I am trying to program a small server+client in Javascript on Firefox, using XPCOM.
To get the HTTP message in Javascript, I am using the nsIScriptableInputStream interface.
This f**ing component through the read() method randomly cut the message and I cannot make it reliable.
Is anybody know a solution to get reliably the information? (I already tried a binary stream, same failure.)
J.
I had the same problem with unreliability... I ended up using XMLHTTPRequest, which when used from the XPCOM component can do cross site requests. The second part of the docs detail how to instantiate the XPCOM version.
If you're looking to serve HTTP request I'd take a look at the POW source code and the use of server sockets, which implements a basic HTTP server in JavaScript. Also check out httpd.js
If you control the protocol (that is, both the client and server) I would highly recommend using Javascript/JSON for your server-to-client messages. The client can open a stream either via dynamically adding a <script> tag to the DOM. The server can then send a stream of Javascript commands like:
receiveMsg({type:"text", content:"this is my message"});
Then the client just needs to define a receiveMsg function. This allows you to rely on fast browser code to parse the message and determine where the end of each message is, at which point it will call your handler for you.
Even if you're working with an existing HTTP protocol and can't use JSON, is there some reason you can't use XMLHttpRequest? I would expect it to be more stable than some poorly documented Firefox-specific XPCOM interface.
--Chouser
Related
so, I've tried to send a javascript XMLHttpRequest on a personally written http server that uses python's core functionality (i.e. socket and regex). took me a while but I finally had it going. so, I tested it out and after debugging the regex for parsing http POST and GET requests, I tested it out through the python console and it worked fine.
in short, the http server receives a GET loopback request with personal identification, and reads whatever text was sent to it as data.
a tts loopback server.
I wanted to do it because asides from selenium that honestly seemed like the only way for me to read random text from the screen using javascript (I could create a browser extension that works alongside it). I already created something for parsing html, so that's not the problem. later I wanted to extend the application and create a GUI using java for generally tts'ing files so I could listen to them while programming.
the problem was that although the socket was bound to port 80 on the loopback interface (127.0.0.1), when I sent an XMLHttpRequest to localhost, the server was not responding. I checked for incoming connections and there were none. from the terminal it worked fine though.
if anyone else is wondering, no, it's not possible. unless it bypasses CORS restriction. (sadly). If anyone wants to do something similar, he has to either bypass CORS restrictions OR if you're building with python you can just use selenium and create a "custom" browser extension.
I taught myself programming so my knowledge is very fragmented and now I have encountered a fragment I know nothing about. Sending and receiving Date. In addition I want to do it across domains. I know about the security policies that prohibit this but have read about some solutions. I still can't make sense of it in relation to my challenge.
What I want to do:
I want to build a plugin that sends data to my server when a function is called. The function is bound to an event listener.
this plugin contains of a little html-form and some js in the back. i want to send json or simular.
my questions:
I) how do I send data to an other server?
II) how do I receive this data? I know about parsing and dom but all I did so far is handle requested data. now this data is posted to my server-app without me knowing beforehand. the data is used to update a DB. the backend is coded in JS or python. I would prefer JS for compatability reasons.
III) how can I test the cross server connection on my local machine? especially without an active internet-connection?
I don't expect a complete guide or the code i need. just the resources and where to get the knowledge-chunks I need to build this.
Thanks a bunch in advance!
I) how do i send data to an other server?
You may use AJAX (or jQuery.ajax a more convenient way)
II) how do i receive this data? i know about parsing and dom but all i
did so far is handel requested data. now this data is posted to my
server-app without me knowing beforehand. the data is used to update a
DB. the backend is coded in JS or python. i would prefer JS for
compatability reasons.
As long as you send some data via AJAX, the browser makes a HTTP call and you could receive the data from server-side. Both JS or python would compatible with your client-side javascript and seldom do there have compatibility issue.
III) how can i test the cross server connection on my local maschine?
especially without an active internet-connection?
localhost and 127.0.0.1 is treated as different host and I usually use these to test cross server scenario. One issue of AJAX is that browser usually disallow Cross Domain calls unless you specify Access-Control-Allow-Origin headers.
