How can i implement an asynchronous callback scenario in Apigee.
For example i need to call a host and the host may take some time to process response. Once the response is ready that needs to be delivered to the caller/client.
Thanks in Advance
Regards
On
Take a look at https://github.com/apigee/api-platform-samples/tree/master/sample-proxies/async-callout and see if that helps. This sample makes the requests to the target, stores the response handles in the JS "session", goes away to do other things, and then retrieves the handles from the "session" and checks the responses.
Can not claim that it is a standard way of doing this, however here is a design:
Assumption: The target host must support registering a call back URL.
When the client calls Apigee proxy, Apigee proxy in the middle can generate a unique callback URL and send to the target as a parameter when making the API request. In the meantime it would have to block the client ( and start polling an internal storage).
The callback URL would be itself be a proxy in Apigee that receives the response from the target side and then updates an entry in Apigee persistence store, which is being polled by the first proxy.
If the callback happens within say x seconds, then the apigee proxy can send the response back to the client. If it does not happen within that time than it can send back some error.
To implement you can use Key Value Map or Caching policy in apigee for the transient persistence store. And for blocking the client and polling the persistence store use java or javascript policies