Concurrent XHR for rpc and prompt

[bilogic]

I have question related to jQuery Terminal

Hi,

I configured prompt to load a URL (using AJAX/XHR) which returns some Laravel session data. However, my URL randomly returns outdated data.

I did some tracing using Chrome's network logs, and see that prompt's URL is loaded concurrently with the RPC's URL.

Is there any way to make it sequential? i.e. prompt URL is loaded only after RPC's URL is completed. Thank you.

[bilogic]

The sequential way is to load prompt URL inside response
Thanks!

[bilogic]

Hi, using response led to more problems. Would you be able to help with the original request?

Thank you.

[jcubic]

Do you a demo somewhere where I can test your code?

[bilogic]

I do have a link.. but it requires a password etc

[bilogic]

This probably best shows what is happening after 1 RPC command is sent

1. Why do they start together?
2. Why does prompt.json get called a 2nd time?

My prompt option is as follows:

prompt: function (callback) {
	$.ajax({
		type: "GET",
		url: "{{ url.prompt }}",
		dataType: "json",
		async: false
	}).done(
		function (data) {
			callback(data.prompt);
		}
	);
}

[bilogic]

Hi,

In case I wasn't clear enough, I'm looking to make fetching prompt's URL sequential because it contains dynamic session data which can change based on the RPC command issued, plus Laravel's sessions are not locked.

While it is possible to switch to locked sessions, that comes with a performance hit.
Also with dynamic data, it is impossible to show the correct data if prompt is loaded before the RPC is complete.

Thank you.

[jcubic]

I'm not sure how async: false will work. Here is working example with rpc demo where I set session in php for each rpc command:

   jQuery(document).ready(function($) {
        $('body').terminal("json-rpc-service-demo.php", {
            login: true,
            greetings: "You are authenticated",
            completion: true,
            onBlur: function() {
                // the height of the body is only 2 lines initialy
                return false;
            },
            prompt: function(setPrompt) {
                $.jrpc('json-rpc-service-demo.php', 'prompt', [],
                       function(response) {
                           setPrompt(response.result);
                       });
            }
        });
    });

and it work, prompt rpc is executed after rpc finish.

[jcubic]

if you're using normal ajax without build in RPC then you need to pause the terminal when you do ajax call, and resume after it finish and you echo the result. If you have problem with timing you probably need pasue/resume or return promise from interpreter (but that promise need to resolve to undefined otherwise the value from promise will get echoed, but if you return and have then(() => { then it should work fine if you don't return anything in then).

[bilogic]

Hi,

I assume you are using PHP's $_SESSION.

It is blocking by default aka locked, i.e. when RPC has called start_session(), prompt's start_session() will not run until the RPC has ended. I'm using Laravel's session (which does not lock) as it offers better performance. As such, you won't face my issue.

I tested using $.jrpc:

• prompt and RPC's URLs are still firing together (I would like prompt to fire only after RPC has ended)
• No option to pass CSRF token to $.jrpc (Maybe you can consider adding this for security)

I'm going to try the pause and resume now and update my results. Thank you.

[bilogic]

Hi,

I managed to get what I wanted. Here is to tie a few loose ends:

Make prompt fire only after RPC has ended

• I surrounded the following 3 lines with if (tmp == "") { ... }
  

  jquery.terminal/js/jquery.terminal.js

  Lines 1382 to 1384 in a476bdd

  	if (is_function(prompt)) {
  	draw_prompt();
  	}

• prompt currently fires twice, first, together with RPC, and again after RPC ends (refer to chrome network logs)
• If the user presses ENTER without any command, we will fire the first prompt (as RPC will not fire)
• If the user presses ENTER with a command, we do not fire the first prompt and let RPC fire prompt after ending
• In both cases, prompt is fired only 1 time.
• I appreciate if this can be added to the library.

AJAX with async: false

• This causes the AJAX not to return until it's done() is finished
• It has little effect on terminal, probably just a slightly longer delay

Thank you for the time and help!

[jcubic]

If you use code to trigger ajax even $.jrpc you need to use pause()/resume(), by default rpc I mean using string as interpreter, that will create RPC client for you. (like in my code). This is not blocking in PHP the request is not fired until first is finished because prompt is called when you call resume(). If it would lock the other session there would be two request but send would take longer but it start when first is finished.

[jcubic]

I can confirm that in your code but you didn't send the link and pass.

[bilogic]

Hi,

I did not send the link as I had solved it. Let me test your pause()/resume() and update shortly. Thank you.

[bilogic]

Would you have an example of where to call pause()/resume()?
I wrote:

prompt: function (callback) {
	terminal.pause();
	$.ajax({
		type: "GET",
		url: "{{ url.prompt }}",
		dataType: "json",
		async: false
	}).done(
		function (data) {
			terminal.resume();
			callback(data.prompt);
		}
	);
}

It causes an infinite loop. terminal.resume() => prompt => $.ajax => .done() => terminal.resume()

[jcubic]

You need to put those in your interpreter, can you show your first argument to .terminal(???

[bilogic]

Here's the terminal portion:

options = {
	// height: 500,
	login: false,
	greetings: "Welcome",
	tabcompletion: true,
	processArguments: false,	// don't convert numbers to integers
	request: function(jxhr, request, terminal) {
		if (csrfToken) {
			jxhr.setRequestHeader(CSRF_HEADER, csrfToken);
			jxhr.setRequestHeader("Accept", "application/json");
		}
	},
	onAfterCommand: function(command) {
	},
	response: function(jxhr, response, terminal) {
		if (!response.error) {
		//		csrfToken = jxhr.getResponseHeader(CSRF_HEADER);
		}
	},
	echo: function () {	
	},
	onCommandChange: function (command, term) {
		// console.log(command);
	},
	onIdle: function (term) {
		term.resize();
		$('#s').trigger('click');
	},
	completion: function (term, string, callback) {		
		return true;
	},
	onBlur: function () {		
		return false;
	},
	prompt: function (callback) {		
		$.ajax({
			type: "GET",
			url: "{{ url.prompt }}",
			dataType: "json",
			async: false
		}).done(
			function (data) {
				callback(data.prompt);
			}
		);
	}
}

terminal = $('#pjax-main').terminal("{{ url.rpc }}", options);

[jcubic]

that's very weird it work with php when I tested, I've just removed session_start and replace it with file on disk and it works. Without having it live nothing I can do, the only thing I can think of is that you use outdated version.

Ps: this will not work:

        onIdle: function (term) {
		term.resize();
		$('#s').trigger('click');
	},
	completion: function (term, string, callback) {		
		return true;
	},
	onBlur: function () {		
		return false;
	},

    completion: function (term, string, callback) {		
	return true;
}

without calling callback make no sens, if you use rpc use completion: true and there are no onIddle maybe you want onInit.

and tabcompletion: true is old option it was removed in version 0.8.0.

[jcubic]

wait, sorry it seems that there are two requests, but they are both the same, this is a bug. There should be only one request to prompt.

[bilogic]

Thanks for highlighting the deprecated functions.

Yes, I have used jquery.terminal for a long time now, I'm migrating to the latest and weeding out the old functions progressively.

Since you now see two prompt requests, I believe we are on the same page :)
Thank you.

[jcubic]

The fix is in devel branch it will be in version 2.2.1.

[bilogic]

Thank you, I can confirm there is only 1 prompt call now.

[jcubic]

There are still issues with async prompt it's executed 2 times on init and the solution work with old jQuery.

[jcubic]

Should be fixed now, also found few other async prompt issues. Those are also fixed.