On Oct 10, 2007, at 11:35 AM, Alex Karasulu wrote:
Ok I had some sleep and low and behold the ideas came to me :). I
think I have a clear picture of
what we need to do to handle this properly. Let me describe that
here then try to figure out how
that fits with what you have done and described below.
First if Emmanuel is right about NTP needing both protocol end
points on the same port for both
transport protocols (UDP/TCP) then there is no need to have twice
the configuration. Then
something like these combinations would suffice:
<ntpServer port=123>
<#directoryService/>
<#udpAcceptor/>
<#tcpAcceptor/>
</ntpServer>
Configures both UDP and TCP transports on port 123.
<ntpServer port=123>
<#directoryService/>
<#tcpAcceptor/>
</ntpServer>
Configures only TCP on port 123.
<ntpServer port=123>
<#directoryService/>
<#udpAcceptor/>
</ntpServer>
Configures only UDP on port 123.
Note that I did not pass in <#apacheDS/> which is not needed since
this service will depend on the
core directory service plus the MINA components. Depending on
which IoAcceptor is set the respective
transport protocol is used. If both are set then both transports
are to be used.
So instead of having the NtpServer class just deal with setting up
a single endpoint for one transport
protocol it will handle all endpoints for all transport protocols
and no more configuration bean. The
component is wired directly but how it's wired determines what is
enabled.
In order to make this work and still be typesafe we either have to:
- create different classes for the tcp and udp IoAcceptor instances
so you can't hook up the wrong one
or
- wrap the IoAcceptor get the appropriate BaseIoAcceptorConfig from
the wrapper. This would work if all uses of udp use the same
acceptor config and all uses of tcp use the same tcp config. I'm not
qualified to guess if this is the case now and in the forseeable
future. In this case the XXXServer class (currently typically
XXXConfiguration) could get a list of IoAcceptorwrapper objects
instead of just one or two.
Another aspect I don't know about here is exactly how MINA
distributes threads between udp and tcp. My guess is that MINA has a
thread pool that it uses for all incoming requests, whether udp or
tcp. If we want to preserve a single thread pool for all requests
this may take some hoop-jumping-through with separate configuration
of the tcp and udp IoAcceptors. On the other hand I've heard rumors
that you can get spring to call a method and use the result as the
reference value, so we might be able to do something with that and
preserve a single MinaBean.
Anyway if someone wants to explain the desired model here or point me
to docs that would be great.
If the other protocols obey the same requirements where both
transport endpoints are needed on the
same port then we can follow this same pattern. We just have to
watch for the special cases if they
do exist.
Now what impact does this have on OSGi and on configuration in DIT
for the future. I don't know that
yet and it's something to think about.
Ok now inline for discussing your changes ...
On 10/10/07, David Jencks <[EMAIL PROTECTED]> wrote:
In rev 583375 I moved all the non-ldap protocol servers into
independent components and provided 2 NTP implementations as a
basis for further discussion.
Ok so you broke it out to have a UdpNtpServer and a TcpNtpServer
which are in them selves what you
deem one implementation approach I guess right?
Then there is this NtpConfiguration which starts both together as a
configuration bean + manager for the
other two services?
NtpConfiguration illustrates the approach of a single component to
configure both udp and tcp versions of the same protocol. This
could trivially be enhanced with flags to enable/disable the tcp or
udp choices. If we decide on this approach I would rename the
class NtpServer.
server.xml configuration of this looks like:
<ntpConfiguration ipPort="80123">
<apacheDs>#apacheDS</apacheDs>
</ntpConfiguration>
Ok then this would be close to what I was pointing out above but it
uses this ApacheDS reference
instead of feeding in the MINA components. I would like to see
these configuration objects go away
all together without even the ServiceConfiguration base class.
Instead an AbstractServer object can
be defined and used for server implementations like NtpServer with
the base configuration details in
it.
This way we don't have a configuration bean + additional code to
start and stop subordinate services.
