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Posted to dev@mina.apache.org by "이희승 (Trustin Lee)" <tr...@gmail.com> on 2008/02/13 05:30:40 UTC
Blocking DNS queries (Was: Re: [AsyncWeb] Ideas for client)
2008-02-12 (화), 11:16 -0700, Mike Heath 쓰시길:
> Eero Nevalainen wrote:
> > Btw, what was the status of DNS resolution in MINA? I remember that at
> > some point DNS resolving used the blocking java API calls. I could
> > imagine that an asynchronous HTTP-client would have to perform a lot of
> > DNS queries(or not, depending on use). Could this become a pithole?
>
> That's a very good point, Eero. I think blocking DNS lookups could
> definitely be a very big pit hole. Did anything ever come from all the
> asynchronous DNS lookup discussions?
>
> And that's not the only DNS issue. If a DNS returns multiple A records
> for a given host name, most browsers will try to connect to the IP
> address from the first A record. If that fails, they'll try the next IP
> address and so on until the connection succeeds or all of the A records
> have been exhausted. We should support this same behavior in AsyncWeb.
I thought it's the operating system who decides which A record to use
and it's often random round-robin style. Is there any related
documentation or is it from your experiment? Just curious.
It would be nice to have a built in DNS lookup mechanism in MINA as we
discussed in our previous discussion, but once the domain name is
resolved, it will be cached by the operation system, so it shouldn't be
a big problem in most cases. It will of course be a problem if someone
is writing a web robot or something similar.
--
what we call human nature is actually human habit
--
http://gleamynode.net/
Re: Blocking DNS queries (Was: Re: [AsyncWeb] Ideas for client)
Posted by Maarten Bosteels <mb...@gmail.com>.
On Feb 13, 2008 10:07 AM, 이희승 (Trustin Lee) <tr...@gmail.com> wrote:
> 2008-02-12 (화), 23:57 -0700, Mike Heath 쓰시길:
> > 이희승 (Trustin Lee) wrote:
> > > 2008-02-12 (화), 11:16 -0700, Mike Heath 쓰시길:
> > >> Eero Nevalainen wrote:
> > >>> Btw, what was the status of DNS resolution in MINA? I remember that
> at
> > >>> some point DNS resolving used the blocking java API calls. I could
> > >>> imagine that an asynchronous HTTP-client would have to perform a lot
> of
> > >>> DNS queries(or not, depending on use). Could this become a pithole?
> > >> That's a very good point, Eero. I think blocking DNS lookups could
> > >> definitely be a very big pit hole. Did anything ever come from all
> the
> > >> asynchronous DNS lookup discussions?
> > >>
> > >> And that's not the only DNS issue. If a DNS returns multiple A
> records
> > >> for a given host name, most browsers will try to connect to the IP
> > >> address from the first A record. If that fails, they'll try the next
> IP
> > >> address and so on until the connection succeeds or all of the A
> records
> > >> have been exhausted. We should support this same behavior in
> AsyncWeb.
> > >
> > > I thought it's the operating system who decides which A record to use
> > > and it's often random round-robin style. Is there any related
> > > documentation or is it from your experiment? Just curious.
> >
> > The way Mozilla browsers handle DNS Round Robin is explained here
> > http://www.mozilla.org/docs/netlib/dns.html under the "Round Robin
> > Support" section.
> >
> > > It would be nice to have a built in DNS lookup mechanism in MINA as we
> > > discussed in our previous discussion, but once the domain name is
> > > resolved, it will be cached by the operation system, so it shouldn't
> be
> > > a big problem in most cases. It will of course be a problem if
> someone
> > > is writing a web robot or something similar.
> >
> > I do agree that in most cases it won't be a problem.
>
> Thanks for the link to the documentation.
>
> So, I guess we need some pluggability in domain name resolution. For
> now, we are using InetSocketAddress and as long as we depend on it, we
> don't have any control over how domain name is resolved in MINA. This
> mean that we need to provide our own endpoint representation classes.
> It will probably cause the major API change, but I think it worth to do
> this. How does that sound? Will we need to implement this in 2.0 or...
> in 3.0? :)
>
I would say 2.0-M2
Maarten
>
> --
> what we call human nature is actually human habit
> --
> http://gleamynode.net/
>
Re: Blocking DNS queries (Was: Re: [AsyncWeb] Ideas for client)
Posted by Mike Heath <mh...@apache.org>.
