Apache Flink is an open-source, unified stream-processing and batch-processing framework developed by the Apache Software Foundation. The core of Apache Flink is a distributed streaming data-flow engine written in Java and Scala. Flink executes arbitrary dataflow programs in a data-parallel and pipeline (hence task parallel) manner. Flink's pipelined runtime system enables the execution of bulk/batch and stream processing programs. Furthermore, Flink's runtime supports the execution of iterative algorithms natively.

Apache Kafka is a framework implementation of a software bus using stream-processing. It is an open-source software platform developed by the Apache Software Foundation written in Scala and Java. The project aims to provide a unified, high-throughput, low-latency platform for handling real-time data feeds. Kafka can connect to external systems (for data import/export) via Kafka Connect and provides Kafka Streams, a Java stream processing library. Kafka uses a binary TCP-based protocol that is optimized for efficiency and relies on a "message set" abstraction that naturally groups messages together to reduce the overhead of the network roundtrip. This "leads to larger network packets, larger sequential disk operations, contiguous memory blocks [...] which allows Kafka to turn a bursty stream of random message writes into linear writes.

Apache Lucene is a free and open-source search engine software library, originally written in Java by Doug Cutting. It is supported by the Apache Software Foundation and is released under the Apache Software License. Lucene is widely used as a standard foundation for non-research search applications. Lucene has been ported to other programming languages including Object Pascal, Perl, C#, C++, Python, Ruby and PHP.

Apache Spark is an open-source unified analytics engine for large-scale data processing. Spark provides an interface for programming entire clusters with implicit data parallelism and fault tolerance. Originally developed at the University of California, Berkeley's AMPLab, the Spark codebase was later donated to the Apache Software Foundation, which has maintained it since. Apache Spark has its architectural foundation in the resilient distributed dataset (RDD), a read-only multiset of data items distributed over a cluster of machines, that is maintained in a fault-tolerant way.

Apache Storm is a distributed stream processing computation framework written predominantly in the Clojure programming language. Originally created by Nathan Marz and team at BackType, the project was open-sourced after being acquired by Twitter.

It uses custom created "spouts" and "bolts" to define information sources and manipulations to allow batch, distributed processing of streaming data. The initial release was on 17 September 2011.

Apache Storm is developed under the Apache License, making it available to most companies to use.

Apache Tomcat (called "Tomcat" for short) is an open-source implementation of the Java Servlet, JavaServer Pages, Java Expression Language and WebSocket technologies. Tomcat provides a "pure Java" HTTP web server environment in which Java code can run.

Tomcat is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation, released under the Apache License 2.0 license.

The CADDY web server is an open-source web server written in Go It uses the Go Standard library for its HTTP functionality and supports HTTPS natively. Caddy simplifies your infrastructure. It takes care of TLS certificate renewals, OCSP stapling, static file serving, reverse proxying, Kubernetes ingress, and more. Its modular architecture means you can do more with a single, static binary that compiles for any platform. Caddy runs great in containers because it has no dependencies—not even libc. You can run Caddy practically anywhere.

Caddy development began in December 2014. The first version was released in April 2015. Version 1.0.0 was released in April 2019. Version 2.0.0 was released in May2020.

Caddy supports various Web standards and is available as statically-compiled binaries for Microsoft Windows, macOS, Linux, Android, and BSD operating systems on x86-64, IA-32, and ARM architectures.

Chronograf is a UI and administrative component of the InfluxDB platform (and the TICK stack).

Consul is a software first released in 2014 for DNS-based service discovery and provides distributed key-value storage, segmentation and configuration. Registered services and nodes can be queried using a DNS interface or an HTTP interface.

GraalVM is a Java VM and JDK based on HotSpot/OpenJDK, implemented in Java. It supports additional programming languages and execution modes, like ahead-of-time compilation of Java applications for fast startup and low memory footprint. The first production-ready version, GraalVM 19.0, was released in May 2019. The most recent version is GraalVM 21.0.0, made available in January 2021.

HAProxy is free, open source software that provides a high availability load balancer and proxy server for TCP and HTTP-based applications that spreads requests across multiple servers. It is written in C and has a reputation for being fast and efficient (in terms of processor and memory usage). HAProxy is used by a number of high-profile websites including GoDaddy, GitHub, Bitbucket, Stack Overflow, Reddit, Slack, Speedtest.net, Tumblr, Twitter and Tuenti and is used in the OpsWorks product from Amazon Web Services.

The Apache HTTP Server, colloquially called Apache, is a free and open-source cross-platform web server software, released under the terms of Apache License 2.0. Apache is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation.

The vast majority of Apache HTTP Server instances run on a Linux distribution, but current versions also run on Microsoft Windows, OpenVMS, and a wide variety of Unix-like systems. Past versions also ran on NetWare, OS/2 and other operating systems, including ports to mainframes.

