An embedded HTTP server is an

HTTP server An HTTP server is a computer (software) program (or even a software component included in an other program) that plays the role of a server in a client–server model by implementing the ''server part'' of the HTTP and/or HTTPS network protocol ...

used in an embedded system. The HTTP server is usually implemented as a software component of an

application Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a c ...

(embedded) system that controls and/or monitors a machine with mechanical and/or electrical parts. The HTTP server implements the HTTP

protocol Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

in order to allow communications with one or more local or remote users using a browser. The aim is to let users to interact with information provided by the embedded system ( user interface, data monitoring, data logging, data configuration, etc.) via network, without using traditional peripherals required for local user interfaces (

display Display may refer to: Technology * Display device, output device for presenting information, including: ** Cathode ray tube, video display that provides a quality picture, but can be very heavy and deep ** Electronic visual display, output devi ...

keyboard Keyboard may refer to: Text input * Keyboard, part of a typewriter * Computer keyboard ** Keyboard layout, the software control of computer keyboards and their mapping ** Keyboard technology, computer keyboard hardware and firmware Music * Musi ...

, etc.). In some cases the functionalities provided via HTTP server allow also program-to-program communications, e.g. to retrieve data logged about the monitored machine, etc.

Usages

Examples of usage within an embedded application might be (e.g.): * to provide a thin client interface for a traditional application; * to provide

index Index (or its plural form indices) may refer to: Arts, entertainment, and media Fictional entities * Index (''A Certain Magical Index''), a character in the light novel series ''A Certain Magical Index'' * The Index, an item on a Halo megastru ...

ing, reporting, and

debugging In computer programming and software development, debugging is the process of finding and resolving '' bugs'' (defects or problems that prevent correct operation) within computer programs, software, or systems. Debugging tactics can involve in ...

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.

Advantages

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

firewall Firewall may refer to: * Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts * Firewall (construction), a barrier inside a building, designed to limit the spre ...

s and

intranet An intranet is a computer network for sharing information, easier communication, collaboration tools, operational systems, and other computing services within an organization, usually to the exclusion of access by outsiders. The term is used in c ...

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.

Typical requirements

Natural limitations of the platforms where an embedded HTTP server runs contribute to the list of the non-functional requirements of the embedded, or more precise, embeddable HTTP server. Some of these requirements are the following ones. * "Small" RAM and

ROM Rom, or ROM may refer to: Biomechanics and medicine * Risk of mortality, a medical classification to estimate the likelihood of death for a patient * Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac * R ...

footprint. The exact size depends on the system, but in many cases anything over several megabytes is not embeddable. * Minimal

CPU A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...

utilization. *

Cross compilation A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a PC but generates code that runs on an Android smartphone is a cross c ...

support for multiple

and operating system combinations. * Easy integration with an existing application, including static linking with the operating system and application. * Serving pages from

memory if there is no

file system In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...

. *

Modularity Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a sy ...

. * Single

thread Thread may refer to: Objects * Thread (yarn), a kind of thin yarn used for sewing ** Thread (unit of measurement), a cotton yarn measure * Screw thread, a helical ridge on a cylindrical fastener Arts and entertainment * ''Thread'' (film), 2016 ...

and multi-thread support. For every specific project, requirements can vary significantly. For example, ROM and RAM footprints can be a very serious constraint and limit the choices of the system designer. C++ or

JVM A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally describes ...

availability for the system can be another constraint. Frequently performance is an issue, because typical embedded systems run multiple simultaneous tasks and an HTTP server is only one of them and may be configured as a low priority task.

References

{{Reflist

External links

libmicrohttpd
contains an extensive list of embedded HTTP server libraries towards the bottom of the page

* ttps://realtimelogic.com/articles/What-is-an-Embedded-Application-Server Embedded Web Server vs. Embedded Application Server

Usages

Advantages

Typical requirements

See also

References

External links