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Web cache as</A><B> Previous:</B> <A NAME="tex2html9136" HREF="node502.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node502.html">36.2.3 Debugging</A>   <B> <A NAME="tex2html9144" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html9146" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <BR><BR><!--End of Navigation Panel--><H1><A NAME="SECTION07230000000000000000">36.3 Representing web pages</A></H1><P>We represent web pages as the abstract class Page. It is defined as follows:<P><PRE>class Page {public: Page(int size) : size_(size) {} int size() const { return size_; } int& id() { return id_; } virtual WebPageType type() const = 0;protected: int size_; int id_;};</PRE><P>It represents the basic properties of a web page: size and URL. Uponit we derive two classes of web pages: ServerPage and ClientPage. Theformer contains a list of page modification times, and is supposed toby used by servers. It was originally designed to work with a specialweb server trace; currently it is not widely used in . The latter,ClientPage, is the default web page for all page pools below. <P>A ClientPage has the following major properties (we omit somevariables used by web cache with invalidation, which has too manydetails to be covered here):<P><UL><LI><TT>HttpApp* server_</TT> - Pointer to the original server of this page. </LI><LI><TT>double age_</TT> - Lifetime of the page.</LI><LI><TT>int status_</TT> - Status of the page. Its contents are explained below.</LI></UL><P>The status (32-bit) of a ClientPage is separated into two 16-bitparts. The first part (with mask 0x00FF) is used to store pagestatus, the second part (with mask 0xFF00) is used to store expectedpage actions to be performed by cache. Available page status are (again,we omit those closely related to web cache invalidation):<P><BR><BR><P>CilentPage has the following major C++ methods: <P><UL><LI><TT>type()</TT> - Returns the type of the page. Assuming pages of the same type should have identical operations, we let all ClientPage to be of type ``HTML''. If later on other types of web pages are needed, a class may be derived from ClientPage (or Page) with the desired type. </LI><LI><TT>name(char *buf)</TT> - Print the page's name into the given buffer. A page's name is in the format of: ServerName:PageID. </LI><LI><TT>split_name(const char *name, PageID& id)</TT> - Split a given page name into its two components. This is a static method. </LI><LI><TT>mtime()</TT> - Returns the last modification time of the page.</LI><LI><TT>age()</TT> - Returns the lifetime of the page. </LI></UL><P><HR><!--Navigation Panel--><A NAME="tex2html9147" HREF="node504.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node504.html"><IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="file:/usr/share/latex2html/icons/next.png"></A> <A NAME="tex2html9141" HREF="node490.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node490.html"><IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="file:/usr/share/latex2html/icons/up.png"></A> <A NAME="tex2html9135" HREF="node502.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node502.html"><IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="file:/usr/share/latex2html/icons/prev.png"></A> <A NAME="tex2html9143" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html"><IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="file:/usr/share/latex2html/icons/contents.png"></A> <A NAME="tex2html9145" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html"><IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="file:/usr/share/latex2html/icons/index.png"></A> <BR><B> Next:</B> <A NAME="tex2html9148" HREF="node504.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node504.html">36.4 Page pools</A><B> Up:</B> <A NAME="tex2html9142" HREF="node490.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node490.html">36. Web cache as</A><B> Previous:</B> <A NAME="tex2html9136" HREF="node502.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node502.html">36.2.3 Debugging</A>   <B> <A NAME="tex2html9144" HREF="node1.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node1.html">Contents</A></B>   <B> <A NAME="tex2html9146" HREF="node590.html" tppabs="http://www.isi.edu/nsnam/ns/doc/node590.html">Index</A></B> <!--End of Navigation Panel--><ADDRESS>2003-09-23</ADDRESS></BODY></HTML>⌨️ 快捷键说明
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