Originally based on the NCSA HTTPd server, development of Apache began in early 1995 after work on the NCSA code stalled Apache played a key role in the initial growth of the World Wide Web, quickly overtaking NCSA HTTPd as the dominant HTTP server, and has remained most popular since April 1996. In 2009, it became the first web server software to serve more than 100 million websites. As of April 2020, Netcraft estimated that Apache served 29.12% of the million busiest websites, while Nginx served 25.54%; according to W3Techs, Apache served 39.5% of the top 10 million sites and Nginx served 31.7%.

Jenkins is a free and open source automation server. It helps automate the parts of software development related to building, testing, and deploying, facilitating continuous integration and continuous delivery. It is a server-based system that runs in servlet containers such as Apache Tomcat. It supports version control tools, including AccuRev, CVS, Subversion, Git, Mercurial, Perforce, ClearCase and RTC, and can execute Apache Ant, Apache Maven and sbt based projects as well as arbitrary shell scripts and Windows batch commands.

Kapacitor is the data processing component of the InfluxDB platform.

Kata Containers is an open source container runtime, building lightweight virtual machines that seamlessly plug into the containers ecosystem. Kata Containers is an open source community working to build a secure container runtime with lightweight virtual machines that feel and perform like containers, but provide stronger workload isolation using hardware virtualization technology as a second layer of defense. Kata Containers also supports multiple hypervisors including QEMU, Cloud-Hypervisor and Firecracker and integrates with the containerd project among others. The Kata Containers community is stewarded by the Open Infrastructure Foundation, which supports the development and adoption of open infrastructure globally. The code is hosted at GitHub under the Apache 2 license.

Kong is an open-source API and Microservices gateway.

Lightstreamer is a web-based asynchronous messaging project, implementing the WebSocket protocol, the Comet model, the push technology paradigm, and the real-time web practices.

Memcached(读作Memcached -cash-dee或Memcached -cash)是一个通用的分布式内存缓存系统。它经常被用来加速动态数据库驱动的网站，通过在RAM中缓存数据和对象来减少必须读取外部数据源(如数据库或API)的次数。Memcached是一款免费的开源软件，使用BSD修订版许可。Memcached运行在类unix操作系统(Linux和OS X)和微软Windows上。这取决于libevent库。

Memcached的api提供了一个分布在多台机器上的非常大的哈希表。当表已满时，后续的插入将导致较旧的数据按照最近最少使用(LRU)顺序被清除。使用Memcached的应用程序通常将请求添加到RAM中，然后返回到较慢的后备存储(如数据库)。

Memcached没有内部机制来跟踪可能发生的失误。但是，一些第三方实用程序提供了此功能。

Memcached最初由Brad Fitzpatrick于2003年5月22日为他的网站LiveJournal开发。它最初是用Perl编写的，后来由Anatoly Vorobey用C重写，然后受雇于LiveJournal。Memcached现在被许多其他系统使用，包括YouTube, Reddit, Facebook, Pinterest, Twitter，维基百科和Method Studios。谷歌应用程序引擎，谷歌云平台，Microsoft Azure, IBM Bluemix和Amazon Web Services也通过API提供Memcached服务。

NATS is an open-source messaging system (sometimes called message-oriented middleware). The NATS server is written in the Go programming language. Client libraries to interface with the server are available for dozens of major programming languages. The core design principles of NATS are performance, scalability, and ease of use.

Synadia develops and provides support for NATS. NATS was originally developed by Derek Collison as the messaging control plane for Cloud Foundry and was written in Ruby. NATS was later ported to Go.

The source code is released under the Apache 2.0 License. NATS consists of:

• The NATS Server - The core Publish-Subscribe Server for NATS.
• NATS Streaming - A data streaming system powered by NATS that adds persistence, message replay, durable subscriptions, etc. to NATS.
• Client libraries for a variety of programming languages
• A connector framework - a pluggable Java-based framework to connect NATS and other services.
• NATS is a CNCF project with Kubernetes and Prometheus (software) integration.

Microservices frameworks such as Micro, Mainflux, and Hemera rely on NATS as their messaging backbone.

NATS is an open-source messaging system (sometimes called message-oriented middleware). The NATS server is written in the Go programming language. Client libraries to interface with the server are available for dozens of major programming languages. The core design principles of NATS are performance, scalability, and ease of use.

Synadia develops and provides support for NATS. NATS was originally developed by Derek Collison as the messaging control plane for Cloud Foundry and was written in Ruby. NATS was later ported to Go.

The source code is released under the Apache 2.0 License. NATS consists of:

• The NATS Server - The core Publish-Subscribe Server for NATS.
• NATS Streaming - A data streaming system powered by NATS that adds persistence, message replay, durable subscriptions, etc. to NATS.
• Client libraries for a variety of programming languages
• A connector framework - a pluggable Java based framework to connect NATS and other services.
• NATS is a CNCF project with Kubernetes and Prometheus (software) integration.

