Ubiquitous Web Caching

1
Ubiquitous Web Caching

• Wenzheng Gu
• Ph.D. Defense
• CISE Department, University of Florida
• November 25, 2003

2
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

3
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

4
Ubiquitous Computing
5
Trends on Wireless and Internet Growth
6
Web Caching
Cache Hit
7
Benefits of Web Caching

• Reduces network bandwidth usage
• ?Lessens user-perceived delays
• Lightens loads on origin servers

8
Internet Caching Protocol (ICP)

• Two Types of Relationship
• parent
• sibling

Parent 1
Parent 2
parent
Child 1
Child 2
Child 3
sibling
9
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

10
The Impact of Mobility on Web Access and Web
Caching (1/2)

• Currently, there is no mobile Web caching
  protocol.
• Changing Network
• By leaving home network, mobile users are
  disconnected from their home cache servers.
• By returning home or visiting other networks,
  users are disconnected from the cache servers
  just visited.
• Hence, users experience degradation of
  performance while mobile and upon their return.
• Changing devices
• Users lose client cached objects, favorites,
  cookies.
• Users lose personal calendar, contact information

11
The Impact of Mobility on Web Access and Web
Caching (2/2)

• Heterogeneity of Devices
• Wide Variety of Web Contents
• Lack of Automated User Intent
• Wireless Network Limitation
• Low Bandwidth
• Disconnection/ Handoff
• Address Migration
• Lack of Context Aware
• Lack of Security

12
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

13
Contributions

• Extended ICP Protocol (x-ICP)
• Support for Mobility in Web Caching
• Experimentally demonstrated and quantified the
  benefits of x-ICP in terms of cache hit rate.
• Adaptation Mechanisms to Cope with Device
  Heterogeneity and Web Content Variety
• Adaptive Web Content
• Adaptive Client and Server Side Algorithms
• Experimentally demonstrated the benefits of our
  adaptive mechanism

14
Architecture of Ubiquitous Web Caching
15
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

16
Mobile IP Routing PER98
Home Network
Internet Host
Home Proxy
Foreign Proxy
Foreign Network
17
Addressing Device Heterogeneity CC/PP

CCP99

• CC/PP stands for Composite Capabilities/
  Preferences Profiles
• The CC/PP describes and manages software and
  hardware profiles that include
• information on the user agent's capabilities
• the user's specified preferences within the user
  agent's set of options

18
Content Negotiation HOL98
19
Content Adaptation SMI98
20
Outline

• Introduction
• Overview
• Motivation and Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

21
Overview of X-ICP

• A Web caching protocol to support mobile users
• Automatically connect the users Foreign Proxy
  with his Home Proxy when a user changes the point
  of attachment on the network
• Deliver users profile
• If network situation permits, deliver cached
  objects from Home Proxy instead of from origin
  Web site
• Collect all the downloaded objects and store them
  on the Home Proxy when a user is on the move so
  that the contents continues to be available upon
  the users return

22
X-ICP Infrastructure
Internet
Cache Exchange Motion Connection
Home
23
Modules of X-ICP
24
X-ICP Processes

• Proxy and X-ICP Services Discovery
• Mobile Node Registration
• Web Object Delivery
• Cache Contents Duplication

25
Outline

• Introduction
• Overview
• Motivation and Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

26
Emulation Environment
LAN
To Internet
Home Proxy--Aswan
Foreign Proxy--Cairo
ICP
client
Solaris 8/Squid 2.4
Solaris 6/Squid 2.4

• Proxy logs from CISE department of UF are used as
  trace data. The field of URL is mainly utilized
  to measure the cache hit rate.
• 3 out of 5 subnets on the CISE network with
  different population were chosen. Traces were
  kept running for 25 days each.
• ICP was implemented to query Aswan and/or Cairo
  in order to locate which object is from where.
• Mobility is emulated by clearing the cache
  everyday, thus compulsory miss is higher.
• Aswan and Cairo are configured as sibling in
  Squid.

27
Emulation Results(1/2)
28
Emulation Results(2/2)
29
Emulation Conclusion

• With x-ICP deployed, a 21 higher hit rates can
  be achieved, which is the hit rate on the Home
  Proxy when users are attached to a Foreign Proxy.

