Re: How hard is Java, really?

From: Nathan Andelin

Joe P. wrote:
Not really. CGIDEV2 actually is quite robust, as it has to re-invent
all of the template caching and substitution that JSP has inherently
built in.

I understand that CGIDEV2 does some things that the servlet wouldn't need
to do, but if I understand correctly the workload management and other
services provided by the servlet are beyond the scope of CGIDEV2;
Launching an instance of the RPG program for each user requesting the
program, handling the communication between each browser and each RPG
program instance, ending RPG program instances,

Oh, this is much easier than you make it sound. In a JAC environment, you
simply make direct program calls to your servers, just as you would in a CGI
environment (assuming that you have a well-designed MVC architecture for you
CGI code).

In a RAC environment, it's actually even easier for RPG programmers. At
session startup, you create a couple of data queues and then submit a job to
batch. If you're thinking ahead, the program you call should actually be a
standard program that initiates the conversation and registers an exit point
in case the job terminates.

The first application program called acts like a menu then and simply calls
other programs as needed. There's really not a lot of overhead.

automatically loading XML
definitions for each application, dynamically generating one or more beans
for each JSP, automatically mapping fields from RPG program data
structures to beans, automatically mapping fields from JSP-HTML forms to
RPG program data structures, dynamically evoking the right JSP for every
output operation for every application,

You have to do all this manually for CGI. You have to define all the
templates, and name all the variables. You have to make sure your RPG code
updates the right variables in the template (for example, in CGIDEV2, you
have to make sure you perform an updHtmlVar for every field). You have to
select the appropriate template for output. You have to extract the right
fields from the form on input.

None of this is any different, except that with JSP most of the work is done
for you and you can concentrate more on the business logic than on creating
templates with little fragments of HTML.

handling and reporting errors,

Have to do this no matter what, no?

updating the file information data structure, and so forth.

No, that's only for the PSC product, where we actually emulate a display
file. If you're writing a purely web-based program, you don't need an
INFDS.

I think I agree with your original premise, though. Given all the
plumbing in your framework, the code that the developer has to
create/maintain doesn't seem to be hard.

Well, unless you're going to do everything from scratch, you need plumbing.
CGIDEV2 is plumbing. Spring is plumbing. Struts is plumbing. Your stuff
is plumbing.

It's just that with JSPs a lot of the plumbing is done for you.

Joe