RE: Java App. Development - Is it Worth ?

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Is there any good useful sites that teach OO concepts. As of now I am
familiar with Java (with simple programming & servlets like that).I searched
'google' and found many interesting things like new OO programming languages
'Blue' like that.

I remember about discussing 'java design patterns' some time ago.

Thanks
TIA
Rizwan


-----Original Message-----
From: Vijosh A [mailto:vijosh@systsoft.com]
Sent: Wednesday, October 10, 2001 6:42 AM
To: java400-l@midrange.com
Subject: RE: Java App. Development - Is it Worth ?

Weining,

You can look for the document : api_java.pdf at :
http://support.crystaldecisions.com/docs

or go to : http://support.crystaldecisions.com/kbase/c2005947.asp

For more information on JNI programming, refer to:
http://java.sun.com/docs/books/tutorial/native1.1/index.html

Cheers
Vijosh


-----Original Message-----
From: java400-l-admin@midrange.com
[mailto:java400-l-admin@midrange.com]On Behalf Of Xu, Weining
Sent: Tuesday, October 09, 2001 5:57 PM
To: 'java400-l@midrange.com'
Subject: RE: Java App. Development - Is it Worth ?


Hi,

Could anyone advice more about using Crystal Report from Java?

Vijosh,
Could you provide the source that you mentioned "Crystal Decisions has also
provided
documentation on using Crystal Reports from Java"?

Gilles,
Could you provide more details about "There is also Java reporting tools
based on Crystal Report."?

Thanks all.

-----Original Message-----
From: Vijosh A [mailto:vijosh@systsoft.com]
Sent: Tuesday, October 09, 2001 7:46 AM
To: java400-l@midrange.com
Subject: RE: Java App. Development - Is it Worth ?


Gilles,

thank you for the reply. it really was informative and made me sit back and
do some introspection.

1. I agree with you that OO experts (designers and developers ) must be
hired. One factor is that  it is not easy to get many experts in the area.
So we had to explore and wade our way ahead. May be the next time many of
these problems related to design may not occur. Our problems related to
design were not many. It was more related to the inability of developers to
achieve the requirements of the design using java.

2. Re. interoperability between C++ & Java - well java is providing JNI
interfaces for the purpose. Crystal Decisions has also provided
documentation on using Crystal Reports from Java. Only problem is that they
are very crude and are not flexible. So the focus seems to be towards such
an integration.

3. Re. Cocoon - Thanx. But don't u think the time factor involved in using
XML etc. is high. I mean we spent so much time on developing a module in
Java. Now our problem is that starting up something in Cocoon is another
long road. Although it is one of the right solutions we are forced to use
Crystal Reports because Crystal Reports is easy and saves u time.

4. Re. Locking -  Server based Synchronized method is a good solution. But
again it would have involved managing servlets, websphere...connection pools
etc.

The solution of stored procedure is the one we have used. but not by locking
the database. but by making the stored procedure return the generated code
back to the program.


The last point related to human problems are also true.

Now the question is that, with so many problems it becomes difficult to
convince the management to get into this kind of development. With the
reduced number of projects that come in, due to ongoing economic recession
and the related cutting down of costs, it becomes really difficult.

I really wonder how many shops are into development of a ERP or SCM system
using JAVA ? If yes are these products or projects ? And what is the
comparative man years between an application developed in JAVA and other
Languages like  RPG or whatever ?

Thanx

Cheers
Vijosh


-----Original Message-----
From: java400-l-admin@midrange.com
[mailto:java400-l-admin@midrange.com]On Behalf Of Ducret, Gilles (CH)
Sent: Tuesday, October 09, 2001 1:20 PM
To: 'java400-l@midrange.com'
Subject: RE: Java App. Development - Is it Worth ?


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Hello,

Some comments:

1. Although principles of OO seems to be easy it is really difficult to
built robust OO application, with a good architecture.
You need experienced people to do that. It is not necessarly specialist
of Java but specialist of Object Orientation.
My opinion is that you must accept to engage experienced OO designer and
developper, and ask them to design and help the other people of the team.

The experience we have here is that the group of experienced Java developper
developped fast their application, while the learners faced lot of problems.

2. I am not sure to understand the point 2, but it looks like an
architecture
design problem. It depends on what you really want to do, but there are way
to develop reports for free using XML, XSL, FOP, you can then generate html,
pdf,
or whatever you want.
If you have a browser based application you can also use Cocoon to do that.
It is free from the Apache Foundation.

There is also Java reporting tools based on Crystal Report.

For our internet project, i will provide soon reporting facilities based on
Cocoon. I just need to describe my data in XML, transform them using XSL and
FOP, and Cocoon will manage the whole. It is completly free and very easy to
develop. As our web "services" already describes the data in XML, we just
have
to write the appropriate XSL file to generate the report in PDF. One guy
is responsible to write the XSL files to generate the PDF. He doesn't need
any knowledge of Java, C++, only XSL.

