The document discusses how the technologies developed in the ROLE project for building personal learning environments using widgets could potentially contribute to and integrate with the Apache Rave project. It provides background on ROLE and describes several ROLE technologies, including the ROLE sandbox for widget development, APIs for inter-widget communication and managing linked data resources, and efforts to support real-time collaboration using XMPP. It suggests areas of overlap between ROLE and Rave and invites the Apache community to explore opportunities for collaboration between the two projects.

1. ROLE Technologies –
A possible contribution to Apache Rave?
Dominik Renzel Sten Govaerts
Chair of Computer Science 5 Department of Computer Science
Advanced Community Information Systems (ACIS) Katholieke Universiteit Leuven, Belgium
RWTH Aachen University, Germany
Apache Hackathon
June 13, 2012, Utrecht, Netherlands
This work by Dominik Renzel is licensed under a
Creative Commons Attribution-ShareAlike 3.0 Unported.
© www.role-project.eu

2. ROLE Background & Motivation

Currently happening: significant shift in education
 From passive lectures to interactive (online) group work
 Online learning tools cherry-picked or handcrafted by educators & learners
 DIY motto “create, disassemble, repurpose“ applied to educational products
 Learners & educators create mash-up learning apps, lessons & processes
 More collaboration, personalization, freedom, effectiveness
 ROLE: Inherent DIY support using widget-based Personal Learning
Environments
© www.role-project.eu

3. ROLE Vision
• Empower learners to build their
ROLE Vision own responsive learning
environments
Responsiveness
• Awareness and reflection of own
learning process
User-Centered
• Individually adapted composition
of personal learning environment
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4. ROLE Technologies – How to sustain?
?
?
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5. The ROLE Sandbox (role-sandbox.eu)
 Public installation of ROLE SDK for development & testing purposes
 ROLE Reference Container for Widget-based PLE
Space
Widget List
(add/remove)
Member List
(join/leave)
Space Chat
Widgets
(max/minimize)
Does this already remind you of Apache Rave?
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6. ROLE APIs
ROLE APIs
How to make your widget communicate in real-time –
The ROLE Interwidget Communication (IWC) API
© www.role-project.eu

7. ROLE XMPP-based Real-time Communication & Collaboration

8. ROLE Interwidget Communication – Concept
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9. ROLE Interwidget Communication – Facts
 Message-based communication between widgets
 Two different forms
 Single-user-single-browser:
 Integration of local widget instances to full applications
 Realized with HTML5 Web Messaging (other mechanisms realizable, too)
 Multi-user-multi-browser:
 Remote user collaboration in real-time
 Realized with XMPP Publish-Subscribe
 Message types
 Events: what happened upon sending message
 Intents: what should happen on receiving message
 (Use of semantic descriptions in message representations)
 Context
 In general: XMPP Publish-Subscribe Channel
 ROLE Reference Implementation: ROLE Spaces
 Refers to Epic RAVE-25

10. ROLE Interwidget Communication – Client API
Function Description
connect(callback) Connects the client to local interwidget communication.
After successful call, the client is able to publish and
receive intents. Received intents are passed to the
callback function.
disconnect() Disconnects the client from interwidget communication.
publish(intent) Publishes a JSON-encoded intent.
Initialize ROLE IWC Client
var iwcClient = new iwc.Client();
iwcClient.connect(function(intent){
// process intent
});
Publish ROLE IWC Intent
iwcClient.publish(intent);
© www.role-project.eu

11. ROLE IWC – Intent Message Format
var intent = {
"component": "",
"sender":"bob@somewhere.org?http://widget.org/sender.xml",
"data":"http://data.org/some/data",
"dataType":"text/xml",
"action":"ACTION_UPDATE",
"categories":["category1","category2"],
"flags" :["PUBLISH_GLOBAL", "own_flag"],
"extras":{"key1":"val1", "key2":"val2"}
};
 Google Android-like Intents
 component(*) (String) - the component name of a specific recipient widget
(explicit intent) or the empty string to indicate broadcasting (implicit intent)
 sender (String) - sender & sender widget.
 action (String) - the action to be performed by receivers (e.g. ACTION_UPDATE)
 data(*) (String) - data in form of a URI (e.g. http://myresource.org/microblogs/1)
 dataType(*) (String) - the data type in MIME notation (e.g. text/html)
 categories (Array) - categories of widgets to process the intent (e.g. ["editor"])
 flags (Array) - flags controlling intent processing (e.g. ["PUBLISH GLOBAL"])
 extras (JSON) - auxiliary data (e.g. {"examplekey":"examplevalue“})
© www.role-project.eu

