Technology Choices to Make Before Developing Your First J2EE Application

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Technology Choices to Make Before Developing Your
First J2EE Application

• Toon Koppelaars
• Centraal Boekhuis
• Netherlands

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My Mission This Week

• Technology choices to make before starting J2EE
  project
• A DB-Centric approach to J2EE application
  development
• Business Rules Specification, Classification,
  Implementation

Application Development Is Moving In The Wrong
Direction
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Contents

• J2EE MVC
• Different Types of Applications
• Your Technology Choices
• Conclusion

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J2EE
SQL PL/SQL in Database
Java in App Container
EJB
EJB
EJB
JavaScript in Browser
Application server
Java
Java in JVM in OS
J
Servlet
Java in Web Container
D
Servlet
Applet
B
Java in JVM in Browser
JSP
HTML
JSP
C
RDBMS
Browser
Web server
Middle Tier
Data Tier
Client Tier
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J2EE
Pick your Architecture
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Browser
HTML from a Servlet
Application server
Apache
File System
OC4J
Html pages
Class files
Other Components
Other Components
JVM
jdbc
Database server
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MVC

• Popular Design Pattern Separate code into 3
  parts
• Model handling business logic
• Data retrieval manipulation
• Including checking involved Business Rules
• View creating user interface (UI)
• Front-end generation html/xml in browser
• The LOOK of the application
• Control dealing with UI events ? page flow
  control
• Triggered by user using the UI
• The FEEL of the application

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Browser
1
Application server
Apache
File System
OC4J
JSP files
Class files
Other Components
Other Components
JVM
jdbc
Database server
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Browser
1
Application server
Apache
File System
Control
OC4J
View
JSP files
Class files
Model
Other Components
Other Components
JVM
jdbc
Database server
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Different MVC Approaches

• Your first choice

Fat Lots of code in this tier Thin Not so
much code in this tier
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Thin / Fat / Thin
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Thin / Fat / Thin

• Html based applic. the J2EE way
• Thin ? html with little JavaScript
• Fat ? all business logic
• Thin ? no PL/SQL, no views,

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Fat / Fat / Thin
Single table query PK-based DML
M
Model-FW EJB
VC
Applet, Swing
Client Middle Data
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Fat / Fat / Thin

• Rich GUI (client/server) the J2EE way
• Fat ? rich GUI, applet or Java in OS
• Fat ? all business logic
• Thin ? no PL/SQL, no views,

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Fat / Thin / Thin
Single table query PK-based DML
JDBC Model-FW
MVC
Client Middle Data
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Fat / Thin / Thin

• Client/Server early days (pre Oracle7)
• Fat-fat ? including all business logic
• Thin ? middle tier not used
• Thin ? No PL/SQL, etc.

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Fat / Thin / Fat
Multi table query Complex DML (updateable)
Views Triggers Stored PL/SQL
M
JDBC Model-FW
VC
Client Middle Data
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Fat / Thin / Fat

• Client/Server the right way (cw FFT)
• Fat ? rich GUI
• Thin ? middle tier not used
• Fat ? lots of business logic in PL/SQL

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Thin / Fat / Fat
M
Multi table query Complex DML (updateable)
Views Triggers Stored PL/SQL
Model-FW EJB
M
C
Struts
V
JSP UIX
Client Middle Data
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Thin / Fat / Fat

• Best of both worlds?
• Thin ? html frontend
• Fat ? some business logic in middle tier
• Fat ? some business logic in data tier

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Thin / Fat / Fat

• Best of both worlds ? there is a trap!
• How do we divide the business logic?
• Set rules, or else expect software that is hard
  to maintain

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Thin / Thin / Fat
Multi table query Complex DML (updateable)
Views Triggers Stored PL/SQL
JDBC Model-FW
M
C
Struts
V
JSP UIX
Client Middle Data
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Thin / Thin / Fat

• My personal favorite
• Thin ? html frontend
• Thin ? KISS no Java if could be PL/SQL
• Fat ? full use of our mature RDBMS

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Fat / Fat / Fat
Multi table query Complex DML (updateable)
Views Triggers Stored PL/SQL
M
M
Model-FW EJB
MVC
Client Middle Data
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Fat / Fat / Fat

• Run, Run, Run!
• Fat client including business logic
• Fat middle tier
• Fat data tier

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Contents

• J2EE MVC
• Different Types of Applications
• Your Technology Choices
• Conclusion

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ADF Your Choices Within MVC

• By the time you know how fat and thin
• Here is your second choice
• What technology will you use?
• For Model
• For View
• For Control

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ADF
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Two ways to Rome

• You invest lots of time
• And make educated technology choices
• You consult people you trust
• And have them convince you of their preferred
  technology choices
• You drag drop with ADF
• yeah rightjust kidding

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Model Choices

• Would you like bottom-up or mid-down?
• windows on data application
• BC4J
• Build database access from the tables up
• If you really must go OO or UML
• EJB or just Java class hiearchy Toplink
• Build data persistence from object-model down

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View Choices

• What do you already know?
• Thin
• Nothing ? Go UIX
• Something ? Use that (probably JSP)
• Fat
• Nothing ? go WebForms
• Remains committed technology by Oracle
• Something ? Use that (Swing, AWT, )
• In near future
• Java Server Faces (next release of UIX)

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Control Choices

• This one is easy
• Struts
• Maybe in near future
• Oracles ADF-Controller
• You could even build your own

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Choices within Choices

• As mentioned earlier
• You can play around with Model-code
• IF you chose bottom-up!
• For instance BC4J
• All business rules in BC4J?
• All business rules in PL/SQL?
• Attend my thursday presentation

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Conclusion

• Choices to make, in order
• What type of application?
• What type of development approach?
• And then what technology?
• Our choices ? traditional approach
• If Thin client then,
• M/V/C BC4J / UIX / ltour owngt
• In a DB-Centric way
• If Fat client then,
• Traditional Client/Server technology ? WebForms

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Conclusion

• Take time to proof your choices
• Build a small toy application before you start on
  the real thing
• The M of MVC
• If you use both Java and PL/SQL
• Do your programmers know when to do what where?
• Set rules in this area

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t.koppelaars_at_inter.nl.net t.koppelaars_at_centraal.bo
ekhuis.nl
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The New Belief

• Thou shall model thou business (logic) in an
  OO-way and UML is thou vehicle to do this
• Your BL-Code is the centre of the universe
  instead of your persistent data
• Your BL-Code will not end up in PL/SQL.

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Open Source

• Its for free!
• Application servers
• Integrated development environments
• Database management systems
• My view
• Developer productivity and maintenance cost are
  the drivers
• Not license costs

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Open Source

• Does your SW-architecture enforce
• Rich use of PL/SQL?
• Are you not afraid to
• Use Oracle frameworks for productivity?
• Just one EAR-file, or
• Multiple applications, single-sign-on, portal,
  Webforms