CGI (Common Gateway Interface) is the legacy extension interface for running external programs to generate dynamic data. CGI programs are typically designed in PERL for host platforms and C/C++ in embedded devices since PERL is typically too CPU and memory intensive for embedded devices. Each web-page managed by CGI is typically designed as a standalone computer program, and it is therefore not uncommon to have a large number of CGI programs in a CGI managed web-application.
CGI cannot be used in embedded devices if the operating system does not support the process model since CGI is an API, based on passing environment variables from a web-server to an external process. The following comparison therefore applies to using a web-server with operating systems such as embedded Linux and QNX.
CGI is particularly slow in embedded devices with limited CPU since the web server must request the operating system to load, initialize, and execute the external CGI processes. A CGI process is typically loaded, initialized, executed, and terminated by the operating system for each web-page accessed. Starting up the CGI process takes up much more time and memory than the actual work of generating the output. Due to speed issues, web-applications designed using CGI in CPU limited devices will in many cases be too impractical for normal use. The users of the web-application may become impatient and regard the web-application of poor quality.
In Barracuda, web applications are extremely fast as they are part of the server if designed in CSP or loaded into the server at startup if designed in LSP. Additionally, since Barracuda is designed from the ground up for resource constrained devices, web-applications designed using CSP or LSP are generally blinding fast.
Lua Server Pages, or LSP for short, and C/C++ Server Pages, or CSP for short, are technologies that enable you to make dynamic and interactive web pages. LSP is similar to CSP except that LSP does not need to be compiled. Lua is a lightweight functional programming language, designed as a scripting language with extensible semantics as a primary goal.
One can find many discussions online when searching, for example, on Google for CGI versus ASP, or CGI versus PHP, etc. One soon gets a more clear understanding that developing CGI applications are much more cumbersome than more modern alternatives. These discussions are typically related to CGI developed in PERL or other high-level scripting languages. A CGI process developed in the C/C++ language is for obvious reasons much slower to design than to design a CGI script in PERL or any other scripting language. In addition, a CGI C/C++ framework must either be developed or purchased separately. This framework/library must be linked with all CGI programs (pages) developed, and CGI applications for embedded devices become extremely tedious and expensive to develop. CGI processes designed in C/C++ scale poorly, and it can become very expensive to add features and/or change web-applications designed using CGI.
Barracuda, on the other hand, provides a feature rich and easy to use web-framework that CSP and LSP applications can take advantage of. We dare to compare our LSP plug-in in functionality and ease of development with high end application servers such as those that can run ASP .NET web applications.
We often get questions about the size of the Barracuda Embedded Application Server, though customers typically do not think about the size of the web-application, which can easily and rapidly increase in size. A CGI based web-application designed in C/C++ increases in size rapidly as pages are added. Barracuda stores applications designed in LSP as ZIP files, thus considerably reducing the size compared to CGI based web-applications.
It is difficult to compare the Barracuda Embedded Application Server to other web-servers since the Barracuda Embedded Application Server is an application server. For example, a web-server such as Apache cannot be considered an application server until it is integrated with a framework such as PHP. It is easier to compare Barracuda to application servers such as J2EE based application servers although differences lie between size, speed, and language. Barracuda is much smaller and faster than J2EE application servers. Barracuda is implemented in C code while J2EE servers are implemented in Java.
In functionality the Barracuda Embedded Application Server provides features that are very similar to features in Servlets and JSP. Servlets are comparable to directory functions in Barracuda, but directory functions are more powerful. It is easier to design MVC and REST based applications by using Barracuda. JSP is similar to CSP or LSP, though both CSP and LSP are much faster than JSP. Web applications designed in LSP and the Lua scripting language are much easier to design than JSP. The development time is also shorter for LSP than JSP.
The Barracuda Embedded Application Server provides two server side technologies for generating dynamic content: CSP (C/C++ Server Pages) and LSP (Lua Server Pages). LSP is by far the easiest and most cost effective method of creating dynamic content and managing the interaction between a HTTP client and the server. The Lua scripting language used in LSP is comparable to PHP's ease of use. PHP is a scripting language widely used to write web applications, since it is easier to learn than, for example, Java. Thus, in a nutshell, LSP is comparable to the ease of using PHP, but with a framework similar to JSP/Servlets.
From experience, we know that designing device management applications using web servers together with basic application frameworks such as CGI take a significantly longer time to develop than device management applications designed using the Barracuda Embedded Application Server. Thus our product drastically reduces the overall price and time to market for the complete device management application.
Saturday, December 05th, 2009