Walk-through a true story of developing a Grails web application from the ground up. some tips and how to guides for those of you who want to start developing on Grails or are using Grails and would like to learn from other experience.

2. Grails – from scratch to
production
How we build successful application
Tal Maayani
November 2013

3. Agenda
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About the lecturer
Choosing the technology: Grails vs…
Common pitfalls
Development methodologies
Continuous Integration
Q&A

4. Choose the right technology
• Project type: self service web application with a rich back office
• Project roadmap: workflow, many integrations with external
vendors, analytic, payments
• Timeline: start development within a short period, full power development
within 3 months, production within 6 months
• Budget
• Available in-house skillset
 Requires fast web development framework like Spring
,Play, Rails, Grails, Django

5. Comparing between alternatives
Feature
Grails
Rails
Language
Groovy - JVM based
Ruby - Interpreter based
Approach
Domain oriented
Database oriented
Thread support
Native
Poor
Hardware requirements
Requires more memory, and
strong CPU
mediocre memory and CPU
Learning Curve
Fast for a java developers
operates in Database model
Maturity
Less Mature (Founded at 2008)
More mature (Founded at 2004)
Scalability
Offer good scalability
Lack scalability
Libraries
Offers all java based libraries
No java libraries
longer than Grails since Rails

6. Why we chose Grails?
• Build on known technologies that we already used
• Spring, Hibernate, Tomcat, Quartz
• Fast development
• Scaffolding , Smart reloading, Hundreds of plugins (~1000), groovy
• MVC web application
• Domain, GSP, Controller

7. Common Grails pitfalls
• Writes java in groovy
experts
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 Use outsource grails
Difficult debugging (comparing to java)
 More logging
Maintaining data model
 Liquibase
Groovy dynamic nature
 Test everything
Some plugins are unstable
 Smart use of plugins
Highly hardware demands
 Use strong machines

8. Groovy Ecosystem
Spoke
Gradle
Grails
Junit
Build framework
RAD Platform
Gpars
Gaelyc
Muti-threading
Toolkit for GAE
EasyB
Codenarc
GContract
Griffon
Static code
Analysis
Design by contract
BDD
Swing UI
And many more …

9. Development process
Highlights
• Holistic thinking:
• production deployment, performance, testing, interfaces
• Lean development
• Development of only what is required
• Test on production like environment
• System test as soon as possible
• Learn from mistakes

10. Grails Plugins
Recommendations
• Do not blind use plugins
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Plugins dependencies and footprint considerations
Performance consideration (startup overhead)
Write your own set of plugins (configuration, health check, authentication, taglibs)
Maintain up to date plugin
• JS wrapper plugins (Jquery, bootstrap) –
• Not always up to date and maintained
•  sometimes it is preferable to copy the js library instead of using the plugin

11. Plugins that we used
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In house development
Spring web flow – state machine for managing flows
aws – enable use of amazon via grails service
Cache, zipped resources
Less-css
Spring security
Quartz
Yammer metrics

12. AWS Configuration Loader Plugin
• Enable the use of external configuration file for per environment
settings
• Server name, performance tuning, etc.
• Receive configuration file
• Local file – for development
• S3 URL – when running on amazon. Use access and secret keys.
• How it works?
• Copy the external configuration file locally and merge config.groovy

13. Liquibase Plugin
• Use when
• You are using relational DB on production
• Have a frequent schema changes
• Major functionality
• Keep record of every db schema change, use DSL to record these
changes
• Enforce object model & DB match (using MD5)
• Allows to have business logic (in groovy) to support migrations

14. Liquibase Plugin – cont.
• Drawbacks (for 1.3.6 and below)
• Maintenance
• Do not use per environment configuration in datasource.groovy
• Extension
• Allow running any sql script in change set
For example: Quartz schema

15. Health Check
• Get report for instance health
• Access to various data sources (MySQL, Mongo, Oracle)
• Access to other components
• Triggered from monitoring system
• Report generated ad hoc
• Implemented in grails plugin
• Building block per access point

16. Working with Amazon
EC2 vs. Elastic Beanstalk
Capability
EC2
Beanstalk
Configuration
Management
Flexible, can run scripts on
instance build, deployments.
Can use CM like chef or puppet
Use prebuild AM with given
configuration. Can use limited Yml
script for customization
Monitoring, Load
Balancing, Auto
scaling
Need to configure
Automatically defined
Application
management
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Manage logs, environment
configuration, versions, externalize
configuration properties
Stopping
environment
Environment can be stopped
Environment cannot be stopped
Deployment
Custom script
AWS API call

17. Continuous Integration
Using Amazon
 Dev. commits
 Build server run unit tests
 Build server deploy war to dev integration environment
 Build server deploy war to amazon QA environment
Build server triggered Selenium to run subsystem test against QA
War is ready (PSP)

18. KPI Measurements
• Define a set of goals that measures success
• Total # of users, abandonment rate, conversion rate
• Define measurements tools
• Systematically and periodically measure
• Learn from the results