AOLserverAmerica Online’sopen source webserver

Dossy Shiobara

February 2005

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About Dossy Shiobara

• I've been using AOLserver since late 1999 to serve my own personal websites, as well as helping to support others who use it.

• In 2003, I joined AOL where I support the sites at AOL that use AOLserver as well.

• I'm currently the Project Leader of the AOLserver project.

• I’m the initial developer of two AOLserver modules, nsmysql and nsfreetds. I’ve also contributed to the core server, as well as nsopenssl and other modules.

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A brief history of AOLserver

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NaviSoft (before Nov 1994)

• Company started by producing high-quality client- and server-side tools for web publishing: NaviPress and NaviServer.

• NaviPress was one of the first WYSIWYG HTML editors.

• NaviPress could send changes up to NaviServer (using HTTP PUT) making web site management and updating simple.

• Because of this capability, NaviPress/NaviServer was one of the first entrants into the distributed web authoring space.

• NaviServer was designed to be multi-threaded from the beginning. (In comparison, multi-threaded Apache was only declared GA or “General Availability” or non-beta in Apache 2.0.35 in April 2002.)

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AOL (after Dec 1994)

• In 1994, AOL realizes the need to enter into the Internet and World Wide Web space.

• AOL acquires NaviSoft, Inc. on November 30, 1994.

• NaviServer is renamed AOLserver, NaviPress to AOLpress.

• AOL offers commercial web hosting through NaviService, then GNN Hosting, then PrimeHost, using AOLserver/AOLpress.

• AOL launches Digital City, Inc. (DCI) in 1996 on AOLserver platform. Continues to use AOLserver for other web properties over the years (Moviefone.com, Mapquest.com, etc.).

• AOLserver 3.0 released as open source on July 8, 1999.

• AOLserver 4.0 released in November, 2003

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So, what is AOLserver?

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What can I do with AOLserver?

• Run a server with high quality code resulting in very few security vulnerabilities found in the wild.

• Easily administrate your servers through configuration files that are programs themselves.

• Rapidly develop applications using a mix of C and Tcl that leverage a scalable, multi-threaded architecture.

• Serve existing CGI (using nscgi), PHP (using PHP’s AOLserver SAPI module), and JSP/Java Servlets (using Tomcat and nsjk2).

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What can’t I do with AOLserver?

• Not suited for hosting different customers within the same server process because of multi-threaded nature. Each customer needs their own server process.

• Not many off-the shelf applications available to download, install and run.

• No support for mod_perl at the moment.

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Who uses AOLserver?

• Commercially:

– America Online: AOL.com, Moviefone.com, Mapquest.com, etc.

– KnowNow’s LiveServer

• Educational/Academic:

– dotLRN (.LRN) – distance e-learning (MIT Sloan School of Business, etc.)

– SMLserver – Standard ML ’97 (IT University of Copenhagen)

• Others:

– ArsDigita Community System (ACS)

– OpenACS – community site toolkit (Greenpeace, Creative Commons, etc.)

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How do I get AOLserver?

• AOLserver is freely available, open source software, hosted at SourceForge.

• AOLserver is approximately 75K lines of C code and 5K lines of Tcl code.

• AOLserver project website is at http://aolserver.com/.

• Site contains download links of source tarballs, links to the AOLserver Wiki, and other documentation links.

• For more information on Tcl, go to http://www.tcl.tk/.

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Examples

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Server configuration

• The server configuration is just another Tcl script that gets executed at server start-up.

• Example “nssock” (HTTP listener) module configuration snippet:

ns_section“ns/server/${servername}/modules”

ns_param nssock nssock.so

ns_section“ns/server/${servername}/module/nssock”

ns_param port 80

ns_param hostname www.example.com

ns_param address 192.168.0.1

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AOLserver Dynamic Pages (ADPs)

Source:

<%

set now [clock seconds]

ns_adp_puts “It is now $now, or [clock format $now].”

%>

Output:

It is now 1109047145, or Mon Feb 21 11:39:05 PM EST 2005.

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Another way of doing it

Source:

<% set now [clock seconds] %>

It is now <%= $now %>, or <%= [clock format $now] %>.

Output:

It is now 1109047145, or Mon Feb 21 11:39:05 PM EST 2005.

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Servlet-like request handling

Bind a Tcl proc to handle requests for a particular URL:

ns_register_proc GET /demo/time getTime

proc getTime {} {

set now [clock seconds]

set page “<html><body>\n”

append page “It is now $now, or [clock format $now].\n”

append page “</body></html>\n”

ns_return 200 text/html $page

}

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Query a SQL database

Query a SQL database to build up part of an HTML page:

set page “<html><body>\n”set db [ns_db gethandle userdb]set row [ns_db select $db “SELECT username FROM users”]while {[ns_db getrow $db $row]} {

append page “User: [ns_set get $row username]<br/>\n”}append page “</body></html>\n”ns_set free $rowns_db releasehandle $db

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Perform a task in a background thread

Perform a task in a background thread:

ns_schedule_proc 3600 hourlyCheck

proc hourlyCheck {} {

set errors [… collect errors from log file …]

if {[string length $errors]} {

ns_sendmail errors@mydomain.com \

aolserver@mydomain.com \

“Errors Encountered” $errors

}

}

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Summary

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AOLserver …

• was originally named NaviServer when first created in 1994.

• is an open source webserver available from SourceForge.

• is mostly written in C, approximately 75K LOC today.

• uses Tcl as its embedded scripting language, another 5K LOC.

• has employed a multi-threaded design from the start.

• is suitable for rapidly developing fast, scalable, dynamic and data-driven web applications.

• has been proven stable and capable over the years through aggressive use in some of the world’s busiest websites at AOL.

• has been ported to many platforms: Solaris, Linux, Win32, MacOS X, BSD, Irix, HP-UX, etc.

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Questions? Comments?