The document discusses the architecture and features of Apache Sling, a content-centric web framework used for managing content and applications. It outlines the different types of content management systems (CMS), the roles of Java Content Repository (JCR), and how Sling utilizes its capabilities for content delivery. The agenda includes definitions of CMS, content-centric design principles, and practical demonstrations of Sling's functionalities.

1. Webmardi - 07.07.2015
at Lausanne

2. Content-centric web
architectures
Case study : Apache Sling

3. Fabrice HongMatthieu CornutTitouan Galopin
AEM team AEM team

4. Agenda
1. What is a CMS?
2. Content-centric design
3. Sling content delivery
4. How Sling uses the JCR
5. Demo

5. 1.What is a CMS?

6. Content
Management
System

7. Editable by the author
=
Not managed by developer

8. The aim: let the author
manage as much things
as possible

9. What is really editable
by the author?

10. The minimal CMS

11. The minimal CMS
Editable pages
Content edition

12. The minimal CMS
Editable pages
Content edition
id title body date
1 Accueil Bienvenue ... 07-07-15
... ... ... ...

13. The classical CMS

14. The classical CMS
Editable pages organised
in categories
Content organisation

15. The classical CMS
Editable pages organised
in categories
Content organisation
id parent title body date
1 NULL Accueil Bienvenue! 07-07-15
2 1 Sous-page ... 07-07-15

16. The enterprise CMS

17. The enterprise CMS
Editable types of content
Content type composition

18. The enterprise CMS
Editable types of content
Content type composition
Implementation ? Hum ...

19. The ideal way: nodes
Most generic storage method

21. when to use it ?
2. Content-centric design

22. structure
data
Who is the leader ?
structure
data

25. Back to IT
Predefine the structure Let the structure emerge
or

26. Ask yourself
Is it known in advance ?
● The final result
● The evolution
o consumers
o the interface
o the scale

27. Caching - ajax injection
Caching - SSI
CDN Caching - ajax injection
Add servers
Thin / Thick client
CDN Caching - ESI
! page loading, SEO
! dev env.
! business logic, SEO
! server price
Visitor number
Visitor location
Interactivity
Slow Backend
integration
Evolutions Solutions Down sides

28. moreover, conditions are constantly
evolving...
The right balance is not
easy to choose

29. STRUCTURE FIRST in an
impredictible ecosystem
or, how should we extend the house ?

31. DATA FIRST can be ambivalent

32. Apache Sling
a content-centric web framework

33. Some history about Apache Sling
● Initially : internal framework powering CQ5 (WCMS from Day Software)
● 2007 - Donated to Apache Software foundation
● 2009 - Graduated as Apache top level project
● 2010 - Day Software aquired by Adobe. CQ5 renamed to AEM
● Sling still used by AEM

34. Java Content Repository (JCR)
Stack
Apache Sling
Java Runtime Environement
Servlet Engine App Server (optional)
OSGIFramework
CMS App
Apache Felix
Apache
Jackrabbit

35. And how you *should* leverage it
3. How Sling uses the JCR

36. Before all : some specs

37. A CMS data structure
Hierarchies can store nearly every logic in a natural and readable way

38. JCR features
“Content Repositories are the best of
databases and file systems”
JCR 1.0 : JSR-170
JCR 2.0 : JSR-283

39. How do Sling uses the JCR ?

40. title
author
news list content
navigation
footer
edit
Example : online newspaper website

41. Services
Controller
Templates
Url
Mapping
Url
Mapping
● Mapping news?id=23 -> newsController
● Get / store content from database
● Map content to template vars
● Select template
● CRUD
● Access Control Management
● Versioning
Services
Controller
Templates
DatabaseDatabase
Server
Static
Standard web framework
Web
Client
In Sling, it will be entirely in database

42. Typical content
● Page organisation
● Internal page structure
● Authoring content

43. But also:
Validation rules
Rendition scripts Jobs
Java

44. The answer to life, the universe and
everything
The JCR
In a Sling application :
● Externalize what does not require java skills
o rapid testing / developing / demos
o visualisation (in opposition to JAR content)
● Leverage JCR features

45. Practical for development
news-list
news1
news2
Filesystem
mappable ● Human readable
● IDE friendly
● VCS friendly

46. JCR (Apache Jackrabbit)
And Sling ?
Apache Sling
Java Runtime Environement
Servlet Engine App Server (optional)
OSGIFramework
CMS App
events, search, versioning, access control
?

47. How a Sling application *should* interact
with the JCR ?
4. Sling Content Delivery

48. Services
Controller
Templates
Url
Mapping
Url
Mapping
Services
Controller
Templates
Database
Server
Static logic
Standard webapp
Web
Client
Database

49. Server
Web
Client
REST API
binding
Sling idea
Java Content Repository (JCR)
REST:
● CRUD ops. for each nodes
○ GET, POST, PUT, DELETE
● Cacheable
● Stateless / scalable
Templates /
ComponentsContent

50. Server
Web
Client
REST API
binding
Sling idea
Java Content Repository (JCR)
Templates /
ComponentsContent
Content first !
website/news.jsp?id=341
website/news/webmardi/2015_07_07-sling.html

51. How to write in database ?
<form method="POST">
<input type="text" name="title"/>
<input type="text" name="content"/>
<input type="submit" name="save"/>
</form>
Security ? Binding Logic ?
Access
Control
Management
Event
observation
Servlet / Filters
OSGI
Services
● REST force server side simplicity
● Boilerplate layers replaced by safeguards
● Everything that is externalized in JCR is interoperable

52. The client chose the
representation

53. content
news-list
news1
news2
components
news
news.jsp
.content.xml
title
contentof type
refers
Server
news-list/news2.html
news-list/news2.small.html
Content representation
small.jsp
Web
Client
path selector extension (additional discriminator for servlet)
Sling rendering resolution

54. news.esp
<div class="newsTitle">
<%= currentNode.title %>
</div>
<div>
<div class="newsContent">
<%= currentNode.content %>
</div>
<% sling.include("./author", "replaceSelectors=quickLink") %>
</div>

55. Scriptable in
● JSP
● ESP
● Groovy
● Ruby
● Velocity

56. More resilient to external
evolution ?

57. Caching - ajax injection
Caching - SSI
CDN Caching - ajax injection
Add servers
Thin / Thick client
CDN Caching - ESI
! page loading, SEO
! dev env.
! business logic, SEO
! server price
Visitor number
Visitor location
Interactivity
Slow Backend
integration
Evolutions Solutions Down sides

58. Component inclusion
newsList
news1
news2
Application Server Web Server
CDN
other content
Switzerland
Cache
China
Application includes Server side includes Ajax includes
ajax or html include
ajax or html include

59. Conditions for ambivalence
Must be flexible on:
where components are included
how to the components is represented
content-centric -> independence of components :
each component is responsible for loading its data and dependencies
newsList/news1.html
newsList/news1.json
newsList/news1.small.html

60. Extreme example
Sling Dynamic Include allows to switch dynamically
between :
● Server side include
● Edge side include
● Ajax include

61. 5. Demo

62. Summary
● Structure first or Data first
o One shot project / Evolutive system
o relation with agilty ?
● Go along with the technology
o leverage JCR features
o leverage sling REST approach