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  1. JDK
  2. JDK-4819087

Monitoring traffic through NIO Channel

    Details

    • Type: Enhancement
    • Status: Closed
    • Priority: P4
    • Resolution: Duplicate
    • Affects Version/s: 1.4.1
    • Fix Version/s: None
    • Component/s: core-libs
    • Labels:
    • Subcomponent:
    • CPU:
      x86
    • OS:
      windows_xp

      Description



      Name: jl125535 Date: 02/14/2003


      FULL PRODUCT VERSION :
      java version "1.4.1"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1-b21)
      Java HotSpot(TM) Client VM (build 1.4.1-b21, mixed mode)

      FULL OPERATING SYSTEM VERSION : Microsoft Windows XP
      [Version 5.1.2600]

      A DESCRIPTION OF THE PROBLEM :
      I need to be able to report statistics on the amount of data
      being sent over a socket by my application. With the old IO
      classes this was easy to do because you could simply "wrap"
      a Socket with a class that would record the reads and writes.

      In NIO there is no way to do this. Following is an e-mail I
      send to "###@###.###" that will help to explain and
      the response will also be helpful...
      ------------------------------

      > Date: Fri, 12 Jul 2002 20:50:03 -0500

      > I'm wondering if the access levels might be a little too tight on
      > the New IO API's. I'm trying to wrap a SocketChannel so that I can
      > keep track of how much data is transmitted. This is proving to be
      > remarkably difficult to do due to the method access levels and use of
      > "final".
      >
      > Normally, I'm a big proponent of making security as tight as
      > possible, but I really can't find a way to do what I need. Here are
      > the problems I hit:
      >
      > Simply wrapping SocketChannel:
      > - Registration with selectors won't work because you'll get an
      > IllegalSelectorException.
      > - I can't override register(...) because it's final.
      >
      > So, I tried to provide a SelectorProvider and Selector that wrapped
      > the defaults. But, register(Selector,int,Object) is protected in
      > AbstractSelectableChannel, so I can't return a wrapped implementation
      > that can call to the real channel. To clarify, here's what I'm trying
      > to do:
      >
      >> public class StatWrapperSelector extends AbstractSelector {
      >> private AbstractSelector engine;
      >>
      >> /** Creates a new instance of StatWrapperSelector */
      >> public StatWrapperSelector( AbstractSelector engine ) {
      >> super( engine.provider() );
      >>
      >> this.engine = engine;
      >> }
      >>
      >> ....
      >>
      >> protected SelectionKey register(AbstractSelectableChannel ch, int
      >> ops, Object att) {
      >> return engine.register( ( ( StatSocketChannelWrapper ) ch ).sock,
      >> ops, att );
      >> }
      >
      > The line in red won't work because it's protected.
      >
      > The other way I could think of to do this is with a
      > java.lang.reflect.Proxy, but that won't work because there aren't
      > interfaces for everyone.
      >
      > So, unless there's some way to do this that I'm missing (which is very
      > possible... there aren't many examples out yet), it doesn't appear
      > that there's a way to do this.
      >
      > Any suggestions?

      Sorry, but there's currently no way to do this. Even if we
      removed the various final and protected keywords, your
      derived channel would most likely not work with a selector
      as intended since the selector/channel implementations are
      so tightly bound together.

      During the NIO design process we considered defining a
      SelectableChannelProxy class that would support this sort of
      pattern, but it proved too difficult to implement within our
      time constraints. We might revisit this idea in the 1.5
      release.

      - Senior Staff Engineer 901 San Antonio Road
        Core Java Platform Group Palo Alto, CA 94303
        Java Software xxx-xxx-xxxx
        Sun Microsystems, Inc. ###@###.###
      -----------------------------------

      There are many reasons in my application that the
      SelectableChannelProxy mentioned would be very helpful, so I
      would ask that it be implemented.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      CUSTOMER WORKAROUND :
      None using NIO.
      (Review ID: 166198)
      ======================================================================

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              • Assignee:
                Unassigned
                Reporter:
                jleesunw Jon Lee (Inactive)
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