passing data between ChannelHandlers

[Matt DeLuco]

Thank you, Norman!

I have to say though, this all seems like a very roundabout way of keeping
track of session data for a Channel.

Is there any interest in adding a session interface to HttpRequest,
something like javax.servlet.http.HttpSession found in
javax.servlet.http.HttpRequest?

I thought if there was an interface one could implement the storage
mechanism - file/database/memcached, etc.

MD


On Mon, Oct 24, 2011 at 6:16 AM, Norman Maurer <norman.maurer at googlemail.com
> wrote:

> Hi there,
>
> just to follow up. I committed some code to handle the removal without
> user interaction:
>
>
> https://issues.jboss.org/browse/NETTY-447?page=com.atlassian.jirafisheyeplugin:fisheye-issuepanel#issue-tabs
>
> So it will be in the next release...
>
> Bye
> Norman
>
> 2011/10/24 Norman Maurer <norman.maurer at googlemail.com>:
> > Hi Matt,
> >
> > comments inline..
> >
> > 2011/10/24 Matt DeLuco <list_usr at spacebox.net>:
> >> 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?
> >
> > I think thats the easiest way and should work very well.
> >
> >> 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?
> >
> > Just add an SimpleUpstreamChannelHandler and override the
> > channelClosed(..) method. There you can remove it.
> > I think it would also be nice to allow the ChannelLocal to cleanup it
> > self by register and ChannelListener to it that takes care of the
> > remove and so prevent the leak. I will open a jira issue for it and
> > implement it.
> >
> >
> >> 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
> >>> >> >>
> >>> >> >
> >>> >> > _______________________________________________
> >>> >> > netty-users mailing list
> >>> >> > netty-users at lists.jboss.org
> >>> >> > https://lists.jboss.org/mailman/listinfo/netty-users
> >>> >> >
> >>> >> _______________________________________________
> >>> >> netty-users mailing list
> >>> >> netty-users at lists.jboss.org
> >>> >> https://lists.jboss.org/mailman/listinfo/netty-users
> >>> >
> >>> >
> >
> > Bye,
> > Norman
> >
>
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