Eclipse tips: tasks Productive developer tips: technical debt Web applications Grails Twitter application: step 1

1. Groovy: Efficiency Oriented Programming
Lecture 9
Master Proteomics & Bioinformatics - University of Geneva
Alexandre Masselot - summer 2011

2. Contents

3. Contents
‣ Eclipse tips: tasks

4. Contents
‣ Eclipse tips: tasks
‣ Productive developer tips: technical debt

5. Contents
‣ Eclipse tips: tasks
‣ Productive developer tips: technical debt
‣ Web applications

6. Contents
‣ Eclipse tips: tasks
‣ Productive developer tips: technical debt
‣ Web applications
‣ Grails

7. Contents
‣ Eclipse tips: tasks
‣ Productive developer tips: technical debt
‣ Web applications
‣ Grails
‣ Twitter application: step 1

8. Eclipse tips

9. Eclipse tips
‣ Annotate code with tasks

10. Eclipse tips
‣ Annotate code with tasks
‣ TODO / FIXME

11. Eclipse tips
‣ Annotate code with tasks
‣ TODO / FIXME
‣ Add comments into your code
void mutate(){
//TODO check that mutation **does** modify position
board.piecesPositions[
randomGenerator.nextInt(board.maxPieces)] =
[
randomGenerator.nextInt(board.size),
randomGenerator.nextInt(board.size)
]
}

12. Eclipse tips (cont’d)

13. Eclipse tips (cont’d)
‣ Lines is prefixed with an icon

14. Eclipse tips (cont’d)
‣ Lines is prefixed with an icon
‣ The task view

15. Technical debt

16. Technical debt
‣ Increasing the debt:
- poor code
- repeat in code/process (DRY)
- postponing refactoring
- skipping tests

17. Technical debt
‣ Increasing the debt:
- poor code
- repeat in code/process (DRY)
- postponing refactoring
- skipping tests
‣ Interest are expensive

18. Technical debt
‣ Increasing the debt:
- poor code
- repeat in code/process (DRY)
- postponing refactoring
- skipping tests
‣ Interest are expensive
‣ A common solution: use prototyping

19. What do you know about www?

20. A simple (static) web query

22. protocol

23. protocol server host

24. protocol server host resource path

26. 1 find the server (DNS)

27. 1 find the server (DNS)
2 pass the local resource requested

28. 1 find the server (DNS)
2 pass the local resource requested
3 server loads the resource to be served

29. 1 find the server (DNS)
2 pass the local resource requested
3 server loads the resource to be served
4 resource sent back to the browser (client)

30. 1 find the server (DNS)
2 pass the local resource requested
3 server loads the resource to be served
4 resource sent back to the browser (client)
5 browser interprets the response

31. 1 find the server (DNS)
2 pass the local resource requested
3 server loads the resource to be served
4 resource sent back to the browser (client)
5 browser interprets the response
6 browser loads additional resources (+ requests)

32. 1 find the server (DNS)
2 pass the local resource requested
3 server loads the resource to be served
4 resource sent back to the browser (client)
5 browser interprets the response
6 browser loads additional resources (+ requests)
7 browser displays results

34. Static is not alway enough
dynamic url queries

35. An action is performed on the server side
parameter are passed

37. action path

38. action path parameter(s)

39. action path parameter(s)
Instead of a static resource, the results is computed

40. Master your browser!
Today: firefox (idem for chrome, safari, ~IE)

41. View page source
(best inspiration is by copying others)

43. Install firebug & web developer add-ons

44. display loaded resources
firebug > network

45. static page

47. dynamic resource + interactions

49. More operations can be undertaken within page
But cycle query->server->rendering
is always respected

50. More operations can be undertaken within page
But cycle query->server->rendering
is always respected

51. Why using/building web based applications?

52. A script does not suit everyone (unfortunately)

53. Classic deploy: window based application

54. A web browser: a powerful GUI

55. A web transaction

56. A web transaction
‣ Url request
- http://host:8080/entry/show?ac=P12345&format=fasta

57. A web transaction
‣ Url request
- http://host:8080/entry/show?ac=P12345&format=fasta
‣ Action
- build the model

58. A web transaction
‣ Url request
- http://host:8080/entry/show?ac=P12345&format=fasta
‣ Action
- build the model
‣ View generation
- html contents creation

