My scenario as follows:
One java program is updating some random files to a SFTP location.
My requirement is as soon as a file is uploaded by the previous java program, using java I need to download the file. The files can be of size 100MB. I am searching for some java API which is helpful in this way. Here I even don't know the name of files. But I can keep a regular expression for this. A same file can be uploaded by previous program periodically. Since file size is high I need to wait until the complete file to be uploaded.
I used Jsch to download files, but I am not getting how to poll using jsch.
Polling
All you can do is to keep listing remote directory periodically, until you find a new file. There's no better way with SFTP. For that you obviously use ChannelSftp.ls().
Regarding selecting files matching certain pattern, see:
JSch ChannelSftp.ls - pass match patterns in java
Waiting until the upload is complete
Again, there's no support for this in widespread implementations of SFTP.
For details, see my answer at:
SFTP file lock mechanism.
Related
I want to provide support to convert single-page and multi-page tiff files into PDFs. There is an executable in Bit Miracle's LibTiff.NET called Tiff2Pdf.
How do I use Tiff2Pdf in my application to convert tiff data stream (not a file) into a pdf data stream (not a file)?
I do not know if there is an API exposed because the documentation only lists Tiff2Pdf as a tool. I also do not see any examples in the examples folder using it in a programmatic way to determine if it can handle data streams or how to use it in my own program.
libtiff tools expect a filename so the background run shown below is simply from upper right X.tif to various destinations, first is default
tiff2pdf x.tif
and we can see it writes a tiff2pdf file stream to console (Standard Output) however it failed in memory without a directory to write to. However on second run we can redirect
tiff2pdf x.tif > a.pdf
or alternately specify a destination
tiff2pdf -o b.pdf x.tif
So in order to use those tools we need a File System to receive the file objects, The destination folder/file directory can be a Memory File System drive or folder.
Thus you need to initiate that first.
NuGet is a package manager simply bundling the lib and as I don't use .net your a bit out on a limb as BitMiricle are not offering free support (hence point you at Stack Overflow, a very common tech support PLOY, Pass Liability Over Yonder) however looking at https://github.com/BitMiracle/libtiff.net/tree/master/Samples
they suggest memory in some file names such as https://github.com/BitMiracle/libtiff.net/tree/master/Samples/ConvertToSingleStripInMemory , perhaps get more ideas there?
I am working on an API that needs to download a file from server A and upload it to server B in the same network. It's for internal use. Each of the files will have multiple versions and will need to be uploaded to server B multiple times and all the versions of the same file will share the same file name. This is my first time dealing with file manipulation so please bare with me if my question sounds ignorant. Can I use HttpClient.PostAsync for the uploading part in this effort? Or can I just use Stream.CopyToAsync if it's ok to just copy over? Thanks!
Stream.CopyToAsync copies stream from one to another inside memory of same server.
In your case, you can use HttpClient.PostAsync, but one the other server there should be some api to receive the stream content and save to disk.
I'm developing an application using Adobe Flex 4.5 SDK, in which the user would be able to export multiple files bundled in one zip file. I was thinking that I must need to take the following steps in order for performing this task:
Create a temporary folder on the server for the user who requested the download. Since it is an anonymous type of user, I have to read Sate/Session information to identify the user.
Copy all the requested files into the temporary folder on the server
Zip the copied file
Download the zip file from the server to the client machine
I was wondering if anybody knows any best-practice/sample-code for the task
Thanks
The ByteArray class has some methods for compressing, but this is more for data transport, not for packaging up multiple files.
I don't like saying things are impossible, but I will say that this should be done on the server-side. Depending on your server architecture I would suggest sending the binary files to a server script which could package the files for you.
A quick google search for your preferred server-side language and zipping files should give you some sample scripts to get you started.
I am trying to transfer a file to a remote Unix server using scp. On that server, there is a service which polls the target directory to detect incoming files for processing. I would like to ensure that the polling service does not pick up new files before the copy is complete. Is there a way of doing that?
My file transfer process is a simple scp command embedded in a larger Java program. Ideally, a solution which did not involve changing the Jana would be best (for reasons involving change control processes).
You can scp the file to a different (/tmp) directory and move the
file via ssh after transfer is complete. The different directory needs to be on the same partition as the final destination directory otherwise there will be a copy operation and you'll face a similar problem. Another service on the destination machine can do this move operation.
You can copy the file as hidden (prefix the filename with .) and copy, then move
If you can modify the polling service, you can check active scp processes and ignore files matching scp arguments.
You can check for open files with lsof +d $directory and ignore them in the polling server
I suggest copying the file using rsync instead of scp. rsync already copies new files to temporary filenames, and has many other useful features for file synchronization as well.
$ rsync -a source/path/ remotehost:/target/path/
Of course, you can also copy file-by-file if that's your preference.
If rsync's temporary filenames are sufficient to avoid being picked up by your polling service, then you could simply replace your scp command with a shell script that acts as a wrapper for rsync, eliminating the need to change your Java program.
You would need to know the precise format that your Java program uses to call the scp command, to make sure that the options you feed to rsync do what you expect.
You would also need to figure out how your Java program calls scp. If it does so by full pathname (i.e. /usr/bin/scp), then this solution might put other things at risk on your system that depend on scp (like you, for example, expecting scp to behave as it usually does instead of as a wrapper). Changing a package-installed binary like /usr/bin/scp may also "break" your package registration, making it difficult to install future security updates because a binary has changed to a shell script. And of course, there might be security implications to any change you make.
All in all, I suspect you're better off changing your Java program to make it do precisely what you want, even if that is to launch a shell script to handle aspects of automation that you want to be able to change in the future without modifying your Java.
Good luck!
I'm looking for a way to upload files/dirs structure from one server to another..
The only way it's possible in my case is SFTP upload, is there any easy way to upload it, using script or something without making archive of files/dirs, I want to recreate on remote server?
Thank you!
Perhaps a solution could be found using recursive scp (scp -r)? Or are you limited explicitly to sftp only?
There's also a client named lftp which has sftp and scripting support - much like batch file I would imagine - a list of ftp commands. (http://lftp.yar.ru/lftp-man.html)
You may want to consider Syncplify.me FTP Script! as a solution. It allows you to write very simple scripts to achieve your goal.
For example, uploading an entire directory to a remote SFTP server would actually be a single line of code added to one of the ready-made templates.
http://www.syncplify.me/products/ftp-script/
edtFTPj/PRO is a Java SFTP client that has a comprehensive scripting engine. Being Java you can run it on any platform where Java is supported.
Here's some more details on the scripting support. It has an 'mput' command that uploads all the files in the current directory to the remote directory.
Recursive transfers aren't yet supported, but could easily be added if required - email support if you are interested.