introducing scalate, the scala template engine

Copyright © 2010 Progress So3ware Corpora6on and/or its subsidiaries or affiliates. All rights reserved. A Progress So3ware Company

A Progress So3ware Company

ScalateIntroducing the Scala Template EngineJames Strachan, FuseSource

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Thursday, June 16, 2011


Your presenter is: James Strachan

James Strachan• [email protected]• twi1er: @jstrachan• blog: h1p://macstrac.blogspot.com/

So3ware Fellow at FuseSource long term Open Source contributor

• created Apache Camel• created the Groovy programming language• co-‐founder of–Apache Ac6veMQ, Camel, ServiceMix, Fabric, ...–Scalate

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mailto:[email protected]

mailto:[email protected]

http://macstrac.blogspot.com

http://macstrac.blogspot.com

FuseSource sponsors projects at the Apache So3ware Founda6on


FuseSource -‐ experts in open source integra6on and messaging

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CXF

ActiveMQ

Camel

ServiceMix

JAX-WS, WS-*, RESTfor Web and Restful Integration

Enterprise Messaging,multi platform and language support,

JMS,STOMP,AMQP1.0,Highly available and fault tolerant

Enterprise Integration Patterns framework

Enterprise Service Bus,distributed,clustered, OSGi, JBI

Karaf OSGi based container, supporting multiple archive types, remote

management, dynamic configuration, extensible shell



Some recommended books...



Agenda

scala and mescalate overviewgeQng startedQ & A

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Scala and me

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Scalate Overview

its a Scala based Template Engine• Scala T E => scalate

h1p://scalate.fusesource.org/

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http://scalate.fusesource.org



Design Goals

make an awesome template engine • framework & container agnosJc

support different template flavours under same API• there isn’t really a one size fits all

reuse the power & type safety of Scala• catch errors in templates at edit/build Jme– templates are for life, not just for Christmas!

• IDE friendly for smart compleJon

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Features

Templates are compiled & cached as fast Scala objects

Template objects are staJcally typed to catch typos• apart from Mustache

Scalate is equivalent to the combinaJon of JSP, JSTL, JSP EL & SiteMesh/Tiles• Scala replaces JSP EL and Scala funcJons replace JSP custom tags

• Scalate template languages are richer, more powerful & usually more DRY than JSP + JSTL

• Scalate has in built layout support replacing SiteMesh/Titles

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How Scalate works

TemplateEngine is used to load Templates• typically templates are converted into scala code and compiled to avoid runJme parsing

• can customize various things...– caching & reloading– how URIs are resolved (classpath, file system etc)

– interna6onalisa6on

RenderContext is used to render a template• has a Map[String,Any] like set of a1ributes for passing/sharing state

• loads of helper methods for use inside the template– localisa6on, including other templates, views, layouts etc

template languages implemented using Scala parser generators

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Scalate Template Languages

SSP

Scaml

Jade

Mustache

Scuery

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SSP

SSP “Scala Server Pages” • like a non-‐sucky JSP :)

easiest template engine to start with if folks know• ASP, JSP, GSP, Erb, Velocity, FreeMarker style templates

supports JSP / Erb style syntax • <% statements %>

• <%= expression %>

• ${expression}

examples:• Dear ${people.map(_.name).mkString(“, “)} how are you?

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SSP also supports Velocity style tokens

#if (lineItems.find(_.price > 10).isDefined)

<b>Welcome big spender!</b>

#end

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Scaml

Scaml is a Scala port of HAML• HAML started in the Rails world and became a very popular alternaJve to Erb templates

• whitespace sensiJve (which is handy for markup, avoids badly nested markup)

• uses %foo to indicate <foo>...</foo>

• -‐ for statements

• = expressions

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Jade

Jade out in JavaScript / Rails worlds as a simpler more DRY version of HAML / Scaml • avoid the % to indicate element name– folks tend to use lots of elements; few are mul6-‐line text content

• use | to indicate text content inside an element when mulJple lines required

• Implemented as just a slightly different surface parser on Scaml

Jade + markdown are the hotness!

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Mustache

no logic in the scripts

can be used from JavaScript on the client side or Scala / Scalate on the server side

uses {{foo}} mustaches for values

use {{#foo}} and {{/foo}} for blocks/loops/condiJonals

good if you want your designer to own the templates• though dynamically typed

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Scuery

more of a HTML/XHTML transformaJon engine really

uses CSS3 parser & transformaJon engine

templates are regular HTML pages (possibly with mock data) owned by your designer

use the transform API (jQuery-‐ish) to transform the HTML to inject/replace with dynamic data

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Tips on picking a template language

If you want your designers to own your templates• consider mustache or scuery

if you want developers to hack your templates• want to generate HTML/XML really DRY? – use jade

• otherwise SSP

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Scalate Layouts

TemplateEngine.layoutStrategy defines the strategy

default implementaJon uses the “layout” a1ribute to define the template used for laying out any template

to change the layout you want to use...• -‐ a1ributes(“layout”) = “/my/layouts/foo.jade”

to disable layouts• -‐ a1ributes(“layout”) = “”

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Using Scalate

can use TemplateEngine directly if doing code generaJon

in web applicaJons add this to your web.xml <filter> <filter-name>TemplateEngineFilter</filter-name> <filter-class>org.fusesource.scalate.servlet.TemplateEngineFilter</filter-class> </filter> <filter-mapping> <filter-name>TemplateEngineFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>

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http://web.xml

http://web.xml


Framework support

bowler

jersey

lit

playframework

scalatra

servlets

sbt / lity

spring mvc

unfiltered

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mod your TemplateEngine!

package scalate

import org.fusesource.scalate.TemplateEngineimport java.io.File

class Boot(engine: TemplateEngine) {

def run: Unit = { // lets change the workingDirectory engine.workingDirectory = new File("myScalateWorkDir") }}

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Precompile your templates

<build> <plugins> <plugin> <groupId>org.fusesource.scalate</groupId> <artifactId>maven-scalate-plugin</artifactId> <version>1.5.0</version> <executions> <execution> <goals> <goal>precompile</goal> </goals> </execution> </executions> </plugin> </plugins></build>

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GeQng Started

install Scalate• h1p://scalate.fusesource.org/download.html

• add SCALATE_HOME/bin to your PATH

scalate create jersey mygroup myarJfact

cd myarJfact

mvn je1y:run

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http://scalate.fusesource.org/download.html

http://scalate.fusesource.org/download.html


Sta6c site genera6on

maven plugin to generate a complete staJc website for your project using Scalate

deploy it to some web server using maven’s wagon transports• scp / webdav etc

allows real Jme updates of templates & layouts while ediJng docs

your own personal offline wiki using git for source control & versioning• use a text editor to edit, erm, text files! :)

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Demo 6me!

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Demo templates & web app here:hhps://github.com/scalate/scalate/tree/master/samples/scalate-‐example


https://github.com/scalate/scalate/tree/master/samples/scalate-example


















Any Ques6ons?

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twiher: @jstrachan

hhp://fusesource.com

h1p://scalate.fusesource.org/











introducing scalate, the scala template engine

Technology

so3ware fellow

scala funcjons

sitemeshtiles scala

scala code

agenda scala

template localisa6on

template engine scala

mustache scalate