Part III Running Web Applications in VS .NET

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Part III Running Web Applications
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You can keep a count of how many times this memory-leaking application has serviced requests and kill it by programming around it Listing 14-1 shows a simple example of how request-processing count is kept in a simple C-based FastCGI application As the listing shows, when the maximum number of requests have been processed the FastCGI application exits
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Listing 14-1: memory_hogc
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#include <fcgi_stdioh> void main(void){ int maxRequests = 100; before exiting int requestCount = 0; requests processed so far while(FCGI_Accept() >= 0) { /* body code */
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// maximum num of request // used to keep count of // start of response loop
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printf( Content-type: text/html\r\n ); printf( \r\n ); printf( Number of requests processed so far is %d , requestCount++); /* some memory leaking code could go here */ /* end of application code */ if(requestCount >= maxRequests) { /* clean-up code goes here */ exit 0; } /* end of body code */ } / * termination or clean-up code (if any) */ exit(0); }
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Migrating a sample script
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This section demonstrates how to migrate fontsizecgi, a simple CGI script (written in Perl), which is listed in Listing 14-2
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14 Configuring Apache for FastCGI
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Listing 14-2: fontsizecgi
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#!/usr/bin/perl -w # Variables my $MAX = 10; my $i; # Content Header print Content-type: text/html\n\n ; # Main loop for ($i=0; $i < $MAX; $i++){ print <FONT SIZE=$i>Font Size = $i</FONT><BR> ; } exit 0;
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This CGI application produces the output shown in Figure 14-5
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Figure 14-5: Output of the fontsizecgi script
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Now let s convert this to a FastCGI application First you need to make sure you have installed the FCGI module from a Comprehensive Perl Archive Network (CPAN) site by following these steps:
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1 As root, from the command-line run the following command:
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perl MCPAN e shell
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2 At the cpan> prompt enter the install FCGI command, which will install the latest version of this CPAN module if you do not already have the latest 3 As the second line in the above script, add the following line:
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use FCGI;
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This tells Perl to load the FCGI module when running the script 4 Identify the initialization block of the CGI application For this script the initialization block consists of the following two variable declarations:
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my $MAX = 10; my $i;
5 Identify the response loop and body blocks of the CGI application Because every request must be responded to with an appropriate Content-Type header, the body of the main code begins with this line:
print Content-type: text/html\n\n ;
The for loop responsible for the actual processing is the rest of the body 6 Now that the body code is identified, you need to put the response loop around it This is done using the following code:
while(FCGIaccept() >= 0) { # body code goes here }
Now the body looks like this:
while(FCGI::accept() >= 0) { print Content-type: text/html\n\n ; for ($i=0; $i < $MAX; $i++){ print <FONT SIZE=$i>Font Size = $i</FONT><BR> ; } }
FastCGI applications act like server applications, so the following line is only executed if by the Web server or by the administrator sends the application a signal to terminate:
exit 0;
The FastCGI version of the entire application is listed in Listing 14-3
14 Configuring Apache for FastCGI
Listing 14-3: fontsizefcgi
#!/usr/bin/perl # Load the FCGI module use FCGI; # Global variables my $MAX = 10; my $i; # FastCGI Loop while(FCGI::accept() >= 0) { # Content Header print Content-type: text/html\n\n ; # Main Loop for ($i=0; $i < $MAX; $i++){ print <FONT SIZE=$i>Font Size = $i</FONT><BR> ; } } exit 0;
Setting Up FastCGI for Apache
To install mod_fastcgi with Apache, follow these steps: 1 Download the latest mod_fastcgi module for Apache from wwwfastcgicom for Apache 2 Extract the source in the /usr/local/src directory A new directory called mod_fastcgi_version is created Read the INSTALL file in this new directory for details on how to install the module, as the installation changes from time to time 3 Copy the new directory to a subdirectory called fastcgi under the modules directory within your Apache source tree 4 From the Apache source distribution directory, run the following configure --enable-module=fastcgi and any other options that you want to specify with the configure script (See 3 for details on other options available for the configure script) If you have already compiled Apache you can replace configure with configstatus in the preceding command to ensure that all of the options you specified when you ran configure last time are applied again 5 Run make and make install to compile and install Apache with mod_fastcgi support