Web Messaging for Open for Web of Things

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Web Messaging for Open and Scalable Distributed Sensing Applications

ICWE2010, Vienna, Austria - 6 July 2010

Vlad Trifa, Dominique Guinard, Vlatko Davidovski,

Andreas Kamilaris, and Ivan Delchev

The Internet of ThingsNetworked devices everywhere

Lots of different devices ‣ Capabilities/functions‣ Applications/middleware‣ Networking protocols

Internet connectivity‣ Cheap‣ Ubiquitous‣ HTTP also possible

Web of Things [1]:Use the Web to combine heterogeneous mobile devices to create interactive ad-hoc applications!

[1] Online at: http://www.webofthings.com

RESTful SunSpotEmbedded NanoHTTPD

‣ Talks HTTP (over 802.15.4)‣ Becomes a Web device

Properties and functions are Web resources, so can be

‣ Browsed‣ Bookmarked‣ Shared

But also use twitter, send emails, chat, etc..

D. Guinard, V. Trifa, T. Pham, and O. Liechti. Towards Physical Mashups in the Web of Things. In Proceedings of the 6th International Conference on Networked Sensing Systems (INSS 2009), 2009.

Show Time!

Wait - what about eventing & streaming ?

The Web wasn’t quite made for that...

Need more than Pull, more than Push!

Web mainly request/response (HTTP)Need for eventing & streaming for many users

‣ Sensor data represented as sequence of messagesScalable pub/sub for devices as substrate

‣ Use the Web to build distributed event driven appsParameterized subscriptions (channels/queries)

‣ Specify what sensors, devices, locations, etc...Many solutions (XMPP, etc....)

‣ None really integrate with the Web ‣ ATOM/ATOMpub is RESTful, but not push

Here comes the real-time Web!Very active community expanding Use the Web for distributed event driven appsComet

‣ Keeps the HTTP connection open‣ Long polling‣ Ajax push

Web Hooks‣ Bi-directional‣ Push from server to HTTP callbacks

RESTful Messaging System (RMS)Similar to pubsubhubbub (PuSH) or RestMS

‣ But lighter (less options) to run on devicesInterested by a generic “Web push” mechanism

‣ Simple to use‣ No complex client required

Minimal pub/sub support‣ queues‣ subscriptions

RMS/rms/channels - every sub-resource represents a hierarchical channel where entities can post data to, ex: /rms/channels/ethz/ifw/floor/d/49.2/rms/subscriptions - contains each subscription of entities to individual channels/rms/channels/x/publishers - contains all entities that are publishing data on the channel x/rms/channels/y/subscribers - contains all entities that are subscribed to events on the channel y

Usage examples

curl ­­basic ­­request POST ­­data "temperature=23" http://localhost:8080/aparat/rms/channels/simulation

curl ­­request POST ­­data "rms­subscription­callback­url=http://192.168.1.1/handler" http://localhost:8080/aparat/rms/channels/simulation

Subscribe to a channel:

Publish to a channel:

Live DemoPlogg Smart Meter

‣ Talks HTTP (over Zigbee)‣ Becomes a Web device

Posting through RMS‣ /aparat/rms/channels/.../hifi

Browser client using Comet (Ajax Long Polling)

Show Time!

Many devices - one receiver

Many receivers

Real deployment setup

Web of Things @ Percom

Vlad Trifa - SAP/ETH Zurich

ConclusionLeverage REST as native API for devices

‣ Inherit all the tools & expertise in Web technologies‣ Caching, security, scalability

Flexibility through real-time Web‣ Loose coupling between application components‣ Pub/sub helps to scale and is good for ad-hoc interactions

Good performances‣ 100 msg/s delivered with low latency, 200 subscribers

notified with 360ms delay in average‣ Real deployment 15 devices sampling@1Hz (< 60 ms delay)

Web of Things, 7.4.2010 Vlad Trifa - SAP/ETH Zurich

Take away notesGood performances for Web messaging and integrates devices directly with existing Web (REST).

The Web goes physical!

Tools & best practices for Web-enabled things are needed.

Web engineering can contribute a lot towards building a programmable world.

We need applications (deployments) and testing!

Thanks for your attention !

www.webofthings.com