Generate Dynamic Content On Cache Server

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Generate Dynamic Content On Cache Server

• Masters Project
• Aparna Yeddula
• Dept. of Computer ScienceUniversity of Colorado
  at Colorado Springs

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Outline of the Talk

• Introduction to Dynamic Cache Server(DCS)
• Related Literature
• ESI (Edge Side Include) Language Akamais
  solution to how a web page be dynamically
  generated.
• JSP/Servlet use of customized JSP tags with
  servlets to realize subset of ESI tags in a DCS.
• Performance Comparison between ETS and JDCS (Java
  Dynamic Cache Server)
• Lessons Learned
• Future Directions
• Conclusion

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Introduction

• Caching.
• Web proxy server.
• Advantage With caching Faster, not consume
  Internet bandwidth.
• Disadvantage With out caching heavy burden on
  original server.
• Serving Static pages
• What data its handling and what time to refresh
  data.
• Serving Dynamic pages
• Distinguish dynamic portions and static, know
  where to find dynamic data.
• Most cache server did not provide such services.
• Solution Akamai had proposed Edge Side Include
  (ESI) language, provide solution for dynamic
  caching.

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Related Literature

• Active Cache Wisconsins Java Cache Server.
  http//www.cs.wisc.edu/cao/papers/active-cache/SE
  CTION00100000000000000000
• ETS http//www.esi.org
• CDN Akamai, Digital Island http//www.akamai.com/
  index_flash.html

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ESI features
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ESI (Edge Side Include) Language

• ESI is an XML-based markup language and similar
  to HTML-like markup language.
• The ESI assembly model is comprised of a template
  containing fragments.
• The template is the container for assembly.
• Each fragment is treated as separate entity.
• ESI enables Web pages to be broken down into
  fragments of differing cache-ability profiles.
  Like each fragment has its own time-to-live (TTL)
  attribute.
• Advantage Reduce processing overhead on the
  origin server.

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EdgeSuite overview

• Akamai EdgeSuite move web content to the edge of
  the internet.
• Allowing dynamic content assembly at the edge of
  the network.
• Intelligent routing technology.
• EdgeSuite is a complete outsourced solution that
  delivers the content.

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Edge side include Test Server (ETS)

• ETS is available from Akamai. http//akamai.com
• The ETS server now sits in-between the origin
  server and the user.
• Each fragment of the page needs to be retrieved
  from the origin server.
• The ETS server determines which parts of the page
  need to be retrieved from the Origin Server.
• We can install ETS on the same machine as the
  origin test server.

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ESI Example

• ltesiincludegt tag example
• For example,
• ltesiinclude src"http//example.com/1.html"
  ttl1hr/gt
• ltesichoosegt tag example
• For example,
• ltesichoosegt
• ltesiwhen test"(HTTP_HOST)128.198.192
  .174'"gt
• ltesiinclude src"http//www.example.com/advance
  d.html"/gt
• lt/esiwhengt
• ltesiotherwisegt
• ltesiinclude src"http//www.example.com/newuser
  .html"/gt
• lt/esiotherwisegt
• lt/esichoosegt

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Realize DCS using JSP/Servlet

• ETS free version does not implement TTL, DataBase
  support
• We explored the use of Customized JSP Tag with
  servlets.
• Allows us to investigate the performance issues
  in Dynamic Cache Server Design.

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JSP (Java Server Pages) custom tag specifications

• To use the JSP custom tags, we need to define
  three separate components
• JSP file.
• tag library descriptor (tld).
• tag handler class.

simple-taglib.tld ltnamegthellolt/namegt lttagclassgt c
wp.tags.HelloWorldTag lt/tagclassgt

• Helloworld.jsp
• lt_at_ taglib
• uri"simple-taglib.tld
• prefix"jspx" gt
• ltjspxhello /gt

HelloWorldTag.java public class HelloWorldTag
extends TagSupport
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The JSP file

• lt!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0
  Transitional//EN"gt
• lthtmlgt
• ltheadgt
• lt_at_ taglib uri"simple-taglib.tld prefix"jspx"
  gt
• lttitlegtltjspxhello /gtlt/titlegt
• lt/headgt
• ltbodygt
• ltjspxhello /gt
• ltjspxhellogt body tag ltjspxhello/gt

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Cond..

