Scala for Sling. Building RESTful Web Applications with Scala for Sling. LOGO SPEAKER S COMPANY

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1 Scala for Sling Building RESTful Web Applications with Scala for Sling Michael Dürig Day Software AG LOGO SPEAKER S COMPANY

2 AGENDA 2 > Introduction > What is Apache Sling? > What is Scala? > Scala for Sling > Summary and questions

3 Introduction 3 > Michael Dürig Developer for Day Software > Michael Marth Technology Evangelist for Day Software

4 Overview 4 > What to expect Proof of concept Experimental code > What not to expect Product showcase, tutorial Live coding (demo code available from > Prerequisites Basic understanding of Java content repositories (JCR) Prior exposure to Scala a plus

5 AGENDA 5 > Introduction > What is Apache Sling? > What is Scala? > Scala for Sling > Summary and questions

6 Sling builds on JCR 6 > Web application framework for JCR JCR (JSR-170/JSR-283): Apache Jackrabbit OSGi-based: Apache Felix > Scriptable application layer for JCR JSR-223: Scripting for the Java platform > REST over JCR Content resolution for mapping request URLs to JCR nodes Servlet resolution for mapping JCR nodes to request handlers (i.e. scripts)

7 URL decomposition 7 GET /forum/scala4sling.thread.html

8 URL decomposition 8 GET /forum/scala4sling.thread.html Repository

9 URL decomposition 9 GET /forum/scala4sling.thread.html Repository Repository path

10 URL decomposition 10 GET /forum/scala4sling.thread.html Repository Repository path Application selection

11 URL decomposition 11 GET /forum/scala4sling.thread.html Repository Repository path Script selection Application selection

12 AGENDA 12 > Introduction > What is Apache Sling? > What is Scala? > Scala for Sling > Summary and questions

13 Scala builds on the JVM 13 > Multi-paradigm language for the JVM Conceived by Martin Odersky and his group (EPFL, Lausanne) Fully interoperable with Java IDE plugins for Eclipse and IntelliJ IDEA > Concise, elegant, and type safe Touch and feel of a genuine scripting language Smoothly integrates object oriented and functional features Great for creating DSLs

14 Type inference: the scripting touch 14 > Values val x = 42 // x has type Int val s = x.tostring // s has type String val q = s.substring(s) // type mismatch; found String, required Int > Type parameters class Pair[S, T](s: S, t: T) def makepair[s, T](s: S, t: T) = new Pair(s, t) val p = makepair(42.0, "Scala") // p has type Pair[Double, String]

Type inference: the scripting touch 15 > Values

found String, required Int public final S s;

s, T t) { super(); class Pair[S, T](s: this.

t S, t: = t; T) = new Pair(s, t) val p =

0, "Scala") // p has type Pair[Double, String]

15 Type inference: the scripting touch 15 > Values val x = 42 // x has type Int val s = x.tostring // s has type String val q = s.substring(s) class Pair<S, // T> type { mismatch; found String, required Int public final S s; public final T t; > Type parameters public Pair(S s, T t) { super(); class Pair[S, T](s: this.s S, t: = T) s; def makepair[s, T](s: this.t S, t: = t; T) = new Pair(s, t) val p = makepair(42.0, "Scala") // p has type Pair[Double, String] public <S, T> Pair<S, T> makepair(s s, T t) { return new Pair<S, T>(s, t); public final Pair<Double, String> p = makepair(42.0, "Scala");

16 XML <pre>literals</pre> 16 > HTML? Scala! val title = "Hello Jazoon 09" println { <html> <body> <h1>{ title </h1> { (for (c <- title) yield c).mkstring(" ") </body> </html>

17 XML <pre>literals</pre> 17 > HTML? Scala! val title = "Hello Jazoon 09" println { <html> println { <body> Elem(null, "html", Null, TopScope, <h1>{ title Elem(null, </h1> "body", Null, TopScope, { Elem(null, "h1", Null, TopScope, (for (c <- title) Text(title) yield c) </body> </html>.mkstring(" ), ") ) ) Text( (for (c <- title) yield c).mkstring(" ") )

18 XML <pre>literals</pre> 18 > HTML? Scala! val title = "Hello Jazoon 09" println { <html> <body> <h1>{ title </h1> { (for (c <- title) yield c).mkstring(" ") </body> </html> <html> <body> <h1>hello Jazoon 09</h1> H e l l o J a z o o n 0 9 </body> </html>

