Re: The "Presentation" Layer

[john e <jacobus1968@xxxxxxxxxxx>]

Joe wrote:

> The entire page-at-a-time browser interface all the way up to JSP Model 
> 2 has been server/client

I don't understand. Whether page-at-a-time or ajax, it's always client/server and not server/client because the browser always initiates the request. The browser is under control. The server responds to requests, whether this is with a complete page or simply some data.

Having all application code on the server and "nothing" (i.e. only HTML) on the client doesn't make it server/client.  It's just that you're entire application is structured as functions that are executed as a result of the browser (client) making requests.

If the server outputs a complete page to the browser then this is a response to a request of the client. When done the server simply waits for the next request. This is different from server/client where the client program on the host is under control. It outputs a screen to the terminal whenever it wants to, not after receiving a request from the terminal. 

> Date: Fri, 18 Jul 2008 08:43:31 -0500
> From: joepluta@xxxxxxxxxxxxxxxxx
> To: web400@xxxxxxxxxxxx
> Subject: Re: [WEB400] The "Presentation" Layer
>
> john e wrote:
> > A green-screen terminal is also a peer in the network, but in practice it acts more as a server, and the program running on the host is the client. E.g. the program requests the terminal to display a format. So most of the time a terminal takes on the server role. However, at first, when logging into the system, a terminal initiates a session and has the client role.
> This is a great explanation, John, and is why I call the traditional
> 5250 type of application "server/client" to differentiate from
> "client/server". With server/client, the user actually communicates
> with the server device, such as the 5250 terminal. The component
> running on the host is actually the client, sending requests to the
> server. That's in fact why my product is called "PSC" which stands for
> "PBD Server Client".
>
> The entire page-at-a-time browser interface all the way up to JSP Model
> 2 has been server/client, which is why the browser was such a good
> replacement for 5250. With the popularity of AJAX, however, we've
> changed to a client/server model, in which the user talks to the client,
> which is typically a JavaScript application running in the browser.
> That application makes small requests for data or processing from the
> host in a true client/server model.
>
> The AJAX model is much closer to a thick client than a thin client. The
> primary difference from traditional fat client is that in AJAX you
> download the client program, or at the very least the definitions of the
> widget sand so on, for each page. With fat client the entire user
> interface is compiled into a program and then installed on the client.
>
> Joe
> --
> This is the Web Enabling the AS400 / iSeries (WEB400) mailing list
> To post a message email: WEB400@xxxxxxxxxxxx
> To subscribe, unsubscribe, or change list options,
> visit: http://lists.midrange.com/mailman/listinfo/web400
> or email: WEB400-request@xxxxxxxxxxxx
> Before posting, please take a moment to review the archives
> at http://archive.midrange.com/web400.

_________________________________________________________________
Probeer Live Search: de zoekmachine van de makers van MSN!
http://www.live.com/?searchOnly=true