how can I upload a file with sockets to a ftp server? I am reading something with "STOR" in RFC...It is the same how i transfer a file between two computers?A sample code would be helpfuly...thanks
I don´t advice to use raw sockets to upload FTP files, instead use something like SimpleFTP, it's easier to use and it will save you a lot of time. And since you're learning Java, you should do it on the easiest possible way.
JavaWorld presents a discussion of some FTP client libraries. To begin with, they even teach you how to use the "built-in" Java URLConnection to do FTP with in a simple way. That should get you started!
Instead of uploading a file to a ftp I'd suggest that you write your own server and client software and have them communicate with eachother if you want to learn to use sockets in java.
When you have learned that you can read the RFC for ftp which should tell you how to communicate with the FTP server. You need to learn and understand the ftp protocol in order to construct valid packets with data to send and in order to parse the data you receive from the ftp server.
its usually requests, responses and data sent back and forth.
Filedata itself is just sent in its raw form unless the ftp server requires encryption, but requests and responses can be in any form, binary values, decimal values, strings etc all depending on the protocol and the type of request.. You need to know this to setup a valid communication channel.
I don't know the ftp protocol myself so I'm just demonstrating examples so you'll easier understand what it's all about.
You really do not want to write your own implementation of the FTP protocol - it's not as simple as it might seem at first glance.
I'm using commons ftp , which gives you a nice API to all ftp operations.
If you don't need that much control, you could use URLConnection from the standard java library.
What language are you using?
You can use the FTP functions if you have access to the APIs.
Related
I have a Java client/server desktop application, where the communication between client and server is based on Sockets, and the messages exchanged between client and server are serialized objects (message objects, that incapsulate requests and responses).
Now I need to make the client able to upload a file from the local computer to the server, but I can't send the File through the buffer, since the Buffer is already used for exchanging the message objects.
Should i open another stream to send the file, or is there any better way to upload a file for my situation?
I need to make the client able to upload a file from the local computer to the server
- Open a Solely Dedicated Connection to the Server for File uploading.
- Use File Transfer Protocol to ease your work, and moreover its quite easy and reliable to use the Apache's common lib for File uploading and downloading....
See this link:
http://commons.apache.org/net/
You really only have two options:
Open another connection dedicated to the file upload and send it through that.
Make a message object representing bits of a file being uploaded, and send the file in chunks via these message objects.
The former seems simpler & cleaner to me, requiring less overhead and less complicated code.
You can keep your solution and pass the file content as an object, for example as a String - use Base64 encoding (or similar) of the content if it contains troublesome characters
I am currently writing and Android app, and I need to do some stuff with a server. Actually I just don't know where to begin, since I don't know very much about server side.
My Android app will send Java objects and images to my server, so what do I need to write or use on my server ? Is it possible to write Java code instead of PHP on the server side ?
Could you please give me the steps to prepare my server ?
Is it possible to write Java code instead of PHP on the server side ?
You can use any programming language you like for server side programming. This question provides some useful information on various Java based approaches using the HTTP protocol.
will send Java objects
You will need to serialise them to a data format. JSON and XML are popular for transmitting structured data across HTTP.
and images to my server
HTTP allows the transmission of files and Java can construct the request.
I see that you just want to communicate between the server and client(Android). I would recommend considering REST style web service for your server, where you can use either JSON (recommended) or XML format.
How to implement REST in a web application?
I am currently trying to transfer a file from a Android device to a Java TCP Server, but I am unable to find a good example which explains the structure I would need to implement this. There are many Java Client&Server examples there which explain file transfer but I want to make sure if this will still work once one throws an Android Device in there.
My question is how do I implement this sort of structure? And if it doesn't work, would I be better sending the file over an HTTP connection to a PHP server? I see a lot of examples and documentation online for the later method so I presume it is more reliable. I would however prefer to use a Java server.
The file consists of a large set of coordinates recorded by the Android device which will then be sent to the server. I have not yet established how I will store this data yet but I was originally going to store them in a primitive text file.
Design
The first thing you need is something to allow you to run Java code on your server.
There are a number of options. Two of the most popular technologies are Glassfish and Apache Tomcat.
Crudely speaking Apache Tomcat is sufficient for simple client-server communication and Glassfish is used if you need to do more complex stuff. Both allow Servlets (which are essentially self contained server classes written in Java) to run on the server-side.
They handle communication with the client by launching a JVM (Java Virtual Machine) each time they receive a request. The Java servlet can run inside the JVM and respond do some processing if required before sending a response back to the client.Each new request is run in a new instance of a servlet. This makes dealing with multiple concurrent requests simpler (no need for more complex threading).
Networking (sending data to and from the server)
In networking situations the client can be a PC, an Android phone, or any other device capable of connecting to the internet. As far as the server is concerned, if the client can communicate using HTTP (a standard protocol which it understands) the it doesn't care what sort of device it is. This means that solutions for PC desktop client-server applications are similar to one for a phone.
