I am using wxWidgets to download the contents of a website into a wxHtmlWindow control. This works flawlessly, except for one thing. The entire gui seems to freeze while the data is being downloaded, which is highly problematic for my application. In most other wxWidgets class methods, events continue to be processed automagicly for you even if the call in question is said to be blocking. This does not appear to be the case here, and I am wondering how I might tell wxWidgets to download the page in the background? I am currently using the LoadPage method.
I guess I could use a second thread, but with the restrictions that wxWidgets imposes on changing the state of any window through any thread other than the main one makes me hesitate to dive into this. Is there a better way? The raw http class, for instance, does not block the window while it's downloading so I don't understand why wxHtmlWindow, which surely must be using the raw http class internally, does not have the same behavior.
Unfortunately wxHtmlWindow uses synchronous sockets to fetch contents of a URL. Call hiearchy goes like this: wxHtmlWindow -> wxHtmlParser -> wxFileSystem -> wxURI -> wxHTTP -> wxHTTP::GetInputStream . The GetInputStream method will use the open a socket in blocking mode.
You will need to use a separate thread to fetch the contents of a website.
Related
I was wondering if it is possible to use Julia to perform computations on a webpage in an automated way.
For example suppose we have a 3x3 html form in which we input some numbers. These form a square matrix A, and we can find its eigenvalues in Julia pretty straightforward. I would like to use Julia to make the computation and then return the results.
In my understanding (which is limited in this direction) I guess the process should be something like:
collect the data entered in the form
send the data to a machine which has Julia installed
run the Julia code with the given data and store the result
send the result back to the webpage and show it.
Do you think something like this is possible? (I've seen some stuff using HttpServer which allows computation with the browser, but I'm not sure this is the right thing to use) If yes, which are the things which I need to look into? Do you have any examples of such implementations of web calculations?
If you are using or can use Node.js, you can use node-julia. It has some limitations, but should work fine for this.
Coincidentally, I was already mostly done with putting together an example that does this. A rough mockup is available here, which uses express to serve the pages and plotly to display results (among other node modules).
Another option would be to write the server itself in Julia using Mux.jl and skip server-side javascript entirely.
Yes, it can be done with HttpServer.jl
It's pretty simple - you make a small script that starts your HttpServer, which now listens to the designated port. Part of configuring the web server is that you define some handlers (functions) that are invoked when certain events take place in your app's life cycle (new request, error, etc).
Here's a very simple official example:
https://github.com/JuliaWeb/HttpServer.jl/blob/master/examples/fibonacci.jl
However, things can get complex fast:
you already need to perform 2 actions:
a. render your HTML page where you take the user input (by default)
b. render the response page as a consequence of receiving a POST request
you'll need to extract the data payload coming through the form. Data sent via GET is easy to reach, data sent via POST not so much.
if you expose this to users you need to setup some failsafe measures to respawn your server script - otherwise it might just crash and exit.
if you open your script to the world you must make sure that it's not vulnerable to attacks - you don't want to empower a hacker to execute random Julia code on your server or access your DB.
So for basic usage on a small case, yes, HttpServer.jl should be enough.
If however you expect a bigger project, you can give Genie a try (https://github.com/essenciary/Genie.jl). It's still work in progress but it handles most of the low level work allowing developers to focus on the specific app logic, rather than on the transport layer (Genie's author here, btw).
If you get stuck there's GitHub issues and a Gitter channel.
Try Escher.jl.
This enables you to build up the web page in Julia.
i want to handle any download request coming from Webview. how it is possible ? the documentation https://developer.blackberry.com/native/reference/cascades/bb__cascades__webresourcerequestfilter.html and https://developer.blackberry.com/native/reference/cascades/bb__cascades__webdownloadrequest.html are describing the parameters but couldn't figure out how to do it.
Your question is not clear on what you don't understand. Remember this is not a training forum, the idea is that you should try things, review the documentation and then ask specific questions to get the best out of a forum.
Moreover it is not clear whether you are trying to handle the download request at the Server, or capture the request before the download attempt leaves the BB.
I'm going to assume you want to display a web page on the BlackBerry but make sure that any resource requests that the page generates, are filtered by your program, so that you can supply the data (assuming you have it).
I implemented something like this a while ago and remember that it was not simple to figure out what was going on, but I played with it a bit and it all made sense.
I don't remember using WebDownloadRequest and can't really see how it helps in this case.
The key is WebResourceRequestFilter. You create your own WebResourceRequestFilter making sure you implement the required methods. Then you use WebPage::setNetworkResourceRequestFilter(WebResourceRequestFilter*) to make sure the webpage will ask your WebResourceRequestFilter for its resources. The first method the web page invokes is filterResourceRequest(), and the return from this invocation determines which other methods in your WebResourceRequestFilter, the Webage will invoke.
I suggest you implement a WebResourceRequestFilter, put some debugging in filterResourceRequest(), but always return FilterAction Accept, which means the web page will use its normal processing to obtain the resources. Then try various other FilterAction return values and see what happens...
I am currently trying to use the "Invocation tags" of Mate to call my web services and delegate the WS-responses to my fault/result handlers.
I want to use the generated proxies, provided by the Flex Builder, and not the plain <WebService> or <WebServiceInvoker> tags.
I actually failed using several techniques:
<WebServiceInvoker> does not work with the generated proxies.
<AsyncMethodInvoker> needs some complicated successType that I could not get to work with the WS-calls. And defining the events seems redundant to me. I want it simple and easy to read, the code will be touched by other people than me!
