| 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 |
I have a question about the "internals" which just occurred to me.
As I understand the Performance FM, what happens is that when you do a
SHOW (say) for one of its computed statistics, it gets the necessary
base data from the base AM using two SHOWs, then calculates the
statistic you asked for and gives it to you.
What I don't understand is how this request gets routed within MCC.
Clearly the base AM has set up a dispatch table saying it knows how to
deal with (say) SHOW NODE4 type of stuff. Does the Perf FM also say
this? And if so how does the internal router know who to give which
kind of request?
Or does it all go to the base AM, which then sends stuff it can't
handle to Perf? But if so, how does it know to do this?
Or is there some kind of multicast, with all but one of the requested
MMs saying "huh?" and subsequently being ignored?
Or is there something else that I'm missing?
John
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 2114.1 | how dispatching occurs | TOOK::CALLANDER | MCC = My Constant Companion | Wed Jan 15 1992 09:00 | 21 |
The internals of MCC are set up to dispatch based on 3 items. These are
the command (Verb), the entity (Class/subclass...), and the partition
(attribute or event).
The show command is what is called an examine directive. The PA module
enrolls in the function module dispatch table an entry for the
SHOW/*/STATISTICS commands, while the access modules register into the
access module dispatch table entries for SHOW/*/? (where ? equals one
entry for each partition supported by the AM).
When and mcc_call_function is performed (this is what the PMs do), then
the functional tables are always searched for a dispatch match before
searching the access table. If an mcc_call_access is done, then only
the access table is searched.
If this unclear there is more information on this subject in the SRM
chapter 4 and 10 (section 10.5).
jill
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