> if we change the default
subscription mode to be non-durable for non-persistent topics, then what
will happen to users who previously had durable subscriptions on that
topic? Are we ruining something if we create non-durable subscriptions
instead?
I think it doesn't matter. Currently, the durable subscription on
non-persistent topics is actually non durable. It will be removed
after restarting the broker. Users should not depend on this logic. It
seems that it does not affect existing user behavior too much.
> Can we add another phase to this PIP - say on version x we add WARN and
override mode to non-durable, and on version x+1 we fail the client?
+1. We can add a section called the `Compatibility` section to this
PIP. +1 to throw this exception in future versions.
Thanks,
Zike Yang
On Tue, Feb 14, 2023 at 5:11 PM Asaf Mesika <asaf.mes...@gmail.com> wrote:
>
> Can we add another phase to this PIP - say on version x we add WARN and
> override mode to non-durable, and on version x+1 we fail the client?
>
> On Tue, Feb 14, 2023 at 9:48 AM Jiuming Tao <jm...@streamnative.io.invalid>
> wrote:
>
> > Hi Asaf,
> >
> > If we fail the client when users use Durable subscription to subscribe
> > NonPersistentTopic, it will lead to break change.
> >
> > Users have to change their code, so we can change the `subscriptionMode`
> > from `Durable` to `NonDurable` and print WARN log when users choose
> > `Durable`, then, users don’t need to change their code and we will not
> > introduce break change.
> >
> > The PIP will deprecate Durable subscriptions on NonPersistentTopic, all
> > the subscriptions on NonPersistentTopic will be NonDurable.
> >
> >
> > Thanks,
> > Tao Jiuming
> >
> >
> >
> >
> > > 2023年2月14日 03:24，Asaf Mesika <asaf.mes...@gmail.com> 写道：
> > >
> > > Clarifying: as Pengu wrote in the pip comment - if we change the default
> > > subscription mode to be non-durable for non-persistent topics, then what
> > > will happen to users who previously had durable subscriptions on that
> > > topic? Are we ruining something if we create non-durable subscriptions
> > > instead?
> > >
> > >
> > > On Mon, Feb 13, 2023 at 9:16 PM Asaf Mesika <asaf.mes...@gmail.com>
> > wrote:
> > >
> > >> Can we fail the client if they choose NonDurable subscription mode on a
> > >> non-persistent topic, instead of writing WARN log messages?
> > >>
> > >>
> > >> On Mon, Feb 13, 2023 at 4:26 AM guo jiwei <techno...@apache.org> wrote:
> > >>
> > >>> Agree，+1
> > >>>
> > >>>
> > >>> Regards
> > >>> Jiwei Guo (Tboy)
> > >>>
> > >>> On Thu, Feb 9, 2023 at 7:07 PM Jiuming Tao
> > >>> <jm...@streamnative.io.invalid> wrote:
> > >>>>
> > >>>>
> > >>>> It makes sense
> > >>>>
> > >>>> Thanks,
> > >>>> Tao Jiuming
> > >>>>
> > >>>>
> > >>>>> 2023年2月9日 15:44，Baodi Shi <ba...@apache.org> 写道：
> > >>>>>
> > >>>>> Agree, and we can add verification on the client side. When the topic
> > >>> is
> > >>>>> non-persistent and uses durable to subscribe, print warns logs:
> > >>>>> “non-persistent not support durable subscribe will use non-durable to
> > >>>>> subscribe.”
> > >>>>>
> > >>>>>
> > >>>>>
> > >>>>> Thanks,
> > >>>>> Baodi Shi
> > >>>>>
> > >>>>> 在 2023年2月9日 15:10:12 上，Jiuming Tao <jm...@streamnative.io.invalid>
> > >>> 写道：
> > >>>>>
> > >>>>>> Agree. But we need to take care of the compatibility. How do we
> > >>> handle
> > >>>>>>
> > >>>>>> this compatibility?
