[Demexp-dev] Does the server need to call the client?

[Augustin]

On Friday 01 September 2006 07:03 pm, you wrote:
> > This function can be used if the client wants to "call" the server and
> > get a reply to a particular question.
> > What I am not yet clear about, is how would the server "call" the client
> > in case some events happen that the client needs to be aware of.
>
> Currently, the server never calls the client.


I am not sure if the server needs to call the client or not.

Here is the situation I am thinking about.

I will pull all the public data from the server (all the questions, and  the 
answers, nb of votes and elected choice). I will create a "node" (a page of 
content in the Drupal lingo) for each question. The node will be displayed to 
anonymous users, and for the search engines to index.


The nodes (questions) will be updated each time a registered user uses the web 
client to submit an answer, or cast a vote.

The problem is that the web client cannot know of the activity going on 
between the server and all the hard clients.

I was thinking that the server could be set up to 'call' (via xml rpc) the web 
client, whenever another client is updating the data. This way the web client 
knows it needs to update its own internal records. 


Now, I understand that this particular way of doing might be troublesome for 
you (requires much more coding). 
There is a probably much better way to do it, that would never require the 
server to call the web client.

I can use Drupal to schedule some cron jobs, and call the server at regular 
intervals: the method would be 
"what-has-changed-since-last-time-i-called-you?".

I don't know how you store the data, server side, and how the hard clients 
remain up to date, but I imagine you already use a similar system. 
Certainly you have a last-updated timestamp for each question...

Is that the way it works, now?


The question really is: what procedure do you currently use to make sure that 
the clients (hard clients or the web client) always have the most up to date 
data.

I can tell you one thing, though: it would be too much resource intensive for 
the web client to call the server at each page view!



Augustin.






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