59. A web transaction
‣ Url request
- http://host:8080/entry/show?ac=P12345&format=fasta
‣ Action
- build the model
‣ View generation
- html contents creation
‣ Rendering

60. A web transaction
‣ Url request [browser]
- http://host:8080/entry/show?ac=P12345&format=fasta
‣ Action [server]
- build the model
‣ View generation [server]
- html contents creation
‣ Rendering [browser]

61. Groovy + web = Grails

62. Grails with STS eclipse

63. Grails with STS eclipse
‣ Help > dashboard > extensions > Grails

64. Grails with STS eclipse
‣ Help > dashboard > extensions > Grails
‣ Download Grails
- http://grails.org/Download

65. Grails with STS eclipse
‣ Help > dashboard > extensions > Grails
‣ Download Grails
- http://grails.org/Download
‣ Uncompress in local directory
- e.g. ~/local/grails-1.3.7

66. Grails with STS eclipse
‣ Help > dashboard > extensions > Grails
‣ Download Grails
- http://grails.org/Download
‣ Uncompress in local directory
- e.g. ~/local/grails-1.3.7
‣ Configure Grails in STS preferences
- possible to host multiple versions

67. Grails with STS eclipse
‣ Help > dashboard > extensions > Grails
‣ Download Grails
- http://grails.org/Download
‣ Uncompress in local directory
- e.g. ~/local/grails-1.3.7
‣ Configure Grails in STS preferences
- possible to host multiple versions
‣ Reference
- http://grails.org/doc/latest/

68. Grails with STS eclipse (cont’d)
‣ Configure shortcut for grails command prompt

69. Grails with STS eclipse (cont’d)
‣ Configure shortcut for grails command prompt
‣ Preference > keys
> open grails command prompt
- <ctrl> <alt> G
- (maybe need to deactivate another shortcut)

70. Grails with STS eclipse (cont’d)
‣ Configure shortcut for grails command prompt
‣ Preference > keys
> open grails command prompt
- <ctrl> <alt> G
- (maybe need to deactivate another shortcut)
‣ Calling grails command on selected project

71. STS: creating a new Grails application

72. STS: creating a new Grails application
‣ File > new
> Grails project

73. New Grails project structure

74. New Grails project structure
%PROJECT_HOME%
+ grails-app
+ conf ---> configuration artifacts
+ controllers ---> controller artifacts
+ domain ---> domain classes
+ i18n ---> message bundles for i18n
+ services ---> services
+ taglib ---> tag libraries
+ util ---> special utility classes
+ views ---> views
+ layouts ---> layouts
+ lib
+ scripts ---> scripts
+ src
+ groovy ---> other Groovy source files
+ test ---> generated test classes
+ web-app
+ WEB-INF ---> static documents

75. New Grails project structure
%PROJECT_HOME%
+ grails-app
+ conf ---> configuration artifacts
+ controllers ---> controller artifacts
+ domain ---> domain classes
+ i18n ---> message bundles for i18n
+ services ---> services
+ taglib ---> tag libraries
+ util ---> special utility classes
+ views ---> views
+ layouts ---> layouts
+ lib
+ scripts ---> scripts
+ src
+ groovy ---> other Groovy source files
+ test ---> generated test classes
+ web-app
+ WEB-INF ---> static documents

76. Launching the application
‣ Launch the server, either:
- Run As > Grails Command (run-app)
- <ctrl> <alt> G run-app↵
- command line (in the project folder): run-app