So let me list it out:
AbstractServer (or AbstractService )
Replaces ServiceConfiguration as base class for protocol
servers. This is the common
denominator for all servers running in ApacheDS. It may need
some properties moved
into some subtypes since the present ServiceConfiguration has
more than the common
denominator.
Is this any different from renaming ServiceConfiguration to
AbstractService? I tried to avoid extra renamings since I thought it
would make the actual changes into components harder to see.
XxxServer
Takes IoAcceptors. Some servers need one for each transport
some may only need one.
Some may take both but optionally. These protocol servers then
manage binding to the
appropriate port for the transports. If somewhere down the
line configurations differ
dramatically for one transport verses another this model still
works. You can still have a
UdpXxxServer and TcpXxxServer subtyping the base XxxServer or
directly extending the
AbstractServer base class. In these transport specific
subtypes they may only expose
getter/setter pairs for IoAcceptors for their respective
transport. So this model is most
flexible for whatever comes down the pike.
AbstractNtpServer, TcpNtpServer, and UdpNtpServer illustrate the
approach of a component per protocol version. server.xml
configuration of this looks like:
<udpNtpConfiguration ipPort="81123">
<apacheDs>#apacheDS</apacheDs>
</udpNtpConfiguration>
<tcpNtpConfiguration ipPort="81123">
<apacheDs>#apacheDS</apacheDs>
</tcpNtpConfiguration>
This might not at all be necessary if we attack this problem like
the way suggested above.
I don't have a strong preference between these two approaches and
think they both are equally good components. I think the first,
single component managing both servers, will be easier for our
users to understand and configure, although it might be
conceptually slightly less pure.
I think we can do it right and be pure. We just need to think
about it more but at some point we must stop and
implement it so we're not stuck thinking forever. This is why your
commit was a great move it helps look at an
example we can take to the next step of the discussion. Thanks for
it.
Whatever the outcome of this discussion I think the next step,
other than conforming the protocol servers to whatever we decide,
is to move the mina setup code in ApacheDS into a separate
component: this would replace the ApacheDS reference in all these
servers.
Yes this would be good. I noticed you made these servers dependent
on the server-jndi module just to
pass in the ApacheDS reference. I'd like to see this dependency go
away where the dependency is really
on the core and MINA components.
More below ...
<OT>
There's an extreme danger here of making a mountain out of a
molehill :-)
These comments are counter productive and whether deliberate or not
are threatening to bypass
further reasoning about this matter by trivializing the discussion
as being excessive. You are entitled
to this opinion but not to shorting this discussion and just doing
it some way.
I'm not trying to force anything and am listening to your
suggestions since I value them. I pushed to
champion your effort to remove these configuration beans and
brought about the bigbang effort even
though others were worried about it's impact. This move has pushed
out my personal objectives as
well but we believed in your ideas. This is why I am following
through with them and trying to do it
to the best of my ability by completely removing these
configuration beans.
This is a two way street. As I extend the benefit of the doubt and
patience you're way you owe me
some patience as well. Not saying you're not giving it. But the
comment above is a subtle indicator
that your patience is wearing thin. When this happens stop and
think about the big step we all took
to meet your wishes.
Also consider that you are new to this project and may not have
complete information to foresee
problems down the line. On the flip side, you're in a unique
position to really show us how wrong
some of our design decisions are because of your fresh new
perspective. Plus you're not a newbie
and a solid engineer as witnessed by your past contributions. We
know how incredible you are.
So bear with me because something in the back of my head is telling
me to do this right with
a little more discussion. We'll get to the bottom of this but
let's consider all our options.
I agree saying "extreme" was extreme and uncalled for. However to my
mind both proposals accomplish 95% of the possible improvements,
making all the protocol servers into components under their own
lifecycle control, rather than data used by an external controller.
I'm happy to keep talking more or less indefinitely but I think that
if we write the code we will start finding better ways than if we
just talk about stuff abstractly.
</OT>
thanks
david jencks
Alex