19 Implicits: pimp my library 19 > Implicit conversion implicit def translate(s: String) = new { def togerman = s match { case "Example" => "Beispiel" //... case _ => throw new Exception("No translation for " + s) val german = "Example".toGerman > Déjà vu? Similar to extension methods in C# Similar to conversion constructors in C++ Equivalent to type classes in Haskell

20 Objects are functions are objects 20 > Object as function object Twice { def apply(n: Int) = 2*n println(twice(21)) // prints 42 > Function as object def twice(n: Int) = 2*n val doubler = twice(_) println(doubler(21)) // prints 42

21 AGENDA 21 > Introduction > What is Apache Sling? > What is Scala? > Scala for Sling > Summary and questions

22 Demo application: Forum 22

23 Forum: html.scala 23 package forum { object html { import html_bindings._ //... println { <html> <body> Welcome to the { currentnode("name") forum { Calendar.getInstance.getTime { ThreadNewForm.render { ThreadOverview.render(currentNode) </body> </html>

$Forum: html.scala 24 package forum { object html { import html_bindings._ //... GET /forum.$

24 Forum: html.scala 24 package forum { object html { import html_bindings._ //... GET /forum.html println { <html> <body> Welcome to the { currentnode("name") forum { Calendar.getInstance.getTime { ThreadNewForm.render { ThreadOverview.render(currentNode) </body> </html>

25 Forum: html.scala 25 package forum { object html { import html_bindings._ //... Put Sling variables into scope (currentnode, request, response, etc.) println { <html> <body> Welcome to the { currentnode("name") forum { Calendar.getInstance.getTime { ThreadNewForm.render { ThreadOverview.render(currentNode) </body> </html>

26 Forum: html.scala 26 package forum { object html { import html_bindings._ /** //... * Print out an object followed by a new line character. x the object to print. */ println { def println(x: Any): Unit = out.println(x) <html> <body> Welcome to the { currentnode("name") forum { Calendar.getInstance.getTime { ThreadNewForm.render { ThreadOverview.render(currentNode) </body> </html>

$Forum: html.scala 27 package forum { object html { import html_bindings._ /** //... * Print out an object followed by a new line character. * @param x the object to print.$

27 Forum: html.scala 27 package forum { object html { import html_bindings._ /** //... * Print out an object followed by a new line character. x the object to print. */ println { def println(x: Any): Unit = out.println(x) <html> <body> Welcome to the { currentnode("name") forum { Calendar.getInstance.getTime { ThreadNewForm.render { ThreadOverview.render(currentNode) </body> </html>

28 Forum: html.scala 28 package forum { object html { import html_bindings._ // implicit... def rich(node: Node) = new { def apply(property: String) = node.getproperty(property).getstring... println { <html> <body> Welcome to the { currentnode("name") forum { Calendar.getInstance.getTime { ThreadNewForm.render { ThreadOverview.render(currentNode) </body> </html>

29 Forum: thread overview 29 object ThreadOverview { // imports omitted def render(node: Node) = emptyunless(node.hasnodes) { <h1>threads</h1> <ul>{ node.nodes map tolistitem </ul> private def tolistitem(node: Node) = { <li> { node("subject") (<a href={ node.path + ".thread.html">show thread</a>) </li>

30 Forum: thread overview 30 object ThreadOverview { def emptyunless(condition: Boolean)(block: => NodeSeq) = // imports omitted if (condition) block else Empty def render(node: Node) = emptyunless(node.hasnodes) { <h1>threads</h1> <ul>{ node.nodes map tolistitem </ul> private def tolistitem(node: Node) = { <li> { node("subject") (<a href={ node.path + ".thread.html">show thread</a>) </li>

31 Forum: form data 31 object ThreadNewForm { def render = { <h1>start a new thread</h1> <form action="/content/forum/*" method="post" enctype="multipart/form-data"> subject <input name="subject" type="text" /> <textarea name="body"></textarea> logo <input name="logo type="file" /> <input type="submit" value="save" /> <input name=":redirect" value="/content/forum.html" type="hidden" /> </form>