> > >>>>>>
> > >>>>>>
> > >>>>>> How about set `isDurable = false` when create
> > >>> `NonPersistentSubscription`?
> > >>>>>>
> > >>>>>> In `NonPersistentSubscription`, we can change the constructor from
> > >>>>>> ```
> > >>>>>> public NonPersistentSubscription(NonPersistentTopic topic, String
> > >>>>>> subscriptionName, boolean isDurable,
> > >>>>>> Map<String, String> properties) {
> > >>>>>> this.topic = topic;
> > >>>>>> this.topicName = topic.getName();
> > >>>>>> this.subName = subscriptionName;
> > >>>>>> this.fullName = MoreObjects.toStringHelper(this).add("topic",
> > >>>>>> topicName).add("name", subName).toString();
> > >>>>>> IS_FENCED_UPDATER.set(this, FALSE);
> > >>>>>> this.lastActive = System.currentTimeMillis();
> > >>>>>> this.isDurable = isDurable;
> > >>>>>> this.subscriptionProperties = properties != null
> > >>>>>> ? Collections.unmodifiableMap(properties) :
> > >>>>>> Collections.emptyMap();
> > >>>>>> }
> > >>>>>>
> > >>>>>> ```
> > >>>>>>
> > >>>>>> to:
> > >>>>>>
> > >>>>>> ```
> > >>>>>> public NonPersistentSubscription(NonPersistentTopic topic, String
> > >>>>>> subscriptionName,
> > >>>>>> Map<String, String> properties) {
> > >>>>>> this.topic = topic;
> > >>>>>> this.topicName = topic.getName();
> > >>>>>> this.subName = subscriptionName;
> > >>>>>> this.fullName = MoreObjects.toStringHelper(this).add("topic",
> > >>>>>> topicName).add("name", subName).toString();
> > >>>>>> IS_FENCED_UPDATER.set(this, FALSE);
> > >>>>>> this.lastActive = System.currentTimeMillis();
> > >>>>>> this.isDurable = false;
> > >>>>>> this.subscriptionProperties = properties != null
> > >>>>>> ? Collections.unmodifiableMap(properties) :
> > >>>>>> Collections.emptyMap();
> > >>>>>> }
> > >>>>>>
> > >>>>>> ```
> > >>>>>>
> > >>>>>> In the broker side, for non-persistent topic, there is no durable
> > >>>>>> subscriptions.
> > >>>>>> In the client side, users don’t need to change their code.
> > >>>>>>
> > >>>>>> Thanks,
> > >>>>>> Tao Jiuming
> > >>>>>>
> > >>>>>> 2023年2月9日 15:01，Zike Yang <z...@apache.org> 写道：
> > >>>>>>
> > >>>>>>
> > >>>>>>> It makes sense, for non-persistent topic, it should not create a
> > >>> durable
> > >>>>>> subscription.
> > >>>>>>
> > >>>>>>
> > >>>>>> Agree. But we need to take care of the compatibility. How do we
> > >>> handle
> > >>>>>>
> > >>>>>> this compatibility?
> > >>>>>>
> > >>>>>>
> > >>>>>> BR,
> > >>>>>>
> > >>>>>> Zike Yang
> > >>>>>>
> > >>>>>>
> > >>>>>> On Thu, Feb 9, 2023 at 2:43 PM Jiuming Tao
> > >>>>>>
> > >>>>>> <jm...@streamnative.io.invalid> wrote:
> > >>>>>>
> > >>>>>>>
> > >>>>>>
> > >>>>>>>> We can add validation to inform the user that a durable
> > >>> subscription on
> > >>>>>> a
> > >>>>>>
> > >>>>>>>> non-persistent topic is invalid.
> > >>>>>>
> > >>>>>>>
> > >>>>>>
> > >>>>>>> It makes sense, for non-persistent topic, it should not create a
> > >>> durable
> > >>>>>> subscription.
