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Conference azur::mcc

Title:DECmcc user notes file. Does not replace IPMT.
Notice:Use IPMT for problems. Newsletter location in note 6187
Moderator:TAEC::BEROUD
Created:Mon Aug 21 1989
Last Modified:Wed Jun 04 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:6497
Total number of notes:27359

665.0. "notification without polling" by FRAMBO::HIRSCH () Mon Jan 28 1991 07:20

    Hi,
    
    some questions about notification mechanisms :
    
    Events from the entities can be detected by the director using polling
    mechanisms. 
    
    Is it in the current version of DECmcc also possible, that entities
    themselves send (asynchronously) events to the director, so that the
    director is notified about these events without having explicitly polled
    for them ?
    
    If yes, how is it done, i.e. from where does the entity know the
    address of the associated director (or is it done via a broadcast
    mechanism) ?
    
    Is this feature generally available or is it restricted to certain
    entities/AM's ?
    
    If the feature is not yet available, for which version is it planned
    and which type of asynchronous notification will be available ?
    
    
    Thanks in advance !
    
    Paul
    
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665.1Events start arriving in MCC V1.1TOOK::MATTHEWSTue Jan 29 1991 13:4411
    Hi, I am the manager of the decnet AMs. For MCC V1.1, the kernel,
    alarms, dna4 Am, and notification services all provide some level
    of asynchronous event support. Events from Node4 entities are made
    available at the Call_access interface by the DNA4 AM. We have tested
    this extensively with the Alarm FM. Other Access Modules will be
    implementing complementary support in the near future. The DNA5 AM
    actually has a prototype working with alarm support but due the 
    inability to test this with real DNA5 entities prior to our code
    freeze dates, this is being deferred to some kit after MCC V1.1.
    There is advanced development work going on with other Access Modules
    to integrate more asynchronous events into MCC.
665.2event managerGOSTE::CALLANDERWed Jan 30 1991 13:5740
    
    Paul,
    
    Some more information, to add to what Wally said. How you detect
    an event at the entity level is up to the AM (or service provider)
    that is waiting on them. How they get reported inside of MCC is
    described in the SRM V1.1, we use the term Event Manager to refer
    to the internal mechanisms.
    
    The Event Manager is NOT a poller, polling for events would mean
    you would miss too many. Instead the Event Manager provides an input
    and output mechanism for getting at the events. The events are stored
    on a system wide basis.
    
    The AM uses the mcc_event_put routine for putting the event into
    the event manager. To get an event out you use the mcc_event_get
    (check SRM for exact details on routine names). Each xM that wants
    to support events must provide an entry point in the dispatch tables
    for the GETEVENT directive. This verb is what is known as an event
    directive-type (again reference the SRM for more information). This
    entry point is called by any module that wants access to the events
    supported by your module. When it is called, the entry point routine
    should handle making the appropriate mcc_event_get requests.
    
    The event manager is available in the V1.1 system, along with the
    Notification FM which is a generic FM used for retrieving events
    and alarming information in a consistent fashions for the PMs, see
    the BMS Use manual for more information.
    
    I'd like to end this by saying this is a QUICK overview of the ins
    and outs but by no means is a complete picture. You need to get
    the V1.1 SRM if you are looking for coding/implementation details.
    If you are just looking to use the end user functions I suggest
    you go to the Use books (you might want to wait until the V1.1 final
    set of docs are ready) and read up on the support events from the
    different modules (namely DNA4, Alarms, and Notificaiton for the
    V1.1 product).
    
    jill