IIS 6

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IIS 6

• Throw it out and start over

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Kernel and Applications
Word
Firefox
Outlook
Kernel
Disk Cache
diskdriver
videodriver
ethernetdriver
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What is the Kernel?

• Support for devices, file systems, network, and
  video
• Manages memory, programs, files
• Object for each running program, thread, open
  file, network connection, loaded module
• Extended by installing drivers
• Configured in the registry

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Windows services from DLLs that call the Kernel
DLL
DLL
DLL
DLL
Application Program
Kernel
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Windows vrs Kernel

• Case insensitive file names
• Disk Letters
• stream of bytes

• Unicode case sensitive file names
• Devices and partitions
• sectors, buffers, commands
• Processors
• Real memory
• PnP, power mgmt

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Kernel Environment

• Programs don't see it
• Call to Kernel routine makes Kernel data visible
• All objects for all programs (process, thread,
  module, memory, devices, open files) visible in
  one place
• No end-user services

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Windows NT 3.1
WindowsFile Server
Open Access Control
Kernel
file server support
file system
DISK CACHE
ReadWrite
Ethernet
disk driver
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A Browser Request Arrives(Windows or Unix)
Kernel
Ethernet
Addressed to this machine?What protocol?
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Browser Request Processing(Windows or Unix)
Kernel
Addressed to this machine?What port
(application)?
TCP/IP
Ethernet
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Browser Request Processing(Windows or Unix)
IIS 5 or Apache
What virtual directory?
Port 80
Kernel
TCP/IP
Ethernet
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Browser Request Processing(Windows or Unix)
IIS 5 or Apache
Tomcat
/uPortal
Kernel
TCP/IP
Ethernet
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Browser Request ProcessingWindows Server 2003
Kernel
Addressed to this machine?What port
(application)?
TCP/IP
Ethernet
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Browser Request ProcessingWindows Server 2003
Kernel
HTTP.SYS
TCP/IP
Port 80
Ethernet
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HTTP Request Headers
PORT 80
Application
Mapped Extension
GET /ponies/aqueduct/race2/odds.xyz
HTTP/1.1Host www.handicap.yale.edu...
Virtual Host
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IIS Web "Sites"
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HTTP.SYS

• Called by TCP/IP when data arrives on a port
  associated with IIS
• Reads HTTP headers into Kernel memory
• Maps porthostnameapplication to a running
  process
• Passes request to that process

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ISAPI
ApplicationProcess
some.dll
Kernel
HTTP.SYS
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Low Level API for Servers

• IIS
• Apache
• Tomcat

• ISAPI
• mod_xxx
• Servlet

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High Level API for Servers

• IIS
• Apache
• Tomcat

• ISAPI
• ASP.NET
• mod_xxx
• PHP, ...
• Servlet
• JSP, Taglib, JSF, ...

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ISAPI

• ActiveX (object based system api)
• Filters
• A DLL configured for a Site that scans all
  requests
• Extensions
• A DLL configured by application that receives
  requests based on the URL file extension

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Configure ISAPI Mappings
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ISAPI in IIS 5
App
Apps
IIS
Extension
Filter
Extension
Extension
Kernel
TCP/IP
Ethernet
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ISAPI in IIS 6
App
App
App
Extension
Extension
filter
filter
filter
Kernel
HTTP.SYS
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Web is another File Server
App
Send Back File
Kernel
DISK CACHE
HTTP.SYS
Disk Driver
Ethernet Driver
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Cache (for a time) frequent program response
App
Cache Response
Kernel
URL CACHE
Same URL
HTTP.SYS
Ethernet Driver
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System Architecture

• Web protocols are now part of the kernel
• Process file requests like "net share"
• HTML or XML(WebServices) applications become
  normal programs run by the OS processing request
  callbacks from the Kernel
• No trade off of integrity for performance
• Ordinary program security for Web
• Each Web app has its own process, address space,
  userid, permissions, ...

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Restriction until SP 1

• SSL goes up to IIS process before being handed
  off to application
• In SP 1, Windows Cryptography services extended
  to Kernel so HTTP.SYS can do SSL

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IIS 5 Extension Mapping
.asp
.pl
ASP.DLL
ISAPI Perl
ScriptEngine
JS
PL
VBS
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IIS 5 .NET (or IIS 6)
.asp
.pl
.asax, .aspx, ...
ASP.DLL
ISAPI Perl
aspnet_isapi.dll
CLI
ScriptEngine
.NET Framework
JS
PL
VBS
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.NET

• New code format and environment
• CLI is a superset of Java JVM (IKVM translates
  Java Jar to .NET DLL/EXE)
• Supports all languages
• Access to all Windows services, but much easier
  to code than WIN32
• API for Longhorn services
• Mono and Portable.NET run on Unix

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Mapping in the Process

• Get to the Process because of the port,
  hostname, and /dirname
• Run each Filter
• Try to match file extension to a mapped DLL name.
  If found, pass the request to it using ISAPI
  protocol
• Default match the URL to a file and send it back

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Architecture Again

• Every other Web Server (Apache, Netscape) is
  designed as a file server that runs programs on
  the side
• IIS is an application routing engine that runs
  program elements, and the default program if no
  other takes control sends files back to the
  Browser

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ASP.NET
Codebehind
OnloadOnClick OnMouseOver Event Handlers
lthtmlgt
html extends code
lt/htmlgt
Compile code and HTML into an Application
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Architecture Again

• Classic Web applications run a script (PHP, Perl)
  source program
• ASP processed HTML text with embedded interpreted
  script code
• ASP.NET compiles the code and HTML into an
  executable module. All program, no data (except
  for extern stray files).

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Servlet form of ASP.NET

• Application implements IHttpHandler
• void ProcessRequest(HttpContext)
• HttpContext.Request
• HttpContext.Response
• HttpContext.Application
• HttpContext.Session
• VS "codebehind" applications implement the
  interface through library, just as Java server
  handles JSP/Taglib transparently

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Recap
.asax, .aspx, ...
ISAPI from the Kernel
aspnet_isapi.dll
HttpContext (Request, Response)
CLI
IHttpHandler
Assembly
codebehind
rt
html
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Microsoft Does It Again

• Dec 7, 1995 - Bill Gates declares the Web as the
  future, announces IE integration with Windows GUI
• Implementation bugs poked holes in the "sandbox"
  causing Security errors
• Now IIS 6 does the other end integrating the Web
  Server into the OS program services

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Not The Same Problem

• CICS, RPC, CORBA, Named Pipes, J2EE
• Same thing different protocol
• This is what Terminal Servers, Application
  Servers, Database Servers, File Servers do
• Paradigm shift for Web Server design, but routine
  for OS design