1. A Component-based Architecture for Mobile Information Access
Anupam Joshi
CSEE Department, UMBC

2. Overview
The Problem - The information required by a mobile user may not be readily available on the network.
It is possible to compute required information dynamically using available resources on the network.
Thesis provides an architecture to compute information ‘on the fly’, taking into account various limitations of mobile scenario.
Implement this architecture to build a financial services system.

3. Problems w/ Mobile Computers
Network layer
Low/variable Bandwidth
Network disconnection
Application layer
Limited capability ( Display, Compute power etc)

4. Existing Efforts in Mobile Information Access
Focuses on delivering available information to mobile computers
Principally proxy based transcoding or caching
What if information needs to be computed ‘on the fly’?
Server side ( e.g. : CGI scripts )
Location of resources is ‘known’
Almost all computation at server
Client side ( e.g. : Java script, java )
Assumes some capability at client.
Size of data transfer may be large.
Statically defined location of execution

5. Need for distribution of computation depending on
Needed Features
Need for distribution of computation depending on
capabilities of client, mobility of components, data size, cost, security.
Service location mechanisms
Disconnection Management.
Componentization of software, Raw data availability

6. Proposed Architecture
Delivery layer - Handles the limitations of mobile client and wireless network (e.g.: Use Transcoding)
Broker Layer - Determine services required, locate services, distribute computations effectively, shield the mobile client from limitations of service location platform.
Dynamic service location layer - Mechanisms for locating services.

7. Dynamic service location
Implementation based on ‘XReggie’ platform
XReggie overcomes some limitations of Jini platform
XML match at lookup service instead of normal Java interfaces.
Constraints and similarity match.
Services express their constraints as XML attributes.
Example constraints for software services.
Mobility
RAM-required
Size
JVM version
Cost
Data-Format

8. Dynamic service location
Examples of constraints for data services
Size
Local-processing
Cost
Format

9. Broker Determines individual services required Locates the services
Use XML attributes to locate appropriate service
Distributes computations
Many ways of distributing computation.
Move data, move code, move data and code.
Take into account constraints of services and mobile client
Constraints of services known from XML attributes with which services register
Constraints of mobile client also known from XML attributes.

10. Broker
The objective of the broker is to optimize “cost” subject to various constraints such as
Processing power of mobile client
Size of data and software
Cost of services
Network bandwidth and disconnection possibility
Decision depends on which parameters are considered
Brokers registers a “GUI” interface with Xreggie
May be voice in the future.

11. Execution Platform as a Service
Mobile client may not be powerful enough to compute.
Execution Platform
Generic ‘computational power’ service
Executes Jini services in succession
For each service to be executed
Service ID
Method name
Argument List
Registers as a Jini service

12. Delivery Handles limitations of mobile client and wireless network
Implemented using Ronin framework
Key feature used is - ‘Delegation’
Advantages
Transport object appropriate for a mobile client could be chosen
Transport object appropriate for a network could be chosen
Shields rest of application from mobility aspects
Implemented a Disconnection handling deputy

13. Mobile client To execute a software component on mobile client
Following arguments are supplied
Service ID
Method name
argument list
Mobile host need not have any prior information about service. Broker acts as middleware between mobile client and Jini.
Results are either sent back to broker for further computation or displayed.

14. Application Financial services system Quote service
Real time quote from yahoo
Average of stock price over any period
Historic stock data from yahoo
Component for ‘mean’
Option pricing
Options pricing component based on Black-Scholes model
Profit-loss on options
Options pricing component
Component to compute profit-loss

15. Infrastructure overview

16. Averaging of stock price
Components involved
Historic stock data provider
Software component to compute mean
Execution platform
Options for distribution
Send software component to data site and return the results to mobile user
Send data and software component to execution platform and return the results to mobile user
Send data and software component to mobile user for execution at client

17. Experiments

18. Options for distribution
Options pricing
Components involved
Software component to compute the option price
Execution platform
Options for distribution
Send software component to mobile host for execution
Send software component to execution platform and return the results to the user

19. Experiments

20. Conclusions
Presented an architecture to compute information required by a mobile user ‘on the fly’ using available resources.
The architecture takes into consideration, the resources available at mobile client and other factors such as cost while distributing computation.
The architecture also supports handling of limitations of mobile client and wireless network.
Presented an implementation of this architecture using extensions to Jini and Ronin frameworks.
Developed a financial information system using the implementation.

21. Future work
Importance of standards - XML, software components, data formats
Improvement of broker
Consider more parameters in distributing computation
knowledge recommender agents such as PYTHIA could be used to effectively distribute computation
Non Java mobile client