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At Systematic we are using Groovy technologies to build a fairly standard 4-tier Java web application for a customer. This lecture describes our experience. We will tell you about the choices we made, how we built up knowledge about Groovy, what our biggest mistake was, and how we dealt with it. We used Grails for the user interface, pure Groovy for implementing web services, Geb for automating tests of the user interface, and Spock for automated tests in general. We will tell you where these technologies provided great benefits, and where they were the source of trouble and frustration. This lecture does not presuppose deep knowledge about Grails and Groovy. It should be of interest to any professional software developer who is considering replacing Java with Grails and Groovy. Systematic A/S is a Danish software house headquartered in Århus. We employ about 450 people in 7 nations. We provide solutions for the defence, healthcare and public sector.
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We chose Grails and Groovyfor a real-world project.
Was it wise?
Jan Reher, Systematic
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Topics
• The system we built• Technologies that start with a G• Mistakes made, lessons learned• The presentation I would have liked to hear
two years ago
• Was it wise?
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Founded in 1985430 employees, 400 in Denmark
• Defence• Healthcare• Public Sector• Intelligence and National Security
Jan Reher
Does:• Software design• Programming• Technical leadership• Requirements elicitation• Workshop facilitation• Teaching• Knowledge networking• Process improvement
Likes:• Most of what he does• C++• Functional programming• Tolkien• Gardening• Karate• Desk-top role playing games
jan.reher@systematic.com
MS, Computer ScienceBS, Mathematics, Physics15 years at Systematic
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5
Demo
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Property Trading Process
Account Switching Process
e-nettet.dk
Two major features
Work started August 2011First version in production May 2013
Work started August 2012First version in production 2014
Backend
Business logic
Common Component
Portal Actor System
Internet Explorer
HTTPS
HTTPSHTTPSMQ
Common Component
Common Component
Business logic
Business logic
HTTPSMQ
Data base
Architecture
No security
Session level OCES (X.509)securitySession data only
Per-call OCES (X.509)security
Internet,no security
SOAP, WSDL, XSD
Java, JAXB, JPAOracle WebLogic
Oracle DB
GrailsOracle WebLogic
Internet Explorer
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Product framework
<complextype name=”SavingsAccountRequest”>…</complextype>
class SavingsAccountRequest {// fields// constraints}
<g:render template=”…”/>…
savingsAccountRequest/_show.gsp
class SavingsAccountRequest {// fields// getters and setters}
JAXB
manually
manually
<g:render template=”…”/>…
savingsAccountRequest/_edit.gsp
SavingsAccountRequest.java
SavingsAccountRequest.xsd
Product framework, types
SavingsAccountRequest.groovy
ISOMORPHIC
ISOMORP
HICISOMORPHIC
Specification
View
Model
DTO
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Product framework, objectsSavingsAccountRequest
Edit form
SavingsAccountRequest
Java (JAXB) object
SavingsAccountRequest
Grails object
bindData()
IsomorphicMapper
Back-endWeb service operation
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Product Framework, labels
BetaltPALSkatForegaaende5AarFoerUudnyttetPALSkat
Betalt PAL skat foregående 5 år før uudnyttet PAL skat
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Testing
• Unit tests in Spock
• Integration tests in Spock
• Automated GUI tests in Geb and Spock
Not surveying the Grails landscape
Spring WS plugin ?JSON RESTful API for GORM plugin ?Something else?
Therefore:• Look for third-party solutions• Invest in background knowledge
Backend
Business logic
Common Component
Portal Actor System
Internet Explorer
HTTPS
HTTPSHTTPSMQ
Common Component
Common Component
Business logic
Business logic
HTTPSMQ
Data base
Mistake!
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Believing that Groovy is just Java
Programmer quote:The biggest mistake was to think that you can just ”write Java in Groovy”. You end up getting the worst of both.
Lesson: Invest in learning Groovy.
Mistake!
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Not investing in education
Programmer quote:
The biggest mistake was lack of initial education, understanding and preparation for developing Grails applications.This can be due to a downside of another tool we are using: Scrum. The fact we had to deliver functionality a very short time after project start didn't leave time for proper education and understanding of the framework. We still have to live with code written at that time.
Lesson:• Invest in learning Grails.• Grow experts
Mistake!
Quote from grails.org:Build modern, sophisticated and robustGroovy web applications in record time!
Letting the consultant work aloneMist
ake!
Programmer quote:The biggest mistake was to let a consultant do all the difficult stuff alone, instead of acting as a consultant, and helping us do the the difficult stuff.
Lesson: Get an expert. Have him teach and coach. Do not let him work alone.
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Using Groovy on the back-end
• Groovy/Java interaction works fine
• Slow compilation• Long turn-around• Ungroovy code
Mistake!
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The biggest mistake
Not surveying the Grails landscapeBelieving that Groovy is just JavaNot investing in educationLetting the consultant work aloneUsing Groovy on the back-end
Mistake!
Letting the consultant work alone
page (#)
Happy notes
GrailsGroovySpockGebOnline resources and communityBooksProject enthusiasmProject benefits
Hooray!
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We chose Grails and Groovyfor a real-world project.
Was it wise?
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