Re: Simple way to configure an action?
On 2005-01-24, Larry Meadors [EMAIL PROTECTED] wrote: Maybe we are approaching this from the wrong direction. what is the problem you are trying to solve? Perhaps I am. I have an action which retrieves a couple of values from a database. If the retreival fails, it return some reasonable default values instead. It is these defaults which I want to be user configurable, that is, configurable from some initialization file. The introspection/set-parameter feature, found in PlugIns, would solve my problem, but it isn't available for actions, only actionmappings. On Sun, 23 Jan 2005 17:09:45 -0600, Eddie Bush [EMAIL PROTECTED] wrote: Actions are, effectively, singletons. [...] This means actions have to be thread-safe, and suggests that the best place to configure things would be in the mapping itself, or some other way (resource bundle, propeties file, singleton, factory). The action is specialized, it is only responsible for making sure the values are set in the request's session, so it will not be called from different actionmappings. Further, as soon as the action have been instantiated the configurable member variables will be used as read-only values. So there is no concurrency issue involved. -- Fredrik Jonson - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Simple way to configure an action?
OK, I think i understand what you are trying to do. You could override the constructor of your action to read in a properties file. If you have multiple actions, you could make it a base class that uses some common naming convention, that may simplify things. On Mon, 24 Jan 2005 08:02:04 + (UTC), [EMAIL PROTECTED] wrote: On 2005-01-24, Larry Meadors [EMAIL PROTECTED] wrote: Maybe we are approaching this from the wrong direction. what is the problem you are trying to solve? Perhaps I am. I have an action which retrieves a couple of values from a database. If the retreival fails, it return some reasonable default values instead. It is these defaults which I want to be user configurable, that is, configurable from some initialization file. The introspection/set-parameter feature, found in PlugIns, would solve my problem, but it isn't available for actions, only actionmappings. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Simple way to 'configure' an action?
Another possible approach is to create a DefaultValues class, something along
these lines:
public class DefaultValues {
private HashMap defaultValues;
{
setDefaultValues();
}
public static HashMap getDefaultValues() {
return defaultValues;
}
private static void setDefaultValues() {
// Insert code to read in property file here
// and store them in defaultValues
}
public static void resetDefaultValues() {
setDefaultValues();
}
}
The benefit I think is that it keeps your default values independant of the
Actions. Having the resetDefaultValues() method gives you a way to
reinitialize the values without taking your app down (i.e., maybe on an Admin
page you provide a Reset Default Values button that results in that method
being called). By putting the property file read in the Action constructor,
I'm not sure you'd be able to do this since Struts creates the one instance of
your Action and gets a reference to it per request. I suppose you could do the
above in an Action essentially and call setDefaultValues() from the constructor
rather than a static initializer, but then you get into the question of whether
that's thread-safe, since an Action has to be.
In either case, just mentioning another possibility. :)
--
Frank W. Zammetti
Founder and Chief Software Architect
Omnytex Technologies
http://www.omnytex.com
On Mon, January 24, 2005 8:13 am, Larry Meadors said:
OK, I think i understand what you are trying to do. You could override
the constructor of your action to read in a properties file. If you
have multiple actions, you could make it a base class that uses some
common naming convention, that may simplify things.
On Mon, 24 Jan 2005 08:02:04 + (UTC), [EMAIL PROTECTED] wrote:
On 2005-01-24, Larry Meadors [EMAIL PROTECTED] wrote:
Maybe we are approaching this from the wrong direction. what is
the problem you are trying to solve?
Perhaps I am. I have an action which retrieves a couple of values
from a database. If the retreival fails, it return some reasonable
default values instead. It is these defaults which I want to be
user configurable, that is, configurable from some initialization
file.
The introspection/set-parameter feature, found in PlugIns, would
solve my problem, but it isn't available for actions, only
actionmappings.
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Re: Simple way to configure an action?
