[ The Java FAQ Daily Tips, weekly publication ]
Foreword: Excuse me for
possible mistakes. English is not native language for me.
In this issue:
Hello dear friends!
Question: Do you know any P2P (peer to peer) projects like Napster,
Morpheus based on Java?
Answer: Interest in peer-to-peer (P2P) technology is growing rapidly,
as evidenced by the popularity of services like Napster, Gnutella, and
SETI@home. Seeing the potential of P2P computing to enable access to a broader,
deeper Web, Sun started a small research effort called Project JXTA.
Until recently, however,
P2P technologies have been used primarily in singlefunction applications, such
as instant messaging. Taking the concept of P2P much farther, Sun Microsystems
founder and chief scientist Dr. Bill Joy conceived the idea of Project JXTA as a
means of integrating P2P into the very core of the network architecture.
Project JXTA is a set of
simple, open peer-to-peer protocols that enable any device on the network to
communicate, collaborate, and share resources. JXTA peers create a virtual, ad
hoc network on top of existing networks, hiding their underlying complexity [see
Figure 1]. In the JXTA virtual network, any peer can interact with other peers,
regardless of location, type of device, or operating environment - even when
some peers and resources are located behind firewalls or are on different
network transports. Thus, access to the resources of the network is not limited
by platform incompatibilities or the constraints of a hierarchical client-server
Project JXTA technology
espouses the core technology objectives of ubiquity,
platform independence, interoperability, and security. JXTA technology runs on
any device, including cell phones, PDAs, two-way pagers, electronic sensors,
desktop computers, and servers. Based on proven technologies and standards such
as HTTP, TCP/IP and XML, Project JXTA is not dependent on any particular
programming language, networking platform, or system platform and can work with
any combination of these.
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Question: I tried to send Ctrl+Alt+Del key code to system from my
class, but it does not work...
Answer: The problem is that this combination is served differently
from all "normal" key combinations on hardware level. When you press those three
buttons an interrupt of processor occurs. When an interrupt occur processor
looks at its number and executes special program in specific memory location. If
you want to use this key combination you need to find proper windows library and
use it through JNI. Java does not serve this special case...
Question: I am not strong in networking... Is it possible to create
two ServerSockets listening in two different ports on one IP address?
If so how can I manage them?
Answer: Sure, you can. Just create them in different threads and call
Latest posts on our message
Setting out java
Hi. I'm kinda
relatively new to creating gui's and i kinda get some of the
concepts in swing. However, I'm slowly finding that I'm coding
everything in one class which is pretty bad since i'm writing a
relatively thick gui client.
Are there any patterns or anything of the sort for laying out swing
Help W/ Binary File
Downloading from http server!
I am attempting to write a program which will download multiple zip
files from specified websites. I am having problems though, when the
http server requires a domain, name and password. The password also
has unusual characters in it, such as #, and /. The program
currently creates a listing of all the files to be downloaded and
puts them into an array, but I would really like it to go one step
further, and actually have it download them, which I haven't gotten
to work yet. I would greatly appreciate any info on how to download
binary files through http connections requiring windows style
I wanted to
implement blinking minimised window when any new message comes to me
like the ones in the messenger.
I am working in linux
close and garbage collection
I have developed
a server application that can accept one connection at a time. One
of the server options is that the client can request to chat with
the server.If this is the case, the the server opens a chat window
which uses another class 'chatserver' in order to wait for and
accept connection. However, i found out that if the user on the
server closes the ChatGui of the server (maybe because they finished
chatting) and they reopen it after about 4 minutes a bind exception
will be thrown. After testing i found out that the Gui is disposed
but the serversocket still waits and accepts connections while
another gui opens and tries to bind the same port. i have a cleanup
method that closes I/O streams and closes the serversocket and
socket objects as well.
Does anyone have anyidea how to force the server socket release the
Thank you in advance.
when i compile i
get a grey screen?!?!?
When I compile my
program and run it I get a grey screen? It compiles okay with no
errors. Any know where i could be going wrong?
I have a password
box that will be linked to a database. Once the users enter their
password they will have another panel where they can register their
hobbies. It is not for the net but simply on JBuilder for the
moment. I had no problem setting up the GUI for both the password
and the other panel (the database link will be for later!) but as
I'm a very novice programmer I don't know how to link the two so
that on a user's screen there is a smooth transition between the
password and the hobby panel. The password class looks like this:
borders / insets
I have a popup menu but, though I remove the borders, there is still
space at the top and bottom of the JPopupMenu. There is also a white
line at the left side and a grey line (or component?) on the right
of the JPopupMenu. How can I remove this space / lines from a
JPopupMenu? Is this something that can be done through methods of
the Swing components or is it necessary to use L&F API to remove
these insets and borders?
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