asynchronous processing in Apigee Edge

[#1]

I have a requirement to perform an asynchronous job(let's call js function X) for an API A.

I am planning to implement it using the following approach.

1. Create API B and expose function X in it using nodejs.

2. Create API A and call API B from nodejs using the callback (async).

3. API A will return immediately to the consumer after the async call to API B.

4. Once API B processing is completed, the flow will return to callback processing of nodejs of API A and do appropriate processing as required.

In step 3, I have called API B using async callbcak. As per my understanding, that creates another thread (per call) and lives until the API A processing is completed. Also, a callback thread (shared) will keep runing in the nodejs runtime.

Is above approach ok or have drawbacks/defects from implementation / standards perspective ?

[gnanasekaran]

flow looks good - and should work as expected, as you described

the threading model you described may not be accurate, but that's okay - the flow is correct

Just for clarity -

In 3 - API A will return immediately after you call response.end() in your node.js, you would typically do this after you start your async jobs

In 4 - control is returned to the callback in node.js

One additional comment, since its all nodejs, you could also call function X directly from your API A's nodejs,

Having API B also have its own advantages like - analytics, management etc.

[#3]

@Mukundha Madhavan ,

Thanks for your inputs. So, for each call back (async calls) new thread is instantiated ?

[gnanasekaran]

no, nodejs is single threaded event loop - so callback just goes to event queue