Debug proxy does not respond when appium session is open

[debugger89]

Im facing the an issue while trying to interact with the debug proxy web service connectivity when there is a Appium web session up and running.

Environment :

Mac Os X 10.14.1
Xcode 10.1
Appium Server 1.10
IOS Simulator : IPhone 5 - 10.3.1

Issue re-production steps

1. Start an Appium web session in the simulator.
   DesiredCapabilities desiredCapabilities = new DesiredCapabilities(); desiredCapabilities.setCapability(MobileCapabilityType.BROWSER_NAME, "Safari"); desiredCapabilities.setCapability(MobileCapabilityType.PLATFORM_NAME, "iOS"); desiredCapabilities.setCapability(MobileCapabilityType.PLATFORM_VERSION, "10.3"); desiredCapabilities.setCapability(MobileCapabilityType.NEW_COMMAND_TIMEOUT, "10000"); desiredCapabilities.setCapability(MobileCapabilityType.DEVICE_NAME, "iPhone 5"); URL url = new URL("http://127.0.0.1:4723/wd/hub"); driver = new IOSDriver(url, desiredCapabilities);
2. Now try to use the debug proxy web service for getting a screenshot. (The websocket message is sent via a 3rd party chrome extension)
   ws://127.0.0.1:9191/devtools/page/1
{ "id": 1, "method": "Page.startScreencast", "params": { "format": "jpeg" } } {"id":1,"result":{}}

Expected result :

The web socket should receive another message with the screenshot base64 image string.
`
{
"id": 1,
"method": "Page.startScreencast",
"params": {
"format": "jpeg"
}
}

{"id":1,"result":{}}

{
"method": "Page.screencastFrame",
"params": {
"data": "iVBORw0KGgoAAAANSUhEUgAAAUAAAAHMCAYAAACk4......",
"metadata": {
"pageScaleFactor": 2,
"offsetTop": 0,
"deviceWidth": 320,
"deviceHeight": 460,
"scrollOffsetX": 0,
"scrollOffsetY": 0,
"timestamp": "2019-01-01T08:14:17.433Z"
},
"sessionId": 1
}
}
`

Observations

Appium remote debugger log suggests that the message is captured by remote debugger but my websocket client never gets the message.

[RemoteDebugger] Debugger returned data for message '-17' but we were not waiting for that message! result: '{"result":{"type":"string","value":"980,1409,2"},"wasThrown":false}'; error: 'null'

If the appium session is terminated, the above message works without any issue and returns the intended result.

[artygus]

hi @debugger89 please isolate your problem from appium, it's not clear whether this is appium or iwdp issue right now. can you reproduce it using ios-webkit-dbug-proxy binary only?

[debugger89]

This issue is occuring only when there is Appium session is open as per my knowledge. Which from the backend uses the debug proxy protocol for interacting with the webviews.

[artygus]

Looked through description a couple of times and I have the following questions:

iwdp shouldn't work with simulators in XCode >= 10 (issue #250). Can you confirm iwpd at least lists simulator as inspectable device? ios_webkit_debug_proxy -l

Im facing the an issue while trying to interact with the debug proxy web service connectivity when there is a Appium web session up and running.

Could you please clarify that sentence. And what do you mean by debug proxy web service connectivity, web service part specifically?

Now try to use the debug proxy web service for getting a screenshot. (The websocket message is sent via a 3rd party chrome extension)

What chrome extension do you use?

And the last thing, did you open the issue in appium? doesn't seem like there's a misbehaviour in proxy job of proxying messages. Screencast commands in chrome and safari protocols has different specs, there're adapters available for bringing back compatibility between dev tools protocols https://github.com/google/ios-webkit-debug-proxy#using-with-devtools

[debugger89]

Here are the steps i have followed.

1. Start the IWDP. It connects to the simulator on port 9222 port.
   
2. Navigate to the http://localhost:9222/json. And following page debug information are listed.
   
3. Try to communicate with the page via the websocket whose url is webSocketDebuggerUrl in the given json. Though a Chrome extension

Yes I have logged a issue in Appium. Needed to check if this is a limitation in IWDP where two concurrent users cannot use the service.

[debugger89]

Update :
I tried the same thing using the https://github.com/RemoteDebug/remotedebug-ios-webkit-adapter but got the same results.

[artygus]

Okay, now I see what you mean, unfortunately one page can have only one debug session at a time. This is not a proxy limitation, I guess this is a webinsectord limit, can't find a link to any offical source though.