Is there any provision in which i can limit my file upload to some limt ?
I'm using FileUploadField in my GWT screen.
Is there any way i can apply some check that only allows me to upload file max. upto 10MB only ?
TIA !
That is the job of the server. Javascript (and thus abstractions of Javascript such as GWT) are not allowed access to the file being uploaded. The server side should check the file side and throw an exception.
According to http://www.artofsolving.com/node/50 finding the error client side is tricky. You have to actually parse the html results in the iframe used for the upload in the onSubmitComplete event.
As the above answer stated It is not able to be done due to security. It is possible via ActiveX but I am in no way recommending that.
So you can not have a way to check it front end but you could make it seem like it.
Your servlet in this instance would use a push technology such as Comet to send the status of that file such as too big or completed back to the UI.
Related
I am currently working on a GWT screen which has a requirement of browsing GWT file once but submitting it to server many times.
But in GWT upload after clicking on submit. or even submitting using singleUploader.submit() method. File browsed by FileInputType get cleared.
Can you suggest any method to upload single file many times using gwt-upload?
Not sure if it is possible. I would try to use https://developer.mozilla.org/en/docs/Web/API/XMLHttpRequest/Using_XMLHttpRequest
and would create (using native javascript) two instances of XmlHttpRequest and would try to send them both.
The anticipated problem here is that input element on the page would receive incoming events as a result of the upload process (loadstart, progress, etc). I am in doubt that it can properly handle two parallel flows of those events successfully.
Another way is to try to send the upload requests consequently, but then you will have to generate second form submit. Which is not trivial, and browsers do not support that on the high level.
I'm facing a weird problem in GWT. I generate an excel file on server side for users to download. But after the download the file should get deleted.
I have put logic to delete it on server-Side on 2 occasions. One when user logs out and another when browser is closed.
When the user logs out, it works perfectly as it has enough time to make a call to the server whereas in case of addclosehandler, it loses connection and file remains as it is.
i.e. the method on server side does not get executed.
I tried to find another way to call the method directly by importing the package and inheriting in gwt.xml. But an error was thrown at the compile time and rightly so that server side cant be inherited.
Please get me out of this.
Thanks in advance.
But after the download the file should get deleted. I have put logic
to delete it on server-Side on 2 occasions.
This does not have to do anything with the client. I don't know excactly how your progam works but generally it should work like this:
Client makes a request
Servlet generates the bytes (Is there really a need to store the bytes in a file?)
sends them to client
And that's it.
I have the following situation. We are using Zend Framework to create a web application that is communicating with it's database through REST services.
The problem I'm facing is that when a user tries to upload a big video file for example, the service is taking some time (sometimes a few minutes) to receive the request (which is also sending the video file encoded with base64_encode PHP function.) and returns the response for successful save or error.
My idea is to track how much of the data is sent and show the user a JS progress bar, which will be useful in these cases.
Does anyone have an idea, how I can track how much of the data is sent through the service and based on this I'll be able to show a progress bar?
Zend provides progress bar functionalities that might be paired with some javascript/jquery client.
You will easily find some example implementations like this one:
https://github.com/marcinwol/zfupload
However I don't think that REST services are the best solution for uploading videos as base64 encoding will make files bigger and slower to upload.
Check out Zend_File_Transfer that might be better suited to your needs:
http://framework.zend.com/manual/1.12/en/zend.file.transfer.introduction.html
I followed these instructions
http://code.google.com/webtoolkit/usingeclipse.html
There appears to be no entry point function for the server? How do I run background threads or code not related to the rpc services that the server exports?
For example, what if some embedded database needs to be updated every 5 minutes. So then a background thread would fetch this new data to do the updating
GWT is client-side technology and has nothing to do with server-side. You can use any servers-side technology with it. If you use java/servlets then you can optionally use GWT-RPC, which is nice, but not required.
Web applications are based around request-reply paradigm: when there is a request, they handle it and send back the reply. Servlets are designed around this paradigm. They are used at some of the largest sites and are not just a toy (as you noted in other comment).
When you need something to run periodically, then this is usually the job for Job Schedulers. I'd recommend Quartz, which has great documentation. There is also an example how to initialize it in servlet environment.
thats not how web applications are supposed to work. Read http://code.google.com/intl/de-AT/webtoolkit/doc/latest/tutorial/clientserver.html
If you want to run some processing when request comes and potentially include some dynamic parts, you can just make your pages to be JSP or servlets. GWT does not need to be used in HTML files. Just the page served by server need to be HTML. So something like server side entry point is either JSP or servlet. Otherwise you need to use PRC. But if you needed to run RPC for every page loaded, you could consider this tip of embedding RPC in the base response.
The application is simple, an HTML form that posts to a Perl script. The problem is we sometimes have our customers upload very large files (gt 500mb) and their internet connections can be unreliable at times.
Is there any way to resume a failed transfer like in WinSCP or is this something that can't be done without support for it in the client?
AFAIK, it must be supported by the client. Basically, the client and the server need to negotiate which parts of the file (likely defined as parts in "multipart/form-data" POST) have already been uploaded, and then the server code needs to be able to merge newly uploaded data with existing one.
The best solution is to have custom uploader code, usually implemented in Java though I think this may be possible in Flash as well. You might be even able to do this via JavaScript - see 2 sections with examples below
Here's an example of how Google did it with YouTube: http://code.google.com/apis/youtube/2.0/developers_guide_protocol_resumable_uploads.html
It uses "308 Resume Incomplete" HTTP response which sends range: bytes=0-408 header from the server to indicate what was already uploaded.
For additional ideas on the topic:
http://code.google.com/p/gears/wiki/ResumableHttpRequestsProposal
Someone implemented this using Google Gears on calient side and PHP on server side (the latter you can easily port to Perl)
http://michaelshadle.com/2008/11/26/updates-on-the-http-file-upload-front/
http://michaelshadle.com/2008/12/03/updates-on-the-http-file-upload-front-part-2/
It's a shame that your clients can't use ftp uploading, since this already includes abilities like that. There is also "chunked transfer encoding" in HTTP. I don't know what Perl modules might support it already.