OSGi Community Event 2014 Abstract: Let's say you need to provide an internet service to your users. Chances are that your service should be available via REST. Let's say your service should both provide data to users as well as accept data posted by users, and possibly some logic. Now let's assume your service turns out to become incredibly popular, with lots and lots of users. Sounds like you need Sling and OSGi in the cloud. In this talk Carsten and David will go through the OSGi and Sling architecture to achieve this. The talk outlines how the OSGi Cloud Ecosystems RFC is used in combination with Apache jclouds to achieve vendor independence. It also discusses how automatic scaling depending on measured load is achieved to ensure responsiveness. The resulting system is a dynamic cloud application handling any REST API, which can scale up and down depending on the need. Speaker Bios: David Bosschaert David Bosschaert works for Adobe Research and Development. He spends the much of his time on technology relating to OSGi in Apache and other open source projects. He is also co-chair of the OSGi Enterprise Expert Group and an active participant in the OSGi Cloud efforts. Before joining Adobe, David worked for Red Hat/JBoss and IONA Technologies in Dublin, Ireland. Carsten Ziegeler Carsten Ziegeler is senior developer at Adobe Research Switzerland and spends most of his time on architectural and infrastructure topics. Working for over 25 years in open source projects, Carsten is a member of the Apache Software Foundation and heavily participates in several Apache communities including Sling, Felix and ACE. He is a frequent speaker on technology and open source conferences and participates in the OSGi Core Platform and Enterprise expert groups.

1. Creating a REST API for Cloud services using OSGi and Sling
Carsten Ziegeler and David Bosschaert
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2. Speakers
● David Bosschaert (davidb@apache.org)
– R&D Adobe Research Dublin
– Co-chair OSGi EEG
– Open-source and cloud enthusiast
● Carsten Ziegeler (cziegeler@apache.org)
– R&D Adobe Research Switzerland
– OSGi Board, CPEG and EEG member
– ASF member
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Agenda
●A REST site
with Apache Sling
●Scale it up!
with OSGi and jclouds

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5. Te Next Great Application
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

6. ROA and REST
● htp://…/products.jsp?id=5643564
● htp://…/slingshot/slingshot1/public/travel/pet.(html|json)
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7. Resource Oriented Architecture
● Every piece of information is a resource
● User home, category, item, image, comment
● Descriptive URI
● Stateless web architecture (REST)
● Request contains all relevant information
● Targets the resource
● Leverage HTTP
● GET for rendering, POST/PUT/DELETE for operations
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

8. SlingShot Content Structure
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
/
slingshot1 slingshot2
public
travel
home pet
images comments ratings
pet.jpg

9. Resource-frst Request Processing
● Request: /slingshot1/public/travel/pet/comments.10.json
● Resource: /slingshot1/public/travel/pet/comments
● Extension: json
● Selector: 10
● Method: GET
● Resource Type : slingshot/comments
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

10. Resource-frst Request processing
1. Resolve the resource
2. Resolve processing script
3. Build execution chain
4. Execute
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

11. Scripting Inside
● It’s your choice
● JSP, servlet, ESP, Scala, Sightly
● javax.script
● own script handlers
● Default servlets
● JSON, XML
● POST/update/create/delete handling
● Error handling
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

12. © 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
<sling:defineObjects/>
<div class="comment">
<%
final ValueMap attr = resource.getValueMap();
final String title = attr.get(PROPERTY_TITLE,
resource.getName());
final String description = attr.get(PROPERTY_DESCRIPTION, "");
final String userId = attr.get(PROPERTY_USER, "");
%>
<h4><%= ResponseUtil.escapeXml(userId) %> :
<%= ResponseUtil.escapeXml(title) %></h4>
<p><%= ResponseUtil.escapeXml(description) %></p>
<p><%= ResponseUtil.escapeXml(
attr.get(SlingshotConstants.PROPERTY_CREATED, "")) %></p>
</div>

13. Resource Providers
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
/
slingshot1
public
travel
home pet
images comments ratings
pet.jpg
MongoDB
FS
JCR
Apache Jackrabbit

14. Scale UP!
● Efectively use the cloud
● Scale up/down based on need
● start small = cheap
● No downtime
● when moving to larger machines
● No cloud-provider specifcs
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

15. Sling
OOSSGGii NNooddee
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
28/10/14
Sling in the cloud
Load Balancer(s)
OOSSGGii NNooddee
Sling
Director
traffic

16. OOSSGGii NNooddee
Sling
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
Sling
28/10/14
Director
OOSSGGii NNooddee
Sling
Director
provision
inspect
discover
OOSSGGii NNooddee
Sling
OOSSGGii NNooddee
jclouds
create
destroy
mmeettrriiccss
OSGi Cloud Ecosystems (RFC 183)
FrameworkNodeStatus Service

17. Sling
OOSSGGii NNooddee
Sling
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
28/10/14
Busy times
Load Balancer(s)
OOSSGGii NNooddee
Sling
Director
traffic
OOSSGGii NNooddee
OOSSGGii NNooddee
Sling

18. Sling
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
28/10/14
Quiet times
Load Balancer(s)
OOSSGGii NNooddee
Director
traffic

19. Sling Sling
Sling Sling
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28/10/14
Really Quiet times
Load Balancer(s)
OOSSGGii NNooddee
Director
Docker
instances

20. Summary
● Use Sling to build your REST service
● Write your app using anything that can interact with REST
● Native app
● Javascript
● …
● Use OSGi Cloud Ecosystems, Apache jclouds and Docker to scale
● Be cloud-vendor independent!
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

21. Interested in OSGi and Cloud?
● Come to the OSGi Cloud Workshop
Wednesday October 29 at 15:15 (Seminarräume 1-3)
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.

22. Innovation at Adobe
© 2014 Adobe Systems Incorporated. All Rights Reserved. Adobe Confdential.
22
Links
● Apache Sling – htp://sling.apache.org
● Apache jclouds – htp://jclouds.apache.org
● SlingShot Sample application – htp://svn.apache.org/repos/asf/sling/trunk/samples/slingshot
● OSGi Cloud Ecosystems RFC 183 – htps://github.com/osgi/design/tree/master/rfcs/rfc0183

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