The document discusses using Grails for developing an enterprise telecom application. It describes the application and deployment environment, how Grails improved development productivity, and key plugins and techniques used. Grails enabled faster development through GORM and scaffolding. AST transformations and custom components further improved code readability and maintainability. While there were frustrations with Grails, overall the developers found Groovy and Grails empowering and were enthusiastic about the technology.

1. Grails EE
Ivo Houbrechts
Ixor

2. About myself
▸ Ivo Houbrechts
▸ Belgium
▸ Grails user and plugin developer
▸ ivo.houbrechts@ixor.be
2

3. About Ixor
▸ Since 2002
▸ 40 experienced ICT professionals
▸ Software development for the JVM
▸ Consultancy and product development
▸ Loyal customers in Finance, Telecom and
Government
3

4. Agenda
▸ Grails as part of Java EE
▸ Enterprise telco app
▸ Development environment
▸ Development productivity
▸ Plugins
▸ Conclusions
4

5. Agenda
▸ Enterprise telco app
▸ Development environment
▸ Development productivity
▸ Plugins
▸ Conclusions
4

6. Enterprise application
5

7. The application
▸ Order intake and customer care
– used by call center and dealers
– 1000 users
▸ 75 tailored screens
– complex compositions
6

8. Deployment
▸ ESB backend
– SOAP web services
– no direct database access
– domain defined in XSD’s
– Spring / JAXB (code generation)
▸ Weblogic 10 cluster
7

9. Development environment
8

10. To Grails or not to Grails
▸ Spring MVC + Freemarker
– no components
– (almost) no IDE support
▸ project behind schedule
➭ speed up with Grails
9

11. To Grails or not to Grails
▸ Spring MVC + Freemarker
– no components
– (almost) no IDE support
?
▸ project behind schedule
➭ speed up with Grails
9

12. Build
▸ Multi module Maven project
–Command line Grails
• Mix Ivy and maven dependency resolution
• CI agents need both Maven and Grails
• Improved maven support in Grails 2.1
–9 modules
• JAXB / WS
• AST
• Grails inline plugins
• Grails war, ear, config resources
10

13. Development team
▸ 2 scrum teams, 14 developers
▸ Groovy / Grails experience is rare
▸ Learning curve
– 2 weeks self study
– dynamic language
– Intellij IDEA
▸ Vast majority enthusiastic
11

14. Development productivity
12

15. Modularization
▸ (inline) plugin system
▸ plugins are standalone apps
– views, web.xml, bootstrap, spring beans, url mappings...
▸ reuse across applications
▸ plugin compilation time
– Grails 2 binary plugins
13

16. AST transformations
▸ Compiler plugin
▸ Rather complex
▸ Only for framework developers?
14

17. AST transformations
▸ Compiler plugin
▸ Rather complex
14

18. AST example 1
BillingType getBillingType() {
return data.customer.customerBillingInfo.customerBillType
}
void setBillingType(BillingType billingType) {
data.customer.customerBillingInfo.customerBillType =
billingType.data
}
15

19. AST example 1
BillingType getBillingType() {
return data.customer.customerBillingInfo.customerBillType
}
void setBillingType(BillingType billingType) {
data.customer.customerBillingInfo.customerBillType =
billingType.data
}
@PropertyDelegate('customer.customerBillingInfo.customerBillType')
BillingType billingType
15

20. AST example 2
private productOffering
ProductOffering getProductOffering() {
if (!productOffering) {
productOffering = ProductCatalog.get(ProductOffering,
data.typeInfo.productOfferingId)
}
return productOffering
}
16

21. AST example 2
private productOffering
ProductOffering getProductOffering() {
if (!productOffering) {
productOffering = ProductCatalog.get(ProductOffering,
data.typeInfo.productOfferingId)
}
return productOffering
}
@ProductCatalog('typeInfo.productOfferingId')
ProductOffering productOffering
16

22. AST example 3
List<ContactInfo> getContactInfoList() {
List<ContactInfo> result = []
for (contactInfo in data.customer.contactInfoList.contactInfo) {
result << contactInfo.createNewWrapperInstance()
}
return result
}
void clearContactInfoList() {
data.customer.contactInfoList.contactInfo.clear()
}
void addToContactInfoList(ContactInfo contactInfo) {
data.customer.contactInfoList.contactInfo << contactInfo.data
}
void addAllToContactInfoList(List<ContactInfo> contactInfoList) {
for (contactInfo in contactInfoList) {
addToContactInfoList(contactInfo)
}
}
void removeFromContactInfoList(ContactInfo contactInfo) {
data.customer.contactInfoList.contactInfo.remove(contactInfo.data)
}
17

23. AST example 3
List<ContactInfo> getContactInfoList() {
List<ContactInfo> result = []
for (contactInfo in data.customer.contactInfoList.contactInfo) {
result << contactInfo.createNewWrapperInstance()
}
return result
}
void clearContactInfoList() {
data.customer.contactInfoList.contactInfo.clear()
}
void addToContactInfoList(ContactInfo contactInfo) {
data.customer.contactInfoList.contactInfo << contactInfo.data
}
void addAllToContactInfoList(List<ContactInfo> contactInfoList) {
for (contactInfo in contactInfoList) {
addToContactInfoList(contactInfo)
}
}
void removeFromContactInfoList(ContactInfo contactInfo) {
data.customer.contactInfoList.contactInfo.remove(contactInfo.data)
}
@PropertyDelegate('customer.contactInfoList.contactInfo')
List<ContactInfo> contactInfoList
17

