I'm working on an Adobe AIR application which can upload files to a web server, which is running Apache and PHP. Several files can be uploaded at the same time and the application also calls the web server for various API requests.
The problem I'm having is that if I start two file uploads, while they are in progress any other HTTP requests will time out, which is causing a problem for the application and from a user point of view.
Are Adobe AIR applications limited to 2 HTTP connections, or is something else probably the issue?
From searching about this issue I've not found much but one article did indicated that it wasn't limited to just two connections.
The file uploads are performed by calling the File classes upload method, and the API calls are done using the HTTPService class. The development web server I am using is a WAMP server, however when the application is released it will be talking to a LAMP server.
Thanks,
Grant
Here is the code I'm using to upload the file:
protected function btnAddFile_clickHandler(event:MouseEvent):void
{
// Create a new File object and display the browse file dialog
var uploadFile:File = new File();
uploadFile.browseForOpen("Select File to Upload");
uploadFile.addEventListener(Event.SELECT, uploadFile_SelectedHandler);
}
private function uploadFile_SelectedHandler(event:Event):void
{
// Get the File object which was used to select the file
var uploadFile:File = event.target as File;
uploadFile.addEventListener(ProgressEvent.PROGRESS, file_progressHandler);
uploadFile.addEventListener(IOErrorEvent.IO_ERROR, file_ioErrorHandler);
uploadFile.addEventListener(Event.COMPLETE, file_completeHandler);
// Create the request URL based on the download URL
var requestURL:URLRequest = new URLRequest(AppEnvironment.instance.serverHostname + "upload.php");
requestURL.method = URLRequestMethod.POST;
// Set the post parameters
var params:URLVariables = new URLVariables();
params.name = "filename.ext";
requestURL.data = params;
// Start uploading the file to the server
uploadFile.upload(requestURL, "file");
}
Here is the code for the API calls:
private function sendHTTPPost(apiFile:String, postParams:Object, resultCallback:Function, initialCallerResultCallback:Function):void
{
var httpService:mx.rpc.http.HTTPService = new mx.rpc.http.HTTPService();
httpService.url = AppEnvironment.instance.serverHostname + apiFile;
httpService.method = "POST";
httpService.requestTimeout = 10;
httpService.resultFormat = HTTPService.RESULT_FORMAT_TEXT;
httpService.addEventListener("result", resultCallback);
httpService.addEventListener("fault", httpFault);
var token:AsyncToken = httpService.send(postParams);
// Add the initial caller's result callback function to the token
token.initialCallerResultCallback = initialCallerResultCallback;
}
If you are on a windows system, Adobe AIR is using Microsofts WinINet library to access the web. This library by default limits the number of concurrent connections to a single server to 2:
WinInet limits the number of simultaneous connections that it makes to a single HTTP server. If you exceed this limit, the requests block until one of the current connections has completed. This is by design and is in agreement with the HTTP specification and industry standards.
... Connections to a single HTTP 1.1 server are limited to two simultaneous connections
There is an API to change the value of this limit but I don't know if it is accessible from AIR.
Since this limit also affects page loading speed for web sites, some sites are using multiple DNS names for artifacts such as images, javascripts and stylesheets to allow a browser to open more parallel connections.
So if you are controlling the server part, a workaround could be to create DNS aliases like www.example.com for uploads and api.example.com for API requests.
So as I was looking into this, I came across this info about using File.upload() in the documentation:
Starts the upload of the file to a remote server. Although Flash Player has no restriction on the size of files you can upload or download, the player officially supports uploads or downloads of up to 100 MB. You must call the FileReference.browse() or FileReferenceList.browse() method before you call this method.
Listeners receive events to indicate the progress, success, or failure of the upload. Although you can use the FileReferenceList object to let users select multiple files for upload, you must upload the files one by one; to do so, iterate through the FileReferenceList.fileList array of FileReference objects.