Microservices frameworks such as Micro, Mainflux, and Hemera rely on NATS as their messaging backbone.

NGINX，也会被写做Nginx，或nginx，或NginX，是一个web服务器，也可以用作反向代理、负载平衡器、邮件代理和HTTP缓存。该软件由Igor Sysoev开发，并于2004年公开发布。NGINX是免费的开源软件，根据两条款BSD许可协议发布。大量的web服务器使用NGINX，通常用作负载均衡器。

2011年成立了一家同名公司，提供支持和Nginx Plus付费软件。2019年3月，该公司被F5 Networks以6.7亿美元收购。

截至2020年2月，Netcraft估计Nginx服务了所有活跃网站的36.48%，排名第一，高于Apache的24.51%，而根据W3Techs的数据，Apache以40.1%排名第一，Nginx以31.8%排名第二。

Node.js is an open-source, cross-platform, back-end, JavaScript runtime environment that executes JavaScript code outside a web browser. Node.js lets developers use JavaScript to write command-line tools and for server-side scripting - running scripts server-side to produce dynamic web page content before the page is sent to the user's web browser. Consequently, Node.js represents a "JavaScript everywhere" paradigm, unifying web application development around a single programming language, rather than different languages for server- and client-side scripts.

Though .js is the standard filename extension for JavaScript code, the name "Node.js" doesn't refer to a particular file in this context and is merely the name of the product. Node.js has an event-driven architecture capable of asynchronous I/O. These design choices aim to optimize throughput and scalability in web applications with many input/output operations, as well as for real-time Web applications (e.g., real-time communication programs and browser games).

The Node.js distributed development project was previously governed by the Node.js Foundation and has now merged with the JS Foundation to form the OpenJS Foundation, which is facilitated by the Linux Foundation's Collaborative Projects program.

Corporate users of Node.js software include GoDaddy, Groupon, IBM, LinkedIn, Microsoft, Netflix, PayPal, Rakuten, SAP, Voxer, Walmart, Yahoo!, and Amazon Web Services.

phpMyAdmin is a free and open source administration tool for MySQL and MariaDB. As a portable web application, it has become one of the most popular MySQL administration tools, especially for web hosting services. phpMyAdmin is written in PHP, intended to handle the administration of MySQL over the Web. phpMyAdmin supports a wide range of operations on MySQL and MariaDB. Frequently used operations (managing databases, tables, columns, relations, indexes, users, permissions, etc) can be performed via the user interface, while you still have the ability to directly execute any SQL statement.

Prometheus is a free software application used for event monitoring and alerting. It records real-time metrics in a time series database (allowing for high dimensionality) built using a HTTP pull model, with flexible queries and real-time alerting. The project is written in Go and licensed under the Apache 2 License, with source code available on GitHub, and is a graduated project of the Cloud Native Computing Foundation, along with Kubernetes and Envoy.

RabbitMQ is an open-source message-broker software (sometimes called message-oriented middleware) that originally implemented the Advanced Message Queuing Protocol (AMQP) and has since been extended with a plug-in architecture to support Streaming Text Oriented Messaging Protocol (STOMP), MQ Telemetry Transport (MQTT), and other protocols.

The RabbitMQ server program is written in the Erlang programming language and is built on the Open Telecom Platform framework for clustering and failover. Client libraries to interface with the broker are available for all major programming languages.

Docker is a set of the platform as a service (PaaS) products that use OS-level virtualisation to deliver software in packages called containers. Containers are isolated from one another and bundle their own software, libraries and configuration files; they can communicate with each other through well-defined channels. All containers are run by a single operating system kernel and therefore use fewer resources than virtual machines.

The service has both free and premium tiers. The software that hosts the containers is called Docker Engine. It was first started in 2013 and is developed by Docker, Inc.

A Docker registry is a repository for Docker images. Docker clients connect to registries to download ("pull") images for use or upload ("push") images that they have built. Registries can be public or private. Two main public registries are Docker Hub and Docker Cloud. Docker Hub is the default registry where Docker looks for images. Docker registries also allow the creation of notifications based on events.

Solr is an open-source enterprise-search platform, written in Java, from the Apache Lucene project. Its major features include full-text search, hit highlighting, faceted search, real-time indexing, dynamic clustering, database integration, NoSQL features and rich document (e.g., Word, PDF) handling. Providing distributed search and index replication, Solr is designed for scalability and fault tolerance. Solr is widely used for enterprise search and analytics use cases and has an active development community and regular releases.

Solr runs as a standalone full-text search server. It uses the Lucene Java search library at its core for full-text indexing and search and has REST-like HTTP/XML and JSON APIs that make it usable from most popular programming languages. Solr's external configuration allows it to be tailored to many types of applications without Java coding, and it has a plugin architecture to support more advanced customization.

