How to use dynamic URL in Apigee Service Callout

This is a easy one.I need the <URL> element in the Apigee Service callout(SC) as dynamic one.

Eg: <URL>http://{dynamicURL}</URL>

Where dynamicURL will be determined at runtime and this value will be different for every request. It will have the complete target URL such as (ip:port/abc/orderid/1234)

<HTTPTargetConnection>
<Properties />
<URL>http://{dynamicURL}</URL>
</HTTPTargetConnection>

Have tried these:

In a JS policy, tried setting servicecallout.{scpolicyname}.target.url in the context. In this case only the dynamic ip:port is getting sent. The URI is missing /abc/orderid/1234.
In the AssignMessage policy, created a header and tried using it in SC URL element like request.header.name, {request.header.name}, with $ at front.
In the AssignMessage policy, created a variable & tried using it in SC like {dynamicURL} with $ at front.

This is a common usecase and I'm sure there must be a easy way to do. Need your help with this.

Thanks,

Somu

Solution

You can use a combination of the ServiceCallout and AssignMessage policy.

You can set the ip:port in the ServiceCallout policy itself. Set this in the element <URL>http://{dynamicURL}</URL> of the <HTTPTargetConnection>, just as you noted.

As for the rest of the URI, you can use the AssignMessage policy <Path> element. Here is an example:

<AssignMessage enabled="true" continueOnError="false" async="false" name="GenerateAuthorizationPayload">
    <FaultRules/>
    <Properties/>
    <IgnoreUnresolvedVariables>false</IgnoreUnresolvedVariables>
    <AssignTo createNew="true" type="request"/>
    <Set>
    <Payload contentType="text/xml">
        <soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:v1="urn:sample">
           <soapenv:Header/>
           <soapenv:Body>
              <v1:Login/>
           </soapenv:Body>
        </soapenv:Envelope>
    </Payload>
    <Path>/abc/orderid/1234</Path>
    <Verb>POST</Verb>
    </Set>
</AssignMessage>

You should also be able to put a {variable} inside of the <Path> tags if you need flexibility there.

It is the combination of these 2 policies that you get a dynamic ip:port/path.