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Generate Dynamic Content On Cache Server

This project proposal by Aparna Yeddula explores the concept of dynamic content generation on cache servers using the Edge Side Include (ESI) language and other web services specifications.

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Generate Dynamic Content On Cache Server

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  1. Generate Dynamic Content On Cache Server Master’s Project Proposal by Aparna Yeddula

  2. Introduction • Caching • fetching document. • pass to the browser. • save copies. • Referred to as a web proxy server. • Subsequent requests from other users of the cache get the saved copy. Advantage: Faster and does not consume Internet bandwidth over the often-congested network links. Maters/Proposal

  3. Maters/Proposal

  4. Intro… • With out caching generating dynamic web page imposes heavy burden on the original web server. To alleviate that, the generation of dynamic web pages can be done at the cache servers. • One of the content delivery network providers Akamai had proposed Edge Side Include (ESI) language for specifying how a web page can be dynamically generated. Maters/Proposal

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  6. Edge side include Test Server (ETS) • The ESI assembly model is comprised of a template containing fragments. • The template is the container for assembly. • Each fragment of the page need to be retrieved from the origin server. • Each fragment has its own time-to-live (TTL) attribute, which specifies how long the cache server maintains the copies. • Fragments are separate resources, they can be assigned their own cacheability and handling information. Maters/Proposal

  7. ESI Example • ‘<esi:include>’ tag example The include element specifies a fragment for assembly. <esi:include src="URI" ttl=“1hr" /> For example, <esi:include src="http://example.com/1.html" ttl=“1hr”/> • ‘<esi:choose>’ tag example The conditional elements add the ability to perform logic based on expressions. For example, <esi:choose> <esi:when test="$(HTTP_HOST)==‘128.198.192.174'"> <esi:include src="http://www.example.com/advanced.html"/> </esi:when> <esi:otherwise> <esi:include src="http://www.example.com/newuser.html"/> </esi:otherwise> </esi:choose> Maters/Proposal

  8. Web services specifications • The web services model is independent of languages, platforms, and object models. • Each time a service request is received, a new object is created. The request for the method call, and the object is destroyed after the method call is returned. Maters/Proposal

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  10. DOTNET Models • Direct client model • The client browser issues a GET HTTP request .asmx page directly to the web service. • When we call a web service from a browser, we access the description page, which lists the methods that are included in the Web service. The protocol that is used in this case is HTTP, and the data is returned as XML. • Web server or the proxy client model • The client browser issues a GET HTTP request .aspx page to the web server. The server parses and compiles the page. The code invokes the proxy to call the web service. Here the request and response between the servers is using XMLP. And the web server sends the response to the client in HTTP [6]. Maters/Proposal

  11. JSP (Java Server Pages) custom tag specifications • JSP custom tag can be used to implement XML languages including ESI. • To use the JSP custom tags, we need to define three separate components: • JSP file that uses the tag library. • tag library descriptor (tld) file that maps the XML elements names to the tag implementations. • tag handler class that defines the tag’s behavior. Maters/Proposal

  12. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <%@ taglib uri="simple-taglib.tld“ prefix="jspx" %> <title><jspx:hello /></title> </head><body> <H1 align="center"> JSP Custom Tag Test Page </H1> <H2>First JSP Custom Tag <jspx:hello /> </H2> </body></html> The JSP file Maters/Proposal

  13. <!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.1//EN" "http://java.sun.com/j2ee/dtd/web-jsptaglibrary_1_1.dtd"> <taglib> <tlibversion>1.0</tlibversion> <jspversion>1.1</jspversion> <uri> simple-taglib.tld</uri> <tag> <name>hello</name> <tagclass>cwp.tags.HelloWorldTag</tagclass> </tag> </taglib> Tag library descriptor file Maters/Proposal

  14. import javax.servlet.jsp.*; import javax.servlet.jsp.tagext.TagSupport; // tells system what to do when it sees the tag // This is a simple tag example to show how content is added to the output stream when a tag is encountered in a JSP page. public class HelloWorldTag extends TagSupport {   // doStartTag is called by the JSP container when the tag is encountered public int doStartTag() { JspWriter out = pageContext.getOut(); out.println("<tr><td> Hello World </td></tr>"); // Must return SKIP_BODY because we are not supporting a body for this tag } return SKIP_BODY; } Tag handler class Maters/Proposal

  15. JSP FILE <body> <%@ taglib uri="include-taglib.tld" prefix="jspx" %> <jspx:include uri="http://uccs.edu/page.html" ttl="1"/> </body> TLD FILE <tag> <name>include</name> <tagclass>cwp.tags.IncludeTag</tagclass> <attribute> <name>uri</name> <required>true</required> </attribute> <attribute> <name>ttl</name> <required>true</required> </attribute> </tag> JSP Example Maters/Proposal

  16. JSP Example public int doStartTag() throws JspException { public void setUri (String name) { uriName = name; } // Set Ttl called when set the Tag attribute public void setTtl (String name){ ttlName = name; } } Maters/Proposal

  17. Tasks Already Complete 1.      Study how to change the date and time of the web page based on the Java Script. 2.      Study how to change the date and time using DOTNET on the server side with .asmx page. 3.      Study how to change the date and time using DOTNET on the server side with .aspx page. 4.      Study how to use Java socket library to process the http request and response. 5.      Study database access using Microsoft access and Active Server Page (ASP). 6.      Study how ESI works. 7.      Study how JSP custom tags to implement ESI. In Progress Testing the performance of my project with the ESI proposed by Akamai, using a simple PERL program to test the time taken to deliver the document. Deliverables My project report documenting the approach and code to the project, related work and the lessons learned in this project. Maters/Proposal

  18. References • [1] Microsoft DOTNET sample training modules http://www.microsoft.com/traincert/training/developer/dotnet.asp • [2] Active Cache: Caching Dynamic Contents on the Web http://www.cs.wisc.edu/~cao/papers/active-cache/SECTION00100000000000000000 • [3] ESI Resources http://www.esi.org/language_spec_1-0.html • [4] “Core Servlets and Java Server Pages” by Marty Hall • [5] “Core Web Programming” by Marty Hall and Larry Brown • [6] DOTNET Training http://www.imguniversity.com/WebUPublic/default.asp?URL=%2E%2E%2FWebSyllabus%2FwsStudentClassList%2Easp Maters/Proposal

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