> > >>>>>>
> > >>>>>>>
> > >>>>>>
> > >>>>>>> Thanks,
> > >>>>>>
> > >>>>>>> Tao Jiuming
> > >>>>>>
> > >>>>>>>
> > >>>>>>
> > >>>>>>>> 2023年2月8日 23:06，Baodi Shi <ba...@apache.org> 写道：
> > >>>>>>
> > >>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> But it seems that currently all Durable subscriptions on
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>> non-persistent topics are NonDurable, and I wonder if that
> > confuses
> > >>>>>>
> > >>>>>>>>> users.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>
> > >>>>>>
> > >>>>>>>> We can add validation to inform the user that a durable
> > >>> subscription on
> > >>>>>> a
> > >>>>>>
> > >>>>>>>> non-persistent topic is invalid.
> > >>>>>>
> > >>>>>>>>
> > >>>>>>
> > >>>>>>>>
> > >>>>>>
> > >>>>>>>> Thanks,
> > >>>>>>
> > >>>>>>>> Baodi Shi
> > >>>>>>
> > >>>>>>>>
> > >>>>>>
> > >>>>>>>>
> > >>>>>>
> > >>>>>>>> 在 2023年2月8日 10:48:32 上，Zike Yang <z...@apache.org> 写道：
> > >>>>>>
> > >>>>>>>>
> > >>>>>>
> > >>>>>>>>> I agree to remove all subscriptions when there're no consumers on
> > >>> the
> > >>>>>>
> > >>>>>>>>> non-persistent topic. The configuration
> > >>>>>>
> > >>>>>>>>> `subscriptionExpirationTimeMinutes ` should not take effect on
> > the
> > >>>>>>
> > >>>>>>>>> non-persistent topic.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> But it seems that currently all Durable subscriptions on
> > >>>>>>
> > >>>>>>>>> non-persistent topics are NonDurable, and I wonder if that
> > >>> confuses
> > >>>>>>
> > >>>>>>>>> users.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> But for `NonPersistentDispatcherMultipleConsumers`,
> > >>>>>>
> > >>>>>>>>> `NonPersistentStickyKeyDispatcherMultipleConsumers`, I’m not sure
> > >>> that
> > >>>>>>
> > >>>>>>>>> if it matters when we auto delete the subscriptions which has no
> > >>>>>>
> > >>>>>>>>> consumers connected.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> It doesn't matter IMO.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> Thanks,
> > >>>>>>
> > >>>>>>>>> Zike Yang
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> Zike Yang
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> On Tue, Feb 7, 2023 at 9:22 PM Jiuming Tao
> > >>>>>>
> > >>>>>>>>> <jm...@streamnative.io.invalid> wrote:
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> I think we are talking about the durable subscription of the
> > >>>>>>
> > >>>>>>>>> non-persistent
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> topic, right?
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> Yes, non-durable subscriptions created by Reader, if the reader
> > >>>>>>
> > >>>>>>>>> disconnected, the subscription will be deleted automatically.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> For `NonPersistentDispatcher`, it has the following
> > >>> implementations:
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> 1. NonPersistentDispatcherMultipleConsumers
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> 2. NonPersistentDispatcherSingleActiveConsumer
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> 3. NonPersistentStickyKeyDispatcherMultipleConsumers
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> For `NonPersistentDispatcherSingleActiveConsumer`, auto delete
> > the
> > >>>>>>
> > >>>>>>>>> subscription when there isn’t consumer connected affect nothing.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> But for `NonPersistentDispatcherMultipleConsumers`,
> > >>>>>>
> > >>>>>>>>> `NonPersistentStickyKeyDispatcherMultipleConsumers`, I’m not sure
> > >>> that
> > >>>>>> if
> > >>>>>>
> > >>>>>>>>> it matters when we auto delete the subscriptions which has no
> > >>>>>> consumers
> > >>>>>>
> > >>>>>>>>> connected.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> If it doesn’t matter, I agree with you.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> Auto delete the durable subscriptions when there aren’t consumers
> > >>>>>>
> > >>>>>>>>> connected to the non-persistent topic.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> Thanks,
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>> Tao Jiuming
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> 2023年2月7日 19:58，PengHui Li <peng...@apache.org <mailto:
> > >>>>>>
> > >>>>>>>>> peng...@apache.org>> 写道：
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> I think we are talking about the durable subscription of the
> > >>>>>>
> > >>>>>>>>> non-persistent
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> topic, right? For the Reader API (non-durable subscription), the
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> subscription will be
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> removed after the reader disconnects. If not, it should be BUG.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> IMO, we should remove the subscription automatically if all the
> > >>>>>> consumers
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> are disconnected for the non-persistent topic. The consumers can
> > >>> only
> > >>>>>> get
