SAPAPIM – Guide to create single API Proxy with multiple Target End Point and capability to change the target URI during execution

MYUSERDB_2: Customer User Store

API Portal -> Develop->Create

Select any one of the providers we created earlier

*Note we have selected URL=”/” as rest of the path we will set during execution

Crate a copy and rename both the XML file as “myuserdb1.xml” “myuserdb2.xml”

Update <name>, <provider_id>, <isDefault> tags in each file as shown

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<TargetEndPoint xmlns="http://www.sap.com/apimgmt">
    <name>myuserdb1</name>
    <provider_id>MYUSERDB_1</provider_id>
    <additionalAPIProviders/>
    <isDefault>true</isDefault>
    <relativePath>/</relativePath>
    <properties/>
    <faultRules/>
    <preFlow>
        <name>PreFlow</name>
     </preFlow>
    <postFlow>
        <name>PostFlow</name>
    </postFlow>
    <conditionalFlows/>
    <loadBalancerConfigurations>
        <isRetry>false</isRetry>
        <healthMonitor>
            <isEnabled>false</isEnabled>
        </healthMonitor>
    </loadBalancerConfigurations>
</TargetEndPoint>

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<TargetEndPoint xmlns="http://www.sap.com/apimgmt">
    <name>myuserdb2</name>
    <provider_id>MYUSERDB_2</provider_id>
    <additionalAPIProviders/>
    <isDefault>false</isDefault>
    <relativePath>/</relativePath>
    <properties/>
    <faultRules/>
    <preFlow>
        <name>PreFlow</name>
    </preFlow>
    <postFlow>
        <name>PostFlow</name>
    </postFlow>
    <conditionalFlows/>
    <loadBalancerConfigurations>
        <isRetry>false</isRetry>
        <healthMonitor>
            <isEnabled>false</isEnabled>
        </healthMonitor>
    </loadBalancerConfigurations>
</TargetEndPoint>

Now Open the APIProxyEndpoint->default.xml

Update <routeRules> as shown

*This will let us point to different target based on condition

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ProxyEndPoint default="true" xmlns="http://www.sap.com/apimgmt">
    <name>default</name>
    <base_path>/multiroute_proxy</base_path>
    <properties/>
    <routeRules>
        <routeRule>
            <name>myuserdb2</name>
            <conditions>queryinfo.userdb = "userdb2"</conditions>
            <targetEndPointName>myuserdb2</targetEndPointName>
            <sequence>1</sequence>
            <faultRules/>
        </routeRule>
        <routeRule>
            <name>myuserdb1</name>
            <conditions>queryinfo.userdb = "userdb1"</conditions>
            <targetEndPointName>myuserdb1</targetEndPointName>
            <sequence>2</sequence>
            <faultRules/>
        </routeRule>
    </routeRules>
    <faultRules/>
    <preFlow>
        <name>PreFlow</name>
     </preFlow>
    <postFlow>
        <name>PostFlow</name>
    </postFlow>
    <conditionalFlows/>
</ProxyEndPoint>

Import the modified .zip

API Portal-> Import -> MULTIROUTE_PROXY_API.zip

Open the proxy and check the new route

Now add a policy to accept the query parameter “userdb” from consumer/client application

Go to Policies -> ProxyEndpoint -> Preflow   and add the policy as shown

<ExtractVariables async="true" continueOnError="false" enabled="true" xmlns='http://www.sap.com/apimgmt'>
    <Source>request</Source>
	<QueryParam name="userdb">
	    <Pattern ignoreCase="true">{userdb}</Pattern>
	</QueryParam>
	<VariablePrefix>queryinfo</VariablePrefix>
	<IgnoreUnresolvedVariables>true</IgnoreUnresolvedVariables>
</ExtractVariables>

Policy Editor- > Target Endpoint-> PreFlow Create a JavaScript policy  as shown

<!-- this policy allows us to execute java script code during execution of an API Proxy -->
<Javascript async="false" continueOnError="false" enabled="true" timeLimit="200" xmlns='http://www.sap.com/apimgmt'>
	<!-- contains reference to any library scripts that help the main code file -->

	<!-- contains the name of the main code file -->
	<ResourceURL>jsc://setTargetPath.js</ResourceURL>
</Javascript> 

Create setTargetPath.js file and add code as shown

//Add your target path . You can retrive it from external config or based on any condition
//For this example as its same for both the API provider , we are putting it directly 

var target_path = "";

if (context.getVariable('request.queryparam.userdb') === 'userdb1') {
    
    target_path = "service/scim/" ;
    
}else if (context.getVariable('request.queryparam.userdb') === 'userdb2'){
    
    target_path = "service/scim/"
}

context.setVariable("target.copy.pathsuffix", true);
context.setVariable('target_path', target_path); 

Now Export the project and update “myuserdb2.xml”<relativePath> tag with “target_path” variable  as shown

Import the updated .zip file to API management

Save and Deploy

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<TargetEndPoint xmlns="http://www.sap.com/apimgmt">
    <name>myuserdb2</name>
    <provider_id>MYUSERDB_2</provider_id>
    <additionalAPIProviders/>
    <isDefault>false</isDefault>
    <relativePath>/{target_path}</relativePath>
    <properties/>
    <faultRules/>
    <preFlow>
        <name>PreFlow</name>
        <request>
            <isRequest>true</isRequest>
            <steps>
                <step>
                    <policy_name>setTargetPath</policy_name>
                    <condition> </condition>
                    <sequence>1</sequence>
                </step>
            </steps>
        </request>
    </preFlow>
    <postFlow>
        <name>PostFlow</name>
    </postFlow>
    <conditionalFlows/>
    <loadBalancerConfigurations>
        <isRetry>false</isRetry>
        <healthMonitor>
            <isEnabled>false</isEnabled>
        </healthMonitor>
    </loadBalancerConfigurations>
</TargetEndPoint>