Yaws API discussion

[Alex Peake]

Let me state a counter-point.

Microsoft, in its release of ASP.NET also took this approach of separating the UI from the data.
However, they have just released a product called WebMatrix, which goes back to the "old" way - my
guess is that too many people are comfortable with the "mixed" approach and so Microsoft responded.

>From my own point of view, I have built large dynamic web sites with this mixed approach, and have
had no problems evolving the solution at all.

Alex


> -----Original Message-----
> From: owner-erlang-questions@REDACTED
> [mailto:owner-erlang-questions@REDACTED]On Behalf Of Eric Merritt
> Sent: Monday, July 15, 2002 10:14 AM
> To: mickael.remond@REDACTED; erlang-questions@REDACTED
> Subject: Re: Yaws API discussion
>
>
> Mickael,
>
>  Per your request I am going to make a few
> suggestions. I would, however, warn readers that I
> will be swimming in what some consider a holy war
> area. I do not intend any kind of little war here, I
> am just providing suggestions based on my experience
> and knowlege.
>
> I believe that the problem you are having stems from a
> core problem with the paradigm yaws has adopted. Yaws,
> like PHP and JSP Scriptlets, is founded upon the idea
> that actual logic should be embedded in the html page.
> This is a bad thing(TM). It limits scalability of the
> application by quite a bit. I am not refering to
> scalability in terms of speed or performance, but to
> scalablity in terms of application size,
> reliablity/maintenance, and extensablility.
>
> I am rambling here so forgive me. Back in the early
> '80s users of smalltalk realized that the ui design
> paradigms of the time were lacking for large projects.
> To address the issue they came up with a paradigm
> called MVC (Model, View, Controller). This basically
> stated that your model (data, logic) should be
> seperated from your controller (flow control logic)
> and all of that should be seperated from your view
> code. It eventually was expoused that the view code
> should be extreamly limited. In that it only allows
> you to manipulate data provided from your model layer.
>
>
> This was a really good idea for UIs, and when the WEB
> came about it proved to be a really good idea for
> webapplications as well.
>
>  To use some hisorical examples, the inventors of JSP
> realized this same issue after they released the first
> JSP specification. In that original specification JSPs
> allowed only scriptlets (which is java code imbedded
> in the html and delimited by <% %> tags). This
> approach was obviously not MVC like in any way. In
> fact, it cuased quite allot of headaches for
> developers then (and even in somecases now). Thier
> next release included the idea of 'TagLibs' which are
> custom tags that use data from provided from some
> backend process (via session and request variables).
> Now the use of scriptlets are frowned upon almost
> universally and are actaully not allowed to be used in
> most big projects. This still wasn't really a complete
> MVC solution as the coder had to code allot of the
> controller and logic framework himself, but it did
> provide a foundation. Projects like Struts have made
> good use of this foundation and provide full blown MVC
> frameworks now. Using these frameworks has made web
> application programming much much easier.
>
>
> Well to get back to your problem. If your
> Model/Controller layer only provided data to your view
> and your view simply made use of that data all you
> would need to do is include the header and it could
> make use of all the data that was globally available
> in the page. In JSPs that is simply an <@include 'page
> location'> directive. The included page then simply
> makes use of the data already provided.
>
> I realize that the yaws api is based to quite a large
> extent on PHP, but PHP is a very poor choice for
> large, extensable applications. Don,t get me wrong PHP
> is a great thing for quick and dirty applications.
> Basically for those applications that only span a few
> pages or that are only designed to live a short time.
> Anything beyond that and PHP starts to fall down.
>
> I would suggest that you take a look at some of the
> Java page rendering technology. They have allot of
> experience in this type of thing by now. Probably
> start out with the taglib stuff and then take a look
> at Struts (available at jakarta.apache.org/struts).
> Perhaps also take a look at webmacro
> (www.webmacro.org) and velocity
> (jakarta.apache.org/velocity). I personally like the
> idea of taglibs and compiled pages (I think they are
> much faster), but the template engines and thier
> restricted data manipulation langauges are nice as
> well.
>
> I guess I went kind of long, sorry. I also hope I did
> not get anyone too angry.
>
> Thanks,
> Eric
>
> --- mickael.remond@REDACTED wrote:
> > Hello,
> >
> > I feel that there is a need to improve an aspect of
> > yaws api.
> >
> > The ssi function can be used to include some
> > external html template. My need is to be able to add
> > some dynamic generated values (for example the title
> > in the html header portion)
> >
> > I am thinking on the best way to do that. The most
> > evident thing is to pass a dictionnary of
> > substitution that needs to be  performed in the
> > included file.
> >
> > I think it might not be interesting to implement
> > nested evaluation of included files.
> >
> > What do you think ?
> > Any clever idea ?
> >
> > --
> > Mickakl Rimond
> > http://www.erlang-fr.org/
> >
>
>
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