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> the new incoming messages after they connect to the
> > >>> non-persistent
> > >>>>>> topic.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> It looks like even if we leave the subscription there; it will
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> help nothing.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> The behavior should be the same as creating a new subscription
> > >>> with
> > >>>>>> the
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> same subscription name.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> For subscription management, users are not able to disable the
> > >>>>>>
> > >>>>>>>>> subscription
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> auto-creation of the non-persistent topic? We don't have any
> > >>> metadata
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> persist
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> in the metadata store. After the broker restarts, we will lose
> > >>>>>>
> > >>>>>>>>> everything.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> So I think we don't need to introduce a new configuration.
> > >>> Instead, we
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> should
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> figure out if there is a strong reason to leave the durable
> > >>>>>> subscription
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> after
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> all the consumers are disconnected. If there is no strong
> > >>> reason, I
> > >>>>>> tend
> > >>>>>>
> > >>>>>>>>> to
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> fix
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> incorrect behavior directly.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> Best,
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> Penghui
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> On Tue, Feb 7, 2023 at 4:14 PM Jiuming Tao
> > >>>>>> <jm...@streamnative.io.invalid
> > >>>>>>
> > >>>>>>>>> <mailto:jm...@streamnative.io.invalid>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>> wrote:
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> Hi,
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> I’ve opened a new PIP to discuss:
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> Currently, in Pulsar, we have a configuration named
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> `subscriptionExpirationTimeMinutes` to manage the subscription
> > >>>>>>
> > >>>>>>>>> expiration
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> of `PersistentTopic` and `NonPersistentTopic`.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> When we set a value which is greater than 0 to
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> `subscriptionExpirationTimeMinutes`, it will affect both
> > >>>>>>
> > >>>>>>>>> `PersistentTopic`
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> and `NonPersistentTopic`. Their inactive subscriptions will get
> > >>>>>> expired
> > >>>>>>
> > >>>>>>>>> and
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> will clean automatically.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> For `NonPersistentTopic`, its subscriptions can be clean
> > >>> because we
> > >>>>>>
> > >>>>>>>>> don't
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> guarantee its data integrity. But for `PersistentTopic`, if we
> > >>> clean
> > >>>>>> its
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> subscriptions automatically may lead to data loss.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> However, their subscription expiration is managed by the same
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> configuration(`subscriptionExpirationTimeMinutes`), we can't
> > >>> manage
> > >>>>>>
> > >>>>>>>>> their
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> subscription expiration independently.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> So I want to introduce a new configuration named
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> `nonPersistentSubscriptionExpirationTimeMinutes` to manage
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> `NonPersistentTopic`'s subscription expiration.
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> Please feel free to leave your comments, the PIP link:
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> https://github.com/apache/pulsar/issues/19448 <
> > >>>>>>
> > >>>>>>>>> https://github.com/apache/pulsar/issues/19448> <
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> https://github.com/apache/pulsar/issues/19448 <
> > >>>>>>
> > >>>>>>>>> https://github.com/apache/pulsar/issues/19448>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> Thanks,
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>>> Tao Jiuming
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>>>
> > >>>>>>
> > >>>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>>>
> > >>>>
> > >>>
> > >>
> >
> >
