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Posted 20 Jul 2008

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Webio - An embedded web server

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4.88/5 (33 votes)
20 Jul 2008BSD3 min read
A C-language web server with embedded files and CGI.


Webio is a small-footprint web server, designed to be embedded in an application or an embedded system. It's useful when you want to implement a complex browser based GUI (which can be accessed by everything from PCs to cell phones) in a very efficient manner. Webio compiles and runs equally well under Linux and Windows, and should be easy to port to most other platforms. It comes with a programmer's manual (progman.html) which explains how to use it and how to port it.


In 1996, I wrote one of the first web servers designed for embedded devices. In those days, most embedded devices had no file systems, so I created the "HTML compiler" to embed the files into the code image. Similarly, the lack of a file system led to C-language CGI functions.

Creating basic GUIs with this system was so easy that I started using it in Windows applications in preference to the Windows GUI. Back then, before JavaScript and CSS, it was somewhat limited - for example, it wouldn't make a very good "photo shop" type program - but for basic GUIs, it was great.

As my company started using Linux and Browser-enabled hand-held devices, a really huge advantage became obvious - my new applications worked everywhere, not just on Windows. The user was not tied on one OS or one type of device. They didn't even have to be near the machine running the application.

In 2007, I needed a similar server for an open-source project. I had left the previous company, which still retained the rights to the my old server. They wouldn't open source it, and nothing suitable was available in the public domain. I decided to create a second generation version of the server and release it under the BSD license so I would never have to write it again.

The result is Webio - my second (and hopefully last) embedded web server.

Using the code

The Windows version is probably of most interest to CodeProject readers, and so the .zip file is made available here. Follow these steps:

  1. Unzip it (preserving the directory structure).
  2. Type buildfs to compile the embedded file system.
  3. Open the project file with Visual C++ 6.0 or newer, and click Build.

You should get a little application which, when run, allows your PC to act as a web server - point a browser at it. You can do this in loopback by typing "http://127.1" in your browser's location bar.

Points of interest

Webio has a few improvements over my first embedded web server:

  • The "HTML compiler" is now a full-fledged file system builder, designed from the group up to generate not only file images in your C code, but also generate code for C-language CGI.
  • The server buffers all code-generated output, allowing accurate Content-Length fields on files with variable sized SSIs.
  • A fast path for binary files improves performance.
  • Portability across Windows/Linux/Embedded systems is enhanced.


  • July 2008 - First public release.
  • July 27th - Updated, call this release 1.1. Changes:
    • Added command line option to set the HTTP port (default is still 80).
    • Error message is more helpful if another web server already has port 80.
    • Fixed some typos and omissions in the manual.


This article, along with any associated source code and files, is licensed under The BSD License


About the Author

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Comments and Discussions

GeneralRe: A Recipe for displaying dynamic content Pin
ravenspoint23-Jul-08 10:02
Memberravenspoint23-Jul-08 10:02 
GeneralRe: A Recipe for displaying dynamic content Pin
ravenspoint23-Jul-08 10:39
Memberravenspoint23-Jul-08 10:39 
GeneralRe: A Recipe for displaying dynamic content Pin
ravenspoint23-Jul-08 13:11
Memberravenspoint23-Jul-08 13:11 
GeneralRe: A Recipe for displaying dynamic content Pin
ravenspoint24-Jul-08 9:30
Memberravenspoint24-Jul-08 9:30 
GeneralUsing Webio in a C++ program Pin
ravenspoint23-Jul-08 4:07
Memberravenspoint23-Jul-08 4:07 
GeneralBuild & Run workarounds Pin
ravenspoint22-Jul-08 8:34
Memberravenspoint22-Jul-08 8:34 
GeneralRe: Build & Run workarounds Pin
ravenspoint22-Jul-08 9:02
Memberravenspoint22-Jul-08 9:02 
GeneralRe: Build & Run workarounds Pin
jbartas22-Jul-08 18:52
Memberjbartas22-Jul-08 18:52 
I really like that idea (making the port a command line option). I've also found some bugs in the fsbuilder. I'll try to get it implemented and updated by this weekend.


Generalbuild error in VC++7.0 Pin
sms9121-Jul-08 17:49
Membersms9121-Jul-08 17:49 
GeneralRe: build error in VC++7.0 Pin
vva13321-Jul-08 19:24
Membervva13321-Jul-08 19:24 
GeneralNice project! Pin
Rynus_Rein20-Jul-08 10:43
MemberRynus_Rein20-Jul-08 10:43 

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