Apache Lucene and Apache Solr are both produced by the same Apache Software Foundation development team.

Spiped (pronounced "ess-pipe-dee") is a utility for creating symmetrically encrypted and authenticated pipes between socket addresses, so that one may connect to one address (e.g., a UNIX socket on localhost) and transparently have a connection established to another address (e.g., a UNIX socket on a different system). This is similar to 'ssh -L' functionality, but does not use SSH and requires a pre-shared symmetric key.

Telegraf is a server agent for collecting metrics or events and sending them to a variety of output targets. It is part of the Influx Data suite of products.

Apache TomEE (pronounced "Tommy") is the Java Enterprise Edition of Apache Tomcat (Tomcat + Jakarta EE = TomEE) that combines several Java enterprise projects including Apache OpenEJB, Apache OpenWebBeans, Apache OpenJPA, Apache MyFaces and others. In October 2011, the project obtained certification by Oracle Corporation as a compatible implementation of the Java EE 6 Web Profile.

Traefik is an HTTP load balancer and reverse proxy often used with microservice implementations.

Apache ZooKeeper is a software project of the Apache Software Foundation. It is essentially a service for distributed systems offering a hierarchical key-value store, which is used to provide a distributed configuration service, synchronization service, and naming registry for large distributed systems (see Use cases). ZooKeeper was a sub-project of Hadoop but is now a top-level Apache project in its own right.

Alpine Linux is a Linux distribution based on musl and BusyBox, designed for security, simplicity, and resource efficiency. It used a hardened kernel until release 3.8 and compiles all user-space binaries as position-independent executables with stack-smashing protection.

Because of its small size, it is commonly used in containers providing quick boot-up times.

An Amazon Machine Image (AMI) is a special type of virtual appliance that is used to create a virtual machine within the Amazon Elastic Compute Cloud ("EC2") infrastructure. It serves as the basic unit of deployment for services delivered using EC2.

Bash is a Unix shell and command language written by Brian Fox for the GNU Project as a free software replacement for the Bourne shell. First released in 1989, it has been used as the default login shell for most Linux distributions and all releases of Apple's macOS prior to macOS Catalina. A version is also available for Windows 10 via the Windows Subsystem for Linux. It is also the default user shell in Solaris 11.

Bash is a command processor that typically runs in a text window where the user types commands that cause actions. Bash can also read and execute commands from a file, called a shell script. Like all Unix shells, it supports filename globbing (wildcard matching), piping, here documents, command substitution, variables, and control structures for condition-testing and iteration. The keywords, syntax, dynamically scoped variables and other basic features of the language are all copied from sh. Other features, e.g., history, are copied from csh and ksh. Bash is a POSIX-compliant shell, but with a number of extensions.

The shell's name is an acronym for Bourne Again Shell, a pun on the name of the Bourne shell that it replaces and the notion of being "born again".

A security hole in Bash dating from version 1.03 (August 1989), dubbed Shellshock, was discovered in early September 2014 and quickly led to a range of attacks across the Internet. Patches to fix the bugs were made available soon after the bugs were identified.

A collection of common dependencies often use for installing various language modules (gems, packages, etc.)

BusyBox is a software suite that provides several Unix utilities in a single executable file. It runs in a variety of POSIX environments such as Linux, Android, and FreeBSD, although many of the tools it provides are designed to work with interfaces provided by the Linux kernel. It was specifically created for embedded operating systems with very limited resources. The authors dubbed it "The Swiss Army knife of Embedded Linux", as the single executable replaces basic functions of more than 300 common commands. It is released as free software under the terms of the GNU General Public License, version 2.

CentOS (from Community Enterprise Operating System) is a Linux distribution that provides a free, community-supported computing platform functionally compatible with its upstream source, Red Hat Enterprise Linux (RHEL). In January 2014, CentOS announced the official joining with Red Hat while staying independent from RHEL, under a new CentOS governing board.

The first CentOS release in May 2004, numbered as CentOS version 2, was forked from RHEL version 2.1AS. Since version 7, CentOS officially supports only the x86-64 architecture, while older versions also supported the IA-32 architecture. As of December 2015, AltArch releases of CentOS 7 are available for the IA-32 architecture, Power ISA, and for the ARMv7hl and AArch64 variants of the ARM architecture. CentOS 8 was released on 24 September 2019.

In December 2020, Red Hat terminated CentOS development. Red Hat will however continue to support a related rolling-release distro, CentOS Stream.

The CirrOS project provides a set of small Linux disk and Kernel images well suited for test activities.

Debian, also known as Debian GNU/Linux, is a Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of Debian (0.01) was released on September 15, 1993, and its first stable version (1.1) was released on June 17, 1996. The Debian Stable branch is the most popular edition for personal computers and servers. Debian is also the basis for many other distributions, most notably Ubuntu.

