Re: Sending notifications to server functions

[Paulo Sergio <pa...@gmail.com>]

Hi Robert,
i'm finally back to this issue :)

On Dec 19, 2007 10:44 PM, Robert Burrell Donkin <
robertburrelldonkin@gmail.com> wrote:

> On Dec 19, 2007 4:05 PM, Paulo Sergio <pa...@gmail.com> wrote:
> > Hi all!
> > As some of you know i'm trying to implement IMAP IDLE. while doing it ,
> i
> > need some way to notify the session of changes in the mailbox.
> > At the moment i have a service running on james startup, and receiving
> the
> > notifications, these notifications are received using jgroups. To achive
> > this i created a new service that starts at the initialization phase
> along
> > with IMAP server and remote management service, i know that Imap extends
> > from abstractjamesservice, instead my service (the notifications
> receiver  )
> > extends from AbstractLogEnabled and implements Serviceable,
> Configurable,
> > Disposable, Initializable, ObjectFactory, NotificationProvider.
> > NotificationProvider is an interface that means that this server can
> notify
> > for changes, and that it contains a list of listeners.
>
> sounds good so far
>
> > So after this "brief" description here goes the question: how can i
> register
> > Imapserver (or imapsession) as a listener for this service?
> > the idea is that when Imapserver (or imapsession) is notified it writes
> a
> > message to the client indicating the changes (folowing IDLE spec)
>
> this isn't the only way but i'd approach this by creating an adapter
> service that depends on both your new service and the imap service.
> upon initialisation, it registers itself as a listener. when an event
> is received it performs the appropriate call on the imap service.
>

yes , this was my idea, but i seem to be missing some obvious thing...
please correct me if i'm wrong:

- The services are all initialized at the same time, before starting to
accept connection from clients.
- A client should only be on the "notifiable" list after it sends "IDLE",
otherwise it doesn't need to receive notifications
- The clients should be registered as listeners right after moving to IDLE
STATE .

The problem is :
- The List of listeners must be accessible from the service that is
receiving notifications
- The object that contains the list of listeners must be accessible from the
IdleProcessor

from James architecture seems complicated to share this object...
Should it be part of the session object?
Should the session objecte be the one implementing the notifiable interface?
(it should be a component that has the ability to write responses to the
client)

sorry for the noob questions...

Cheers,
Paulo F.





>
> (FWIW i prefer loosely coupled finely grained systems)
>
> - robert
>
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Re: Sending notifications to server functions

[Robert Burrell Donkin <ro...@gmail.com>]

On Jan 4, 2008 3:53 PM, Paulo Sergio <pa...@gmail.com> wrote:
> Hi Robert,
> i'm finally back to this issue :)
>
> On Dec 19, 2007 10:44 PM, Robert Burrell Donkin <
>
> robertburrelldonkin@gmail.com> wrote:
>
> > On Dec 19, 2007 4:05 PM, Paulo Sergio <pa...@gmail.com> wrote:
> > > Hi all!
> > > As some of you know i'm trying to implement IMAP IDLE. while doing it ,
> > i
> > > need some way to notify the session of changes in the mailbox.
> > > At the moment i have a service running on james startup, and receiving
> > the
> > > notifications, these notifications are received using jgroups. To achive
> > > this i created a new service that starts at the initialization phase
> > along
> > > with IMAP server and remote management service, i know that Imap extends
> > > from abstractjamesservice, instead my service (the notifications
> > receiver  )
> > > extends from AbstractLogEnabled and implements Serviceable,
> > Configurable,
> > > Disposable, Initializable, ObjectFactory, NotificationProvider.
> > > NotificationProvider is an interface that means that this server can
> > notify
> > > for changes, and that it contains a list of listeners.
> >
> > sounds good so far
> >
> > > So after this "brief" description here goes the question: how can i
> > register
> > > Imapserver (or imapsession) as a listener for this service?
> > > the idea is that when Imapserver (or imapsession) is notified it writes
> > a
> > > message to the client indicating the changes (folowing IDLE spec)
> >
> > this isn't the only way but i'd approach this by creating an adapter
> > service that depends on both your new service and the imap service.
> > upon initialisation, it registers itself as a listener. when an event
> > is received it performs the appropriate call on the imap service.
> >
>
> yes , this was my idea, but i seem to be missing some obvious thing...
> please correct me if i'm wrong:
>
> - The services are all initialized at the same time, before starting to
> accept connection from clients.

yes, that's the way avalon does stuff

> - A client should only be on the "notifiable" list after it sends "IDLE",
> otherwise it doesn't need to receive notifications
> - The clients should be registered as listeners right after moving to IDLE
> STATE .

there are different approaches this but that way seems reasonable

> The problem is :
> - The List of listeners must be accessible from the service that is
> receiving notifications
> - The object that contains the list of listeners must be accessible from the
> IdleProcessor

that's one way to do it

> from James architecture seems complicated to share this object...

JAMES is based on IoC and messaging so communication through a shared
object is less natural than a messaging based solutions (for example,
delievering an event to all sessions. IDLE sessions would act upon
this message whereas others could ignore it.)

> Should it be part of the session object?
> Should the session objecte be the one implementing the notifiable interface?
> (it should be a component that has the ability to write responses to the
> client)

IMHO the best answer to this depends on the handling of the client
protocol side. how do you intend to implement the IDLE command?

- robert

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