Is there a way to send data packets from an active Python script to a webpage currently running JavaScript?
The specific usage I'm looking for is to give the ability for the webpage, using JavaScript, to tell the Python script information about the current state of the webpage, then for the Python script to interpret that data and then send data back to the webpage, which the JavaScript then uses to decide which function to execute.
This is for a video game bot (legally), so it would need to happen in real time. I'm fairly proficient in Python and web requests, but I'm just getting into JavaScript, so hopefully a solution for this wouldn't be too complex in terms of Javascript.
EDIT: One way I was thinking to accomplish this would be to have Javascript write to a file that the Python script could also read and write to, but a quick google search says that JavaScript is very limited in terms of file I/O. Would there be a way to accomplish this?
For security reasons, javascript in a browser is usually restricted to only communicate with the site it was loaded from.
Given that, that's an AJAX call, a very standard thing to do.
You can make HTTP requests using the XMLHttpRequest API, which Jquery abstracts with $.ajax and $.get. You can also use the lower level Websockets network API:
https://developer.mozilla.org/en-US/docs/WebSockets
Note that the XMLHttpRequest API will only allow requests to the same server, OR requests that return an appropriate Access-Control-Allow-Origin header.
It sounds like the Javascript is only going to send information, not receive any. In that case, you're in luck. I'm guessing you are also running the Javascript and the Python on the same machine.
Run a Python webserver on the machine the browser is running on. Here's a simple example:
http://webpy.org/install
Once visiting http://127.0.0.1:8080/ in your browser gives the message Hello World!, you can start adding more addresses to your website, for example http://127.0.0.1:8080/report_data, http://127.0.0.1:8080/report_event etc.
Your Javascript can then make AJAX requests using jQuery.ajax or XMLHTTPRequest, to the address http://127.0.0.1:8080/report_data, and pass the information as GET parameters.
I'm pretty new to WebSockets and this may be completely insane. If so, please let me know what I should be doing instead.
The idea is that I'd like to have a WebSocket connection in the browser that ultimately interfaces with a database. Because the db shouldn't be exposed to the browser there would be, of course, a server layer in between that takes in the WebSocket message and then converts that into something like a POST, or DELETE request. The server would then pass that message along to the database.
So the question is: Is there some kind of standard for translating WebSocket messages into HTTP requests?
I found one blog post where the guy made sure his WebSocket messages from the browser came in the form {"method":"POST","content":"foo"} so they could be understood with normal JSON parsing. Is something like this ok or is there a more acceptable "right way."
Something like this is not only ok, it is the only way. You need a protocol in order to communicate between server and client (otherwise how would a server/client understand what you want from it?). Whatever you choose it will be fine (you can even use standard HTTP over WebSockets). Creating your own protocol (like with the example you came up with) is perfectly fine as well. I prefer JSON-based protocols because it is easy to work with them (JSON parsers are built-in or easily available in most known lanugages)
I had a discussion with my colleague about Flash security. We're in the phase of planning some things for our web project that is using Flash plugin to display content. We need to dynamically pull settings for the Flash application from the server, using JSON.
Proposal that I offered was that we should save an extra HTTP request to pull the data file after the plugin is loaded and embed the JSON directly in the page containing the Flash plugin. Flash would fire a Javascript function that'd return the deserialized JSON data to it.
My colleague opposed this proposal with significant "security concerns".
I believe that there's literally zero difference between these two approaches besides the fact that his approach requires additional HTTP request. All of this is client/server and client should never be trusted. If I want to change the data that is in the JSON query, I can do that in both cases. File pull is little more difficult to hack though, but possible with custom HTTP proxy.
What are your thoughts?
There is no difference. Both can be fabricated.
if you really care that much about delivering original settings to the .swf:
don't use http - httpFox is a brilliant plugin - use a server that supports RTMP/RTMPE and NetConnection.call() to retrieve the data.
create an algorithm for validating original json so that your app won't work if the config doesn't pass the test.
after the config is loaded your swf might check the values with the server (not all at a time) and throw an error if something goes wrong