My remark about the article is the lack of a simple examples for the first part (like a simple ECHO server)
Yeah, that's been suggested a couple of times now; my plan is to write complete source code for the tetris game, and make the final article just a description of the source code plus javadocs link plus the downloadable source itself.
Just haven't had time
for example I wondered if I needed to cancel the key or unregister the channel when I finished to read a packet and want to register the channel as OP_WRITE, that can sound obvious but a simple example could solved it in 2 sec.
The different ops are independent. You can be registered for read and write simultaneously on one selector, or simultaneously on multiple selectors. They don't interact AT ALL, except that each key can only have one attachment.
but if you give me time next week (need to finish my work travel) I think I can write a simple echo server:) I whould like to write doc about NIO & server when I finished to understand the whole block, but my english doesn't help me much
If you (or anyone else) wants to compose the example snippets in the articles into complete working source I'm happy to help debug and advise on getting it working (and I can probably provide much of the necessary code for you) if I can then publish it in the article (with obvious credit to you of course). Best of all would be if someone would actually write a tiny tetris game as described in the article.
Part of the problem is that it's harder for me to write complete code because I have to be very careful not to copy code from my day job, and I find that difficult. So it's easy for me to contribute ideas and bits of code, and someone else will produce an example in their own "style" and I won't get into any trouble for giving away any of our classes