330 Java Tips.pdf - FTP Server

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Networking addy itself- 127.0.0.1. Not useful. Answer: Try this: Working that out, I tried String hostname = InetAddress.getLocalHost().getHostName(); System.out.println(hostname); InetAddress[] ads = InetAddress.getAllByName(hostname); for (int i=0; i
Networking in a read. Is there a thread function I could use? I tried use BufferedReader.ready() to make my read not blocking (BufferedReader.ready() returns true only if the the stream is readable otherwise loop so there is no actual blocking) but my problem with that was that BufferedReader.ready() doesn't throw an exception if the other side disconnects so I'm left looping infinitely. I'm really stuck here so if anyone can give me a strategy (I don't need it spelled out to me just general "I used this function type help) I'd really appreciate it. Answer 1: I've found the only way to unblock a (Socket) read-blocking thread is to close() the socket from another thread. That'll throw an IOException in the read() call. -- Michiel Answer 2: Another method that seems to work is to set a socket timeout to something moderately short (like 10 seconds). The blocked read will throw an exception when the timeout occurs. Then the thread can inspect the state of a variable (set by another thread calling an appropriate method) to see if it should terminate. This approach also makes it trivial to implement a longer inactivity timeout if desired and gives the network thread an opportunity to do some maintenance work if it wants. -- Peter Q: I get the impression that only read operations from a Sockets InputStream throw an Exception if the opposite Socket has closed the socket. Writing to the Socket's outputStream works fine... Is there a way to detect if what I write into a Socket's outputstream is actually still being received by the other side? Or will I have to check that I actually get a response via the InputStream, and if not, try to open a new Socket and resend the request again? Answer: You can try calling flush() after writing the output, but there's no guarantee that you'll get an immediate exception. The underlying TCP/IP software may go through timeout and retry logic before giving up. That's probably why you'll usually find out about a broken socket when waiting to read. You should rewrite client so that it sends a request and waits for a response. If it doesn't get a response, it should try to make a new connection and do the request/response thing again. If it doesn't work the second time, it should give up for the time being. Perhaps it really makes sense that one has to verify 'by hand' that requests go through. -- Duane Morse Q: ... I imagine, I'll have to cut my file into small datagrams. I just made a little chat program (client and server) and I would like to add the possibility to transfer files. The client and the server are communicating with TCP/IP using a socket. I imagine, I'll have to cut my file into small datagrams. Is it necessary ? Has someone an idea or a link to source code of such a function ?? Answer: No. If you were using UDP/IP (DatagramSocket and friends) then it would need to be split up. The point of TCP is to avoid this need. Simple send the entire file in a stream. file:///F|/350_t/350_tips/networking.htm (4 of 5) [2002-02-27 21:18:49]
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