Debian is one of the oldest operating systems based on the Linux kernel. The project is coordinated over the Internet by a team of volunteers guided by the Debian Project Leader and three foundational documents: the Debian Social Contract, the Debian Constitution, and the Debian Free Software Guidelines. New distributions are updated continually, and the next candidate is released after a time-based freeze.

Since its founding, Debian has been developed openly and distributed freely according to the principles of the GNU Project. Because of this, the Free Software Foundation sponsored the project from November 1994 to November 1995. When the sponsorship ended, the Debian Project formed the nonprofit organization Software in the Public Interest to continue financially supporting development.

Fedora is a Linux distribution developed by the community-supported Fedora Project which is sponsored primarily by Red Hat, a subsidiary of IBM, with additional support from other companies. Fedora contains software distributed under various free and open-source licenses and aims to be on the leading edge of free technologies. Fedora is the upstream source of the commercial Red Hat Enterprise Linux distribution, and subsequently CentOS as well.

Since the release of Fedora 30, five different editions are currently available: Workstation, focused on the personal computer, Server for servers, CoreOS, focused on cloud computing, Silverblue, focused on an immutable desktop specialized to container-based workflows and IoT, focused on IoT devices.

As of February 2016, Fedora has an estimated 1.2 million users, including Linus Torvalds (as of 2015), creator of the Linux kernel.

gVisor is a container sandbox developed by Google that focuses on security, efficiency and ease of use released on May 2018.[1][2] gVisor implements around 200 of the Linux system calls in userspace, for additional security compared to Docker containers that run directly on top of the Linux kernel and are isolated with namespaces. Contrary to the Linux kernel the project is written in the memory-safe programming language Go to prevent common pitfalls which frequently occur with software written in C. gVisor is being used in Google's production environment like App Engine standard environment, Cloud Functions, Cloud ML Engine and Google Cloud Run according to Google and Brad Fitzpatrick. Most recently gVisor has been integrated with Google Kubernetes Engine and it allows users to sandbox their Kubernetes pods for use cases like SaaS and multitenancy.

Mageia is a Linux-based operating system, distributed as free and open source software. It was forked from the Mandriva Linux distribution. The Greek term mageía (μαγεία) means enchantment, fascination, glamour, wizardry.

The first release of the software distribution, Mageia 1, took place in June 2011.

Oracle Linux (abbreviated OL, formerly known as Oracle Enterprise Linux or OEL) is a Linux distribution packaged and freely distributed by Oracle, available partially under the GNU General Public License since late 2006. It is compiled from Red Hat Enterprise Linux (RHEL) source code, replacing Red Hat branding with Oracle's. It is also used by Oracle Cloud and Oracle Engineered Systems such as Oracle Exadata and others.

Potential users can freely download Oracle Linux through Oracle's E-delivery service (Oracle Software Delivery Cloud) or from a variety of mirror sites, and can deploy and distribute it without cost. The company's Oracle Linux Support program aims to provide commercial technical support, covering Oracle Linux and existing RHEL or CentOS installations but without any certification from the former (i.e. without re-installation or re-boot). As of 2016 Oracle Linux had over 15,000 customers subscribed to the support program.

Photon OS is an open source Linux distribution optimized for the cloud. It is maintained by VMware.

Robot Operating System (ROS or ros) is robotics middleware (i.e. collection of software frameworks for robot software development). Although ROS is not an operating system, it provides services designed for a heterogeneous computer cluster such as hardware abstraction, low-level device control, implementation of commonly used functionality, message-passing between processes, and package management. Running sets of ROS-based processes are represented in a graph architecture where processing takes place in nodes that may receive, post and multiplex sensor data, control, state, planning, actuator, and other messages. Despite the importance of reactivity and low latency in robot control, ROS itself is not a real-time OS (RTOS). It is possible, however, to integrate ROS with real-time code. The lack of support for real-time systems has been addressed in the creation of ROS 2.0, a major revision of the ROS API which will take advantage of modern libraries and technologies for core ROS functionality and add support for real-time code and embedded hardware.

Software in the ROS Ecosystem can be separated into three groups:

Copy
   - language-and platform-independent tools used for building and distributing ROS-based software;  
   - ROS client library implementations such as roscpp, rospy, and roslisp;  
   - packages containing application-related code which uses one or more ROS client libraries.  
    

Both the language-independent tools and the main client libraries (C++, Python, and Lisp) are released under the terms of the BSD license, and as such are open source software and free for both commercial and research use. The majority of other packages are licensed under a variety of open source licenses. These other packages implement commonly used functionality and applications such as hardware drivers, robot models, datatypes, planning, perception, simultaneous localization and mapping, simulation tools, and other algorithms.

