Embedded HTTP server

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An embedded HTTP server is a component of a software system that implements the HTTP protocol. Examples of usage within an application might be:

To provide a thin-client interface for a traditional application.
To provide indexing, reporting, and debugging tools during the development stage.
To implement a protocol for the distribution and acquisition of information to be displayed in the regular interface — possibly a web service, and possibly using XML as the data format.
To develop a web application

There are a few advantages to using HTTP to perform the above:

HTTP is a well studied cross-platform protocol and there are mature implementations freely available.
HTTP is seldom blocked by firewalls and intranet routers.
HTTP clients (e.g. web browsers) are readily available with all modern computers.
There is a growing tendency of using embedded HTTP servers in applications that parallels the rising trends of home-networking and ubiquitous computing.

[edit] Typical requirements

Natural limitations of the platforms where an embedded HTTP server runs contribute to the list of the functional requirements of the embedded, or more precise, embeddable HTTP server. Some of these requirements in random order

"Small" RAM and ROM foot print. The exact number depends on the system, but in many cases anything over several megabytes is not embeddable.
Low CPU consumption.
Cross compilation support for multiple CPU and operating system combinations.
Easy integration with existing application, including static link with the operating system and application.
Serving pages from the RAM if there is no file system.
Modularity.
Single thread and multi-thread support.

For every specific project requirements can vary significantly. For example, ROM and RAM footprints can be very serious constraint and limit the choices of the system designer. C++ or JVM availability for the system can be another constraint. Frequently performance is an issue, because typical embedded system runs multiple simultaneous tasks and an HTTP server is only one of them and is usually a low priority task.