Re: Your opinion on communication architecture

[Maxime Poulin]

Is it supported by all the browsers and web servers ?

-----Original Message-----
From: Ernie V [mailto:[EMAIL PROTECTED]]
Sent: Thursday, February 10, 2000 4:55 PM
To: [EMAIL PROTECTED]
Subject: Re: Your opinion on communication architecture

Use the JSDT to send post the messages to a shared data structure. Make your servlets and applets JSDT clients that listen for such posting events. The poster of the event can name the explicit recipient or any number of recipients. There are implementations in http so you can go through firewalls. The shared data can be any kind of object. The JSDT takes care of the serializing and deserializing for you.
 

-ernie
 
 

Maxime Poulin wrote:

 

Hi all and welcome to the second edition of this fabulous chronicle "Your Opinion On ..."

As you might remember, the first subject of this outstanding serie was entitled "Your opinion on a servlet architecture", to which a lot of great people participated... Well, this conversation thread, which took place on this mailing list, was started up with a mail I sent containing the description of a basic applet-servlet architecture I had. The thread went on, and I've gathered a lot of absolutely excellent ideas and propositions from you people. This resulted in the fact that the basic model I had, after reading all the mails and propositions, becaome at least trice as good as it was. I implemented it - again, based on my first draft and greatly improved by your ideas - and I received the congratulations of the team here. So first, I return to you all these congratulations !

hehe :)

Now, for the second edition of this chronicle, I have another problem to submit. It is somewhat smaller than the previous one, but yet, still represents a problem...

So here it is :

I am building a soft which will contain servlets (the Control), an applet (the View) and a database (the Model). Nothing new here, I will use the same architecture we built up together in the first chronicle. The client will use the applet to "query" the database through the servlets, using different pre-defined screens. For example, a screen which displays the inventory will use the InventoryServlet. The applet will just send the criterias for the search, such as the year, the plant etc. It is important to note that the applet will not sent a SQL query to the servlet, since the applet is not aware on how the servlet gets the data.

SO, the idea is that when the applet will send its requests to the servlets, it will send it as a Serialized object. And this is what interests me here, how to build a good architecture of Requests-responses for this project.

Basically, we could imagine 2 "top-of-hierarchy" classes, GenericRequest and GenericResponse (hmm, here, I do not intend to make any link with HTTPServletRequest or HTTPServletResponse, the names are just appropriate).

The types of request could be like :
Get the "resultset" (although I do not want to serialize the resultset 'cause I will have to import the jdbc package in my Applet) using these criterias, through that servlet.

Get this information concerning the software configuration.

Validate this information (such as a password).

Get a specific value from the database.

Get an image or any other media.

The types of responses could be like :
Return the "resultset" for this specific query (as a 2d array most probably)

Return the information requested.

Return the validation.

Return the URL for the desired media.

Return a return code.

I would like all the types of "request" be a subclass of GenericRequest, which is serializable, and all the types of "Answers" be a subclass of GenericResponse, also serializable.

The applet will be able to send multiple requests without waiting for an answer, with a threaded communication manager I built. So I must be able to identify the requests and answers in some way...

I tried to figure out how to do this... I don't know, I kind of get stucked right at the beginning... I built much more complicated things and yet I fail with this simple problem, building a nice clean message hierarchy. I can imagine some more or less nice architecture but I do not feel them right...

So could anyone give me a startup for this ? Or point me to a web site where this issue is discussed (like how to model messages or something like that) ? As easy as it may seem, I am really stucked with this thing...

Thank you very much all !

Max.