From: JK
Thanks for the reply. I considered using Cloudscape because I was hoping
for quick gratification: actually being able to complete an IBM tutorial
'as is', without getting sidetracked on some configuration issue!
Yeah, but unfortunately the tutorial was written when Cloudscape was still
the database du jour. Now Derby has replaced it (and it's a good thing for
cross-platform development as far as I can tell, since it's now part of the
Apache Foundation and I think you can assume it's going to be more widely
available).
But I think you should be using DB2, and we'll get to that.
Am still trying to _understand_ everything that I _know_ about this new
world where it takes more than an "F-spec" to complete the plumbing
between the database and the language and I likely have many
misconceptions. Please feel free to correct me if it looks like I'm
starting to lurch into the ditch.
Trust me, I'm not fan of DataSources and JNDI. They are an attempt to
standardize the confusion brought about by an arbitrary implementation of a
poorly thought-out design, but other than that Mrs. Lincoln, how was the
play? <grin>
In a super-condensed form, JNDI allows you to specify all the gazillion
parameters required to connect to a database and then give that set a simple
name. You can then connect to that name, rather than having to specify the
various database parameters. The idea also is that a database usually needs
to be connected to using pretty much the same parameters, so that if you set
up a connection for one application you should be able to reuse that
connection for another application (with some caveats, obviously, but that's
the idea).
1) In order to run EGL inside of WDSc on a standalone PC, some sort of
local database is necessary. If Cloudscape is deprecated I'll take
another stab at
it using Derby instead - there was mention of Derby in the Tomcat .ppt on
the jsayles website. This should suffice for the tutorial and initially
getting familiar with the IDE.
Ah no, that's the beauty of the Java Toolbox and JDBC in general! You can
run an application on a PC but it will talk to a database on the host
transparently. I mean, you need to be able to access the host via TCP/IP,
but as long as you're on the LAN, the application will run using data on the
host!
The first time I wrote an application on the PC that ran using data on the
host I was blown away. And then I was able to take that application and
basically just copy it directly to the System i (using Windows Explore and a
mapped drive) and it ran there!
With web applications, they will run inside of WDSC (you can use the
built-in WebSphere Server for testing) and then you can export the web
application and import it into the server on the host, and you're up and
running!
2) Yes, the ultimate goal is to connect to data on our iSeries. Since the
DDS to DDL conversion is not yet complete, I suppose they are they are
technically still QSYS files instead of tables, but that is another issue
for another time. Did I infer correctly from your reply " move straight to
a DB2 connection " that EGL can access DB2 data without Tomcat or WAS as
an intermediary?
Absolutely. And the beauty of DB2 for i5/OS is that your physical files
have a dual nature; they can be accessed as SQL tables without any
additional work on your part. So JDBC access allows you to directly read
and write DB2 files. How cool is that?
3) Might I suggest another article in your series on EGL: a conceptual
overview and a bullet-list of the steps necessary to d/l, install and
configure EGL geared towards us RPG-o-saurs?
Yup, I tend to agree. As soon as 7.1 comes out (hopefully Q1 or Q2) and IBM
gives us a firm idea of pricing for System i shops, I'd love to have a
complete tutorial on installing RBD along with WDSC and then running a
simple application.
There are gotchas. For example, JDBC likes commitment control, and on the
System i that means you have to journal your physical files, otherwise you
get a real testy error message. I hate unnecessary journaling, so I find
that to be a pain. It took a couple of emails with the EGL team to figure
out that I needed to specify NOCOMMIT on my connection.
On the one hand is the surplus
of trivial WDSc articles on the wonders of color-coded opcodes in LPEX and
how to change library lists in RSE. On the other hand are intense debates
about the relative merits of JSF vs. JSP development and other things I've
heard of but don't understand the implications of.
Hee hee... guilty on both counts.
Like I said, I'm trying to wait until the next release. I didn't put out my
WDSC book until V5.1 of WDSC because it really wasn't ready for prime time.
There are a couple of things that will be fixed in RBD 7.1 that will really
make EGL an option for System i developers, so I'm targeting that time
frame.
Joe
midrange.com