The FileReference.upload() and FileReference.download() functions are
nonblocking. These functions return after they are called, before the
file transmission is complete. In addition, if the FileReference
object goes out of scope, any upload or download that is not yet
completed on that object is canceled upon leaving the scope. Be sure
that your FileReference object remains in scope for as long as the
upload or download is expected to continue.
I wonder if something there could be giving you issues with uploading multiple files. I see that you are using browserForOpen() instead of browse(). It seems like the probably do the same thing... but maybe not.
I also saw this in the File class documentation
Note that because of new functionality added to the Flash Player, when publishing to Flash Player 10, you can have only one of the following operations active at one time: FileReference.browse(), FileReference.upload(), FileReference.download(), FileReference.load(), FileReference.save(). Otherwise, Flash Player throws a runtime error (code 2174). Use FileReference.cancel() to stop an operation in progress. This restriction applies only to Flash Player 10. Previous versions of Flash Player are unaffected by this restriction on simultaneous multiple operations.
When you say that you let users upload multiple files, do you mean subsequent calls to browse() and upload() or do you mean one call that includes multiple files? It seems that if you are trying to do multiple separate calls that that may be an issue.
Anyway, I don't know if this is much help. It definitely seems that what you are trying to do should be possible. I can only guess that what is going wrong is perhaps a problem with implementation. Good luck :)
Reference: http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/FileReference.html#upload()
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/net/FileReference.html#browse()
Just because I was thinking about a very similar question because of an error in one of my actual apps, I decided to write down the answer I found.
I instantiated 11
HttpConnections
and was wondering why my Flex 4 Application stopped working and threw an HTTP-Error although it was working pretty good formerly with just 5 simultanious HttpConnections to the same server.
I tested this myself because I did not find anything regarding this in the Flex docs or on the internet.
I found that using more than 5 HTTPConnections was the reason for the Flex application to throw the runtime error.
I decided to instantiate the connections one after another as a temporally workaround: Load the next one after the other has received the data and so on.
Thats of course just temporally since one of the next steps will be to alter the responding server code in that way that it answers a request that contains the results of requests to more then one table in one respond. Of course the client application logic needs to be altered, too.
Related
I have a mobile service sync table that is giving me absolutely HORRENDOUS performance.
The table is declared as:
IMobileServiceSyncTable<Myclass> myclassTable;
this.client = new MobileServiceClient("my url here");
var store = new MobileServiceSQLiteStore(“localdb.db”);
store.DefineTable<Myclass>();
this.client.SyncContext.InitializeAsync(store);
this.myclassTable = client.GetSyncTable<Myclass>();
Than later in a button handler I’m calling into:
this.myclassTable.ToCollectionAsync();
The problem is, the performance is horrific. It takes at best minutes and most times just sits there indefinitely.
Is there anything in the above that I’ve done that would explain why performance is so absolutely terrible?
this.myclassTable.ToCollectionAsync();
For IMobileServiceSyncTable table, the above method would execute the SELECT * FROM [Myclass] sql statement against your local sqlite db.
The problem is, the performance is horrific. It takes at best minutes and most times just sits there indefinitely.
AFAIK, when working with offline sync, we may invoke the pull operation for retrieving a subset of the server data, then insert the retrieved data into the local store table. For await this.myclassTable.PullAsync(), it would send request and retrieve the server data with the MaxPageSize in 50, and the client SDK would send another request to confirm whether there has more data and pull them automatically.
In summary, I would recommend you checking with your code to locate the specific code which causes this poor performance. Also, you could leverage adding diagnostic logging, capturing the network traces via Fiddler to troubleshoot with this issue.
I needed a audio conversion library. After already pulling my hair..I have given up on the fact that there is no such audio library out there..every library out there has some or the other problem.
The only option left is ffmpeg which is the best but unfortunately you cannot use it in asp.net (not directly I mean). Every user on the website that will convert a file; will launch an exe?; I think I will hit the server memory max soon.
Bottom Line: I will try using ffmpeg.exe and see how many users it can support simultaneously.
I went to the ffmpeg website and in the windows download section I found 3 different version; static, shared and dev.
