bingenito / netcore-webview-test

Testing the performance of .net core + WebView2 + JS + WebSocket

ASP.net Core Communication with WebView2

The Goal

I wanted to test both the latency and throughput between a ASP.net Core app and a web page hosted in WebView2.

Communication Channels

• WebSocket - The backend app starts a websocket server
• postMessage - WebView2 supports chrome.webview.postMessage()
• hostObjects - WebView2 supports exposing a C# object via chrome.webview.hostObjects and directly calling methods on it

All three communication channels are asynchronous, the functions return a Promise. In every case the JavaScript code awaits for the returned Promise.

Test Cases

1. Latency - I wanted to see the visual latency, so I created a WPF app hosting WebView2 and a webpage in it. When you grab the window with the mouse inside (not the title bar) then the JavaScript code handles the "mousemove" messages and sends WindowMove requests/messages to the backend. It measures the turnaround time and shows a running average.
2. Throughput - On a button click I send 1/10/100 KB messages until 10MB of total data is sent. The total time is measured with performance.now() and the throughput is displayed on the page. In this case I still await for the returned Promise before sending the next message.

Results

I tested this on my (aging) PC: Intel Core i3-2130 (3.4GHz), 8GB DDR3 RAM, Samsung EVO 840 SSD

Test	WebSocket	postMessage	hostObjects
Window Move	5 ms	4.8 ms	4.8 ms
Throughput 1KB/msg	2.1 MB/s	2.1 MB/s	2.3 MB/s
Throughput 10KB/msg	15.3 MB/s	14.5 MB/s	15.5 MB/s
Throughput 100KB/msg	36 MB/s	42 MB/s	42 MB/s

When I open the DevConsole (F12) the results are surprisingly different:

Test	WebSocket	postMessage	hostObjects
Window Move	9 ms	8 ms	8 ms
Throughput 1KB/msg	1.6 MB/s	1.5 MB/s	1.6 MB/s
Throughput 10KB/msg	10.5 MB/s	11.5 MB/s	11.5 MB/s
Throughput 100KB/msg	30 MB/s	40 MB/s	40 MB/s

Conclusion

The results are very close. WebSocket seems to be the slowest, probably doing all the JSON serialization/deserialization and all the message correlation on the JS side inefficiently.