(1) erocci is a model-driven REST framework that implements the OCCI standard to build scalable REST APIs and services in an extensible way. (2) It is designed to reduce code and improve scalability by relying on the OCCI meta-model and using the Erlang programming language and OTP framework. (3) Example use cases include building REST backends for applications, exposing existing APIs through REST interfaces, and protocol adapters like translating between a resource-oriented protocol and HTTP/OCCI.

1. erocci
A scalable model-driven REST framework
Jean Parpaillon <jean.parpaillon@free.fr>
November 5th, 2014 erocci - Jean Parpaillon 1

2. REST API : a user point of view
November 5th, 2014 erocci - Jean Parpaillon 2

3. REST API : a user point of view
Data format
JSON format
XML format
Scalar data types (string, integer, float, etc)
Data access protocol
Filtering
Sorting
Pagination
Authnz (tokens, etc), return codes, etc.
Finally...
Application level : data types (structures, relations, etc)
November 5th, 2014 erocci - Jean Parpaillon 3

4. REST API : a user point of view
Data format
Schémas ?
JSON format
XML format
Scalar data types (string, integer, float, etc)
Data access protocol
Filtering
Sorting
Pagination
Authnz (tokens, etc), return codes, etc.
Finally...
One to rule them all ?
A single meta-model ?
Application level : data types (structures, relations, etc)
November 5th, 2014 erocci - Jean Parpaillon 4

5. Let's speak about a standard ?
November 5th, 2014 erocci - Jean Parpaillon 5

6. Let's speak about a standard for REST
A standard
Is not a catalog of schemas
Is not a constraint for developers
Must be implemented (implementable)
A good standard
Should allow to concentrate on the design, not the
implementation details
Allow to build an ecosystem
Allow to accelerate the development, not the contrary
November 5th, 2014 erocci - Jean Parpaillon 6

7. The Open Cloud Computing Interface
OCCI is typed
A ressource is an instance of a kind
A kind is a named list of typed attributes and actions
e.g. : compute : # cores (integer), RAM (float), etc
Attribute : name, type, default value, mutability, etc.
Action : an invocable operation on a ressource
Kinds are inheritable
November 5th, 2014 erocci - Jean Parpaillon 7

8. The Open Cloud Computing Interface
OCCI is extensible
Resource can be associated with mixins
Mixin: a named set of additional attributes and actions
e.g. : IPNetworkInterface adds IP, netmask, etc to a
network interface
User Mixin : aka « tags »
e.g. : http://example.com/occi/mixins#my_project1
November 5th, 2014 erocci - Jean Parpaillon 8

9. The Open Cloud Computing Interface
OCCI is relational
Links are ressources with additional attributes
occi.core.source : resource URI
occi.core.target : URI
A bounded collection is a list of ressources of the same
kind/mixin :
e.g. : GET /collections/compute/
An unbounded collection is a list of ressources with
same prefx :
e.g. : GET /myresources/
November 5th, 2014 erocci - Jean Parpaillon 9

10. The Open Cloud Computing Interface
OCCI is self-described
GET /-/ (capabilities)
List of supported kinds
List of supported mixins
Capabilities returns collection's URL
http://schemas.ogf.org/occi/infrastructure#compute →
/collections/compute/
November 5th, 2014 erocci - Jean Parpaillon 10

11. The Open Cloud Computing Interface
OCCI is meta-model based
Model consistency checking
Automatic model implementation
Rendering independant
text/plain, application/json, …
Transport independant
HTTP, ...
November 5th, 2014 erocci - Jean Parpaillon 11

12. OCCI Ecosystem
Framework
rOCCI (ruby)
occi4java (not maintained)
Specifc implementations
CompatibleOne
PyOCNI
OpenStack, OpenNebula,
etc
Limits
Models are
language/extensions/lib
dependant
See
http://occi-wg/community/
implementations/
Tools
DoYouSpeakOcci : tests
Monitoring (Intel)
November 5th, 2014 erocci - Jean Parpaillon 12

13. Why erocci ?
Generic : a framework to build OCCI applications
Less code, more design
Small, tested, reliable
Easy to deploy
Scalable
Runs embedded in connected objects (IoT)
Scales out to serve millions of users
Extensible
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14. Architecture
November 5th, 2014 erocci - Jean Parpaillon 14

15. Genericity
Only OCCI meta-model is hard-coded
Everything is pluggable :
Authentication mechanism
Transport protocol (HTTP, XMPP, etc)
Data sources (backends)
Allow composition of services by plugging data
sources (backends) at runtime
November 5th, 2014 erocci - Jean Parpaillon 15

16. Less code, more design
A schema for ressources' categories (kinds, mixins)
ACL-based authorizations
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17. Small, tested, reliable
Small
Around 12k lines
Tested
Continuous integration
Reliable
Erlang cowboy web server (LeoFS, MongooseIM, etc)
erlang/OTP platform provides fault tolerance
Process supervision
November 5th, 2014 erocci - Jean Parpaillon 17

18. Easy to deploy
All included erlang/OTP platform
Self contained : no web frontend
Just try it !
November 5th, 2014 erocci - Jean Parpaillon 18

19. Scalable
Thanks to erlang/OTP
Runs on RaspberryPI (~ 100 req/sec)
Scales out to a full cluster
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20. Extensible
Pluggable mechanisms
For those who don't like erlang
D-Bus backend API (experimental)
November 5th, 2014 erocci - Jean Parpaillon 20

21. (1) use case : a REST backend for blog
No need for ORM, web server, database, templating,
etc.
Design your model
Blog entry kind
User kind
Contribution kind (link between a user and an entry)
Choose a storage backend
Choose a transport (HTTP?)
Defnes ACL
And that's all
November 5th, 2014 erocci - Jean Parpaillon 21

22. (2) use case : API adapter
Backend API : write a new data source for your API
Erlang API
D-Bus API (any language)
In any case, implements CRUD operations
Choose a transport
Enjoy scalability, supervision, transports, ACL, etc.
November 5th, 2014 erocci - Jean Parpaillon 22

23. (3) use case : a protocol adapter
You have a resource oriented protocol and want to
expose it through HTTP/OCCI
Use occi_store for storing your data
erocci deals with storage, rendering, scalability, ...
November 5th, 2014 erocci - Jean Parpaillon 23

24. Roadmap
Authn/authz
x509 based authn
oauth
occi_store
Optimizations
Integrate authnz,
pagination (wip)
XMPP
Enable pubsub
(notifcations)
New storage backends
Riak (wip)
ODBC (SQL)
…
Testing
Improve functional tests
Improve unit testing
November 5th, 2014 erocci - Jean Parpaillon 24

25. Eco-system : OCCIware
(1) consortium
Research, industry, standardization
(3) pillars
Theory : proven meta-model (OCCI)
Design : Eclipse-based tools
Runtime : erocci, …
(*) use cases
IaaS, PaaS, SaaS, IoT, ...
Every RESTful services
November 5th, 2014 erocci - Jean Parpaillon 25

26. Resources
Website (WIP)
http://erocci.ow2.org/
Source code
http://github.com/erocci/erocci
Continuous integration
https://travis-ci.org/jeanparpaillon/erocci
Mailing lists
erocci-dev@ow2.org / erocci-info@ow2.org
November 5th, 2014 erocci - Jean Parpaillon 26

27. Thanks !
Questions ?
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