How to troubleshoot Qlik Sense Engine API calls with the browser developer tools

[Damien_V]

When calling the Engine API through a web application, it can be useful to look at Engine API requests/responses in order to troubleshoot the root cause of an issue. When building a mashup with nebula.js / capability API, you can see the underlying Engine API calls in the browser developer tools.

This article explains how to see Engine API requests in the browser developer tools and how to check their responses and see if there is an error.

Environment:

Qlik Cloud 
Qlik Sense Enterprise on Windows 

Resolution

This example shows how to inspect the Engine API calls in Chrome, the same is also applicable to Firefox and Edge.

For Internet Explorer, the use of a third-party tools such as Fiddler will be needed to see those (*Note: Internet Explorer is not supported anymore in recent Qlik Sense versions)

1. In the browser dev tools Network tab, filter on WS for WebSocket and click on the WebSocket connection to the Qlik Sense app.
   
   
   
   
2. Click on the Messages tab, here you will see some green lines and some white lines. Green lines are the requests and white lines are the responses.
   
   
   
   Each of the lines has a handle number and an id number. The handle number is the object the request is done on and the id number is the request id that can be used to track back the response to it.
   
   Handle -1 is the global interface from where apps are getting opened.
   
   Other handles numbers will vary depending on the number of apps/objects opened.
   
   
   
   On the screenshot above, we can see the OpenDoc method being called on the handle -1 and the id is 1.
   
   We can then see in white the response to that call with the same "id":1 on the 4th line and we can see that it returns a "qHandle":1, this is the handle that you will use if you want to interact with the document you have just opened.
   
   
   
   On the screenshot above, we can see that the GetObject method is called on handle 1 (The app opened above), which will return a handle for the object fetched (handle 5 in this case). Then we can see a GetLayout method called on Handle 5 (the object) which will return the layout of the object.
   
   If an error occurs during those Engine API calls, it will appear in the responses of the Engine API request, with the filter in the browser devtools, it's possible to search for keywords of the error messages or try to search for "error" "warn" for more generic errors.
   
   

Read more about the Engine API at the below link: https://qlik.dev/apis/json-rpc/qix