RE: A way to know if file download has ended
THanks for your answer... I will keep all you said in mind. You are certainly right. -Original Message- From: Wade Chandler [mailto:[EMAIL PROTECTED] Sent: lunes, 05 de junio de 2006 17:08 To: Tomcat Users List Subject: Re: A way to know if file download has ended --- Darryl Miles [EMAIL PROTECTED] wrote: Bachler, Elisabeth (Elisabeth) wrote: Thank you to everyone. I will investigate further. Elisabeth Maybe this thread is related (excuse the horid apache web interface) : http://mail-archives.apache.org/mod_mbox/tomcat-users/200604.mbox/%3c444FA1E [EMAIL PROTECTED] Darryl Just remember there are so many other issues. I say that not to be pessimistic, but to be realistic to maybe keep you from spending too much time on it. For instance, when you download a file using Firefox, firefox will be downloading the bytes from the server even while you are deciding to cancel or save and will be storing this information into another buffer. This is why when you finally hit save if the box has been up a while you'll notice a jump in the downloaded bytes then the status of the download speed jumps back down to the real value. I mention that because I don't know how much you are wanting to rely on successfully downloaded which you mentioned in your first email. The user might hit cancel even after the file has technically been successfully downloaded even if only to temp space they can't retrieve in any easy manner. There is also the issue of HTTP proxies and caching and read ahead, all of these things affect HTTP and the ability to be able to tell what actually happened at the byte level between the client and server. Also, even if the user closes the browser ... you can still write to the servlet API output with no error being raised. This is also true in Microsoft ISAPI dlls. I don't even think if you got at the low level where the server is if you could reliably do this because of the proxies and caches I talked about. Your proxies and caches and even the users may not be the only ones in the pipeline, so you always have to keep that in mind. We had an issue one time where bytes were getting cut out of an https connection, but not an http connection, and later we found an ISP in between us and a client had some software in between that was dropping bytes out of https when too much information passed through and we finally figured that out and they fixed it, but not just the fact that they didn't pass the information back wouldn't affect you, but also the fact that the software in between could be reading more bytes than you request at a time to help speed up users of the ISPs connections over HTTP and keep doing this even when the TCP connection is severed. Wade - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: A way to know if file download has ended
This is one of those issues that just can't be solved with simple HTTP and HTML. There isn't a response sent to the server to tell it every single download was successful (or at least not sent back to the web application ... TCP makes sure the last bytes get to the other side successfully or an error occurs, but the applications on the server side can't tell this or at least I don't know how). Then to make the situation more difficult there is no defined event for tying into the HTTP process for when a certain download has occurred successfully. So, one has to use a download manager of some kind to more easily manage things like this. This could be a signed java applet or shockwave file or a COM object (not cross platform so I wouldn't recommend that, but you might think it's ok if you force IE and windows). One could more easily tell if an upload had finished because you at least have a defined form element you can access through DOM, get the name, and then monitor the upload progress. Wade - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Hi, I agree with Wade about not knowing in Tomcat whether download succeeded or not. I tried many code and discussed about it in the forum and came to the conclusion it is not possible. (subject was Last Byte Detection, conclusion was: HTTP is not the good level to detect that.) Good luck, Nicolas - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: A way to know if file download has ended
Thank you to everyone. I will investigate further. Elisabeth -Original Message- From: Nicolas Schwartz [mailto:[EMAIL PROTECTED] Sent: lunes, 05 de junio de 2006 10:48 To: Tomcat Users List Subject: Re: A way to know if file download has ended This is one of those issues that just can't be solved with simple HTTP and HTML. There isn't a response sent to the server to tell it every single download was successful (or at least not sent back to the web application ... TCP makes sure the last bytes get to the other side successfully or an error occurs, but the applications on the server side can't tell this or at least I don't know how). Then to make the situation more difficult there is no defined event for tying into the HTTP process for when a certain download has occurred successfully. So, one has to use a download manager of some kind to more easily manage things like this. This could be a signed java applet or shockwave file or a COM object (not cross platform so I wouldn't recommend that, but you might think it's ok if you force IE and windows). One could more easily tell if an upload had finished because you at least have a defined form element you can access through DOM, get the name, and then monitor the upload progress. Wade - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Hi, I agree with Wade about not knowing in Tomcat whether download succeeded or not. I tried many code and discussed about it in the forum and came to the conclusion it is not possible. (subject was Last Byte Detection, conclusion was: HTTP is not the good level to detect that.) Good luck, Nicolas - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: A way to know if file download has ended
Bachler, Elisabeth (Elisabeth) wrote: Thank you to everyone. I will investigate further. Elisabeth Maybe this thread is related (excuse the horid apache web interface) : http://mail-archives.apache.org/mod_mbox/tomcat-users/200604.mbox/[EMAIL PROTECTED] Darryl - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
RE: A way to know if file download has ended