30
Definitions
Origin Site
Cf Cache Hit Rate on a Foreign Proxy Ch
Cache Hit Rate on a Home Proxy Do Round-trip
delay between Foreign Proxy and Origin
Server Dh Round-trip delay between Foreign
Proxy and Home Proxy
Do
Home Proxy (Ch)
Foreign Proxy (Cf)
Dh

• 
  Execution time for
  entire task without x-ICP
• X-ICP Speedup ----------------------------------
  -----------------------------------
• Execution time for entire
  task using x-ICP when possible

31
Performance Analysis of x-ICP
32
Performance Analysis of x-ICP
Let Do 65ms ? Based on Cottrells study on
Internet
Monitoring at SLAC COT00.
Let Ch 21, ? From our Emulation study based on
CISE Web Caching
logs.
33
Analysis Results on x-ICP
34
Sensitivity Analysis Do
Do65

• Generally speaking, the impact of the average
  regional RTT value is not significant on the
  speedup.

35
Sensitivity Analysis - Ch
Ch21

• The increment of the speedup is negligible when
  the cache hit rate value is small.

36
Evaluation on X-ICP

• With x-ICP deployed, a 21 cache hit rate can be
  achieved on the Home Proxy
• With that 21 hit rate
• a 1.22 times higher speedup can be gained on a
  campus wide high speed network.
• the distance of two proxy servers can be up to
  about 201 miles in terms of current Internet
  environment.

37
Summary on X-ICP

• X-ICP extends ICP caching protocol to support for
  mobility
• X-ICP reduces the users response time
• Under x-ICP, users profile follows the user
  while mobile. This provides for a seamless Web
  experience.

38
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

39
Content Service Overlay Networks
40
Content Types

• XHTML pages
• Content files
• Video
• Image
• Text
• Audio

41
Content Delivery to Heterogeneous Devices

• Existing Approaches
• Content Adaptation
• Content Negotiation
• Our ApproachPartiality Fidelity Markup Language
• Take advantage of the index page
• Insert two types of new tags as metadata
• Priority Tag
• Fidelity Tag

42
The Hierarchy of PFML Elements
PFML
Priority
Fidelity
Other HTML Tags
Choice
Img
Script
Embed
43
The Document Type Definition of PFML
lt?xml version 1.0?gt lt!DOCTYPE PFML
SYSTEM PFML.dtdgt lt!ELEMENT PFML
(Priority)gt lt!ELEMENT Priority
ANYgt lt!ATTLIST Priority name CDATA
IMPLIED gt lt!ATTLIST Priority
value (0123456789) 9 gt lt!ATTLIST
Priority fixed (YN) Y gt lt!ELEMENT
Fidelity (choice)gt lt!ELEMENT choice
(img script embed)gt lt!ATTLIST
choice sourceQuality CDATA 1
type
CDATA IMPLIED
charset
CDATA IMPLIED
language CDATA
IMPLIED
feature CDATA IMPLIED
gt
44
Processing on PFML
9
9
9
0
1
2
xxxxxxxxxx
5
5
Foo.png
Foo.png
5
Foo.gif
Foo.png

.

Foo.gif

• Partiality Adaptation
• Versioning Negotiation

45
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Emulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

46
Priority Tag

• Priority tag is used to divide a web page into
  several portions
• Advantages
• Enable different device users share the same
  index page so that increase the cache hit rate
  and reduces traffic and response time
• Reduce the number of embedded objects to download
  so that bandwidth is saved

47
Example of Priority Tag

• lt?xml version 1.0?gt
• ltPriority value9 fixedYgt
• ltHTMLgt
• lt!--Foos personal Web site. --gt
• ltHEADgt
• ltTITLEgt Foos Home lt/TITLEgt
• lt/HEADgt
• ltBODYgt
• lt!- - self-introduction- -gt
• ltPgt I am lt/Pgt
• lt/Prioritygt
• ltPriority value5 fixedNgt
• lt!- -Personal picture - -gt
• ltIMG SRCFoo.gif BORDERgt
• lt!- - My interests - -gt
• ltPgt I like sports and music lt/Pgt
• lt!- -friends link - -gt
• ltPgtFoo1 lt A HREF HTTP//gtlt/Pgt
• ltPgtFoo2 lt A HREF HTTP//gtlt/Pgt

48
The Adaptive Priority Decision Algorithm

• Page Segment Priority Decision Algorithm
• Agent priority Decision Algorithm

• Algorithm Complexity
• Maintained in O(log n)
• Inserted or Deleted in O(log n)
• Constructed in O(n)

49
Web Caching in Partiality Adaptation

• A mobile device can take advantage of the copy of
  a Web page previously downloaded by some other
  devices, for example, a desktop, in a caching
  hierarchy.
• A device with more capabilities can use the
  partial copy of a Web page downloaded previously
  by a smaller device, and send it to the user
  directly.
• The user community size is bigger so cache hit
  rate could be higher.

