If you have ever Googled "embedded web server" or "embedded web server tutorials", you have likely come across many tutorials on how to create a lightweight web server on, for example, Linux to serve static HTML files. Being able to serve static web pages is one of the most fundamental parts of any embedded web server; however, for device management to be practical, we need to look beyond just serving static web pages. In particular, embedded web servers generally must be able to let the web functionality affect the device operation - the remote browser has to be able to "talk" to the embedded system.
An embeddable application server is a more formalized way of saying an embedded web server that lets you easily build HTML based interactive device management applications.
To get a better understanding of the differences between an embedded web server and an embedded application server, see our What is an Embedded Application Server primer for embedded developers.
For an embedded developer, the first thing that may be considered is that the server side part of the embedded web application must be designed in C code. Although this is very common, it may not be the best solution for many embedded systems. Web applications are very text heavy, and it is time consuming and error prone to develop server side web applications in C code. A better solution may be to use an application server that supports a fast and compact scripting language suitable for embedded systems. For efficient scripting in an embedded environment, there’s a scripting language called Lua and it is especially designed to operate on small (embedded) platforms. It’s specifically defined as an extensible language and is implemented as a C library that gets compiled and linked with your application/firmware. For more information, check out our Lua Fast-Tracks Embedded Web Application Development tutorial.
You may be looking for a CGI enabled web server, but CGI has several drawbacks such as several security issues, being slow, and time consuming development in embedded devices. Older websites were originally implemented using the Common Gateway Interface (CGI). In truth, CGI is only an interface. It’s generally cumbersome to manage and requires a full-up OS like Linux that can load external programs, meaning that deep embedded monolithic systems cannot use CGI. Basic embedded web servers typically specify only function hooks; you must write the functions. With CGI on standard web servers, Perl scripting is very common, but most embedded environments don’t support Perl, meaning you have to revert to C to get things done. All of this makes CGI an unattractive option. See our Barracuda App Server vs CGI whitepaper for more information on why we do not recommend CGI for new design.
The following is a list of hands-on tutorials for the Mako Server, which is a Barracuda Application Server (BAS) derivative product designed for high level operating systems. Mako Server and BAS provide the same programmer API thus the following Mako Server tutorials also apply to the Barracuda App Server. Clicking any of the links below takes you to the Mako Server web site.
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