Does any one know which would be the best? All packed in one exe (static) or dll's separely and exe small, wrt using it in asp.net?
PS: any one has a good library out there..would be great if you can share.
Static builds provide one self-contained .exe file for each program (ffmpeg, ffprobe, ffplay).
Shared builds provide each library as a separate .dll file (avcodec, avdevice, avfilter, etc.), and .exe files that depend on those libraries for each program
Dev packages provide the headers and .lib/.dll.a files required to use the .dll files in other programs.
ffMpeg is the best library out there from what I have used but I wouldn't recommend trying to call it directly from asp.net.
What I have done, is accepted the upload, stored it on the server, or S3 in my case, then have a worker role (if using something like Azure) and a process that continuously looks and monitors for new files to convert.
If you needed a realtime like solution, you could update flags in your database and have an AJAX solution to poll the database to keep providing progress updates, then a link to download once the conversion is complete.
Personally my approach would be
Azure Web Roles
Azure Worker Role
ServiceBus
The WorkerRole starts up and is monitoring the ServiceBus Queue for messages.
The ASP.NET site uploads and stores the file in S3 or Azure
The ASP.NET site then records information in your DB if needed and sends a message to the ServiceBus queue.
The WorkerRole picks this up and converts.
AJAX will be needed on the ASP.NET site if you want a realtime monitoring solution. Otherwise you could send an email when complete if needed.
Using a queuing process also helps you with load as when you are under heavy load people just wait a little longer and it doesn't grind everything to a halt. Also you can scale out your worker roles as needed to balance loads, should it ever become too much for one server.
Here is how I run ffMpeg from C# (you will need to change the parameters for your requirements)
String params = string.Format("-i {0} -s 640x360 {1}", input.Path, "C:\\FilePath\\file.mp4");
RunProcess(params);
private string RunProcess(string Parameters)
{
//create a process info
ProcessStartInfo oInfo = new ProcessStartInfo(this._ffExe, Parameters);
oInfo.UseShellExecute = false;
oInfo.CreateNoWindow = true;
oInfo.RedirectStandardOutput = true;
oInfo.RedirectStandardError = true;
//Create the output and streamreader to get the output
string output = null; StreamReader srOutput = null;
//try the process
try
{
//run the process
Process proc = System.Diagnostics.Process.Start(oInfo);
proc.ErrorDataReceived += new DataReceivedEventHandler(proc_ErrorDataReceived);
proc.OutputDataReceived += new DataReceivedEventHandler(proc_OutputDataReceived);
proc.BeginOutputReadLine();
proc.BeginErrorReadLine();
proc.WaitForExit();
proc.Close();
proc.Dispose();
}
catch (Exception)
{
// Capture Error
}
finally
{
//now, if we succeeded, close out the streamreader
if (srOutput != null)
{
srOutput.Close();
srOutput.Dispose();
}
}
return output;
}
I have a flex application that communicates via BlazeDS with two webapps running inside a single instance of Tomcat.
The flex client is loaded by the browser from the first webapp and all is well. However on the initial call to the second webapp the client receives the following error:
Detected duplicate HTTP-based FlexSessions, generally due to the remote host disabling session cookies. Session cookies must be enabled to manage the client connection correctly.
Subsequent calls to the same service method succeed.
I've seen a few posts around referring to the same error in the context of two flex apps calling a single webapp from the same browser page, but nothing which seems to help my situation - so I'd be very grateful if anyone could help out....
Cheers, Mark
Three potential solutions for you:
I found once that if I hit a remote object before setting up a messaging channel then the CientID would get screwed up. Try to establish an initial messaging channel once the application loads, and before any remote object calls are made.