<MethodInvoker> can't use instances, and it also can't handle the proxies' AsyncToken
<DelegateInvoker> Looked fine at first. It calls the service but doesn't fire valid result events (infinite busy cursor). Even though i can successfully bind to the XYZ_lastResult of the WS-proxies, and a WS-call results in getting valid data from the WS-backend, the <faultHandlers> and <resulthandlers> are not executed. There is some solution for the DelegateInvoker that changes code in the generated proxies, which i definately do not want to do!
So here is my question: Is there a simple(!) way of using default Flexbuilder generated proxies with the Mate Invocation tags?
It appears that your request is not that uncommon to Mate. Check out this couple of threads in their forum:
http://mate.asfusion.com/forums/topic.php?id=424
http://mate.asfusion.com/forums/topic.php?id=421
The solution is to modify some bits of the auto-generated code... which in a way ruins the whole point of using code generation.
An existing (though incomplete) FLEX3 project was given to us to finish (always a nightmare).
It is quite small but highly abstracted (contains well over 150 files to support only about 10 page views). I'm attempting to trace a single mouseclick event through this maze.
Is there a way to print out an actionscript trace and/or component flow using the debugger (or any other tool that anyone knows of)?
The flash.txt file appears worthless since it doesn't contain ActionScript calls and/or component flows.
Thanks
This will print your execution graph:
Trace.setLevel(Trace.METHODS, Trace.LISTENER);
Trace.setListener(handleMethods);
function handleMethods(fqcn:String, lineNumber:uint, methodName:String, methodArguments:String):void
{
trace(methodName);
}
Oof. Yeah, always.
The Profiler might give you useful information, but you need to pay for FlexBuilder Pro to get it, if you don't already have it. I'm not real handy with the Profiler, so I may be off base with that advice. It would be worth checking into, though, if you are already familiar with other profiling tools.
I would probably just start looking at every point that .addEventListener(MouseEvent.CLICK occurs in the code - and .addEventListener("click", just in case the previous developer chose not to use the constant, for some reason.
Obviously, that could show up a lot in 150 files, but that's how I would go about it.
I would also look at any custom events that could get into the mix. Because maybe the CLICK event is handled at some point and the handler dispatches a custom event. And maybe the handler for that custom event dispatches another custom event. Or dispatches a MouseEvent.CLICK event, etc.
Hope that helps. Good luck...
Check out
http://jpauclair.net/2010/02/10/mmcfg-treasure/
esp.
AS3Trace = 1|0
This one is also very useful for
debugging It trace every single call
to any function that is being called
in the SWF at runtime! It’s like
expending the StackTrace to the full
software run time.
And many more.
I have a flex application that repeatedly polls a remote XML file to detect changes, but I've found that once the file hits a certain size, the poll blocks the UI and makes the page unresponsive for a short time.
Is there any way to ensure that the call made to the server or the event from the flash.utils.Timer class runs asynchronously to the main UI thread?
It sounds like the blocking is caused by Flash parsing the XML rather than the actual loading.
If that is the case then you can keep loading the file and just check the size of the raw data you get back - if it's bigger, parse it and take the parsing hit. Otherwise toss the data and wait for the next request.
There's no explicit way to do threading with Flash at this time. Certain tasks happen async naturally (network and pixelbender comes to mind) but that's it.
Branden's right -- the code we write essentially always happens on the main thread; while the network call itself does happen on a background thread, the handling of that call happens on the main one.
One thing to keep in mind is that the WebService and HTTPService classes will likely attempt to serialize your responses automatically, which could mean taking that processing hit unnecesarily. Using URLLoader, on the other hand, could give you more direct access to the response data, allowing you to work more directly with it without the unnecessary overhead of that built-in processing.
In that light, if you find you do have to process the entire XML file, you might consider breaking it up into chunks somehow, and distributing the processing of those chunks into separate functions, rather than handling everything within the scope of a single function. Just doing that might allow the player to continue updating the UI while you're processing that big bunch of text (processing a bit, exiting the function, rendering the UI, entering the next function, rendering, and so on); Oliver Goldman, an engineer on the AIR team, did a presentation on this concept at last year's MAX conference.
Hope it helps!
Like mentioned, AS3 is single threaded. But there are a couple of ways to handle your situation. Here are ur possible choices:
First,make sure you really need to parse entire XML when loaded and cant just keep the loaded xml nodes in memory as the data model (XML being a native data type now). Sometimes I create value objects by passing them an XMLNode and thats kept in memory till a node value is needed at which point I read it. This allows you to keep some of the parsing for later.
If you are using an ArrayCollection or similar structure to hold data, try using a primitive Array ( see http://www.arpitonline.com/blog/?p=114 for an issue I ran into)
See if you can creatively use callLater()(http://livedocs.adobe.com/flex/2/langref/mx/core/UIComponent.html#callLater())
Can you pass the data to the client in a native format like SWX or using Remoting
Can you use data paging? ArrayCollections and I am pretty sure XMLCollection support it
Side Note:
While AS3 is single threaded, Pixel Bender and I think Alchemy (http://labs.adobe.com/technologies/alchemy/) run on a different thread. There have been a couple of experiments on blogs using Pixel Bender to do calculations which dont slow the UI of the app (Example:http://elromdesign.com/blog/2009/02/09/using-pixel-bender-to-do-heavy-lifting-calculations-makes-flash-player-multi-thread/).
Also please vote on this feature enhancement ticket with Adobe if you feel the need for this feature enough:
https://bugs.adobe.com/jira/browse/ASC-3222