passing data between ChannelHandlers

[Matt DeLuco]

I found what I was looking for - a brief example of ChannelLocal is found in
the ChannelHandler documentation (ps: it might be worth repeating in the
ChannelLocal docs..)  But now I'm wondering:

The example shows a DataServerState class - where would that class be
instantiated such that all handlers have access to it?  I thought I might
instantiate it in my server startup code, pass it to the
ChannelPipelineFactory where I could pass it on to the constructor of each
ChannelHandler.  Is there another way?

Also, at some point before the Channel closes would I have to be sure to
remove any ChannelLocal variable references?  That is, ChannelLocals map
values to Channels, so would I have to be sure to remove each reference so
values to closed Channels don't pile up, creating a memory leak?  If so,
how/where could I attach an event handler to a Channel to do this?  Would I
have to do this in a ChannelHandler (I don't like that idea, because which
ChannelHandler do I put it in?) or create some kind of custom
ChannelFactory?

Thanks.

MD


On Fri, Oct 21, 2011 at 3:36 AM, Norman Maurer <norman.maurer at googlemail.com
> wrote:

> I was using it before in a project but remoted it in favor of
> ChannelHandlerContext.setAttachment(..).
>
> But it worked quited fine for me. You can see the old code here:
>
>
> http://svn.apache.org/viewvc/james/protocols/tags/protocols-1.5/impl/src/main/java/org/apache/james/protocols/impl/AbstractChannelUpstreamHandler.java?view=markup
>
> Bye,
> Norman
>
> Ps: What does not work for you ?
>
> 2011/10/21 Matt DeLuco <list_usr at spacebox.net>:
> > Where can I find some examples of ChannelLocal in use?
> > I'm not getting the results I expect, but I don't think I'm using it
> > correctly either.
> > MD
> >
> > On Sun, Oct 16, 2011 at 7:14 AM, Norman Maurer
> > <norman.maurer at googlemail.com> wrote:
> >>
> >> You can set anything you want as attachment. But it's only visible in
> >> the same handler....
> >>
> >> If you want to share stuff between handler you should checkout
> >> ChannelLocal
> >>
> >> Bye
> >> Norman
> >> 2011/10/16, Matt DeLuco <list_usr at spacebox.net>:
> >> > Before composing this message I had noticed
> >> > ChannelHandlerContext.setAttachment(Object) and getAttachment().  But
> >> > for some reason I came to the conclusion that it wasn't intended for
> >> > what I want to do.
> >> >
> >> > I came to that conclusion in part because I found it strange that it's
> >> > only possible to set one attachment, rather than being able to attach
> >> > a set (or map) of objects.  Could I just attach a map to the context
> >> > and store whatever I want in that map, to pass objects between
> >> > ChannelHandlers?
> >> >
> >> > MD
> >> >
> >> >
> >> > On Sat, Oct 15, 2011 at 9:42 PM, Matt DeLuco <list_usr at spacebox.net>
> >> > wrote:
> >> >> Is it possible to pass data between ChannelHandlers, or store data
> >> >> somewhere that the handlers in a specific pipeline/channel can access
> >> >> throughout the lifetime of the request?
> >> >>
> >> >> For example, I have my own class for dealing with http cookies,
> >> >> "CookieMap".  I'd like to have a SimpleChannelHandler that creates a
> >> >> CookieMap to be used by handlers further upstream, and then sets the
> >> >> cookies in the CookieMap on the response on their way back
> downstream.
> >> >>
> >> >> MD
> >> >>
> >> >
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