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Personalized Pocket Directories for mobile Devices Doron Cohen – Miki Hersovici – Yael Petruschka – Yoelle Maarek – Aya Soffer – Dave Newbold.

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Presentation on theme: "Personalized Pocket Directories for mobile Devices Doron Cohen – Miki Hersovici – Yael Petruschka – Yoelle Maarek – Aya Soffer – Dave Newbold."— Presentation transcript:

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2 Personalized Pocket Directories for mobile Devices Doron Cohen – Miki Hersovici – Yael Petruschka – Yoelle Maarek – Aya Soffer – Dave Newbold

3 Mobile Devices

4 Mobile Devices (contd.) Ability to access information anytime and anywhere. Dramatic increase in the use and availibility of mobile devices. Which avenir? – IDC: At the end of 2002: more wireless subscribes than wired users! … – Is it right???

5 Web on mobile devices? Dream to reality … Limiting factors: – Form factor Limited screen. Input capabilities. Other?... – Communication mode: Connection through networks with low bandwith High latency.

6 Web on Mobile Devices? From dream to reality Other restrictions: –L–Limited storage. Less an issue: possibility to add memory sticks. –L–Limited CPU No real impact on the specific application, browsing.

7 Web directory browsing Two common modes of information discovery on the internet (1994): – Search – Browse

8 Search on the internet Finding narrowly defined information. – Google: http://www.google.co.il – Altavista: http://www.altavista.com

9 Browsing on the Internet Good for presenting broad categories of information. – Yahoo: http://www.yahoo.com – Open Directory Project (ODP) : http://www.dmoz.org – Looksmart: http://www.looksmart.com

10 Browsing on the Internet (contd.) Is it popular? – Yes … Being bigger and bigger … Open Directory: – 3 millions sites – More than 40.000 editors. – 500.000 categories. Special purpose and regional directories – Environmental Organization Intranet – Lotus Discovery Server

11 Web directories on Mobile Devices Fast and convenient browsing of directories. Minimal over-the-air communication

12 Web directories on Mobile Devices Proposed solution: – Caching enough information on the device – Communicating with the server only for the last stage. Minimal storage capabilities: – PalmOS, PocketPC … – Nokia 9210, Motorola i85s, Palm Powered Phone Regular connection to the internet.

13 Web directories on Mobile Devices The approach: – intermittent connection communication model: User synchronize its device via a cheap reliable and fast connection: – Sync in Palm. – Other examples?... And caches locally as much information as possible for working offline.

14 Web directories on Mobile Devices Need to define a subscription model that adapts the specific nature of Web Directories – What is the right amount of information to be isolated? – Directory Capsule The portion of directory to transmit to the PDA to be seen offline.

15 Web directories on Mobile Devices Four requirements: – An architecture that supports intermittently connected devices. – A subscription model geared for Web directories and targeted to PDA – A mechanism to ensure that the directory capsule is consistent with the directory server – A fully featured pocket directory browser application for defining, viewing, manipulating directory capsules on the PDA.

16 From Web directories to Local capsules These capsules are dynamic replicas and not static snaphshots of the server s directory. The directory capsule is generated by a mediator: a software component that accesses the Web Directory/Internet, encapsules the rights amount of information

17 From Web directories to Local directory capsules

18 WorkloadInitiated by Heavy -Manually - At some preschuled time Load LightThe userSync

19 From Web directories to Local directory capsules In a Palm context: – The mediator machine: The desktop used to backup the device. – The Synchronization process: HotSync process.

20 A bit formalism … The Directory Model Web directories consist of a hierarchy of categories. Each category may – contain: Documents. Other categories. – Be associated with one or more persons (Authorities)

21 The directory Model. The search in Directory Model. User can submit queries – to The entire category A particular category – About: Categories Documents Persons.

22 The directory Model. Search results can be viewed as Virtual categories: – Categories that answer the query – Documents not in category – Persons.

23 The directory Model. What are the relations between the different entities of the Directory Model. The Directory Information (DI) can be defined as : – DI = (E,R) – E = {E1, E2, …, En} n=1, the set of Entities – R = {Rij; 1 =i,j=n} is the set of directional relationships between Ei and Ej

24 The directory Model. For example, in the Open Directory: – E1 – OD categories – E2 – Web pages – E3 – Persons – E4 – Query Results (Virtual Categories)

25 The directory Model. E4 – Search Results E1 – Category E3 - Person E2 - Site E1 – Category E4 – Query Results E3 - Person E2 – SiteRij

26 The Subscription Model Mechanism for indicating the directory entities in which they are interested The content of these entities will be extracted and stored in the directory capsule. This content will be synchronized with the directory server.

27 The subscription model Question: What is a content of an entity ? The answer will have significant implications in terms of – size of the local replica – Time it takes to refresh this replica.

28 The subscription model We, therefore, define 2 granulaties of content for each data item: – Summaries : are stored for each entity included in the capsule – Details : need only be stored for a subset of these.

29 The subscription Model Summaries of returned sites and categories The query that produced these results E4 Query results Email, summaries of categories edited by person, and bookmarks Person Name, and profile E3 Person The complete site page Site title, description, and URL E2 Site Summaries of editors, of contained sites, of contained and direct parent categories Category name and description E1 Category DetailsSummaries

30 The subscription Model Another definition for categories: – Category Summary: Name, description, and summaries of contained categories and of its parent category – Category details: summaries of editors and of contained sites. Which Differences? Which advantages?

31 Maintaining a Consistent and Fresh Directory Capsule We need an – up to date – Consistent with the parent directory. It is handled by the mediator component. Must be conducted as fast as possible.

32 Maintaining a Consistent and Fresh Directory Capsule The capsule can be divided in: – Capsule definition: user subscription request – Capsule content: data loaded from the Web.

33 Maintaining a Consistent and Fresh Directory Capsule Inconstitency can occur when: – User induced inconstitency: The user added or deleted subscriptions – Directory induced inconstitency: The directory has evolved since the last sync.

34 Maintaining a consistent and Fresh directory capsule

35 The both types of inconstitency are resolved by the Mediator – During Sync: A new definition is obtained from the device. Unsubscribed items are deleted from the content. – During load: The capsule content is updated from the directory: Newly subscribed items are retrieved. Subscribed, modified items are updated Etc …

36 Maintaining a consistent and Fresh directory capsule Load and sync must to not occur concurrently. Special care if the Directory model allows item deletions …

37 Maintaining a consistent and Fresh directory capsule Efficiency enhancement: – An additional mirror of the capsule content could be stored on the desktop. – Why? Computing new and last updated can be achieved during Load Only new and last updated are download to the PDA.

38 Sample Application Lotus Discovery Server.

39 Sample Application

40 Conclusion Remark Model for browsing Web directories with minimal amount of storage capabilities Based on the intermittent connection Does the PDA or mobile phones are the only ones devices needing such a policy???


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