24. AST summary
▸ AST transformation code: 800 lines
– Java
– Groovy in separate module
▸ But:
– 200+ domain classes
– 1000+ usages
– ~10K lines omitted
– improved readability!
18

25. UI components
▸ Version 1
– 12 screens
– html tags in GSPs
– Example: first name edit field
19

26. UI components 2.0
▸ Version 2
20

27. UI components 2.0
▸ Version 2
20

28. UI components
▸ Html in GSPs becomes problematic
– huge GSPs
– virtual impossible to change look and feel
– inconsistent development
➭ custom tags / components with documented
API
21

29. UI components
22

30. UI components
22

31. UI components
▸ Reusable Grails plugin with kitchen sink
▸ 65 components
– Form row
– Input
– Layout (section, box, buttons, links ...)
– Ajax
– Behavior (autocomplete, menu, toggle ...)
23

32. UI components
▸ Grails tag
– documented component API, code completion
– ideal for logic
– not suited for markup:
def box = { attrs, body ->
out << “<div class=”box $clazz>”<div class=”boxHeader”>”
out << attrs.header << “</div><div class=”boxBody”>”
out << body()
out << “<div>”
}
24

33. UI components
▸ tmpl namespace
– markup in GSP
– simple to use
– no documented API, no code completion, etc.
▸ render template from tag
– markup in GSP
– documented API, code completion, etc.
– maintenance hell
25

34. UI components
▸ GSP taglib plugin
– simple to use
– documented API, code completion, etc.
– tags in taglib directory
– generated xxxTagLib.groovy
26

35. UI components
▸ GSP taglib plugin
– simple to use
– documented API, code completion, etc.
– tags in taglib directory
– generated xxxTagLib.groovy
26

36. Plugins
27

37. Rich domain validation
▸ Validation for non-Grails domain classes
– web services
– deep nested objects
– limited build-in support
▸ Extended validation
– cascaded validation
– partial validation
– constraint groups
– instance validation
28

38. Rich domain validation
class OrderItem {
... ▸ Validation for non-Grails domain classes
static web services = {
– constraints
– deep nested objects
//instance constraint
– limited build-in support
forbiddenAtLineLevel(validator: {
...
}) Extended validation
▸
– cascaded validation
//constraint group
– partial validation
characteristicsOnly {
– constraint groups
characteristics(cascade: true)
instance validation
–childOrderItems(cascade:
[excludes:'forbiddenAtLineLevel']])
}
}
}
orderItem.validate(groups: [“characteristicsOnly”],
includes: [“*.delivery”],
28 excludes: [...])

39. 29

40. order.validate(groups: [“deliveryInformation”])
29

41. Rich domain DI
▸ DI for non-Grails domain classes
– @Inject, @Resource
– auto wiring at object initialization and de-serialization
– move logic from controllers to domain classes
▸ see http://livesnippets.cloudfoundry.com
@RichDomain
class Customer {
@Inject
transient CustomerWebService customerWebService
...
}
30

42. Geb
▸ In-browser functional tests
▸ Maintainable tests
– Pages / Modules
▸ Test javascript and (partial) css
– Ajax timing issues
31

43. Webflow
▸ Indispensable for
– wizards
– page flows
▸ see http://livesnippets.cloudfoundry.com
32

44. Resources
▸ Organize javascript and css
– jawr
– less css
▸ Grails 2.0 : resources plugin
33

45. Conclusions
34

46. Developer experience
▸ Frustrations
– Build
– debugger
– Runtime vs compile time errors
– Grails upgrades
▸ Satisfaction
– Groovy power
– Convention over configuration
– Fun
▸ Generally enthusiastic
35

47. Developer experience
▸ Frustrations
– Build
– debugger
– Runtime vs compile time errors
– Grails upgrades
▸ Satisfaction
– Groovy power
– Convention over configuration
– Fun
▸ Generally enthusiastic
35

48. Development cost
▸ Fast kickoff with Grails
– GORM
– Scaffolding
▸ Short term development cost
– Determined by domain complexity
– Technology is minor factor
▸ Long term benefits
– Code size
– Code readability
36

49. Development cost
▸ Fast kickoff with Grails
– GORM
– Scaffolding
▸ Short term development cost
– Determined by domain complexity
– Technology is minor factor
▸ Long term benefits
– Code size
– Code readability
36

50. Development cost
▸ Fast kickoff with Grails
– GORM
– Scaffolding
▸ Short term development cost
– Determined by domain complexity
– Technology is minor factor
▸ Long term benefits
– Code size
– Code readability
36

51. Development cost
▸ Fast kickoff with Grails
– GORM
– Scaffolding
▸ Short term development cost
– Determined by domain complexity
– Technology is minor factor
▸ Long term benefits
– Code size
– Code readability
36

53. ?
38