OSGi Community Event 2015 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.</p> Apache Sling is designed as a set of loosely coupled OSGi bundles aggregated into a single jar or war launcher. Extensibility is internally achieved by using OSGi services. Even though Sling was initially designed for JSR-283 content repositories, building on top of the OSGi service registry allows plugging in multiple data sources - resource providers in Sling parlance. In this talk we will showcase the usage of OSGi extension points in Apache Sling which allows usage of multiple resource providers, from simple filesystem-based providers to complex ones like MongoDB or Cassandra. Running all providers at the same time allows Apache Sling to be used as a REST-based middleware for multiple data sources. This talk will present how this extensibility allows plugging in multiple data sources.

1. http://robert.muntea.nu @rombert
Apache Sling as a RESTful API gateway for your NoSQL datastores
Apache Sling as a RESTful API gateway
for your NoSQL datastores
Robert Munteanu, Adobe Systems
EclipseCon Europe 2015

2. http://robert.muntea.nu @rombert
Who I am

$DAYJOB

Adobe Experience
Manager
 Apache Sling
 Apache Jackrabbit
 Apache Felix

FOSS

Apache Sling

MantisBT

Mylyn Connector for
MantisBT

Mylyn Connector for Review
Board

3. http://robert.muntea.nu @rombert
Agenda
●
Quick facts and figures
●
Meet Barry
●
Demo
●
Why is Sling such a good fit for an API gateway
●
Conclusions, Resources, Q&A

4. http://robert.muntea.nu @rombert
Apache Sling - History
2007
Incubation
2009
TLP
2015
Version 8
200x
Pre-Apache

5. http://robert.muntea.nu @rombert
High-level View of the Code
Source: OpenHub

6. http://robert.muntea.nu @rombert
Level of activity
Source: OpenHub
Source: status.apache.org

7. http://robert.muntea.nu @rombert
Conceptual foundations
REST-based
Content-driven
OSGi-powered
Scripting InsideApache

8. http://robert.muntea.nu @rombert
REST-based
/content/blog/
/content/blog/{0}.html
/
BlogViewController
BlogListController
HomeController
SlingMainServlet
/
/content
/content/blog
/content/blog/hello-world

9. http://robert.muntea.nu @rombert
REST-based
/
/content
/content/blog
/content/blog/hello-world
[sling/redirect]
[sling/redirect]
[blog/welcome]
[blog/page]

10. http://robert.muntea.nu @rombert
Barry – Senior Buzzword Deliverer

11. http://robert.muntea.nu @rombert
Demo time!

12. http://robert.muntea.nu @rombert
How is everything mapped?
/ ( root )
/content/blog/comments
/content/blog/posts
/content/blog/images

13. http://robert.muntea.nu @rombert
How does Sling manage this?
ResourceProvider
JCR NoSQL FS
Couchbase MongoDB
ResourceProviderFactory
Produces

14. http://robert.muntea.nu @rombert
SPI → API
ResourceProviderFactory
OSGi Service Registry
ResourceResolver
Registers Gets

15. http://robert.muntea.nu @rombert
ResourceResolver
Resource getResource(String path);
Iterable<Resource> getChildren(Resource parent);
Iterator<Resource> findResources(String query,
String language);
Resource create(Resource parent, String name,
Map<String, Object> properties) throws
PersistenceException;
void delete(Resource resource) throws
PersistenceException;
void commit() throws PersistenceException;

16. http://robert.muntea.nu @rombert
How do I get to handle a Resource?
1 GET /content/blog/posts/hello_world.json
2 ResourceResolver.resolve(...)
3 ServletResolver.resolveServlet(...)3
4 servlet.doGet(...)

17. http://robert.muntea.nu @rombert
What do clients see out of this?
Resource res = request.getResource();
// 1. reading ...
ValueMap properties = ↵
res.getValueMap();
String title = properties.get(“jcr:title”,↵
“Missing”);
Post post = res.adaptTo(Post.class);
title = post.getTitle();

18. http://robert.muntea.nu @rombert
Why do we need adaptTo?
Adaptable
Resource ValueMap
Map<String,Object> Post

19. http://robert.muntea.nu @rombert
What do clients see out of this?
Resource res = request.getResource();
// 2. writing ...
ValueMap properties = ↵
res.adaptTo(ValueMap.class);
String title = properties.put(“jcr:title”,↵
“Hello, world”);
Post post = res.adaptTo(Post.class);
post.setTitle(“Hello, world”);
res.getResourceResolver().commit();

20. http://robert.muntea.nu @rombert
Demo time!

21. http://robert.muntea.nu @rombert
Oh, but there's more

22. http://robert.muntea.nu @rombert
More features
●
Eventing, Thread Pooling, Job Management,
Caching
●
Scripting: Groovy, Scala, JSP, Sightly, Java, Ruby,
Thymeleaf
●
Flexible resource rendering with resource types
●
Very extensible due to being internally powered
by OSGi – most extension points available to clients

23. http://robert.muntea.nu @rombert
Beyond the NoSQL datastores

24. http://robert.muntea.nu @rombert
Buzzword checklist
✔
RESTful
✔
API gateway
✔
NoSQL
✔
OSGi

25. http://robert.muntea.nu @rombert
Resources
●
Apache Sling – http://sling.apache.org
●
Sling NoSQL providers -
http://sling.apache.org/documentation/bundles/no
sql-resource-providers.html
●
Apache Jackrabbit Oak -
http://jackrabbit.apache.org/oak/

26. http://robert.muntea.nu @rombert
Resources