The main ROS client libraries are geared toward a Unix-like system, primarily because of their dependence on large collections of open-source software dependencies. For these client libraries, Ubuntu Linux is listed as "Supported" while other variants such as Fedora Linux, macOS, and Microsoft Windows are designated "experimental" and are supported by the community. The native Java ROS client library, rosjava, however, does not share these limitations and has enabled ROS-based software to be written for the Android OS. rosjava has also enabled ROS to be integrated into an officially supported MATLAB toolbox which can be used on Linux, macOS, and Microsoft Windows. A JavaScript client library, roslibjs has also been developed which enables integration of software into a ROS system via any standards-compliant web browser.

Scylla is an open-source distributed NoSQL wide-column data store. It was designed to be compatible with Apache Cassandra while achieving significantly higher throughputs and lower latencies. It supports the same protocols as Cassandra (CQL and Thrift) and the same file formats (SSTable), but is a completely rewritten implementation, using the C++20 language replacing Cassandra's Java, and the Seastar asynchronous programming library with threads, shared memory, mapped files, and other classic Linux programming techniques. In addition implementing Cassandra's protocols, Scylla also implements the Amazon DynamoDB API.

Ubuntu is a Linux distribution based on Debian mostly composed of free and open-source software. Ubuntu is officially released in three editions: Desktop, Server, and Core for Internet of things devices and robots. All of the editions can run on the computer alone, or in a virtual machine. Ubuntu is a popular operating system for cloud computing, with support for OpenStack. Ubuntu's default desktop has been GNOME, since version 17.10.

Ubuntu is released every six months, with long-term support (LTS) releases every two years. As of 22 October 2020, the most recent long-term support release is 20.04 ("Focal Fossa"), which is supported until 2025 under public support and until 2030 as a paid option. The latest standard release is 20.10 ("Groovy Gorilla"), which is supported for nine months.

Ubuntu is developed by Canonical, and a community of other developers, under a meritocratic governance model. Canonical provides security updates and support for each Ubuntu release, starting from the release date and until the release reaches its designated end-of-life (EOL) date. Canonical generates revenue through the sale of premium services related to Ubuntu.

Ubuntu is named after the Nguni philosophy of ubuntu, which Canonical indicates means "humanity to others" with a connotation of "I am what I am because of who we all are".

MediaWiki is a free and open-source wiki engine. It was developed for use on Wikipedia in 2002, and given the name "MediaWiki" in 2003. It remains in use on Wikipedia and almost all other Wikimedia websites, including Wiktionary, Wikimedia Commons and Wikidata; these sites continue to define a large part of the requirement set for MediaWiki. MediaWiki was originally developed by Magnus Manske and improved by Lee Daniel Crocker. Its development has since then been coordinated by the Wikimedia Foundation.

MediaWiki is written in the PHP programming language and stores all text content into a database. The software is optimized to efficiently handle large projects, which can have terabytes of content and hundreds of thousands of hits per second. Because Wikipedia is one of the world's largest websites, achieving scalability through multiple layers of caching and database replication has been a major concern for developers. Another major aspect of MediaWiki is its internationalization; its interface is available in more than 300 languages. The software has more than 1,000 configuration settings and more than 1,800 extensions available for enabling various features to be added or changed.

Besides its use on Wikimedia sites, MediaWiki has been used as a knowledge management and content management system on many thousands of websites, public and private, including the websites Fandom, wikiHow and Gamepedia, and major internal installations like Intellipedia and Diplopedia.

Redmine is a free and open source, web-based project management and issue tracking tool. It allows users to manage multiple projects and associated subprojects. It features per project wikis and forums, time tracking, and flexible, role-based access control. It includes a calendar and Gantt charts to aid visual representation of projects and their deadlines. Redmine integrates with various version control systems and includes a repository browser and diff viewer.

The design of Redmine is significantly influenced by Trac, a software package with some similar features.

Redmine is written using the Ruby on Rails framework. It is cross-platform and cross-database and supports 49 languages.

Apache Cassandra是一个免费的、开源的、分布式、宽列存储的NoSQL数据库管理系统，旨在跨多个商用服务器上处理大量数据，提供高可用性，而且没有单点故障。Cassandra为跨越多个数据中心的集群提供了强大的支持，异步无主复制（asynchronous masterless replication）允许为所有客户机进行低延迟操作。Cassandra使用谷歌的Bigtable数据模型提供Amazon DynamoDB的分布设计。

Apache CouchDB is an open-source document-oriented NoSQL database, implemented in Erlang.

CouchDB uses multiple formats and protocols to store, transfer, and process its data, it uses JSON to store data, JavaScript as its query language using MapReduce, and HTTP for an API.

CouchDB was first released in 2005 and later became an Apache Software Foundation project in 2008.