• ltjspxdatabase month"lt strmnt1gt" /gt
• ltjspxifgt
• ltjspxconditiongtlt request.getRemoteAddr()
  gtlt/jspxconditiongt
• ltjspxthengt
• ltjspxinclude uri"http//gallop.uccs.edu
  8888/1.html" ttl"1"/gt
• lt/jspxthengt
• ltjspxelsegt
• ltjspxinclude uri"http//gallop.uccs.edu/2.
  html" ttl"1"/gt
• lt/jspxelsegt
• lt/jspxifgt

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Tag library descriptor file

• lt!DOCTYPE taglib PUBLIC "-//Sun Microsystems,
  Inc.//DTD JSP Tag Library 1.1//EN"
• "http//java.sun.com/j2ee/dtd/web-jsptaglibrary_1
  _1.dtd"gt
• lttaglibgt lttaggt
• ltnamegthellolt/namegt
• lttagclassgtcwp.tags.HelloWorldTaglt/tagclassgt
• lt/taggtlttaggt
• ltnamegt database lt/namegt
• lttagclassgtcwp.tags.DataBaseTaglt/tagclassgt
• ltattributegt
• ltnamegtmonthlt/namegt
• ltrequiredgttruelt/requiredgt
• lt/attributegt
• lt/taggt lt/taglibgt

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Tag handler class

• import javax.servlet.jsp.
• import javax.servlet.jsp.tagext.TagSupport
• public class HelloWorldTag extends TagSupport
•   public int doStartTag()
• JspWriter out pageContext.getOut()
• out.println("lttrgtlttdgt Hello World
  lt/tdgtlt/trgt")
• public int doEndTag()
• if return EVAL_BODY_TAG
• else return SKIP_BODY

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JSP Example

• JSP FILE
• ltbodygt
• lt_at_ taglib uri"include-taglib.tld"
  prefix"jspx" gt
• ltjspxinclude uri"http//uccs.edu/page.html"
  ttl"1"/gt
• lt/bodygt
• TLD FILE
• ltnamegtincludelt/namegt lttagclassgtcwp.tags.Include
  Taglt/tagclassgt
• ltattributegt ltnamegturilt/namegt
  ltrequiredgttruelt/requiredgtlt/attributegt
• ltattributegt ltnamegtttllt/namegt
  ltrequiredgttruelt/requiredgtlt/attributegt

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Servlet Implementation for retrieving attributes
from JSP page

• public int doStartTag() throws JspException
• public void setUri (String name)
• uriName name
• public void setTtl (String name)
• ttlName name

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Implementing Proxy Caching

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Performance Testbed Set up
Client
Dynamic Cache Server
Web Server
gallop.uccs.edu8888 wait.uccs.edu8080
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Benchmarking Results Compare ETS and JDCS

• Result - 1 ESI template page containing HTML
  fragments
• Template page http//gallop.uccs.edu/ayeddula/esi
  /esitag.html
• Fragments are
• 1. http//gallop.uccs.edu8888/examples/staticpage
  .html ttl"5 Seconds"
• 2. http//gallop.uccs.edu/ayeddula/tasks.html
  ttl"5 Seconds"
• Result - 2 JSP Custom tag page containing HTML
  fragments
•  
• Template page http//gallop.uccs.edu8888/example
  s/IncludeTag.jsp
• Fragments in the page are
• 1. http//gallop.uccs.edu8888/examples/staticpage
  .html ttl"5 Seconds"
• 2. http//gallop.uccs.edu/ayeddula/tasks.html
  ttl"5 Seconds"

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Impact when increase in file size