32 Forum: form data 32 object ThreadNewForm { def render = { <h1>start a new thread</h1> <form action="/content/forum/*" method="post" enctype="multipart/form-data"> subject <input name="subject" type="text" /> <textarea name="body"></textarea> logo <input name="logo type="file" /> <input type="submit" value="save" /> <input name=":redirect" value="/content/forum.html" type="hidden" /> </form>

33 Forum: form data 33 object ThreadNewForm { def render = { <h1>start a new thread</h1> <form action="/content/forum/*" method="post" enctype="multipart/form-data"> POST should add new child node to /content/forum/ subject <input name="subject" type="text" /> <textarea name="body"></textarea> logo <input name="logo type="file" /> <input type="submit" value="save" /> <input name=":redirect" value="/content/forum.html" type="hidden" /> </form>

34 Forum: form data 34 object ThreadNewForm { def render = { <h1>start a new thread</h1> <form action="/content/forum/*" method="post" enctype="multipart/form-data"> String, POST should add new child node to /content/forum/... with properties subject and body of subject <input name="subject" type="text" /> <textarea name="body"></textarea> logo <input name="logo type="file" /> <input type="submit" value="save" /> <input name=":redirect" value="/content/forum.html" type="hidden" /> </form>

35 Forum: form data 35 object ThreadNewForm { def render = { <h1>start a new thread</h1> <form action="/content/forum/*" method="post" enctype="multipart/form-data"> String, POST should add new child node to /content/forum/... with properties subject and body of subject <input name="subject" type="text" />... and a child node logo of type nt:file. <textarea name="body"></textarea> logo <input name="logo type="file" /> <input type="submit" value="save" /> <input name=":redirect" value="/content/forum.html" type="hidden" /> </form>

Forum: form data 36 object ThreadNewForm { def render = { <h1>start a new thread</h1> <form action="/content/forum/*" method="post" enctype="multipart/form-data"> subject <input name="subject"

36 Forum: form data 36 object ThreadNewForm { def render = { <h1>start a new thread</h1> <form action="/content/forum/*" method="post" enctype="multipart/form-data"> subject <input name="subject" type="text" /> <textarea name="body"></textarea> logo <input name="logo type="file" /> <input type="submit" value="save" /> <input name=":redirect" value="/content/forum.html" type="hidden" /> </form> Redirect to forum.html on success

37 Extracting form fields 37 > Sling post servlet No action required: used by default Creates nodes and properties for form fields Tweaked with hidden form fields Sensible defaults > Custom POST request handler Write a script POST.scala Process form fields in code Full control over request processing

38 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ // val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", logo.getinputstream) session.save response.sendredirect(request(":redirect"))

39 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ //... POST /forum.html 39 val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", logo.getinputstream) session.save response.sendredirect(request(":redirect"))

$Forum: custom POST request handler package forum { object POST { import POST_Bindings._ //... Add node for this post 40 val node = addnodes(session.root, newpath) node.$

40 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ //... Add node for this post 40 val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", logo.getinputstream) session.save response.sendredirect(request(":redirect"))

41 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ //... Set properties for body and subject val node = addnodes(session.root, newpath) 41 node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", logo.getinputstream) session.save response.sendredirect(request(":redirect"))

42 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ // val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", logo.getinputstream) session.save response.sendredirect(request(":redirect")) If the request contains a logo

43 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ // val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", logo.getinputstream) session.save response.sendredirect(request(":redirect")) If the request contains a logo... add a child node logo of type nt:file

$Forum: custom POST request handler package forum { object POST { import POST_Bindings._ //... 44 val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.$ addnode("jcr:content", "nt:resource") jcr:mimetype and jcr:data val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.

44 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ // val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") jcr:mimetype and jcr:data val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", logo.getinputstream) session.save response.sendredirect(request(":redirect")) If the request contains a logo... add a child node logo of type nt:file... and set properties jcr:lastmodified,

45 Forum: custom POST request handler package forum { object POST { import POST_Bindings._ // val node = addnodes(session.root, newpath) node.setproperty("body", request("body")) node.setproperty( subject", request( subject")) if (request("logo")!= "") { val logonode = node.addnode("logo", "nt:file") val contentnode = logonode.addnode("jcr:content", "nt:resource") val logo = request.getrequestparameter("logo") contentnode.setproperty("jcr:lastmodified", Calendar.getInstance) contentnode.setproperty("jcr:mimetype", logo.getcontenttype) contentnode.setproperty("jcr:data", Save changes and send logo.getinputstream) redirect session.save response.sendredirect(request(":redirect"))

