Re: Review of latest code

["Ilya A. Volynets-Evenbakh" <ilya@total-knowledge.com>]

Alexey Parshin wrote:
> 2008/7/30 Ilya A. Volynets-Evenbakh <ilya@total-knowledge.com 
> <mailto:ilya@total-knowledge.com>>
>
>     I finally started reviewing code.
>     First thing that caught my eye:
>
>     HomeServlet.cpp:
>
>
>     string csp = "HomeView.csp";
>     ....
>     RequestDispatcher* destination = request.getRequestDispatcher(csp);
>
>     This contradicts tech spec:
>     http://www.total-knowledge.com/wiki/index.php/UU_Templates
>     ---------------------
>     Template organization
>     Template mappings
>     Templates (CSP pages) will have identical names, and will be
>     mapped to subdirectories named based on theme.
>
>
> I need an example of the correct mapping. The current code wasn't 
> changed since (in that respect) since Sergey developed it.
There can be more then one HomeView.csp
one will be default/HomeView.csp
another one tkn/HomeView.csp
etc.

default/... is guaranteed to be there - rest aren't.

User sets a preferred theme. That preference is used to get the full 
URL, which will be
<theme name>/<view name> if available, or default/<view name> if not.

This functionality should be abstracted into a member function in 
UUServlet class.



>  
>
>     Now, HomeView.csp itself.
>     Currently it's doing lot of data retrieval work from DB.
>     This sort of conflicts with the original idea of having all data
>     retrieval be done from a servlet,
>     and passing the data as request attributes.
>     (This, by the way, would prevent your exception handling problem
>     we discussed on IRC).
>
>
> This is Ok. I wouldn't worry too much about:
>
> 1) Performance: we need to retrieve these data one way or another. It 
> doesn't matter where - the retrieval time is the same. Actually, 
> generating data into the memory in the servlet and later retrieving it 
> out of memory creates unnecessary delay, even not to significant.
Yes, this data will need to be retrieved, and storing it in the request 
is a bit of overhead.
Although, if we ever decide to add some Servlet-side caching of data, 
it'll be easier to do in
single servlet, rather then multiple views (remember: there will be more 
then one theme).
> 2) Code complexity. The current implementation is much cleaner since 
> it doesn't have to store objects in the session or request in servlet 
> in order to retrieve it later. It also has the advantage of retrieving 
> data when and how we need 'em.
However, it needs to perform error checking, which should really be 
handled by servlet - so that data presence is guaranteed inside view.
And then, copy-paste - remember - we'll have more then one theme.
> The downside of retrieving data in servlets is: If there are several 
> ways to get to the same page, all the servlets redirecting to that 
> page should update page data, isn't it? Then the code updating the 
> data should be duplicated in these servlets.
It's impossible to have more then one servlet redirect to same view page 
(by design).
> --
> Alexey Parshin,
> http://www.sptk.net