This week's book giveaway is in the General Computing forum. We're giving away four copies of Arduino in Action and have Martin Evans, Joshua Noble, and Jordan Hochenbaum on-line! See this thread for details.
I want to write a Java application to send a data file output by a C program running on the server to a client connecting to our web site. Once the file is downloaded to the client machine I want to invoke a local program on the client machine and pass the data file in as input. The connection has to be secured. The initiation of data transfer has to be on the server side since the client doesn't know when the C program will finish writing the file. I'm thinking of writing a client/server application that will communicate through secured socket using Sun's Jsse. The client will connect to the server and listen. When the server gets notified via socket that the data file is ready it will send the data to the listening client to be written out. I'm a Java novice so I don't know whether it can be done like this or if there's an easier altenative that I should look into. So my questions are: 1. Is this feasible given the security issues (secured connection, firewall)? 2. How do I notify the server from within the C program that the file is ready to be sent?
3. Is there an easier alternative? We have Apache Web server + SSL so if I can use the Web server's provided support for https without using Sun's Jsse that will be great. Is signed applet/servlet an alternative? Thanks in advance for any help you can provide. It's urgent that I come up with a solution so any help is appreciated.
Han, If your client is a Java applet, you can't download a file to the client machine. The java security manager prohibits that. The client has to be a application. It can be written in Java, C, or whatever. If there is a firewall in between, you cannot create a socket connection, the firewall does not allow that, unless your firewall administrator gives you a specific port no. The usual way is to use firewall tunnelling technique that uses GET or POST methods. If you want to notify the server program from the C program, you can use socket connection (provided there is no firewall in between). Or use a pipe if they reside on the same machine. Or let the server program read the directory where the output file of the C program will store. It can read the file if it is there. It means some polling is needed.