Channel Switch in GO, can I do this with java.nio

[Jan Burse]

Dear All,

I am just wondering whether a Go programming
language construct can be done in Java by
means of some standard packages.

The Go programming language construct, is the
switch statement over channels:

switch {
c <- channel1:
/* do something 1 */
c <- channel2:
/* do something 2 */
}

I interpret this that the code will try to fetch
data from channel1 and channel2, and depending on
which channel has fist some data, the corresponding
code will be executed?

How could this be done in Java? I have the feeling
that read() does not work since it blocks, and that
available() would not work since it would involve
polling. So something else could solve the problem...

Best Regards

 

[markspace]

I interpret this that the code will try to fetch
data from channel1 and channel2, and depending on
which channel has fist some data, the corresponding
code will be executed?

<http://download.oracle.com/javase/7/docs/api/java/nio/channels/Selector.html>

 

[Jan Burse]

<http://download.oracle.com/javase/7/docs/api/java/nio/channels/Selector.html>

Thank you for the link.

I guess I will find code examples (to gradually help me
understanding the API) by myself via googling the net.
Any prefered site to start with?

Best Regards

 

[markspace]

I guess I will find code examples (to gradually help me
understanding the API) by myself via googling the net.
Any prefered site to start with?

Unfortunately I use hard copy for that. Learning Java, by O'Reilly.
Perhaps you can find an online copy.

 

[Lew]

Unfortunately I use hard copy for that. Learning Java, by O'Reilly.
Perhaps you can find an online copy.

Developerworks has a number of useful articles.
<https://www.ibm.com/search/csass/search/?sn=dw&en=utf&hpp=20&dws=dw&q=Java+NIO&Search=Search>

 

[markspace]

Developerworks has a number of useful articles.
<https://www.ibm.com/search/csass/search/?sn=dw&en=utf&hpp=20&dws=dw&q=Java+NIO&Search=Search>

I like this article. It's old, but since NIO was new when the article
was written, it explains the basics without trying to do anything fancy.
It seem pretty close to the information I have in my book.

<https://www.ibm.com/developerworks/java/tutorials/j-nio/section9.html>

 

[Jan Burse]

I like this article. It's old, but since NIO was new when the article
was written, it explains the basics without trying to do anything fancy.
It seem pretty close to the information I have in my book.

<https://www.ibm.com/developerworks/java/tutorials/j-nio/section9.html>

Thanks for the reference, very helpful.

P.S.:

Just out of habit I would code:

if ((key.readyOps() & SelectionKey.OP_ACCEPT)
== SelectionKey.OP_ACCEPT) {

// Accept the new connection
// ...
}

With a different check:

if ((key.readyOps() & SelectionKey.OP_ACCEPT)
!= 0) {

// Accept the new connection
// ...
}

The same check is also used in the definition
of the method isAcceptable(), so it could be
also coded as:

if (key.isAcceptable()) {

// Accept the new connection
// ...
}

 

[Jan Burse]

I like this article. It's old, but since NIO was new when the article
was written, it explains the basics without trying to do anything fancy.
It seem pretty close to the information I have in my book.

<https://www.ibm.com/developerworks/java/tutorials/j-nio/section9.html>

Something else: Some info around whether this NIO feature
is widely adopted? Anything known about the OS or hardware
support to implement this NIO feature in a JVM?

Further some info around about the origins of this construct,
I browsed over JSR-51 yesterday shortly, but the construct
was not clearly mentioned in the first proposal. Is this
some -ism from ADA or so?

Bye

 

[markspace]

Something else: Some info around whether this NIO feature
is widely adopted? Anything known about the OS or hardware
support to implement this NIO feature in a JVM?

<http://www.cl.cam.ac.uk/cgi-bin/manpage?2+select>

My understanding is that it's critical to using Java in scalable
applications like Tomcat. OS support precedes the adoption of Java's
Select by a decade or more.

 

[Jan Burse]

<http://www.cl.cam.ac.uk/cgi-bin/manpage?2+select>

My understanding is that it's critical to using Java in scalable
applications like Tomcat. OS support precedes the adoption of Java's
Select by a decade or more.

So this select was basically a unix port. Oki, Doki.

 

[Arne Vajhøj]

<http://www.cl.cam.ac.uk/cgi-bin/manpage?2+select>

My understanding is that it's critical to using Java in scalable
applications like Tomcat. OS support precedes the adoption of Java's
Select by a decade or more.

I believe Tomcat started supporting NIO in version 6 and
I am not even sure it is default today.

I consider earlier versions to be scaling OK.

Arne