Flash Builder's network monitoring tool can cause some problems with BlazeDS. I set up a configuration option on application load that checks to see if I'm in the dev environment (it is called just before setting up my channel from #1). If I'm in dev, I assign a UID manually. For some reason this doesn't take well outside the dev environment... been awhile since I set it all up so I can't remember the finer points as to why:
if (!(AppSettingsModel.getInstance().dev))
FlexClient.getInstance().id = UIDUtil.createUID();
BlazeDS by default only allows for a single HTTP session to be setup per client/browser. In my streaming channel definitions I added the following to allow for additional sessions per browser:
<channel-definition id="my-secure-amf-stream" class="mx.messaging.channels.SecureStreamingAMFChannel">
<endpoint url="https://{server.name}:{server.port}/FlexClient/messagebroker/securestreamingamf"
class="flex.messaging.endpoints.SecureStreamingAMFEndpoint"/>
<properties>
<add-no-cache-headers>false</add-no-cache-headers>
<idle-timeout-minutes>0</idle-timeout-minutes>
<max-streaming-clients>10</max-streaming-clients>
<server-to-client-heartbeat-millis>5000</server-to-client-heartbeat-millis>
<user-agent-settings>
<user-agent match-on="MSIE" kickstart-bytes="2048" max-streaming-connections-per-session="3" />
<user-agent match-on="Firefox" kickstart-bytes="2048" max-streaming-connections-per-session="3" />
</user-agent-settings>
</properties>
Problem: Duplicate session errors when flex.war and Livecycle.lca files are hosted in separate JVMs on WebSphere Server.
Solution:
Inside the command file for the event, set FlexClientId to null in execute method before calling remote service (Java method or LC Process).
Guess this approach can be used in other scenarios as well to prevent Duplicate session errors.
EventCommand.as file
—————————–
import mx.messaging.FlexClient;
//other imports as per your code
public function execute(event:CairngormEvent):void
{
var evt:EventName = event as EventName ;
var delegate:Delegate = new DelegateImpl(this as IResponder);
//***set client ID to null
FlexClient.getInstance().id = null;
delegate.functionName(evt.data);
}
I have an ASP.NET running in IIS 7.5 that creates files on the local file system and then attempts to delete after performing some logic in between creation and deletion. I'm running into a situation though where deletion is failing with a response such as "The process cannot access the file 'C:...\Uploads\c1fe593f-85de-4de1-b5d1-7239e1fc0648_Tulips.jpg' because it is being used by another process.'" The file appears to be locked by IIS and I can't delete it. Here's an example of the code for creating and deleteing:
// File.WriteAllBytes(path, rawData); // this seems to leave the file open!
using (var file = File.Create(path))
{
file.Write(rawData, 0, rawData.Length);
file.Close(); // should close when it goes out of scope, but just to be safe
}
Is there some special option I need to pass into File.Create? How do I get around this?
File.WriteAllBytes(path, rawData); should work fine assuming the path parameter you are passing is unique and that you don't have concurrent requests one writing and other trying to read at the same time. To ensure this you could use a ReaderWriterLockSlim to synchronize the access if this situation could potentially occur. Also make sure that there are no other parts of the code that might leak the file handle.
Take a look at SysInternals Process Explorer which could allow you to know exactly where this file handle is leaked.
i have to call an executable in the client machine in asp.net and get the return parameters, i been looking for an example but i couldn't find it.
it this possible to recover the output parameters from one exe in JavaScript?
i know that can i write:
var WshShell = new ActiveXObject("WScript.Shell");
var oExec = WshShell.Exec("My.exe");
but the clients executable returns 0 or 1 that values are the ones i need to collect
Thanks in advance
Browser-based JavaScript can't call executable files on client machines; to do so would be a catastrophic security problem. If you have to run an executable on the client machine, consider asking the user to install a .NET application, an ActiveX control, or something like Java if you want to be platform-independent.
Depending on what you're trying to do, you may not need to run an EXE on the client machine; you can do a LOT with standard cloud-type scenarios (JS or SilverLight on the client, Web services or WCF on the server). Without more information about your situation, however, it's impossible to tell.
EDIT: Based on your comments that you're using the ActiveXObject.Exec method, you can use the StdOut property of the WshScriptExec object that method returns. From MSDN's article on the StdOut property:
if (!oExec.StdOut.AtEndOfStream)
{
input += oExec.StdOut.Read(1);
//...
}