Re: Non destructive read of socket

From:

Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 06 Oct 2009 10:24:59 -0700

Message-ID:

<G4Lym.77697$4t6.9624@newsfe06.iad>

Mark wrote:

Is it possible to do a non-destructive read on a socket in Java? I
want the functionality similar to the C library recv() using the
MSG_PEEK flag.

More information:
I am implementing an API in Java which needs to send a "are you alive"
application message over a socket. In reply it will get a "I am
alive" message. However there may be another type of message already
waiting which the API must not read. The presence of any message will
be enough for the API call to succeed. The "I am alive" message can
just be discarded if it is read later.

I realize I could buffer the messages internally, but I would prefer
to avoid this if possible owning to the risk of losing a message if
the application is terminated.

Rather than either of those, why not use a message dispatcher that reads
any available message, and dispatches it accordingly, including the "I
am alive" message. Alternatively, I think you can set TCP_KEEPALIVE on
the socket, which will handle that at the TCP protocol level, so you
don't have to worry about it at the application protocol level.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>