Apache Sling is an innovative web framework built on top of the Java Content Repository (JCR), that uses OSGi for its component model and fosters RESTful application design. This talk shows how Sling integrates various standard-based technologies, like OSGi and the Content Repository API for Java to create a coherent framework for web application development. We will walk through the development of a simple application with minimal effort and demonstrate how to productize the resulting application. We will pay special attention to some approaches which are not yet part of mainstream development, such as using OSGi for dependecy injection and JCR for persistence.

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Effective Web Application Development with Apache Sling
Effective Web Application Development
with Apache Sling
Robert Munteanu, Adobe Systems
CodeCamp Iași 2016

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Agenda
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What is Apache Sling?
●
Content-Driven/RESTful applications
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What can Sling do for me?
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Demo
●
Wrap-up

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What is Apache Sling?
●
What is Apache Sling?
●
Content-Driven/RESTful applications
●
What can Sling do for me?
●
Demo
●
Wrap-up

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Modular

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RESTful

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Serve

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Library?

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Application Server?

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It’s Apache Sling!

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What is Apache Sling?
Content-Driven
RESTful applications
Modularity
Less @Magic,
Fewer @Suprises
Open Source

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History
2007
Incubation
2009
TLP
2015
Version 8
200x
Pre-Apache

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Code statistics

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Content-driven, RESTful applications
●
What is Apache Sling?
●
Content-Driven/RESTful applications
●
What can Sling do for me?
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Demo
●
Wrap-up

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What is a content-driven application?

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What is a not a content-driven application?
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HTTP proxy for anonymity
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Bitcoin miners
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Stock exchange trading

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What does a content-driven application consist of?
Data Code

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What is a resource?
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The smallest individually addressable unit
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Minimally has a name
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Key-value for properties
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Optionally has a parent
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Optionally has a child

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What is a resource?
GET /news/sling/release-8.html HTTP/1.1

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Resources – Blog post
/posts/hello_world.html
Title : Hello, world
Body: ...
Author [/users/admin]
Publish date: 2016-01-01T23:00:00Z
Comments [/comments/hello_world/resources]
Images [/comments/hello_world/assets]

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Resources – User
/users/admin.json
Name: admin
Last logged in: 2012-05-13T12:00:00Z
Enabled: false

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Resources – Image
/assets/cat_laser_pointer.jpg
Name: Cat following laser pointer. LOL!
Media type: image/jpeg
Contents: <binary>
Thumbs: [/assets/cat_laser_pointer/renditions]

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Serving content – Controller-driven
@GetMethod
@AtLocation(“/users/{name}.html”)
public byte[] handleUser(String
name) { … }
map “users”
map “articles” as “news”
GET “images”

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Serving content – Controller-driven
WelcomeController
/
UserController
/users
ArticleController
/articles

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Serving content – resource-driven

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Serving content – resource-driven
/ [sling:redirect]
content [my/site/listing]
news [my/site/listing]
sling-launchpad-8 [my/site/article]
sling-ide-tooling-11 [my/site/article]
assets [sling:Folder]
sling_logo.png [nt:file]

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What can Sling do for me?
●
What is Apache Sling?
●
Content-Driven/RESTful applications
●
What can Sling do for me?
●
Demo
●
Wrap-up

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Persistence using JCR

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Modularity with OSGi
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The solution we chose for modularity and services
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Comes with lots of add-ons:
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Eventing
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Administrative console
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Configuration
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Hot deployment
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etc
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Forces application to handle the “real-world”
dynamics
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Easy configuration using annotations

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Pluggable repositories
JCR
MongoDB
Couchbase
Filesystem

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Pluggable authentication
Oauth
Form
Oak
External
e.g. LDAP
Basic HTTP

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Templating engines

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Others …
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Caching
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Eventing
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Logging
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Health Checks
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XSS protection
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Validation

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Developer Tools

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Deployment options

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Deployment Topologies - Standalone
Sling + Oak
Segment NodeStore
HTTP Frontend
(httpd, varnish, nginx, etc )

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Deployment Topologies
HTTP Frontend
(httpd, varnish, nginx, etc )
Sling + Oak
Document NodeStore
MongoDB
Sling + Oak
Document NodeStore

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Adminstrative web console

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Adminstrative web console

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Adminstrative web console

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Adminstrative web console

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Demo
●
What is Apache Sling?
●
Content-Driven/RESTful applications
●
What can Sling do for me?
●
Demo
●
Wrap-up

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Resources
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https://sling.apache.org
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https://jackrabbit.apache.org/oak/
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http://www.slideshare.net/rombertw/
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@rombert