An in-kernel web server is an unlimited
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 proto ...
that runs in
kernel space
A modern computer operating system usually segregates virtual memory into user space and kernel space. Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour.
Kerne ...
or equivalent. It is also known as "accelerator".
Benefits
*
Performance
A performance is an act of staging or presenting a play, concert, or other form of entertainment. It is also defined as the action or process of carrying out or accomplishing an action, task, or function.
Management science
In the work place ...
: the path taken by data from a source
device
A device is usually a constructed tool. Device may also refer to:
Technology Computing
* Device, a colloquial term encompassing desktops, laptops, tablets, smartphones, etc.
* Device file, an interface of a device driver
* Peripheral, any devi ...
(i.e. a
disk) to a destination device (i.e. a
NIC
NIC may refer to:
Banking and insurance companies
* National Insurance Corporation, Uganda
* NIC Bank, a commercial bank in Kenya
Politics, government and economics
* National Ice Center, an agency that provides worldwide navigational ice ...
). Proper asynchronous
zero-copy
"Zero-copy" describes computer operations in which the CPU does not perform the task of copying data from one memory area to another or in which unnecessary data copies are avoided. This is frequently used to save CPU cycles and memory bandwid ...
interfaces would make this available from
user-space
A modern computer operating system usually segregates virtual memory into user space and kernel space. Primarily, this separation serves to provide memory protection and hardware protection from malicious or errant software behaviour.
Kern ...
.
*
Scalability
Scalability is the property of a system to handle a growing amount of work by adding resources to the system.
In an economic context, a scalable business model implies that a company can increase sales given increased resources. For example, a ...
: with respect to number of simultaneous
clients.
Event notification of comparable scalability seems unlikely in user-space.
Drawbacks
*Security: Kernel processes run with unlimited privileges.
*Portability. Every kernel needs a specific implementation route.
*Reliability. Failure in the webserver may crash the OS.
Implementations
*
illumos
Illumos (stylized as illumos) is a partly free and open-source Unix operating system. It is based on OpenSolaris, which was based on System V Release 4 (SVR4) and the Berkeley Software Distribution (BSD). Illumos comprises a kernel, device d ...
/
Solaris:
NCAkmod aka Network Cache and Accelerator (NCA) kernel module
*
HP-UX
HP-UX (from "Hewlett Packard Unix") is Hewlett Packard Enterprise's proprietary implementation of the Unix operating system, based on Unix System V (initially System III) and first released in 1984. Current versions support HPE Integrit ...
:
NSAhttp
*
Linux
Linux ( or ) is a family of open-source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991, by Linus Torvalds. Linux is typically packaged as a Linux distribution, which i ...
:
TUXMesiboIn-kernel real-time messaging server
*
Windows NT
Windows NT is a proprietary graphical operating system produced by Microsoft, the first version of which was released on July 27, 1993. It is a processor-independent, multiprocessing and multi-user operating system.
The first version of Wi ...
:
(part of
Internet Information Services, IIS)
*
SPIN
Spin or spinning most often refers to:
* Spinning (textiles), the creation of yarn or thread by twisting fibers together, traditionally by hand spinning
* Spin, the rotation of an object around a central axis
* Spin (propaganda), an intentionally b ...
:
http
The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, ...
*
OpenVMS
OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers using Ope ...
:
WASD.trap
See also
*
Comparison of web server software
Web server software allows computers to act as web servers. The first web servers supported only static files, such as HTML (and images), but now they commonly allow embedding of server side applications.
Some web application frameworks include s ...
*
Service-oriented architecture
In software engineering, service-oriented architecture (SOA) is an architectural style that focuses on discrete services instead of a monolithic design. By consequence, it is also applied in the field of software design where services are provided ...
*
Unikernel
A unikernel is a specialised, single address space machine image constructed by using library operating systems. A developer selects, from a modular stack, the minimal set of libraries which correspond to the OS constructs required for the appl ...
/
Exokernel
Exokernel is an operating system kernel developed by the MIT Parallel and Distributed Operating Systems group, and also a class of similar operating systems.
Operating systems generally present hardware resources to applications through high-lev ...
(eg.
SPIN
Spin or spinning most often refers to:
* Spinning (textiles), the creation of yarn or thread by twisting fibers together, traditionally by hand spinning
* Spin, the rotation of an object around a central axis
* Spin (propaganda), an intentionally b ...
's
loadable kernel modules)
References
*{{note, 1, 1
CITI_TR_00-4High-Performance Memory-Based Web Servers: Kernel and User-Space Performance. Philippe Joubert, Robert B. King, Rich Neves, Mark Russinovich, John M. Tracey. IBM. T. J. Watson Research Center
Web server software