Devoxx 2011 - Scaffolding with Telosys

A pragmatic scaffolding approach
to build Java Web Applications
Laurent Guérin
Telosys Project Leader
Sogeti & OW2 Consortium

Introduction
Sogeti : Company Capgemini : Company
belongs to

: Plateform
Laurent Guérin : Person Telosys : Project
leads

laurent.guerin@sogeti.com

: IDE
located in
hosts

OW2 : Consortium
: License

France : Country

Devoxx 2011 – Laurent Guérin – JAVA scaffolding with Telosys ( http://www.telosys.org ) 2

Introduction

OUTLINE :

- Code generation

- Telosys approach

- The framework

- The tools (demo)

Model Driven
• "Model-First" approach ( MDD, MDA, … )
• Code generation from an existing model
• "Model Driven" => You need a model !
• Model => substantial initial investment
• Process : keep the model up to date !
MODEL Split !
XMI
Service
name

+port 0..n

( XML )
Port Binding Port Type
1
+binding name
name name Param
1 +type
name

StartWithExtensions

+output 0..1 +operation 0..n +operation 0..n
+input Input
0..1 +input
BindingOperation Operation
0..1

Code
name name
1 0..1 Output
+output

+message 1
+fault 0..n +fault 0..n
Message
Fault +message
BindingFault name
name
1 1

+part 0..n
Part
name

TOOL
Template


Scaffolding
• "Database-first" approach
Database
• Very efficient
• No customization between the database Metadata

metadata and the generator
TOOL
• Not enough information …
– Java field name Template

– Java field type
– Validation rules : min, max, regexp, … Code
– Boolean storage values ( 1/0, "T"/"F", … )
– etc …
• Cannot store/reuse further information

Wizards
• Code generation without model / DB “Java Model”
org.eclipse.jdt.core

• IDE tool => Needs user inputs Workspace
files

I.D.E.
• Can also use existing artefacts
as input
– Java class  Java class
– WSDL file  Java classes
• Efficient only for a few kinds of
targets
Code
• Can only be considered as Bulk
generation

"development accelerators"

Telosys approach
• What we want …
– to be able to generate code quickly for entities
management (like scaffolding) with a simple tool
– to add and keep specific information about entities
=> we need a repository to store them (kind of model)
• What we don’t want …
– to spend a lot of time to build a model
– to input further information for each generation
• What we must have …
– a database (“database first”) Metadata
DB
+
– an IDE (Eclipse) that is the developer’s daily tool

Telosys approach
• The 3 steps …
Template
Database updates customizes

Metadata
modify
& add
information Code
Repository Code
generator generator
generates
Repository
(Lightweight
updates model)

1 2 3
Use the Customize the Generate
“Database-first” “lightweight model” the code
approach to build
a “lightweight model”


The tripod of success
What a Method ( agile )

development
project needs…

Tools Framework

( code generation ) ( global & simple )

• The framework is self-sufficient to build a
complete Web application
( "global" / "full stack" framework )
• The tools are provided as Eclipse plugins in
order to make the programmer's life easier

Project’s philosophy
• “Keep it simple and stupid”
( KISP ? )
– lightweight framework
– small tools (easy to install & to use)
• “Conform with the standards”
– servlet/JSP/JSPX, JDBC, JPA, http, XML, …
• “Remain open”
– Open Source (hosted by OW2 consortium)
– Open Format (lightweight model = XML)
– Customizable templates  different targets :
Telosys fwk + other Java Frameworks, Flex, PHP, …

The framework
• Global framework “all in one“

• Only one jar (+ JDBC) => no "jar hell" !
• Designed for "data centric" web applications
• Light (just needs a servlet container and a
database) & based on simple concepts

The "global effect"
One framework
that covers all the application layers
Authenti-
cation

Presentation Application Business Persistence
Services
Screen Java Beans
Maps ( POJO ) DAO
XML conv
"VO" SQL
JSP + taglib Screen
AJAX Managers
Framework
Services Thin persistence
Javascript layer

Very simple objects
Natively AJAX Commons, logging, I18N, … ( "Pure POJO" )

• “Global” means … less “glue”, less objects
(less memory footprint), less configuration, …
=> Coherence & Efficiency
• “Modular” (modules usable separately)

