@pratheek hipparagi,
Please refer to the documentation on Create your first API proxy. This will help you to create a simple API Proxy. While creating the Proxy, use your API that gives the sunset time for a given city in the "Existing API" text field instead of "http://mocktarget.apigee.net" as shown in the documentation.
For your usecase, you could do this:
1. Set the Proxy name as "sunset"
2. Set the Proxy Basepath as "/"
3. If your API is http://myapi.com/sunset/city/<cityname>; where cityname can be dynamic, just set the "Existing API" as http://myapi.com/
After you deploy the API Proxy, you can make the API call as
curl -v "http://<org_name>-<environment>.apigee.net/sunset/city/Bangalore"
The path suffix sunset/city/Bangalore gets added to your target URL.
Since we have choosen the Basepath as "/", it will be better to have conditional flow in your Proxy so that you don't allow all the paths to this proxy that don't have "/sunset/city".
You can read more about Conditional flows in the following links:
Flow variables and conditions
Controlling how a proxy executes with flows
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