이희승 (Trustin Lee) wrote:
<snip>
> So, I guess we need some pluggability in domain name resolution. For
> now, we are using InetSocketAddress and as long as we depend on it, we
> don't have any control over how domain name is resolved in MINA. This
> mean that we need to provide our own endpoint representation classes.
> It will probably cause the major API change, but I think it worth to do
> this. How does that sound? Will we need to implement this in 2.0 or...
> in 3.0? :)
Unless we already have some DNS client code that we're comfortable with,
I think we should push this off to a 2.1 or 3.0 release.
-Mike
Re: Blocking DNS queries (Was: Re: [AsyncWeb] Ideas for client)
Posted by "이희승 (Trustin Lee)" <tr...@gmail.com>.
2008-02-12 (화), 23:57 -0700, Mike Heath 쓰시길:
> 이희승 (Trustin Lee) wrote:
> > 2008-02-12 (화), 11:16 -0700, Mike Heath 쓰시길:
> >> Eero Nevalainen wrote:
> >>> Btw, what was the status of DNS resolution in MINA? I remember that at
> >>> some point DNS resolving used the blocking java API calls. I could
> >>> imagine that an asynchronous HTTP-client would have to perform a lot of
> >>> DNS queries(or not, depending on use). Could this become a pithole?
> >> That's a very good point, Eero. I think blocking DNS lookups could
> >> definitely be a very big pit hole. Did anything ever come from all the
> >> asynchronous DNS lookup discussions?
> >>
> >> And that's not the only DNS issue. If a DNS returns multiple A records
> >> for a given host name, most browsers will try to connect to the IP
> >> address from the first A record. If that fails, they'll try the next IP
> >> address and so on until the connection succeeds or all of the A records
> >> have been exhausted. We should support this same behavior in AsyncWeb.
> >
> > I thought it's the operating system who decides which A record to use
> > and it's often random round-robin style. Is there any related
> > documentation or is it from your experiment? Just curious.
>
> The way Mozilla browsers handle DNS Round Robin is explained here
> http://www.mozilla.org/docs/netlib/dns.html under the "Round Robin
> Support" section.
>
> > It would be nice to have a built in DNS lookup mechanism in MINA as we
> > discussed in our previous discussion, but once the domain name is
> > resolved, it will be cached by the operation system, so it shouldn't be
> > a big problem in most cases. It will of course be a problem if someone
> > is writing a web robot or something similar.
>
> I do agree that in most cases it won't be a problem.
Thanks for the link to the documentation.
So, I guess we need some pluggability in domain name resolution. For
now, we are using InetSocketAddress and as long as we depend on it, we
don't have any control over how domain name is resolved in MINA. This
mean that we need to provide our own endpoint representation classes.
It will probably cause the major API change, but I think it worth to do
this. How does that sound? Will we need to implement this in 2.0 or...
in 3.0? :)
--
what we call human nature is actually human habit
--
http://gleamynode.net/
Re: Blocking DNS queries (Was: Re: [AsyncWeb] Ideas for client)
Posted by Mike Heath <mh...@apache.org>.
이희승 (Trustin Lee) wrote:
> 2008-02-12 (화), 11:16 -0700, Mike Heath 쓰시길:
>> Eero Nevalainen wrote:
>>> Btw, what was the status of DNS resolution in MINA? I remember that at
>>> some point DNS resolving used the blocking java API calls. I could
>>> imagine that an asynchronous HTTP-client would have to perform a lot of
>>> DNS queries(or not, depending on use). Could this become a pithole?
>> That's a very good point, Eero. I think blocking DNS lookups could
>> definitely be a very big pit hole. Did anything ever come from all the
>> asynchronous DNS lookup discussions?
>>
>> And that's not the only DNS issue. If a DNS returns multiple A records
>> for a given host name, most browsers will try to connect to the IP
>> address from the first A record. If that fails, they'll try the next IP
>> address and so on until the connection succeeds or all of the A records
>> have been exhausted. We should support this same behavior in AsyncWeb.
>
> I thought it's the operating system who decides which A record to use
> and it's often random round-robin style. Is there any related
> documentation or is it from your experiment? Just curious.
The way Mozilla browsers handle DNS Round Robin is explained here
http://www.mozilla.org/docs/netlib/dns.html under the "Round Robin
Support" section.
> It would be nice to have a built in DNS lookup mechanism in MINA as we
> discussed in our previous discussion, but once the domain name is
> resolved, it will be cached by the operation system, so it shouldn't be
> a big problem in most cases. It will of course be a problem if someone
> is writing a web robot or something similar.
I do agree that in most cases it won't be a problem.
-Mike