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PPS ...

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PPS ...

Postby pault » Tue Feb 15, 2011 10:26 am

Hello all,

I'm trying to discover the PPS (Persistent Publish/Subscribe)
All I got is a Pdf (http://www.qnx.com/download/feature.htm ... amid=20980) which is basically the help from Momentics.

A simple publisher / subscriber ...ok I can manage that with an example of a second counter which is published and a subscriber reads it...

For my application I want to look after many attributes..
Let's say : I have my main category : Device0 ...Device0 is made of Part1 and Part2 and a Part is made of Value1 and Value2

So : Device
------------|_> Part1
------------|----------|_>Value1
------------|----------|_>Value2
------------|_> Part2
----------------------|_>Value1
----------------------|_>Value2

So, I think that Device1 is a folder and Part1, PArt2 2 objects with attributes Value1, Value2 ...

But how can I see if an attribute changed , ex Value1 on Part1 ...and not but forced to read also Value2... (how can I know which attributes changed ?)


What also if I introduce one more level :

Machine
-----------|_> Device
------------------------|_> Part1
------------------------|----------|_>Value1
------------------------|----------|_>Value2
------------------------|_> Part2
----------------------------------|_>Value1
----------------------------------|_>Value2

So Machine and Devcie0 are folders and I want to look after the changes of Machine...

Then I'm trying the notify groups... and this doc part is very dark to me...

Documentation PPS Book wrote:Creating notification groups
To create a notification group:
1 Open the .notify object in the root of the PPS file system.
2 Read the .notify object; the first read of this file returns a short string (less
than 16 characters) with the name of the group to which other file descriptors
should associate themselves.
To associate a file descriptor to a group, on an open, specify the pathname open option
?notify=group:value, where:
• group is the string returned by the first read from the .notify file
• value is any arbitrary string; a subscriber will use this string to determine which
objects bound to the notification group have data available for reading

This part is made by the subscriber right ?

But what is the publisher supposed to do to trigger the notification ???

Thanks for any help !
pault
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Joined: Wed Dec 08, 2010 9:33 am

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