77. Launching the application
‣ Launch the server, either:
- Run As > Grails Command (run-app)
- <ctrl> <alt> G run-app↵
- command line (in the project folder): run-app
‣ Check console for messages

78. Launching the application
‣ Launch the server, either:
- Run As > Grails Command (run-app)
- <ctrl> <alt> G run-app↵
- command line (in the project folder): run-app
‣ Check console for messages
‣ With your browser:
- http://localhost:8080/eop.lec9.demo

80. url ➙ controller (action) ➙ render
1) write code for controller/action
2) write rendering (html page)

81. Create a controller

82. Create a controller
‣ Either:
-
- command line: create-controller foo.hello

85. New files and directories:
./grails-app/controllers/foo/HelloController.groovy
./test/unit/foo/HelloControllerTests.groovy
./grails-app/views/hello/

86. The controller/action code

87. HelloController.groovy
package foo
class HelloController {
def index = { }
}

88. HelloController.groovy
package foo
class HelloController {
def index = { }
}
‣ hello = controller

89. HelloController.groovy
package foo
class HelloController {
def index = { }
}
‣ hello = controller
‣ index = default action

90. HelloController.groovy
package foo
class HelloController {
def index = { }
}
‣ hello = controller
‣ index = default action
‣ Convention over configuration
grails-app/controllers/HelloController.groovy

91. Invoking the controller

92. Invoking the controller
http://localhost:8080/eop.lec9.demo/hello
http://localhost:8080/eop.lec9.demo/hello/index
‣ No rendering is defined yet:
HTTP Status 404 - /eop.lec9.demo/WEB-INF/grails-app/views/hello/index.jsp
type Status report
message /eop.lec9.demo/WEB-INF/grails-app/views/hello/index.jsp
description The requested resource (/eop.lec9.demo/WEB-INF/grails-app/views/hello/index.jsp) is not available.
Apache Tomcat/6.0-snapshot

93. Invoking the controller
http://localhost:8080/eop.lec9.demo/hello
http://localhost:8080/eop.lec9.demo/hello/index
‣ No rendering is defined yet:
HTTP Status 404 - /eop.lec9.demo/WEB-INF/grails-app/views/hello/index.jsp
type Status report
message /eop.lec9.demo/WEB-INF/grails-app/views/hello/index.jsp
description The requested resource (/eop.lec9.demo/WEB-INF/grails-app/views/hello/index.jsp) is not available.
Apache Tomcat/6.0-snapshot
problem:
we must define the view

94. A simple action
‣ Action = closure
class HelloController {
...
def directText = {
render "Hello World"
}
}

95. A simple action
‣ Action = closure
class HelloController {
...
def directText = {
render "Hello World"
}
}
‣ http://localhost:8080/eop.lec9.demo/hello/directText
Hello World

96. Another simple action

97. Another simple action
‣ Action = closure
class HelloController {
...
def withDate = {
def now = new Date()
render "Hello World at $now"
}
}

98. Another simple action
‣ Action = closure
class HelloController {
...
def withDate = {
def now = new Date()
render "Hello World at $now"
}
}
‣ http://localhost:8080/eop.lec9.demo/hello/withDate
Hello World at Mon May 03 02:38:03 CEST 2010

99. But raw test is soon a bit rough...

100. Enhanced web pages = dynamic html

101. Controller/action
➙ Model (data)
➙ GSP (view)

102. One action ↔ one GSP view

103. GSP by default
‣ One controller = one directory in grails-app/views
- foo.HelloController.groovy ➙ grails-app/views/hello/

104. GSP by default
‣ One controller = one directory in grails-app/views
- foo.HelloController.groovy ➙ grails-app/views/hello/
‣ One action = one .gsp file
- def index = {...} ➙ grails-app/views/hello/index.gsp

105. GSP by default
‣ One controller = one directory in grails-app/views
- foo.HelloController.groovy ➙ grails-app/views/hello/
‣ One action = one .gsp file
- def index = {...} ➙ grails-app/views/hello/index.gsp
‣ .gsp file:
- pure html
- dedicated tags
- model variables can be passed

