Order of Lifecycle Interfaces

[Christian Heller <ch...@tuxtax.de>]

Hi,

just entered this list cause I like the ideas you have in Avalon concerning
the use of "concerns" for components and their lifecycle as mentioned in:
http://jakarta.apache.org/avalon/framework/lifecycle.html
Just some questions:

1 Configurations
Normally, a system has more than just one configuration, e.g. a
SystemConfiguration and a UserConfiguration. Do you mean to configure all
things in Lifecycle point 4 "configure"? Setting system parameters first and
then user parameters, having a higher priority and so overwriting some system
params?

2 Login dialog - GUI
But to get to know the user, the system has to ask per "Login Dialog" for a
login + password etc. Only then the user config can be determined from
his/her home directory.
Problem: To open up a login dialog, the system has to know whether it works
with a Swing or a Servlet/JSP GUI. So, at least this "gui parameter" has to
be read from a config before, the system config.
2.1 Do you think it would make sense to split up the various config concerns
for system, user etc. into new concerns?
2.2 Would it make sense to introduce a new concern "authorizable" or
"authenticable" (I always mix them up) which would have to be placed before
"configure" as the user config has to be read after authentication per login.

3 SystemConfig as command line parameter
Our components are prepared to run standalone and from a container.
To give them at least some very basic settings, I thought about handing over
the location of the SystemConfiguration on command line/from the container?
(Before I open the login dialog to get to know the user and determine the
UserConfig, I need to know at least, if Swing or Servlet GUI is used.)

4 Some of your interfaces don't appear in the life-cycle, such as Executable.
Where to place execute then?

5 Your description of "initialize" is "to allocate memory" etc. Similarly,
"dispose" is to free memory. So what about "finalize" then? Shouldn't the
names of "dispose" be "finalize"?


Many thanks for your answers,
best regards,
Christian

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Re: Order of Lifecycle Interfaces

[Peter Donald <pe...@apache.org>]

On Sun, 3 Feb 2002 10:44, Christian Heller wrote:
> 1 Configurations
> Normally, a system has more than just one configuration, e.g. a
> SystemConfiguration and a UserConfiguration. Do you mean to configure all
> things in Lifecycle point 4 "configure"? Setting system parameters first
> and then user parameters, having a higher priority and so overwriting some
> system params?

In this case it would be recomended that you merge the system properties into 
the user properties.

> 2 Login dialog - GUI
> But to get to know the user, the system has to ask per "Login Dialog" for a
> login + password etc. Only then the user config can be determined from
> his/her home directory.
> Problem: To open up a login dialog, the system has to know whether it works
> with a Swing or a Servlet/JSP GUI. So, at least this "gui parameter" has to
> be read from a config before, the system config.
> 2.1 Do you think it would make sense to split up the various config
> concerns for system, user etc. into new concerns?
> 2.2 Would it make sense to introduce a new concern "authorizable" or
> "authenticable" (I always mix them up) which would have to be placed before
> "configure" as the user config has to be read after authentication per
> login.

I would not architecture my software that way. I would instead design it such 
that the "system" config is used to startup application. Then later on it can 
merge user and system configs and configure new objects that way.

>
> 3 SystemConfig as command line parameter
> Our components are prepared to run standalone and from a container.
> To give them at least some very basic settings, I thought about handing
> over the location of the SystemConfiguration on command line/from the
> container? (Before I open the login dialog to get to know the user and
> determine the UserConfig, I need to know at least, if Swing or Servlet GUI
> is used.)

Often we use the Parameters object to store this sort of information. A few 
projects based on Avalon lifecycles create an "embeddor" which launches the 
rest of the application. The embeddor is generally passed command line 
arguments via Parameters object.

> 4 Some of your interfaces don't appear in the life-cycle, such as
> Executable. Where to place execute then?

Usually Execute replaces Startable in lifecycle stages.

> 5 Your description of "initialize" is "to allocate memory" etc. Similarly,
> "dispose" is to free memory. So what about "finalize" then? Shouldn't the
> names of "dispose" be "finalize"?

We wanted to name it that but finalize is already used by java to indicate a 
method that is called when object is just about to be garbage collected.


-- 
Cheers,

Pete

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