Unlike a relational database, a CouchDB database does not store data and relationships in tables. Instead, each database is a collection of independent documents. Each document maintains its own data and self-contained schema. An application may access multiple databases, such as one stored on a user's mobile phone and another on a server. Document metadata contains revision information, making it possible to merge any differences that may have occurred while the databases were disconnected.

CouchDB implements a form of multiversion concurrency control (MVCC) so it does not lock the database file during writes. Conflicts are left to the application to resolve. Resolving a conflict generally involves first merging data into one of the documents, then deleting the stale one.

Other features include document-level ACID semantics with eventual consistency, (incremental) MapReduce, and (incremental) replication. One of CouchDB's distinguishing features is multi-master replication, which allows it to scale across machines to build high-performance systems. A built-in Web application called Fauxton (formerly Futon) helps with administration.

CrateDB is a distributed SQL database management system that integrates a fully searchable document-oriented data store. It is open-source, written in Java, based on a shared-nothing architecture, and designed for high scalability.

Elasticsearch is a search and analytics engine. It is a search engine provided with distributed, multitenant-capability with an HTTP web interface. Elasticsearch is developed in Java. It centrally stores your data for faster search, finetuned relevancy, and scalable analytics. Elasticsearch allows you to perform and combine many types of searches. These searches include structured, unstructured, geo or metric searches. Elasticsearch lets you explore various trends and patterns in your data. It also provides rapid results, powerful designs, and indexing. Elasticsearch is followed by Apache Solr, based on Lucene.

InfluxDB is an open-source time series database (TSDB) developed by InfluxData. It is written in Go and optimized for fast, high-availability storage and retrieval of time series data in fields such as operations monitoring, application metrics, Internet of Things sensor data, and real-time analytics. It also has support for processing data from Graphite.

KeyDB is a high performance alternative to Redis with a focus on multithreading, memory efficiency, and high throughput. In addition to multithreading, KeyDB also has features such as multi-master configuration, subkey expires, and cron.

KeyDB maintains full compatibility with the Redis protocol, modules, and scripts. This includes the atomicity guarantees for scripts and transactions. Because KeyDB keeps in sync with Redis development KeyDB is a superset of Redis functionality, making KeyDB a drop in replacement for existing Redis deployments.

On the same hardware KeyDB can achieve significantly higher throughput than Redis.

MariaDB is a community-developed, commercially supported fork of the MySQL relational database management system (RDBMS), intended to remain free and open-source software under the GNU General Public License. Development is led by some of the original developers of MySQL, who forked it due to concerns over its acquisition by Oracle Corporation in 2009.

MariaDB intended to maintain high compatibility with MySQL, ensuring a drop-in replacement capability with library binary parity and exact matching with MySQL APIs and commands. However, new features diverged. It includes new storage engines like Aria, ColumnStore, and MyRocks.

Its lead developer/CTO is Michael "Monty" Widenius, one of the founders of MySQL AB and the founder of Monty Program AB. On 16 January 2008, MySQL AB announced that it had agreed to be acquired by Sun Microsystems for approximately $1 billion. The acquisition completed on 26 February 2008. Sun was then bought the following year by Oracle Corporation. MariaDB is named after Monty's younger daughter, Maria. (MySQL is named after his other daughter, My.)

MongoDB is a cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with optional schemas. MongoDB is developed by MongoDB Inc. and licensed under the Server Side Public License (SSPL).

MySQL Server 提供了一个具有查询和连接功能的数据库管理系统，以及具有优秀的数据结构和与许多不同平台集成的能力。它可以在高要求的生产环境中可靠、快速地处理大型数据库。

MySQL Server 软件本身和客户端库使用双授权发行版。它们是在GPL版本2或专有许可下提供的。 MySQL Server是世界上最流行的开源数据库，MySQL Cluster是实时的开源事务数据库。

PostgreSQL, also known as Postgres, is a free and open-source relational database management system (RDBMS) emphasizing extensibility and SQL compliance. It was originally named POSTGRES, referring to its origins as a successor to the Ingres database developed at the University of California, Berkeley. In 1996, the project was renamed to PostgreSQL to reflect its support for SQL. After a review in 2007, the development team decided to keep the name PostgreSQL and the alias Postgres.

PostgreSQL features transactions with Atomicity, Consistency, Isolation, Durability (ACID) properties, automatically updatable views, materialized views, triggers, foreign keys, and stored procedures. It is designed to handle a range of workloads, from single machines to data warehouses or Web services with many concurrent users. It is the default database for macOS Server, and is also available for Linux, FreeBSD, OpenBSD, and Windows.

Redis(Remote Dictionary Server)是一个内存中的数据结构项目，实现了一个分布式的、内存中的键值数据库，具有可选的持久性。Redis支持不同类型的抽象数据结构，如字符串、列表、映射、集、排序集、HyperLogLogs、位图、流和空间索引。该项目由一个项目核心团队开发和维护，截至2015年由Redis Labs赞助。它是在BSD 3条款许可下发布的开源软件。

Vault (first released in April 2015) provides secrets management, identity-based access, encrypting application data and auditing of secrets for applications, systems, and users.

