WSO2 ESB calling parameterized endpoint Looping on Parameters - loops

Question

In my usecase i have to chain two service calls. In particular:
1) The first call returns an xml listing several IDs
2) i have to iterate through the returned ID list and to make an ID parameterized service call for each id-item.
3) Finally i have to collect a whole response made up of each single ID-service-response.
Suppose the first service call returns a response like this one:
<result>
<Link>
<Id>93451</Id>
</Link>
<Link>
<Id>93450</Id>
</Link>
...
The second step is to perform a series of calling to parameterized endpoint like this:
http://myEndpoint/entry/eutils/efetch.fcgi?db=pubmed&rettype=abstract&retmode=xml&id=<ID>
each call of which returns an xml response like this:
<response>
<field1>value1</field1>
<field2>value2</field2>
<field3>value3</field3>
<response>
I have to collect a whole response like this one:
<finalResponse>
<response>
<field1>value1</field1>
<field2>value2</field2>
<field3>value3</field3>
<response>
<response>
<field1>value1</field1>
<field2>value2</field2>
<field3>value3</field3>
<response>
<response>
<field1>value1</field1>
<field2>value2</field2>
<field3>value3</field3>
<response>
</finalResponse>
How can i do? Could you give me some example? Thanks

Answer 1

You need to use iterate mediator and aggregate mediator in combination. Here is a sample code, but you may need to do some modification in order to make it work for your requirements.
<definitions xmlns="http://ws.apache.org/ns/synapse">
<proxy name="SampleProxy">
<target>
<inSequence>
<iterate expression="//result/link/id" preservePayload="true"
attachPath="//link">
<target>
<property name="uri.var.servicepath" expression="//link/id/text()"/>
<sequence>
<send>
<endpoint key="MyEndpoint"/>
</send>
</sequence>
</target>
</iterate>
</inSequence>
<outSequence>
<property name="FinalResponse" scope="default">
<finalResponse />
</property>
<aggregate>
<onComplete expression="//response"
enclosingElementProperty="FinalResponse">
<send/>
</onComplete>
</aggregate>
</outSequence>
</target>
</proxy>
<endpoint xmlns="http://ws.apache.org/ns/synapse" name="MyEndpoint">
<http uri-template="http://myEndpoint/entry/eutils/efetch.fcgi?db=pubmed&rettype=abstract&retmode=xml&id={ID}" method="GET">
</http>
</endpoint>
</definitions>
Full documentation on related sample here.
Find how you can parameterize you url here.