Dynamic load applet from File or MSSQL trigger

Question

Hi,
i have an interesting project that i am researching, i would greatly appreciate if someone can point out some tools to use inorder to reach the following scenario with java.
I seeking to write data to a web applet whenever an insertion is done to a database or a new file is written to one directory on the server.
i need to display the information in the applet without refreshing any page.
i am very new to java, but i found that it could be done in a couple of ways....
1- Opening a channel between the applet and the server that uses HTTP request and response to load and update the applet without refreshing the page.
2-Programming a servlet on the server that communicates with the server and the client applet, it send the applet data when ever an insertion is done on the server.
3-Doing an applet that gets data from a cookie text file on the client machine, using an open channel between the server an the client the server writes these data to a certain directory on the client.
Please advice if any of these relates to the real world, and please provide tips of tools to do that.
Greatly appreciated,
Wafic

Answer 1

OK, lets see how to accomplish that... :-)
1- Opening a channel between the applet and the server
that uses HTTP request and response to load and update
the applet without refreshing the page.The idea of reloading the applet is not effective and leads to extreme performance losses.
But you can use a URLConnection to send requests and retrieve any data on that channel.
2-Programming a servlet on the server that
communicates with the server and the client applet, it
send the applet data when ever an insertion is done on
the server.Here is the tricky part.
To notify the applet you will have to set up some sort of server, as it does not know anything about operations on the web server side.
So you either set up a socket connection to the server or (better) use remote method invocation (RMI) to let the server call the appropriate method and immediately send the data.
This could be methods like (abstracted):
myApplet.getData(String fileData);
or
myApplet.notifyMe(); //triggers the HTTP request to                get the data
This is also not so easy as you will have to start a RMI registry inside the applet.
3-Doing an applet that gets data from a cookie text
file on the client machine, using an open channel
between the server an the client the server writes
these data to a certain directory on the client.This is the part I do not understand.
Why are you sending a text file from the client to the server, which in turn should write the same file back in a client directory ?
Why not using the applet for that ?
Under any circumstances you will have to circumvent the applets security rectrictions on the client side by either signing it or deploying a policy file depending on the JAVA platform version you will be using.
I hope this helps any further.
Oliver