What you are talking about is also "interoperability". How can we make tools
communicate together, especially when they are in different languages like
C++, Java,
RPG?

We have decided to use XML to exchange data between applications. We
sometimes
use MQSeries as transport mechanism. In this case you don't have to "export"
database
object. Generally you should never expose database object to other
applications,
you must have an abastraction layer. It will hide the complexity and only
focuses on services. XML is then very useful to pass the data to these
services.

3. Once again your problem looks like an architecture choice. If you have a
server
to provide this information you can insure that only one client at a time
get
an identifier from the database. You just have to synchronize the method
that get the id from the database.
If you have written a a fat client application, you can also use different
technics:
- use a stored procedure that will manage itself a lock on the table of the
identifier
- write a method that locks the access while one application is getting an
id


To summarize: my feeling is that you had all of these problems because your
java developper and designer were not experienced enough. It seems that your
difficulties can be solved with different architecture.

The problem you faced are not related to Java, but working in a client
server
environment. You would have have exactly the same problem working with
other languages.

My opinion is also that these kind of problems should never be solved by
technic solutions (like how to pass a database object to Crystal Reports),
but by design solutions.

You must write abstraction layer between each level (DB, BO, UI), and also
between the applications.

But, before to be able to do that, you must be really experienced. In OO you
build
blocks and architecture to build block, you don't add lines to a program.

>From my experience, the recent use of XML and XSL gave us a lot of
solutions
to problems that could have been very technical:
- exchange data between java programs and our legacy application
- exchange data between very heteregenous systems and some very old ones
- generate reports easily, for free.

Now my only experience is on object orientation. My opinion is that Java is
a very good choice. I could not come back to C++.


What i also see is some human problems. Some very experienced RPG
programmers
must accept that they can't do very good java programming untill one year,
just
because you must really understand object orientation. This is a task of the
management to manage the learning curve and to hire the appropriate persons
to ease the process.

Cheers

Gilles

-----Original Message-----
From: Vijosh A [mailto:vijosh@systsoft.com]
Sent: mardi, 9. octobre 2001 08:54
To: java400-l@midrange.com; web400@midrange.com
Subject: Java App. Development - Is it Worth ?



Hi all,

we have been developing a java based application for the past 1 year. the
first phase is almost over. some of the issues we faced are -

        1. Lack of experienced people in Java. For starters also, RPG
learning
takes much less time . They program and start delivering in 2 months time.
Whereas with Java people get bogged down with nitty gritties of Java and
Object Orientation to an extent where they often forget the business logic

itself. For e.g. if you have 3 to 4 combo boxes on the screen and if one
triggers the filling of other and vice versa, the listeners really play
squash. YOU OVER SHOOT TIME LIMITS, FRUSTRATION FOLLOWS, A CUT IN YOUR PAY
CHECK ARE THE CONSEQUENCES.

        2. When it comes to developing reports like the ones developed &
implemented using RLU - EXCPT (RPG OpCode, it is another set of woes. You
don't have many reporting tools that integrates with java. They are too
expensive too. If you go for Crystal Reports, then u need to write a C++
interface. Still u don't have any control over Crystal Report once it is
invoked through this interface. Crystal Reports does not recognize the
database object passed by java, whereas it does understand the result sets
sent by VB etc. HERE WE STAND THE RISK OF LOSING THE CUSTOMERS CONFIDENCE
WHEN HE DOES NOT GET REPORTS AS HE USED TO GET WHILE USING AN RPG
APPLICATION.

        3. Next is the problem with ID generation. Suppose u want continuous
generation of employee ID's in a sequential manner. So if u keep the last ID
in a physical file and decide to use a trigger-program combination(which was
the only solution we found to be feasible)then comes the next set of
problems. In a mulitple user environment 2 users can get the same id. To
prevent this  we use a Data Queue. And put the generated ID into the Data
Queue thereby making it possible for requester program to pick it up from
the Data Queue. PALTFORM INDEPENDENCE IS COMPROMISED.

To sum it up, the amount of learning a new guy needs to do and the amount of
self moulding of one's thinking when programming with java is too high. This
leaves both the employee and the employer disillusioned !!!

Thanx for your patience and sorry. Now my question, does everyone face such
problems? If yes what is your approach in solving these issues ? Economic
recession added, Does your company still have the confidence to place bets
on java ?

Thanks

Cheers
Vijosh







>From the Desk of :

Vijosh A.
Senior Consultant
Systems & Software
123, SDF 4, SEEPZ

Andheri (E), Mumbai.

Tel : (91-22) 829 0803/0075
Fax : (91-22) 829 2578


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