ChannelPipeline question

[Frederic Bregier]

Hi Mike,

If I made some mistake, please correct me of course ;-)

"all" means that several channels can shared this handler (stateless).
"one" means that this handler is for one and only one channel (stateful).

bootstrap.getPipeline() => if you add handlers there, they should be "all"
since the pipeline will be shared by all channels that will connect or be
connected through this bootstrap.

In a ChannelPipelineFactory, you can mixed "all" and "one" handlers. For
instance, if you have a handler that can be shared among all channels, then
even included from the factory, it could be "all". On the opposite, usualy
you have at least 1 handler that is "one" in such a construction (generally
the codecd that is a stateful one).
The pipeline will be new for each new channel, but the handlers you put in
it can be shared (statically created in the Factory and reused so "all") or
unique by channel (created in the getPipeline() method so "one").
If all handlers are "all", then I think it is better to use the bootstrap
version since there will be only one Pipeline shared among all channels with
the same handlers. But if you have at least one "one" handler (stateful),
then it is preferable to use the ChannelPipelineFactory.

Or you can added it at runtime (in channelConnected for instance) manually.
Again, the added handler can be "all" (static and reused) or "one" (new one
created).
I feel like, even if it is correct, it somehow less easy to read such a code
since the we don't know where such handlers are added or not. But in some
occasion, you don't have the choice (for instance, a new handler is needed
once the channel is connected for some specific behaviour).

HTH,

Cheers,
Frederic


MikeQ wrote:
> 
> Hi all,
> 
> Quick q about @ChannelPipelineCoverage and setup of handlers.
> 
> As far as I can tell when setting up a new pipeline you have a couple of
> options.
> 
> - Adding handlers using bootstrap.getPipeline()
>     - I believe in this instance all the handlers are singletons (one
> shared by all channels) and must therefore be
> @ChannelPipelineCoverage("all")
> 
> - Adding handlers using a ChannelPipelineFactory
>     - I believe the ChannelPipelineFactory.getPipeline() is called for
> each new channel.  The handlers can therefore be one/all depending on
> whether the getPipeline() implementation creates a new instance each time
> (one) or uses a shared instance (all)
> 
> - Adding handlers during execution of another handler
>     - Similar to ChannelPipelineFactory in that a new instance or shared
> instance can be used
> 
> If someone could confirm/correct the above that would be useful for my own
> understanding.
> 
> Cheers.
> 


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