Re: Configuration initialization per web request issue

Your reply is very helpful. I think i understand the important points about
caching and whether it's cachable or not. This clears up about the
expensiveness without caching, having to reparse everything per request.

I just realized we can get the localized template by passing the locale in
the config.getTemplate(),
so with this, i dont need to use properties anymore.

I will just use cfg.setDirectoryForTemplateLoading() and use multiple ftl
files instead of merging all into one properties file,
therefore having the caching feature and no need for custom template loader
anymore (which in my previous idea wont work well, because all caches will
be purged if the properties file was changed, even if for just one property)

The convinience that i will lose is everything is not inside 1 file anymore
like the properties file, but i think i can cope with it with some tools.

Thank you !

Regards from Jakarta,
Albert


On Sun, Feb 10, 2013 at 5:18 PM, Daniel Dekany <[email protected]> wrote:

> Sunday, February 10, 2013, 5:58:54 AM, Albert Kam wrote:
>
> > I want to use freemarker's multiple StringTemplateLoader-s per each
> > request. This means that i will have to new Configuration() per each
> > request, right ? I wonder if this is the right way to do it, since
> > i've read somewhere that Configuration should be initialized once
> > per webapp because it's expensive ?
>
> The the biggest expense of not using a long-lived/shared Configuration
> instance (and perhaps the only significant expense) is that you trash
> the previously built template-cache each time you create a new
> configuration. The template-cache stores the templates pre-parsed, so
> when you request a template with Configuration.getTemplate(someName,
> someLocale) for the 2nd time, FreeMarker will not load and parse it
> again.
>
> > Why do i need this approach is because i want to get locale
> > specific templates per request, which i put inside a properties
> > file, and then fill up the templates.
> >
> > Example of the entry in the properties file :
> > my.template.key1=my.freemarker.template1.here
> > my.template.key2=my.freemarker.template2.here
> >
> > So the logic what i have in mind is :
> > - i have the keys in the UI (dynamiclly obtained)
> > - i load templates with resourcebundle depending of current user's locale
> > - initialize configuration object
> > - setup multiple string template loaders with those i load from
> > resourcebundle and set them to configuration object via
> MultiTemplateLoader
> > - setup the models n get the template outputs
> > - print them onto UI response
> >
> > All of these can happen per web request.
> >
> > Is this approach appropriate ? Thank you !
>
> The template cache uses name+locale as the key to look up entries, so
> just because you have different locales per request, you don't have to
> give up caching. The problematic case is when the templates have no
> "name" with which you can identify them, or they have but you don't
> have a last modification time for them yet they are changing. In that
> case you can't use the cache for *those* templates. But you can still
> use the a common configuration, you just use `new Template(...)` to
> create ad-hoc Template instances, instead `config.getTemplate(...)`.
> The caveat with `new Template(...)` is that templates that are not
> available with `config.getTemplate(...)` can't be
> #include-ed/#import-ed in other templates.
>
> Of course, to use the template-cache, you need a TemplateLoader that
> stays during the whole life-cycle of the Configuration. A
> StringTemplateLoader that's recreated for each request won't do. So if
> you have some custom template storage, instead of filling a
> StringTemplateLoader each time, maybe you can implement the
> TemplateLoader interface and then do `config.setTemplateLoader(new
> MyResourceBundleTemplateLoader(...))` once.
>
> --
> Best regards,
>  Daniel Dekany
>
>
>
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the practitioner dwells in stability and freedom.
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