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In this particular case I'd probably not look to implement this asynchronously. Unless the delay between sending the command and receiving the respond code is large (which it probably isn't for FTP), and you can safely execute another command not knowing the outcome of the last (which you probably can't), it's not really worth trying to implement this asynchronously.

I'd block execution between sending the command string and receiving the full response back, i.e. in pseudocode you might have an execute method like:

Send command string over the network
Wait for a character to come back (or for a timeout, if you want to do this) using a blocking network read method or using a non-blocking method + Thread.sleep(..)
Check if the character is an 'end of response' token (newline?)
If not, go back to 2, if it is, return full the response string

If you're really determined to go down the asynchronous route, you should have a look at the Callback pattern.

Hope this helps.

dogbert 2010-05-23 18:03:46

It did. I also had a dig through Apache's Commons Net. What they've used is a combination of an EventObject and EventListener. For the response, readLine() is called on an InputStreamReader as long as there's a code and the resulting lines are added to an ArrayList. There doesn't seem to be any asynchronous handling as such and timeout is probably handled by a java.net class.

James P. 2010-05-24 01:12:47

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