106. A static gsp example
(content is always the same)

107. hello/index.gsp

108. hello/index.gsp
<html>
<head>
<title>Hello world index page</title>
</head>
<body>
<h1>Welcome to hello world</h1>
<ul>
<li><a href="/eop.lec9.demo/hello/directText">
simple text hello</a></li>
<li><a href="/eop.lec9.demo/hello/withDate">
text with date</a></li>
</ul>
</body>
</html>

109. Absolute path are not good practice
use grails tag instead
<g:link controller=”...” action=”...”>

110. hello/index.gsp

111. hello/index.gsp
<ul>
<li>
<g:link controller="hello" action="directText">
simple text hello
</g:link>
</li>
<li>
<g:link controller="hello" action="withDate">
text with date
</g:link>
</li>
</ul>

112. hello/index.gsp
<ul>
<li>
<g:link controller="hello" action="directText">
simple text hello
</g:link>
</li>
<li>
<g:link controller="hello" action="withDate">
text with date
</g:link>
</li>
</ul>
‣ Documentation:
http://grails.org/doc/latest/ ➙ tags

113. Dynamic gsp
content (model) is computed by the action

114. Passing data to the .gsp
‣ A new action returning map of values
def when = {
def now = new Date()
return [myTime:now]
}

115. Passing data to the .gsp
‣ A new action returning map of values
def when = {
def now = new Date()
return [myTime:now]
}
‣when.gsp
<body>
<h1>Current time is ${myTime}</h1>
We are <b>${myTime.seconds}</b> seconds past the
minute
<hr/>
<g:link controller="hello" action="index">
back home</g:link>
</body>

117. Getting parameters from the url

118. Passing arguments
‣http://.../hello/ago?nbdays=4

119. Passing arguments
‣http://.../hello/ago?nbdays=4
‣ Controller access parameters through map params
def ago = {
def now = new Date()
def d = now - (params.nbdays as Integer)
[currentTime:now, pastTime:d]
}

120. Passing arguments
‣http://.../hello/ago?nbdays=4
‣ Controller access parameters through map params
def ago = {
def now = new Date()
def d = now - (params.nbdays as Integer)
[currentTime:now, pastTime:d]
}
‣ago.gsp
Current time is ${currentTime}.
<br/>
It was ${pastTime}, ${params.nbdays} days ago

122. How to call an action with parameters?

123. Passing arguments statically

124. Passing arguments statically
‣Through the url
http://.../hello/ago?nbdays=4

125. Passing arguments statically

126. Passing arguments statically
‣ Within a <g:link> tag
<li>
<g:link controller="hello"
action="ago"
params="[nbdays:4]"
>4 days ago</g:link>
</li>

127. Let the user set a parameter: <form>

128. Passing arguments (cont’d)
‣ Within a user entered <form>
<g:form controller="hello" action="ago">
<!-- default value is the one
received from params.nbdays -->
<g:textField name="nbdays"
value="${params.nbdays}" />
<g:submitButton name="submit" value="new date"/>
</g:form>

129. Passing arguments (cont’d)
‣ Within a user entered <form>
<g:form controller="hello" action="ago">
<!-- default value is the one
received from params.nbdays -->
<g:textField name="nbdays"
value="${params.nbdays}" />
<g:submitButton name="submit" value="new date"/>
</g:form>
‣ The form is included here in the ago.gsp

130. Passing arguments (cont’d)
‣ Within a user entered <form>
<g:form controller="hello" action="ago">
<!-- default value is the one
received from params.nbdays -->
<g:textField name="nbdays"
value="${params.nbdays}" />
<g:submitButton name="submit" value="new date"/>
</g:form>
‣ The form is included here in the ago.gsp
‣ Could be in another gsp file (with a static default value)

131. Model - View - Controller