Monitor own network traffic in java - networking

Question

I have a Java program which connects to the internet and send files (emails with attachments, SSL, javamail).
It sends only one email at a time.
Is there a way that my program could track the network traffic it itself is generating?
That way I could track progress of emails being sent...
It would also be nice if it was cross-platform solution...

Answer 1

Here's another approach that only works for sending messages...
The data for a message to be sent is produced by the Message.writeTo method and filtered through various streams that send it directly out the socket. You could subclass MimeMessage, override the writeTo method, wrap the OutputStream with your own OutputStream that counts the data flowing through it (similar to my other suggestion), and reports that to your program. In code...
public class MyMessage extends MimeMessage {
...
public void writeTo(OutputStream os, String[] ignoreList) throws IOException, MessagingException {
super.writeTo(new MyCountingStream(os), ignoreList);
}
}
If you want percent completion you could first use Message.writeTo to write the message to a stream that does nothing but count the amount of data being written, while throwing away the data. Then you know how big the message really is, so when the message is being sent you can tell what percent of the message that is.
Hope that helps...

Answer 2

Another user's approach is here:
Using JProgressBar with Java Mail ( knowing the progress after transport.send() )
At a lower level, if you want to monitor how many bytes are being sent, you should be able to write your own SocketFactory that produces Sockets that produce wrapped InputStreams and OutputStreams that monitor the amount of data passing through them. It's a bit of work, and perhaps lower level than you really want, but it's another approach.

Answer 3

I've been meaning to do this myself for some time, but I'm still waiting for that round tuit... :-)
Anyway, here's just a bit more detail. There might be gotchas I'm not aware of once you get into it...
You need to create your own SocketFactory class. There's a trivial example in the JavaMail SSLNOTES.txt file that delegates to another factory to do the work. Instead of factory.createSocket(...), you need to use "new MySocket(factory.createSocket(...))", where MySocket is a class you write that overrides all the methods to delegate to the Socket that's passed in the constructor. Except the getInputStream and getOutputStream methods, which have to use a similar approach to wrap the returned streams with stream classes you create yourself. Those stream classes then have to override all the read and write methods to keep track of how much data if being transferred, and make that information available however you want to your code that wants to monitor progress. Before you do an operation that you want to monitor, you reset the count. Then as the operation progresses, the count will be updated. What it won't give you is a "percent completion" measure, since you have no idea how much low level data needs to be sent to complete the operation.