50
Experiments on Priority Tags
51
Experiment One on Partiality Adaptation (1/2)
52
Experiment One on Partiality Adaptation (2/2)

• When the speed of wireless network is above
  11Mbps, its 9 times faster to download a 50k Web
  page from an extracted case than from origin
  site.
• Questions?
• What if the speed of wireless network is not fast
  enough?
• What if the Web page is not big enough?
• More experimentation is needed.

53
Experiment Two on Partiality Adaptation (1/2)
54
Experiment Two on Partiality Adaptation (2/2)

• Simulation Data
• On an average of 4843 bytes downloading
• With Priority Tags 5910 ms
• Without Priority Tags 6857 ms
• According to our simulation, using Priority Tags
  can reduce about 1 second response time to the
  cellular phone users to browse the internet.

55
Outline

• Introduction
• Overview
• Challenges
• Contributions
• Related Work
• Extended-ICP Protocol
• Design
• Simulation and Analysis
• Adaptation and Negotiation with Caching
• Priority Fidelity Markup Language
• Partiality Adaptation
• Versioning Negotiation

56
Fidelity Tag

• Fidelity Tags are mainly used for content
  negotiation.
• Allow web server to insert the object lists and
  their attributes into a web page where the
  corresponding web object is embedded.
• Advantage
• Let user make the decision so that eliminates the
  CC/PP file fetching and parsing
• Reduce the number of round-trips

57
Example of Fidelity Tag

• ltFidelitygt
• ltchoice sourceQuality 1 typeimg/gifgt
• ltimg src/images/foo.gif width276
  height110 /gt
• lt/choicegt
• ltchoice sourceQuality0.6 typeimg/pnggt
• ltimg src/images/foo.png width76
  height 30 /gt
• lt/choicegt
• ltchoicegt
• foo
• lt/choicegt
• lt/Fidelitygt
• ltFidelitygt
• ltchoice sourceQuality 0.9 type text/html
  language engt
• ltdoc src/document/paper.html.en /gt
• lt/choicegt
• ltchoice sourceQuality 0.7 typetext/html
  languagefr gt
• ltdoc src/document/paper.html.fr /gt
• lt/choicegt
• ltchoice sourceQuality 1.0 type
  application/postscript language en gt

58
Experiment on Fidelity Tags
59
Total Roundtrip Time
60
Time Measured on the Server Side
61
Evaluation on Fidelity Tags

• We saved about 1 second on the server side by
  using PAVN instead of CC/PP module.
• We saved about 0.8 second on the total
  round-trip time with our implementation on PAVN
  and CC/PP.

62
Summary on PFML

• With the simple Priority and Fidelity metadata
  and associated algorithms, we give a better
  solution to the following problems
• Heterogeneity of Devices
• Wide Variety of Web Contents
• Lack of Automated User Intent
• Low Bandwidth on Wireless Network

63
Conclusion

• Designed a mobile Web caching protocol
• Deliver Web contents from nearby proxy
• Deliver users personal profile
• Designed adaptive PFML and associated algorithms,
  with
• Content adaptation
• Content negotiation

64
Future Work

• To model users behavior while mobile
• How far is the foreign proxy
• How long is the users linger time
• What devices are being used
• The speed of movement
• How frequent to move
• It will help to deploy proxies and to determine
  the functionalities of proxies

65
Publications

• Extended Internet Caching Protocol A Foundation
  for Building Web Caching to Nomadic Users, ACM
  Symposium on Applied Computing, Melbourne, FL,
  January 2003.
• Ubiquitous Web Caching, submitted to Wireless
  Communication and Mobile Computing Magazine, John
  Wiley and Sons, 2003.
• Adaptive Content Delivery with XML, to submit,
  ITC Specialist Seminar on Performance Evaluation
  of Wireless and Mobile Systems Antwerp, Belgium,
  August 2004

66
Questions
67
Thanks!
68
In the core
MPEG4
69
At the end
70
Mobile IP Tunneling
71
Scenario on X-ICP Registration
72
Hops Detection(1/4)

• Deploying x-ICP on different networks can bring
  more overhead.
• If the two proxy servers are too far away from
  each other, x-ICP sibling configuration shouldnt
  take place.
• Hops, RTT, or physical distance of the two
  servers should be detected.

