(2) Abstract
Location-Based Services (LBS) are a popular use case for the Web as well as for mobile devices. However, the vast majority of LBS today is built in a vertically integrated way, where the map imagery and all overlays for it are delivered by the same service provider. We propose an architecture and present a prototype where map imagery as well as overlays are managed in a decentralized way, allowing clients to easily combine and repurpose services. Since in such a scenario, clients may want to keep track of the various LBS providers they are using, we also propose and present an architecture for managing subscription information for services. Both areas of work are based on lightweight Web technologies, most importantly Atom feeds and a RESTful service design around those. Using this architecture, subscription information can be easily shared among clients (allowing users to for example use the same LBS providers on their laptop, their smartphone, and in their car), and display and delivery methods can be adjusted according to client preferences and capabilities (display size, pull or push delivery, and similar considerations).
Feed Subscription Management (FSM)
(22) Managing Decentralization
- LBS can be exposed and used by anyone
- access control and personalization can be implemented if required
- clients need to keep track of what and how they aggregate
- Feed Subscription Management (FSM) is a decentralized service itself
- subscriptions to feeds are managed in feeds (
subscription feeds
) - subscription feeds can be published and reused as bundles
- views are defined by map regions and services for that region
- FSM allows seamless switching between (spatial) feed clients
- subscription and view management uses a RESTful API (based on Atom/AtomPub)
- FSM represents feed subscriptions, query parameters, and views
(23) FSM Architecture
(24) OPML Folder
in FSM
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fsm="http://dret.net/fsm/1.0">
<title>delicious REST</title>
<generator>$Id: opml2fsm.xslt 1407 2010-10-27 19:15:56Z dret $</generator>
<entry>
<title>Delicious/cesare.pautasso/rest</title>
<fsm:subtype>subscription</fsm:subtype>
<link rel="alternate" href="http://feeds.delicious.com/v2/rss/cesare.pautasso/rest"/>
<link rel="http://dret.net/fsm/1.0/subscription_to" href="http://feeds.delicious.com/v2/rss/cesare.pautasso/rest"/>
</entry>
<entry>
<title>Delicious/dret/REST</title>
<fsm:subtype>subscription</fsm:subtype>
<link rel="alternate" href="http://feeds.delicious.com/v2/rss/dret/REST"/>
<link rel="http://dret.net/fsm/1.0/subscription_to" href="http://feeds.delicious.com/v2/rss/dret/REST"/>
</entry>
</feed>
(25) OPML Structure in FSM
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:fsm="http://dret.net/fsm/1.0">
<title>dret subscriptions in Google Reader</title>
<generator>$Id: opml2fsm.xslt 1407 2010-10-27 19:15:56Z dret $</generator>
<entry>
<title>xkcd.com</title>
<fsm:subtype>subscription</fsm:subtype>
<link rel="alternate" href="http://xkcd.com/atom.xml"/>
<link rel="http://dret.net/fsm/1.0/subscription_to" href="http://xkcd.com/atom.xml"/>
</entry>
<entry>
<title>delicious REST</title>
<fsm:subtype>bundle</fsm:subtype>
<link rel="alternate" href="" type="application/atom+xml"/>
<link rel="http://dret.net/fsm/1.0/bundle" href="fsm-67.xml"/>
</entry>
</feed>
(26) FSM in the Web Client
(27) FSM in the iOS Client
[http://creativecommons.org/licenses/by/3.0/]