46 Forum: unit testing 46 object html_bindings extends MockBindings { override def currentnode = new MockNode with MockItem override def request = new MockSlingHttpServletRequest with MockHttpServletRequest with MockServletRequest object Test extends Application { forum.html

$Forum: unit testing 47 object html_bindings extends MockBindings { override def currentnode = new MockNode with MockItem override def$

47 Forum: unit testing 47 object html_bindings extends MockBindings { override def currentnode = new MockNode with MockItem override def request = new MockSlingHttpServletRequest with MockHttpServletRequest with MockServletRequest object Test extends Application { forum.html

48 Forum: unit testing 48 object html_bindings extends MockBindings { override def currentnode = new MockNode with MockItem override def request = new MockSlingHttpServletRequest with MockHttpServletRequest with MockServletRequest object Test extends Application { forum.html

$Forum: unit testing object html_bindings </head> extends MockBindings { override def currentnode = new MockNode with MockItem override def <p>search request all = threads: new$

49 Forum: unit testing object html_bindings </head> extends MockBindings { override def currentnode = new MockNode with MockItem override def <p>search request all = threads: new MockSlingHttpServletRequest object Test extends Application { forum.html <html> <head> <link href="/apps/forum/static/blue.css" rel="stylesheet"></link> <body> <div id="header"> Welcome to the forum Wed Jun 17 17:12:48 CEST 2009 </div> <div id="menu"> <form action="/content/forum.search.html" enctype="multipart/form-data" with MockHttpServletRequest method="get"> <input value="" type="text" size="10" name="query"></input> with MockServletRequest <input value="search" type="submit"></input> </form> </p> </div> <div id="content"> <h1>start a new thread</h1> <span id="inp"> <form action="/content/forum/*" enctype="multipart/form-data" method="post"> <p>subject</p> <p><input type="text" name="subject"></input></p> <p><textarea name="body"></textarea></p> <p>logo</p> <p><input type="file" name="logo"></input></p> <p><input value="save" type="submit"></input></p> <input value="/content/forum.html" type="hidden" name=":redirect"></input> </form> </span> </div> </body> </html> 49

50 AGENDA 50 > Introduction > What is Apache Sling? > What is Scala? > Scala for Sling > Summary and questions

51 Conclusion 51 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) > Disadvantages IDE support shaky, improves quickly though Not much refactoring support as of today

52 Conclusion 52 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) > Disadvantages IDE support shaky, improves quickly though Not much refactoring support as of today

Conclusion 53 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) <p>welcome to { currentnode("name") forum</p> { Calendar.

53 Conclusion 53 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) <p>welcome to { currentnode("name") forum</p> { Calendar.getInstance.getTime { ThreadNewForm.render { ThreadOverview.render(currentNode) > Disadvantages IDE support shaky, improves quickly though Not much refactoring support as of today

54 Conclusion 54 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) > Disadvantages IDE support shaky, improves quickly though Not much refactoring support as of today

55 Conclusion 55 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) > Disadvantages IDE support shaky, improves quickly though Not much refactoring support as of today

56 Conclusion 56 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) > Disadvantages IDE support shaky, improves quickly though Not much refactoring support as of today object html_bindings { def currentnode = new MockNode... object Test extends Application { forum.html

57 Conclusion 57 > Advantages Scala! No language boundary Tool support (i.e. IDE, ScalaDoc, safe refactoring, unit testing) > Disadvantages IDE support shaky, improves quickly though Not much refactoring support as of today

58 Summary 58 > Apache Sling Great for building RESTful web applications Pluggable scripting support (JSR-223) > Scala Great for scripting Supports «on the fly» templates through XML literals Easy unit testing

59 Michael Dürig Michael Marth Day Software AG References: Scala for Sling: The Scala programming language: Apache Sling: LOGO SPEAKER S COMPANY

Rapid JCR applications development with Apache Sling

Rapid JCR applications development with Apache Sling Bertrand Delacrétaz Senior R&D Developer, Day Software, www.day.com Member and Director, ASF bdelacretaz@apache.org blog at http://grep.codeconsult.ch