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Re: [riena-dev] Riena-Singletons

Hi Rienars,

 

Aren´t OSGi services not some other kind of singletons?

I know they have a much nicer name but like a singleton a service exists only once in a JVM and can be shared from multiple clients.

If such a service has session dependent state we have to take care of it.

 

Does RAP provide any patterns for dealing with session dependent services?

 

Tschüß,

Stefan

 

Von: riena-dev-bounces@xxxxxxxxxxx [mailto:riena-dev-bounces@xxxxxxxxxxx] Im Auftrag von Liebig, Stefan
Gesendet: Montag, 6. September 2010 14:58
An: Riena Developers list
Betreff: [riena-dev] Riena-Singletons

 

Hi Rienaers,

 

While working thru our code base I have detected several kinds of "singletons" (some of them I would not call them a singleton):

1.       the classical singelton - a single instance of class (maybe created lazily or not) with the typical static getInstance() method (sometimes it has a different name) with fields (state)

2.       the static singleton - this a class with only static methods and static fields carrrying some state

3.       the pseudo classical singleton - a single instance of a class with getInstance() but without fields (state)

4.       the utility singleton - a class with only static methods without fields (state)

 

1. and 2. are "real" singletons (they have some state). At these singletons we need to look a little bit closer when we also want to use them within RAP. For them we can use SessionSingletonProvider and SingletonProvider.

 

How about 3. and 4., especially 3. ?

Should we transform 3 to 4 (no more getInstance(), just static methods)?

Or …

Should the getInstance() method always be named getInstance()?

 

 

Opinions, feedback, ..

 

Tschüß,

Stefan

 

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