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The function accepts scope as an optional parameter. It retrieves a message property at the given scope, which can be synapse, axis2 or transport. If you provide only the property name without the scope, the default Synapse scope will be used.

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synapse:get-property( [(axis2 | axis2-client | transport),] <property_name> [,<dateformat>] )

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You can use the get-property() function to retrieve Axis2 message context properties or transport headers. For example, synapse:get-property('transport', 'USER_AGENT'). Given below are special properties supported by the get-property() function.
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Similarly, you can use $axis2 prefix with HTTP Transport Properties.
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$ctx
Prefix for Synapse MessageContext properties. For example, to get the value of Synapse message context property with name ERROR_MESSAGE, use the XPath expression $ctx:ERROR_MESSAGE. We have discussed an example below.
Example of $ctx usage:
This example sends a request to a sample proxy service, and sets the target endpoint to a non-existent endpoint reference key. It causes a mediation fault, which triggers the fault sequence.
1. Deploy the following proxy service using instructions in Adding a Proxy Service.
Note the property, <property name="stockerrorprop" expression="$ctx:RESPONSE" gives the value of the Synapse message context property with name "RESPONSE."ERROR_MESSAGE"/> in the fault sequence configuration. It is used to log the error message that occurs due to a  mediation fault.
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language
html/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="$ctx:ERROR_MESSAGE"/>
            <property name="Cause" expression="get-property('ERROR_MESSAGE')"/>
         </log>
      </faultSequence>
   </target>
   <description></description>
</proxy> 
2. Send a StockQuote request using the sample StockQuote client as follows.
ant stockquote -Dtrpurl=http://localhost:8280/services/StockQuoteProxy
3. Note the following message in the ESB log.
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INFO - LogMediator To: /services/StockQuoteProxy, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:54205f7d-359b-4e82-9099-0f8e3bf9d014, Direction: request, stockerrorprop = Couldn't find the endpoint with the key : ep2 
In this example, the property definition, <property name="stockerrorprop" expression="$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 $trp:CONTENT-TYPE are regarded as the same. We have discussed an example below.
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In this example, the property definition, <property name="stockprop" expression="$trp:Content-Type"/> is equivalent to <property name="stockprop" expression="get-property('transport','Content-Type')"/>. Similarly, you can use $trp prefix with HTTP Transport Properties.
$ctx
Gets a property at the default scope.
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