September 2001
Intermediate to advanced
384 pages
11h 59m
English
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Subscription Types
As I mentioned earlier in the chapter, there are two types of subscribers. The first type is an existing instance of a class that supports a sink interface. That instance can be added at runtime to the list of subscribers of a particular event class. This type of subscription is called transient subscription because it exists as long as the subscriber is running and will not persist or survive a system reboot or a crash.
Note that when a particular instance of a class subscribes to an event class, only that instance will receive events published using that class. Other instances will receive the events only if they transiently subscribe themselves.
Adding a transient subscription can only be done programmatically using theCOM+ Catalog interfaces and objects. There is no administrative Component Services Explorer support. On the other hand, since all you give the COM+ Catalog is a pointer to a sink, even a nonconfigured COM component can register as a transient subscription, as long as it supports the sink interface.
Tip
A transient subscription does not even need to be on a Windows 2000 machine, as long as it is registered with a COM+ Catalog on the Windows 2000 machine where the event class resides.
The second type of subscription is used when you want COM+ to instantiate an object of a particular class when an event is published, let it handle the event, and release it. This type of subscription is called persistent subscription. Every event class has a list ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.