Context caches in the Clouds

October 2, 2014M. Said Özcan

by Saad Liaquat Kiani, Ashiq Anjum, Nick Antonopoulos, Kamran Munir and Richard McClatchey

Table of Contents

• Introduction

• The context provisioning architecture

• Context cache

• The bipartite context cache

• Cloud based evolution

• Conclusion

Introduction

• Context (information related to user. i.e user's personal situations)

• Temporal aspect (e.g. valid for a certain duration)

• Different validity durations and access frequencies

• Investigating various context-caching strategies and proposing novel bipartite caching mechanism

• Anything, anytime and anywhere (ubiquitous systems)

• Large number of users, devices, data sources and services

The context provisioning architecture

The context provisioning architecture (cont.)

CxC (Consumer) • Uses context data • Retrieve information by, (a) send subscription to CxB (b) direct on-demand query

CxB (Broker) • Main coordinating component of the architecture • Cache produced context

CxP (Provider) • Provides contextual information • Gathers data from a collection of sensors, network/cloud services • Usually specialized in a particular context domain (e.g. location)

The context provisioning architecture (cont.)• Improving the scalability with federation of multiple context brokers • Providing location transparency to the local clients (CxCs and CxPs) of each broke • Routing of context queries/subscriptions and responses/notifications across

distributed brokers, discovery and lookup functions • Context information is represented in ContextML (XML based schema)

The context provisioning architecture (cont.)

• ContextML, context data relates to an entity (a user, a username, a SIP or an email address etc..) and is of a certain scope (e.g. weather, location, activity and user preferences)

• Also a temporal validity is associated with ContextML encoded context data through the timestamp and expiry tags

• A parser, ContextML Parser, has been implemented as a Java library for Java SE, EE and the Android platforms

• Conceptual diagram of how the system components may operate in a federation of context brokers shown in Figure 3

The context provisioning architecture

Context cache

Context cache (cont.)

Context cache (cont.)

Context cache (cont.)

The bipartite context cache

Cloud based evolution

Conclusion

"The Context Provisioning Architecture employs a caching mechanism at the context broker, which positively affects the mean query satisfaction time between context consumers and

providers."

Thanks