passing data between ChannelHandlers

[Norman Maurer]

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
>>> >> >
>>> >> _______________________________________________
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>>> >> netty-users at lists.jboss.org
>>> >> https://lists.jboss.org/mailman/listinfo/netty-users
>>> >
>>> >
>
> Bye,
> Norman
>