12. Efforts in XMPP Community: XMPP over WebSocket
 XMPP over WebSocket Gateway (WXG)
 Based on "An XMPP Sub-protocol for WebSocket" (J. Moffit, E. Cestari)
 Jetty-based implementation (supporting RFC 6455)
 Source: https://github.com/hocken/wxg
 Web Client Library Extension (strophe.js)
 (Semi-)transparent BOSH/XMPP over WS
 Refers to Strophe Issue 68:
 Source: https://github.com/Gordin/strophejs

13. (XMPP over) BOSH vs. WebSocket
Property BOSH WebSocket
Connections Two concurrent One
Connection Persistence Repeated open/close Persistent
Transportable Data Textual only Textual, binary
Latency High Low
Package Overhead High (180+ bytes for Low (2 bytes for frame
headers per roundtrip) headers)
Uptake High Low
XMPP Servers Most Few
XMPP JS Libraries All Only some experimental
Browser support Most Few
 XMPP over WebSocket to obsolete BOSH with
stable specifications and implementations

14. ROLE Interwidget Communication – Online Resources
 Documentation
 ROLE SDK API Docs (SDK Download)
 Sourceforge MediaWiki (Wiki Page)
 Overview Paper (PDF)
 Demonstration
 ROLE SDK Trailer (youTube Video)
 Demo Space in ROLE Sandbox: http://role-sandbox.eu/spaces/iwc
 Code
 Libraries
 Proxy Part (code)
 Client Part (code)
 Tools
 ROLE IWC Test Stub Widget (code)
 Demo Widgets (cf. Demonstration)
 Synchronized Video Player (code)
 Synchronized Map Navigation (code)
 Collaborative Sketching Widget (code)
 Real-time Shared Note-Taking (code)
© www.role-project.eu

15. ROLE APIs
ROLE APIs
How to make widgets manage Linked Data resources –
The OpenApp API
© www.role-project.eu

16. OpenApp – Concept
 API for Linked Data-style resource management
 Everything is a Resource
 URI
 Representation
 Metadata
 Data
 Resources can have sub-resources
 Access to sub-resources filtered by type or relation to parent
 Special Resources
 Space is topmost resource in a space (shared)
 User is topmost personal resource (protected)

17. OpenApp – Client API
openapp.oo.Resource
 create  getInfo
 del  setInfo
 getSubResources  getMetadata
 refresh  setMetadata
 getRepresentation
 setRepresentation
Get current space & user as resources
var space = new openapp.oo.Resource(openapp.param.space());
var user = new openapp.oo.Resource(openapp.param.user());
Get resource information (JSON object with key/value pairs)
space.getInfo(function(info) {
alert(info);
});

18. OpenApp – Client API (Code Samples continued)
Create data sub-resource under space
space.create({
Get space resource metadata "data",
relation: openapp.ns.role +
type: "my:data:namespace:uri",
metadata: meta,
callback: function(sub){
//do something with new sub-resource
}
});
Find sub-resources via relation and type
space.getSubResources({
relation: openapp.ns.role + "data",
type: "my:data:namespace:uri",
onAll: function(arr) { //alternatively use onEach
//Do something with array of found subresources
}
});

19. OpenApp – Browsing Resources with the Index Page
For any resource open index page with <RESOURCE_URI>/:index

20. CfP – ROLE Widget Enchantment Competition
© www.role-project.eu

21. Visit the ROLE project page
role-project.eu
Download the ROLE SDK
sourceforge.net/projects/role-project
Try the ROLE Sandbox
role-sandbox.eu
Enter the ROLE Widget Competition
role-project.eu/WidgetCompetition
Join ROLE on LinkedIn
linkedin.com/groups?gid=1590487
Share your widgets in the ROLE Widget Store
role-widgetstore.eu/
© www.role-project.eu