Thanks Elisabeth -Original Message- From: Darryl Miles [mailto:[EMAIL PROTECTED] Sent: lunes, 05 de junio de 2006 13:07 To: Tomcat Users List Subject: Re: A way to know if file download has ended Bachler, Elisabeth (Elisabeth) wrote: Thank you to everyone. I will investigate further. Elisabeth Maybe this thread is related (excuse the horid apache web interface) : http://mail-archives.apache.org/mod_mbox/tomcat-users/200604.mbox/%3c444FA1E [EMAIL PROTECTED] Darryl - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: A way to know if file download has ended
--- Darryl Miles [EMAIL PROTECTED] wrote: Bachler, Elisabeth (Elisabeth) wrote: Thank you to everyone. I will investigate further. Elisabeth Maybe this thread is related (excuse the horid apache web interface) : http://mail-archives.apache.org/mod_mbox/tomcat-users/200604.mbox/[EMAIL PROTECTED] Darryl Just remember there are so many other issues. I say that not to be pessimistic, but to be realistic to maybe keep you from spending too much time on it. For instance, when you download a file using Firefox, firefox will be downloading the bytes from the server even while you are deciding to cancel or save and will be storing this information into another buffer. This is why when you finally hit save if the box has been up a while you'll notice a jump in the downloaded bytes then the status of the download speed jumps back down to the real value. I mention that because I don't know how much you are wanting to rely on successfully downloaded which you mentioned in your first email. The user might hit cancel even after the file has technically been successfully downloaded even if only to temp space they can't retrieve in any easy manner. There is also the issue of HTTP proxies and caching and read ahead, all of these things affect HTTP and the ability to be able to tell what actually happened at the byte level between the client and server. Also, even if the user closes the browser ... you can still write to the servlet API output with no error being raised. This is also true in Microsoft ISAPI dlls. I don't even think if you got at the low level where the server is if you could reliably do this because of the proxies and caches I talked about. Your proxies and caches and even the users may not be the only ones in the pipeline, so you always have to keep that in mind. We had an issue one time where bytes were getting cut out of an https connection, but not an http connection, and later we found an ISP in between us and a client had some software in between that was dropping bytes out of https when too much information passed through and we finally figured that out and they fixed it, but not just the fact that they didn't pass the information back wouldn't affect you, but also the fact that the software in between could be reading more bytes than you request at a time to help speed up users of the ISPs connections over HTTP and keep doing this even when the TCP connection is severed. Wade - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: A way to know if file download has ended
--- Guido Schoepp [EMAIL PROTECTED] wrote:
Bachler, Elisabeth (Elisabeth) schrieb:
I have an application that uses tomcat 5.0.19. At
one point in my
application, the user has the possibility to click
on a certain link in
order to download a file.
Once the file is downloaded, I would like the
application to go to a certain
jsp page is there a way to configure tomcat to
do such a thing? I mean,
to redirect to a page only if the download has
been successfully ended?
Maybe this can work:
Write a a servlet (or JSP) that delivers the file to
your user, e.g.
response.setContentType(application/octet-stream);
//or whatever
java.io.InputStream data =
new java.io.FileInputStream(file.bin);
byte[] buf = new byte[4 * 1024];
int len;
while ((len = data.read(buf, 0, buf.length)) !=
-1) {
sout.write(buf, 0, len);
}
After that you can forward to the desired page:
RequestDispatcher dispatcher =
getServletContext().getRequestDispatcher(fwd.jsp);
dispatcher.forward(request, response);
Guido
This is one of those issues that just can't be solved
with simple HTTP and HTML. There isn't a response
sent to the server to tell it every single download
was successful (or at least not sent back to the web
application ... TCP makes sure the last bytes get to
the other side successfully or an error occurs, but
the applications on the server side can't tell this or
at least I don't know how). Then to make the
situation more difficult there is no defined event for
tying into the HTTP process for when a certain
download has occurred successfully. So, one has to
use a download manager of some kind to more easily
manage things like this. This could be a signed java
applet or shockwave file or a COM object (not cross
platform so I wouldn't recommend that, but you might
think it's ok if you force IE and windows). One could
more easily tell if an upload had finished because you
at least have a defined form element you can access
through DOM, get the name, and then monitor the upload
progress.
Wade
-
To start a new topic, e-mail: users@tomcat.apache.org
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
Re: A way to know if file download has ended
Bachler, Elisabeth (Elisabeth) schrieb:
I have an application that uses tomcat 5.0.19. At one point in my
application, the user has the possibility to click on a certain link in
order to download a file.
Once the file is downloaded, I would like the application to go to a certain
jsp page is there a way to configure tomcat to do such a thing? I mean,
to redirect to a page only if the download has been successfully ended?
Maybe this can work:
Write a a servlet (or JSP) that delivers the file to your user, e.g.
response.setContentType(application/octet-stream); //or whatever
java.io.InputStream data =
new java.io.FileInputStream(file.bin);
byte[] buf = new byte[4 * 1024];
int len;
while ((len = data.read(buf, 0, buf.length)) != -1) {
sout.write(buf, 0, len);
}
After that you can forward to the desired page:
RequestDispatcher dispatcher =
getServletContext().getRequestDispatcher(fwd.jsp);
dispatcher.forward(request, response);
Guido
-
To start a new topic, e-mail: users@tomcat.apache.org
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
A way to know if file download has ended
Hello, I have an application that uses tomcat 5.0.19. At one point in my application, the user has the possibility to click on a certain link in order to download a file. Once the file is downloaded, I would like the application to go to a certain jsp page is there a way to configure tomcat to do such a thing? I mean, to redirect to a page only if the download has been successfully ended? Thanks - To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