The "client-server" paradigm
• Once the screen is loaded in the browser, it
converses with the server via AJAX requests
( XML / http )
Client-side http Server-side
<request screen-name="Employee"
screen-id="0" action="get" >
</request> Screen
Manager
Action

<response screen-name="Employee"
screen-id="0" action="get" >
<return code="0" message="Ok" >
</return>
Framework
JavaScript

<data>
<employee id="23" lastName="Wayne"
firstName="John" manager="0" email="" />
</data>
</response>

Service
Service

http://myhost:8080/.../Add.svc?p1=2&p2=6

<response service-name="Add">
<return code="0" message="Ok" />
<values> <value result="8" /> </values>
<data> </data>
</response>


The "Data Objects"
• VO Bean (POJO = “entity record”) Code

• VO List (selectable/sortable list of POJO)
generator

• DataSet (grid of objects)
Book
.java
BookDAO
BookConv VO Bean .java
.java
Data
Database
XML XML Access
<…>
VO List Layer Book
</ … >
Table
Con- BookList
verters .java

DataSet Parsers
Files


The "Data Access Layer"
• Why another persistence framework ?
ORM : JPA (or Hibernate) …
High level & "Object Oriented"
Java objects
Hides the complexity rule the persistence
Sometimes misunderstood by the developers
( "lazy/eager" loading, cache effects, DB
"attached/detached" entities,
"owning side"/"inverse side" links, … ) new new

Telosys DAL (based on DAO pattern)
Intermediate level & "Record Oriented" Database records
One Bean = One Record rule the persistence
The developer keeps the control
No links, no cache, no byte-code enhancement
DB
Very simple API : load, save, insert, update,
exists, loadList, updateList, … new legacy

JDBC API Both are useful,
Low level You have the choice …

"Record Persistence" examples
 A "record" = a bean (POJO)
 Each bean is managed by a dedicated DAO
EmployeeDAO dao = getDAO();
Employee employee = new Employee();
employee.setCode( "123" ); // primary key
int r = dao.load(employee, db);
The developer decides…
if ( r > 0 ) { // if found . What to do
// update
employee.setFirstName("Bill"); . How to do it
dao.update(employee, db);
} . When to do it
else {
// create
employee.setLastName("Wayne"); EmployeeList list = new EmployeeList();
employee.setFirstName("John"); ListQuery query = dao.createQuery(…);
employee.setEmail("jwayne@cinema.com"); int count = dao.count(query, db);
dao.insert(employee, db); dao.loadList(query, list, db);
} dao.updateList(list, db);
if (dao.exists(employee,db)){...}
dao.delete(employee, db); db.commit();
db.rollback();


Links or no links ?
• You have the choice …
• Links can be generated if an “object graph
approach” is chosen (ie with JPA persistence)
Bean
@ManyToOne Code
@OneToMany generator
@ManyToMany
@OneToOne

• With a “record approach” : no need to manage
links between beans, the framework uses
“aggregations” to assemble required beans
Code
Bean generator
Aggregation
(composite) DAO


The screens
Code
generator

request BookMgr BookProc
ScreenMap .java .java
response ScreenManager ScreenProcedure
V C
AJAX acts on …

BookData
.java Book (bean) M
ScreenData
AuthorList
Book.jsp (aggregation
( or .jspx)
0 .. N objects) Shop (bean)
Book.js DataSet


Screen view example
JSP or JSPX, but no HTML !
<%@ taglib uri="/telosys/widgets" prefix="t" %>

<t:screenbody>

<t:label id="L_EmpId" x="40" y="60" txt="Employee Id : " cl="PK_field_label" />
<t:label id="L_LastName" x="40" y="100" txt="Last name : " />
<t:label id="L_FirstName" x="40" y="140" txt="First name : " />
<t:label id="L_Birthdate" x="40" y="180" txt="Birthdate : " />

<t:field x="200" y="60" id="EmpId" cl="PK_field" size="6" maxlength="6" />
<t:field x="200" y="100" id="LastName" size="30" maxlength="30" value="Aaaa" />

<t:button x="460" y="100" id="b1" txt="My button" onclick="b1_onClick();" />

<t:field x="200" y="140" id="FirstName" size="30" maxlength="30" value="Georges" />
<t:field x="200" y="180" id="Birthdate" size="10" maxlength="10" value="" type="Date" />