On Mon, 24 Jan 2005 06:13:23 -0700, Larry Meadors [EMAIL PROTECTED] wrote: OK, I think i understand what you are trying to do. You could override the constructor of your action to read in a properties file. If you have multiple actions, you could make it a base class that uses some common naming convention, that may simplify things. You could also implement this as a filter, which will give you more options then an action for this kind of thing. Espeically in terms of adding this check to a lot of different URLS. On Mon, 24 Jan 2005 08:02:04 + (UTC), [EMAIL PROTECTED] wrote: On 2005-01-24, Larry Meadors [EMAIL PROTECTED] wrote: Maybe we are approaching this from the wrong direction. what is the problem you are trying to solve? Perhaps I am. I have an action which retrieves a couple of values from a database. If the retreival fails, it return some reasonable default values instead. It is these defaults which I want to be user configurable, that is, configurable from some initialization file. The introspection/set-parameter feature, found in PlugIns, would solve my problem, but it isn't available for actions, only actionmappings. - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Simple way to configure an action?
Eddie Bush's solution is the right one. The ActionMapping is specifically intended for the purpose you have in mind, and is available every time an Action's execute method is called. Even if the Action will not be called from different action mappings, it will always have one action mapping. What's the problem with reading the values from the ActionMapping when the action executes? I'm generally believing that the original motivation for Struts to work this way (pool actions instead of creating one per request) has proven not to be all that useful, and some of the benefits of being able to treat an Action as a request-scoped instance are part of what people like about frameworks like Webwork. It might be worth investigating whether there actually are meaningful performance implications to instantiating an Action upon every request, although a bug in the Struts Chain code (fixed only a month or two ago) was causing this very situation, and it didn't have a noticeable impact on a production application I had built upon it. Don Brown's Struts-Spring project had a proxy action which created a new Action instance for each request based on a Spring configuration. The project is discontinued in favor of equivalent behavior in the Spring core, but you can get the details on that (and a link to currently active substitutes) at http://struts.sourceforge.net/struts-spring/index.html Joe At 8:02 AM + 1/24/05, Fredrik Jonson wrote: On 2005-01-24, Larry Meadors [EMAIL PROTECTED] wrote: Maybe we are approaching this from the wrong direction. what is the problem you are trying to solve? Perhaps I am. I have an action which retrieves a couple of values from a database. If the retreival fails, it return some reasonable default values instead. It is these defaults which I want to be user configurable, that is, configurable from some initialization file. The introspection/set-parameter feature, found in PlugIns, would solve my problem, but it isn't available for actions, only actionmappings. On Sun, 23 Jan 2005 17:09:45 -0600, Eddie Bush [EMAIL PROTECTED] wrote: Actions are, effectively, singletons. [...] This means actions have to be thread-safe, and suggests that the best place to configure things would be in the mapping itself, or some other way (resource bundle, propeties file, singleton, factory). The action is specialized, it is only responsible for making sure the values are set in the request's session, so it will not be called from different actionmappings. Further, as soon as the action have been instantiated the configurable member variables will be used as read-only values. So there is no concurrency issue involved. -- Fredrik Jonson - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -- Joe Germuska [EMAIL PROTECTED] http://blog.germuska.com Narrow minds are weapons made for mass destruction -The Ex - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Simple way to configure an action?
Actions are, effectively, singletons. There is a single instance created, no matter how many mappings use it. This means actions have to be thread-safe, and suggests that the best place to configure things would be in the mapping itself, or some other way (resource bundle, propeties file, singleton, factory, ... ), depending on what you're really trying to do. On Sun, 23 Jan 2005 22:42:20 +0100, Fredrik Jonson [EMAIL PROTECTED] wrote: Hello, I've only just started using struts, so I need some input on how to approach struts designs... snip / -- Eddie Bush - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
Re: Simple way to configure an action?
Maybe we are approaching this from the wrong direction...what is the problem you are trying to solve? On Sun, 23 Jan 2005 17:09:45 -0600, Eddie Bush [EMAIL PROTECTED] wrote: Actions are, effectively, singletons. There is a single instance created, no matter how many mappings use it. This means actions have to be thread-safe, and suggests that the best place to configure things would be in the mapping itself, or some other way (resource bundle, propeties file, singleton, factory, ... ), depending on what you're really trying to do. On Sun, 23 Jan 2005 22:42:20 +0100, Fredrik Jonson [EMAIL PROTECTED] wrote: Hello, I've only just started using struts, so I need some input on how to approach struts designs... snip / -- Eddie Bush - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
