RE: [Backalaika-developers] Important question to Fabio at the end

[Fabio P. <fpi...@ho...>]

>When we talk about remoting, server-activated objects have two possible 
>activation modes (or WellKnownObjectMode values): Singleton and SingleCall. 
>These are at opposite ends of a spectrum. SingleCall is stateful: the 
>remote object is only accessed once, the next time it
>will be a different object. Singleton means only one object is created and 
>accessed by all clients.

Nando, I don't agree with the phrase, "SingleCall is stateful".  I agree 
that with SingleCall objects, every remote method call is serviced by a new 
object  instance.  Then how can SingleCall be stateful then?  If a previous 
method call saved some state information in one or more fields of the 
SingleCall  object, they will be lost.

Singleton objects are stateful.  As you said, once a Singleton object is 
created, all clients get the same reference (although note that this will 
only occur if the object is given infinite lifetime, or it's lease is 
renewed).

>I think singleton remoting would be appropriate for us.

I do agree.

>Fabio, FileServerBackup inherits from MarshalByRefObject, this means you 
>also intend it to be server-activated.

Yes, FileServer.Backup is intended to be server-activated.  The fact that it 
inherits from
MarshalByRefObject only means that the type is intended to be  accessed 
across application domain
boundaries.  This does not specify whether  it will be client or server 
activated.  What specifies this
is how we configure the .NET remoting infrastructure using 
RemotingConfiguration class.

>But there's a difference between *singleton remoting* and *a class written 
>in the singleton pattern*.

>Can you explain why the singleton class pattern is needed for 
>FileServerBackup then? I ask because I have never seen anyone say that 
>*singleton remoting* requires a *singleton type*, nor > any examples 
>suggesting it.

Yes, as long as type to be remoted inherits from MarshalByRefObject, it is 
suitable for singleton remoting (if .NET remoting infrastructure is 
configured accordingly).  Type does not have to be a singleton type (type 
implementing Singleton design pattern or anything else for that matter).  
Let me think about this some more ;-)

Fabio

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