular parameter value passed externally by an invoker such as the Call Template Mediator .

Example of $func usage:

  1. Add a sequence template with the following configuration. See Adding a New Sequence Template for detailed instructions.

    Code Block
    languagexml
    <template xmlns="http://ws.apache.org/ns/synapse" name="HelloWordLogger">
   <sequence>
      <log level="full">
         <property xmlns:ns2="http://org.apache.synapse/xsd" xmlns:ns="http://org.apache.synapse/xsd" name="message" expression="$func:message"></property>
      </log>
   </sequence>
</template>

  2. Deploy the following proxy service. For instructions, see Creating a Proxy Service .

    Code Block
    languagexml
    <proxy xmlns="http://ws.apache.org/ns/synapse"
       name="StockQuoteProxy"
       transports="https,http"
       statistics="disable"
       trace="disable"
       startOnLoad="true">
   <target>
      <inSequence>
         <call-template target="HelloWorldLogger">
            <with-param name="message" value="HelloWorld"/>
         </call-template>
         <log/>
      </inSequence>
      <outSequence>
         <send/>
      </outSequence>
      <endpoint>
         <address uri="http://localhost:9000/services/SimpleStockQuoteService"/>
      </endpoint>
   </target>
   <description/>
</proxy>

  3. Send the following StockQuote request using the sample StockQuote client. For information on working with the sample client, see Using the Sample Clients/wiki/spaces/EI6xx/pages/49611458.

    Code Block
    languagexml
    ant stockquote -Daddurl=http://localhost:8280/services/StockQuoteProxy

  4. Note the following message in the log.

    Code Block
    languagexml
    LogMediator To: http://localhost:8280/services/StockQuoteProxy, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:8d90e21b-b5cc-4a02-98e2-24b324fa704c, Direction: request, message = HelloWorld

...