In this Learn Edge example, we will extend the first proxy "do-nothing" proxy so that it calls an actual backend target service. This proxy does actual work!

Be sure to perform the prerequisites if you haven't already.

1. cd api-platform-samples/learn-edge/proxy-to-a-target.
2. ./deploy.sh

1. ./invoke.sh
2. Compare the output to the simplest-proxy output.

Go to the Edge UI and run a Trace on this API. How does it differ from the Trace you saw in the first Learn Edge example, simplest-proxy?

What's a revision? You might notice that when you deployed proxy-to-a-target you created a new revision of the proxy with the name learn-edge. In all of the deploy.sh files, the proxy name is always learn-edge. The deploy script just creates a new revision each time it deploys. If you want to go back to a previous revision, you can go to the Edge UI and select it from the Revision menu. Or, you can just redeploy whichever proxy you want to use from the command-line -- and it will become the current revision. If you have trouble invoking a proxy, check in the UI to be sure the current revision is deployed.

To get our proxy to call a target service, we made a few changes to the simple do-nothing proxy we deployed before.

• In the apiproxy/proxies/default.xml file, we modified the <RouteRule> element.

  Tip: It might help if you open these files and look at them in their entirety.

  <RouteRule name="default">
       <!-- This connects our proxy to the target defined in apiproxy/targets/default.xml -->
       <TargetEndpoint>default</TargetEndpoint>
  </RouteRule>

  The name attribute (set to default) is arbitrary and can be anything you wish. The <TargetEndpoint> element refers to a TargetEndpoint definition. It must exist and have the name "default". Read on to learn about the TargetEndpoint!

• We defined the TargetEndpoint in a file called apiproxy/targets/default.xml. In that file, we added this XML block, which specifies the target of the proxy, an HTTP web service called mocktarget.apigee.net.

  <TargetEndpoint name="default">
     <HTTPTargetConnection>
       <!-- This is where we define the target. For this sample we just use a simple URL. -->
       <URL>http://mocktarget.apigee.net</URL>
     </HTTPTargetConnection>
  </TargetEndpoint>

  Note: The name of the TargetEndpoint (default) is important -- it is the name referred to in the <RouteRule> element in apiproxy/proxies/default.xml. In our configuration, the Route Rule references the Target Endpoint called default.

You deployed a modified proxy that calls a backend target -- an HTTP web service at http://mocktarget.apigee.net.

• Target service -- A backend service to which the proxy routes requests. In this example, we proxied to a service called http://mocktarget.apigee.net.
• RouteRule -- Specifies which target endpoint definition will be called. Route rules can have logic to route calls conditionally to different targets. In this example, we only have one target called default.
• TargetEndpoint -- The name of a target endpoint definition. Target endpoints are defined in the apiproxy/targets directory.
• HTTPTargetConnection -- Specifies an HTTP web service. This is the target service called by the proxy.

• In a browser, hit http://mocktarget.apigee.net/help to see what else the service can do.

• Modify the invoke.sh script to hit one of the other resources. For example: curl http://<your org>-test.apigee.net/v1/learn-edge/json.

  Notable Concept: By default, whatever you add to the base path of the API proxy gets passed to the target unchanged.

• Try changing the proxy to call another REST-based backend service of your choosing. Test the change by redeploying and invoking the proxy. Hint: Edit apiproxy/targets/default.xml.

The next proxy, apikey-security, secures the API proxy with an API key.

Copyright © 2016 Apigee Corporation

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.