73
Sibling Proxy Configuration(2/4)

• On the Foreign Proxy (proxyE)
• Cache_host proxy4.Net1 sibling http-port
  icp-port
• On the Home Proxy (proxy4)
• acl src ProxyE ProxyE.Net2
• Http_access allow ProxyE
• ICP_access allow ProxyE

Care_of_Address
74
Register with Node Monitor (3/4)
75
User Profile Delivery (4/4)

• Bookmarks
• History links
• Contact information
• Cookies

76
RTT vs. Distance (1/3)(courtesy of Stanford
Linear Accelerator Center )
77
RTT vs. Distance(2/3)

• This is a trace-route like simulation conducted
  in our lab.
• Requests are made to the Random selected top 100
  Web sites.
• Round trip time for the first 7 hops (routers)
  are collected.
• The first 6 hops are on campus. It shows the RTT
  lt 2ms on the campus backbone.

78
Page Segment Priority Value Decision
Algorithm(1/2)
Nc total number of clicks increment upon each
click Ns total number of segments of a page
t a function to calculate a specific threshold
with parameters Pi priority value for segment
i Ti the time stamp to generate the Pi Tnow
the current time Ci total number of clicks on
segment i Ci total number of clicks on
segment i sent from client agent   executed on
each access for each segment i Ci ? Ci
Ci Nc ? Nc Ci
79
Page Segment Priority Value Decision
Algorithm(2/2)
executed periodically for each segment i
priority value increment if ( Ci gt t
(Ci,Pi,Nc,Ns) and Pi lt 9 ) Pi ? Pi
1 Ti ? Tnow
priority value decrement expired
means the segment hasnt been touched for a
period else if ( Ti expired and Pi gt 0 )
Pi ? Pi 1 Ti ? Tnow

80
Client Agent Priority Value Decision Algorithm
(1/2)
Nj,c total number of clicks on a page
increment upon each click Nj,s
total number of segments of a page
Np
total number of pages

t a function to calculate a
specific threshold with parameters
Pj,i priority value for
segment I
Pj,c
priority value for a page

Tj,c the time stamp to generate the Pj,c

Vk the total number of pages having priority
k, where 0ltklt9 Pa priority value for a
client agent Ta the time stamp to generate
Pa Cj,i total number of clicks on segment i,
page j. upon each click if (new page) Np
? Np 1 Initialize new (Cj,i)s to 0
Initialize new Pj,c to 0 Cj,i ? Cj,i 1 Nj,c ?
Nj,c 1  
81
Client Agent Priority Value Decision Algorithm
(1/2)

• change priority of agent
• if ( Pj,c ltgt Pj,c)
• k ? Pj,c
• Vk ? Vk -1
• k ? Pj,c
• Vk ? Vk 1
• if (Vk gt t(Np) and Pa gt k)
• Pa ? k
• Ta ? Tnow
• else if (Ta expires and Pa lt 9)
• Pa ? Pa 1
• Ta ? Tnow
• 
  

• at the idle time
• for each page j
• Pj,c ? Pj,c
• change priority of page
• for each segment i
• if ( Cj,i gt t(Nj,c,Nj,s) and Pj,c gt Pj,i)
• Pj,c ? Pj,i
• Tj,c ? Tnow
• else if ( Tj,c expired)
• if ( Pj,c lt 9 )
• Pj,c ? Pj,c 1
• Tj,c ? Tnow

82
RVSA details

• The overall quality Q of a variant is the value
  of Q round5( qs qt qc ql qf )
• qs Is the source quality factor in the variant
  description.
• qt The media type quality factor
• qc The charset quality factor
• ql The language quality factor
• qf The features quality factor

83
Example of RVSA

• Variant list
• "paper.html.en" 0.9 type text/html language
  en,
• "paper.html.fr" 0.7 type text/html language
  fr,
• "paper.ps.en" 1.0 type application/postscript
  language en
• Request Accept- headers
• text/htmlq1.0, /q0.8
• Accept-Language enq1.0, frq0.5
• Computations
• round5 ( qs qt qc ql qf ) Q
• paper.html.en 0.9 1.0 1.0 1.0 1.0
  0.90000 paper.html.fr 0.7 1.0 1.0 0.5
  1.0 0.35000 paper.ps.en 1.0 0.8 1.0 1.0
  1.0 0.80000