• Result - 1 ESI template page containing html
  fragments
• Template page http//gallop.uccs.edu/ayeddula/es
  i/testesi.html
• Fragments are
• http//gallop.uccs.edu8888/examples/staticpage.ht
  ml ttl"5 Seconds"
• http//gallop.uccs.edu/ayeddula/tasks.html
  ttl"5 Seconds"
•  
• Result - 2 JSP custom tag page containing html
  fragments
• Template page http//gallop.uccs.edu8888/exampl
  es/IncludeTag1.jsp
• Fragments are
• http//gallop.uccs.edu8888/examples/staticpage.ht
  ml ttl"5 Seconds"
• http//gallop.uccs.edu/ayeddula/tasks.html
  ttl"5 Seconds"

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JSP with JDBC-ODBC access

• JSP custom tag page containing html fragments
•  
• Template page http//gallop.uccs.edu8888/example
  s/database.jsp
• Fragments are
• JSP file include database tag
• ltjspxdatabase month"lt strmnt1gt" /gt
• TLD file
• ltnamegtdatabaselt/namegt lttagclassgtcwp.DataBaselt/
  tagclassgt
• ltattributegt ltnamegtmonthlt/namegt
  lt/attributegt

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Cont ..

• import javax.servlet.jsp.tagext.TagSupport
  import java.sql.
• public class DataBase extends TagSupport
• public int doStartTag() throws JspException
• Connection connull Statement stmtnull
  ResultSet rsnull
• Class.forName("sun.jdbc.odbc.JdbcOdbcDriver")
• conDriverManager.getConnection("jdbcodbcayedd
  uladb",null,null)
• stmtcon.createStatement()
• rsstmt.executeQuery("select date,text from "
  getMonth )
• while(rs.next()) pageContext.getOut().prin
  tln( rs.getString(1)
• return SKIP_BODY public void
  setMonth(String strMonth)
  getMonthstrMonth

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Varying TTL implementation

• JSP custom tag page containing html fragments
•  
• Template page
• http//gallop.uccs.edu8888/examples/IncludeTag2.
  jsp
• The test four Fragments are
• http//gallop.uccs.edu8888/examples/staticpage.ht
  ml ttl"60 Seconds"
• http//gallop.uccs.edu/ayeddula/tasks.html
  ttl"120 Seconds"

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Demo

• ESI pages
• http//gallop.uccs.edu/ayeddula/esi/testesi.html 
• http//gallop.uccs.edu/ayeddula/esi/home.html
• http//gallop.uccs.edu/ayeddula/esi/test.html
• http//gallop.uccs.edu/ayeddula/esi/conditionesi.h
  tml
• JSP Pages
• http//gallop.uccs.edu8888/examples/IncludeTag.js
  p
• http//gallop.uccs.edu8888/examples/IfExample.jsp
  
• http//gallop.uccs.edu8888/examples/database.jsp

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Lessons Learned

• The ETS server acts as an intermediary between
  the client and the web server.
• HTML code needs to reside on the Origin(main) web
  server NOT on the ETS server.
• Servlet can not read complete cookie data
  triggered through JSP tags.
• It is difficult to implement Time-To-Live
  feature.
• The url in the tag library descriptor should use
  . notation instead of /
• cwp.tags.IncludeTag not cwp/tags/IncludeTag
• The tag library descriptor reads only the
  packages but not direct class handler.
• cwp.tags.IncludeTag not IncludeTag

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Future Directions

• Extend ESI tags to include functions such as
  filtering and merging data, transforming of
  fragments.
• Enable displaying of fragments at different
  layout locations.
• Explore the load balancing features of ESI.

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Conclusion

• Designed and implemented Database tags, ESI
  include and conditional tags using customized
  JSP tags and servlets.
• Compared the performance of JDCS and that of ETS.
• Generated dynamic web pages on cache servers
  which conserve bandwidth.
• Generated dynamic web pages on cache server with
  rotating advertisement.

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References

• 1 Active Cache Caching Dynamic Contents on
  the Web http//www.cs.wisc.edu/cao/papers/ac
  tive-cache/SECTION00100000000000000000
• 3 ESI Resources http//www.esi.org/language_sp
  ec_1-0.html
• 4 Core Servlets and Java Server Pages by
  Marty Hall
• 5 Core Web Programming by Marty Hall and
  Larry Brown