You can use library such as Apache HTTP Components to make it easier to handle HTTP requests and responses between the device and the server. Of course you could write your own classes to do this using Sockets but this would be very time consuming, particularly if you have never done it before.
Storage of Data
If you have time I would recommend implementing some sort of database to store the information.
They have a number of benefits to such as data recovery mechanisms, indexing for fast searching of data, ensure data integrity, better structuring of data and so on.
If you decide to use a database I recommend MySQL. It is a free and more importantly - well documented.
Aside: JDBC can be used to communicate with the database with Java.
Sorry about the in-line hyperlinks - apparently my repuation isn't high enough to post more than two!
Source: Personal experience from implementing a similar design.
i am making a client server program in java, a portion of which requires to send
a complete file (.txt or .docx) file from client to server. I am not sure how to do
it, i have tried using this webpage
http://www.rgagnon.com/javadetails/java-0542.html
, but it seems that it don't work correctly
in form + multi-threaded application, is there any other way to send a complete
file from client to server?
Any help/suggestions are appreciated...
regards
usama
In principle you have to read the file on your client application, open an OutputStream to the server, and write the contents of the file to this stream.
On the server you read from the other end of the stream.
Depending on your architecture, you either will use a new socket-pair for the file transfer, or somehow embed it into your existing communication protocol.
It would be better to use a Messaging Application for your purpose. I would recommend using JMS. I personally use ActiveMQ . If this does not suit your need then try out Apache Mina. It would abstract you from the Network Programming.
I need a simple application, preferably a cross-platform one, that enables sending of files between two computers.
It just need to accept and send the files, and show a progress bar. What applications could I use or how could I write one?
Sending and Receiving Files
The sending and receiving of a file basically breaks down to two simple pieces of code.
Recieving code:
ServerSocket serverSoc = new ServerSocket(LISTENING_PORT);
Socket connection = serverSoc.accept();
// code to read from connection.getInputStream();
Sending code:
File fileToSend;
InputStream fileStream = new BufferedInputStream(fileToSend);
Socket connection = new Socket(CONNECTION_ADDRESS, LISTENING_PORT);
OutputStream out = connection.getOutputStream();
// my method to move data from the file inputstream to the output stream of the socket
copyStream(fileStream, out);
The sending piece of code will be ran on the computer that is sending the code when they want to send a file.
The receiving code needs to be put inside a loop, so that everytime someone wants to connect to the server, the server can handle the request and then go back to waiting on serverSoc.accept().
To allow sending files between both computers, each computer will need to run the server (receiving code) to listen for incoming files, and they will both need to run the sending code when they want to send a file.
Progress Bar
The JProgressBar in Swing is easy enough to use. However, getting it to work properly and show current progress of the file transfer is slightly more difficult.
To get a progress bar to show up on a form only involves dropping it onto a JFrame and perhaps setting setIndeterminate(false) so hat it shows that your program is working.
To implement a progress bar correctly you will need to create your own implementation of a SwingWorker. The Java tutorials have a good example of this in theirlesson in concurrency.
This is a fairly difficult issue on its's own though. I would recommend asking this in it's own question if you need more help with it.
Woof is a cool Python script that might work for you:
http://www.home.unix-ag.org/simon/woof.html
I would strongly consider using FTP. Apache has a FTP client and a server
Edit: spdenne's suggestion of HTTP is also good, especially if everyone has Java 6. If not, you can use something like Tiny Java Web Server.
You can write one by using Socket programming in Java. You would need to write a Server and a Client program. The server would use a ServerSocket to listen for connections, and the Client would use a Socket to connect to that server on the specified port.
Here's a tutorial: http://www.javaworld.com/jw-12-1996/jw-12-sockets.html
Sun's Java 6 includes a light-weight HTTP server API and implementation. You could fairly easily use this to serve your file, using URLConnection to obtain it.
Check out this tutorial, it's a really basic example. You would probably also want to send control headers prior to the actual file being sent, containing the size of the file, filename, etc.
Alternatively, base it on an existing protocol, like this project.
Can you install FTP servers on (one of) your machines ?
If you can, you will just have to use a FTP client (FileZilla for example, which have a progress bar).
Two popular apps are "scp" and "rsync". These are standard on Linux, are generally available on Unix and can be run on Windows under cygwin, although you may be able to find windows-native apps that can do it as well. (PuTTY can serve as an SCP client).
For any sort of pc-to-pc file transfer, you need to have a listener on the destination PC. This can be a daemon app (or Windows system process), or it can be a Unix-style "superserver" that's configured to load and run the actual file-copy app when someone contacts the listening port.
SCP and one of the rsync modes do require that there be some sort of remote login capability. Rsync can also publish resources that it will handle directory. Since the concept of a Windows "remote login" isn't as well-established as it is under Linux, this may be preferable. Plus it limits remote access to defined sources/targets on the destination machine instead of allowing access to any (authorized) part of the filesystem.
To transfer over a network more efficiently. Take a look at this article that explains efficient data transfer through zero copy