<t:radiogroup id="Contract" x="200" y="220">
<t:radioitem id="R_field61" x="0" y="0" value="1" txt="C.D.D. (1)" />
<t:radioitem id="R_field62" x="0" y="20" value="2" txt="C.D.I. (2)" />
</t:radiogroup >

<t:checkbox id="Manager" x="340" y="220" value="1" valueoff="9" txt="Manager" />

</t:screenbody >


Conventions
• "Framework" => "Frame" !
• "CoC" ( Conventions over Configuration )
– The developers know where the files are
– The tools know where to generate files
• Example : 1 Java package 1 web folder

1 screen =
+

What is a Telosys project ?
• Just a standard Java Web Application project
src (server side)

TelosysTools (+) deployment

WebContent (client side) .war

• It can be organized for Maven, or not…
• In Eclipse :
That’s all !
1) Create a new "Web Dynamic project" The project is ready
for development and
2) Import the "Telosys Starter Kit“ code generation

Demo
• How to create a Telosys project …
1) Create a Dynamic
Web Project 2) Import the
Telosys starter kit


Demo (cont’d)
• Test and initialize the Telosys project …
3) Test the
project
( run it )

4) Define the
conventions


The big picture
Everything can be
done in Eclipse

Editors Wizards Properties

Repository Repository Template
Database .dbrep .vm
Meta-data generator ( XML )

Code
.java
generator
Context .jsp / .jspx

.js
Velocity

other …


The demo
• Connection to the database
• Repository generation
• Repository customization
• Basic objects generation (Bean, List, DAO, Conv.)
• Screens generation (server side & client side)
• Template customization
• Links management
• Beans generation for JPA & Validators
• New specific template See demo screenshots at
the end of this presentation

Conclusion
Database Repository Tools Initial code

and the project is
on the rails…


In the future …
• Main goals in the 2012 roadmap
– Repository
• Extendable/unlimited information for
each entity and each Java field
– Screens design
• Official release of the Screen Builder
plugin (WYSIWYG)
Still a lot
– Java Portals of work to
• JSR-168 portlet to embed
screen maps in a portal page
improve
– NoSQL
the rails …
• DAO for GAE/BigTable & Cassandra

Framework features

Screen Maps
Widgets TagLib
DataSet
Services
JavaScript framework
Commons/util classes SQL DAO
Logging
Authentication
XML converters File upload/download

Text/CSV files parser Selectable/Sortable
Internationalization beans lists

Telosys Screen Builder
A visual tool to design the Telosys Screens
( beta version )


Follow the project …
• Web site : http://www.telosys.org

• LinkedIN
http://www.linkedin.com/groups?gid=1340197

• Twitter
http://twitter.com/telosys

• Viadeo (in french)
http://www.viadeo.com/hu03/0024uydjnnwew6j/telosys

Demo
• Use the database meta-data to generate the
initial repository

Database
Generation
rules

Repository
Generator

Repository
.dbrep
( XML )


Demo (cont’d)
• The generated repository is editable
with an Eclipse plugin editor

Database

Java Classes

updatable

Database Java Attributes
O/R Mapping


Demo (cont’d)
• Java fields :
– Each Java field can have additional information
– Useful for
• JSP/TagLib user input validation
• "Bean Validation " annotations ( JSR 303 )
or "Hibernate Validators"


Demo (cont’d)
• Bulk generation


Demo (cont’d)
• Generator templates
– The generator is based on "Velocity"
– The templates ( ".vm" files ) can be modified in order
to conform with each project requirements
• coding style
• comments
• etc… i.e. :
add/remove
serialization


Demo (cont’d)
• Entities links
– The foreign keys can be used to generate
links between entities
–Useful for JPA beans generation


Demo (cont’d)
• Generator project’s variables
– Each project can
define its own
specific variables…

… and use them
in the templates
#if ( $bean_jpa == "1" )
$link.jpaAnnotations(4)
#end


Demo (cont’d)
• Adding a new specific template
– 1) create the new “.vm” file vo_doc_html.vm

– 2) add it in the “templates.cfg” file
HTML documentation ; ${BEANNAME}.html ; doc/html ; vo_doc_html.vm

Title File Folder Template

–3) use it in the tool …


Demo (cont’d)
• Using wizards

New …


Devoxx 2011 - Scaffolding with Telosys

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