I have this specific scenario:
The user is sending me request which contains a URL to a file in my private repository.
The server side catch this request and Download the file.
The server making some calculation on the downloaded file.
The server sending the results back to client.
I implemented this in the "Naive" way. Which mean, I downloading the file (step 2) for each request. In most cases, the user will send the same file. So, I thought about better approach: keep the downloaded file in short term "cache".
This mean, I will download the item once, and use this for every user request.
Now the question is, how to manage those files?
In "perfect world", I will use the downloaded file for up to 30 minutes. After this time, I won't use it any more. So, optional solutions are:
Making a file system mechanism to handling files for short terms. Negative: Complex solution.
Using temporary directory to do this job (e.g. Path.GetTempFileName()). Negative: What if the system will start to delete those files, in the middle of reading it?
So, it's seems that each solution has bad sides. What do you recommend?
When I perform a rollback to a previous build my clients seem to have issues where some files remain stuck in their browser caches. The sequence of events is:
Deploy with build "B" that has the same .html file last modified at 1/2/2016
Make a browser request for the .html file
Deploy an older build "A" that has the same .html file last modified at 1/1/2016
Make a browser request for the same .html file
At the end of the sequence of events, the clients browser will make a Request with the header If-Modified-Since:1/2/2010 which will get a response 304 Not Modified and will get the wrong file version!
Is this correct or are we looking at a red herring to another issue?
This is correct behavior. It makes sense that's what you are seeing. You can modify IIS to expire everything right now. See the following link.
https://technet.microsoft.com/en-us/library/cc770661(v=ws.10).aspx
If this is hosted in Azure, you can go to tools -> console (in the azure portal) and open a command prompt. Then run touch <filename>. This will update the timestamp and invalidate the cache.
I'm trying to download file from FTP using javascript, for which I created the following topic:
Is it possible to download file from FTP using Javascript?
From there I learned that I can use window.open('ftp://xyz.org/file.zip'); to download the file. It opens a browser new window, but the window closes immediately.
How I can I force it to stay open?
Actually I do all these in Silverlight application:
Here is the code:
HtmlPage.Window.Eval("window.open('" + url+ "', 'Download', 'height=500,width=800,top=10,left=10');");
I also tried this,
string targetFeatures = "height=500,width=800,top=10,left=10";
HtmlPage.Window.Navigate(new Uri(url), "_blank", targetFeatures);
But both results in same : it opens a window, and closes it immediately. I see it just for fraction of second!
I know this doesn't answer your question, and I'm sure you know all of this. I'm answering more because I don't see this point brought up often. :)
Silverlight has very limited support for client interactions. Javascript is a shim that in my opinion gets overused to try and bypass things that Silverlight was architectured against. It would have been very easy for Microsoft to include FTP support in Silverlight but it was excluded for a reason.
However, Silverlight has great support for webservice interactions. So the recommended way of getting a file would be to call a webservice that would do the FTP transfer for you and then send the contents down to the Silverlight application via the webservice. Possibly even processing it on the webservice side for any business logic etc.
Like I said, I suspect your requirement is to not use a webservice (to pass the bandwith cost onto the user most likely). But it'd be interesting to know more about your business problem instead of your technical problem for the solution you've chosen.
It closes because it triggers file download. You can open two windows - one for message and one to download file, but I thiunk user will know it is downloading...
If I were you, I'd open up a page that has whatever visual/UI stuff you'd want to show the user, and either have a META tag that redirects to the download URL, or has a javascript blurb to fire off said download. That way, your window will stay open, but the download will still start automatically.
to keep it open use
var test = window.open();
test.location = 'ftp://openbsd.org.ar/pub/OpenBSD/2.0/arc/kernels/bsd.ecoff';
and to not open any window use
window.location = 'ftp://openbsd.org.ar/pub/OpenBSD/2.0/arc/kernels/bsd.ecoff';
or make a normal link
Remember that a browser is not meant to "display" (visually anyway) the FTP protocol, and not all browsers will suport it. If you want to allow the user to download something, consider using a normal http:// protocol, and opening a window normally as others have suggested.
If you really need the download to be hosted via FTP, consider your backend ingesting (and caching) the file and return it to the user via http
There is nothing to be parsed on the browser's side, hence it closes. If you want to have the page open, you'll have todo something dirty. Like creating a html (or php) page and serve the content you want the user to see, then with a hidden i-frame which will call the FTP contents.
This way your user will see the content you want them to see, and the file is being downloaded.
I had the exact same problem, Silverlight opening a new window for downloading a file would flash a blank window up briefly and it would disappear again without the file download occurring.
This seemed to happen in IE 8 (not 9 and up) and could be fixed by going into Tools->Internet Options->Security then click Custom level... (for whatever zone your site would be in) and go to Downloads->Automatic prompting for file downloads and make sure this is Enabled (I also have File download enabled below that). This Automatic prompting for file downloads setting seems to be absent from IE 9+.
Another workaround is to not open in a new window, if the target url immediately downloads a file it won't change the current window so there's no difference in UX:
HtmlPage.Window.Navigate(new Uri("\download.ashx?fileid=12345"));
I have a page that downloads a large HTML file from another domain then serve it to the user. The file is around 100k - 10MB and usually takes about 5min. What was think about doing something like this to make the user experience better.
download file
if file is not download within 10 seconds then displays a page that tells the user that the file is being downloaded
if the server completes the download in 1 second then it will serve the downloaded html
can this be done? do I need to use the async feature?
Updated question: the downloaded file is a html file
In order to provide an 'asynchronous' file download try a trick that Google is using: Create a hidden iframe and set it's source to the file you want to download. You can then still run javascript on your original page while the file is being downloaded through the iframe.
I think you should:
Return an HTML page to the user straight away, to tell them the transfer has started.
Start the download from the other domain in a separate process on your server.
Have the HTML from step 1 repeatedly reload, so you can check if the download has completed already, and possibly give an ETA or update to the user.
Return a link to the user when the initial transfer is complete.
It sounds like you need to use a waiting page that refreshes itself every so often and displays the status of your download. The download can be run on a separate thread using a System.Threading.Task, for instance.
I'm having an issue within my application Pelotonics. When a user downloads a file the system seems to block all incoming requests until that file is done downloading. What is the proper technique to to open a download dialog box (standard from the browser), let the user start downloading the file, then while the file is downloading, let the user continue throughout the application.
The way we're getting the file from the server is we have a separate ASPX page that get's passed in a value through the query string, then retrieves the stream of the file from the server, then I add the "content-disposition" header to the Response and then loop through the file's stream and read 2KB chunks out to the response.outputstream. Then once that's done I do a Response.End.
Watch this for a quick screencast on the issue:
http://www.screencast.com/users/PeloCast/folders/Jing/media/8bb4b1dd-ac66-4f84-a1a3-7fc64cd650c0
by the way, we're in ASP.NET and C#...
Thanks!!!
Daniel
I think ASP.NET allows one simultaneous page execution per session and I'm not aware of any way to configure this otherwise.
This is not a very pretty workaround, but it might help if you rewrote ASP.NET_SESSIONID value to the request cookie in Application_BeginRequest (in global.asax). Of course, you would need to the authentication some other way. I haven't tried this, though.
Another way would be launching a separate thread for the download process, but you would need to find a way how this can be done without the worker thread closing it's resources.
May I ask, is there a reason why don't you just use HttpResponse.TransmitFile?