AdoptOpenJDK is a project which creates pre-built OpenJDK packages and libraries available and licensed under open source licenses.

Amazon Corretto is a no-cost, multiplatform, production-ready distribution of the Open Java Development Kit (OpenJDK). Corretto comes with long-term support that will include performance enhancements and security fixes. Amazon runs Corretto internally on thousands of production services and Corretto is certified as compatible with the Java SE standard. With Corretto, you can develop and run Java applications on popular operating systems, including Linux, Windows, and macOS.

Clojure is a dynamic and functional dialect of the Lisp programming language on the Java platform. Like other Lisp dialects, Clojure treats code as data and has a Lisp macro system. Clojure advocates immutability and immutable data structures and encourages programmers to be explicit about managing identity and its states. This focus on programming with immutable values and explicit progression-of-time constructs is intended to facilitate developing more robust, especially concurrent, programs that are simple and fast. While its type system is entirely dynamic, recent efforts have also sought the implementation of gradual typing.

Composer is an application-level package manager for the PHP programming language that provides a standard format for managing dependencies of PHP software and required libraries. It was developed by Nils Adermann and Jordi Boggiano, who continue to manage the project. They began development in April 2011 and first released it on March 1, 2012. Composer is strongly inspired by Node.js's "npm" and Ruby's "bundler". The project's dependency solving algorithm started out as a PHP-based port of openSUSE's libzypp satsolver.

Composer runs from the command line and installs dependencies (e.g. libraries) for an application. It also allows users to install PHP applications that are available on "Packagist" which is its main repository containing available packages. It also provides autoload capabilities for libraries that specify autoload information to ease usage of third-party code.

Elixir is a functional, concurrent, general-purpose programming language that runs on the BEAM virtual machine used to implement the Erlang programming language. Elixir builds on top of Erlang and shares the same abstractions for building distributed, fault-tolerant applications. Elixir also provides productive tooling and an extensible design. The latter is supported by compile-time metaprogramming with macros and polymorphism via protocols.

Elixir is used by companies such as PagerDuty, Discord, E-MetroTel, Pinterest, Moz, Bleacher Report, The Outline, Inverse, Divvy, FarmBot and for building embedded systems. The community organizes yearly events in the United States, Europe and Japan as well as minor local events and conferences.

Erlang is a general-purpose, concurrent, functional programming language, and a garbage-collected runtime system. The term Erlang is used interchangeably with Erlang/OTP, or Open Telecom Platform (OTP), which consists of the Erlang runtime system, several ready-to-use components (OTP) mainly written in Erlang, and a set of design principles for Erlang programs.

The Erlang runtime system is designed for systems with these traits: * Distributed * Fault-tolerant * Soft real-time * Highly available, non-stop applications * Hot swapping, where code can be changed without stopping a system.

The Erlang programming language has immutable data, pattern matching, and functional programming.The sequential subset of the Erlang language supports eager evaluation, single assignment, and dynamic typing.It was originally proprietary software within Ericsson, developed by Joe Armstrong, Robert Virding, and Mike Williams in 1986, but was released as free and open-sourc software in 1998. Erlang/OTP is supported and maintained by the Open Telecom Platform (OTP) product unit at Ericsson.

F# (pronounced F-sharp) is a functional-first, general-purpose, strongly typed, multi-paradigm programming language that encompasses functional, imperative, and object-oriented programming methods.

F# is developed by the F# Software Foundation, Microsoft and open contributors. An open-source, cross-platform compiler for F# is available from the F# Software Foundation.

Go is a statically typed, compiled programming language designed at Google by Robert Griesemer, Rob Pike, and Ken Thompson. Go is syntactically similar to C, but with memory safety, garbage collection, structural typing, and CSP-style concurrency. The language is often referred to as Golang because of its domain name, golang.org, but the proper name is Go.

There are two major implementations:

• Google's self-hosting compiler toolchain targets multiple operating systems, mobile devices, and WebAssembly.
• gccgo, a GCC frontend.

A third-party transpiler GopherJS compiles Go to JavaScript for front-end web development.

Apache Groovy is a Java-syntax-compatible object-oriented programming language for the Java platform. It is both a static and dynamic language with features similar to those of Python, Ruby, and Smalltalk. It can be used as both a programming language and a scripting language for the Java Platform, is compiled to Java virtual machine (JVM) bytecode, and interoperates seamlessly with other Java code and libraries. Groovy uses a curly-bracket syntax similar to Java's. Groovy supports closures, multiline strings, and expressions embedded in strings. Much of Groovy's power lies in its AST transformations, triggered through annotations.

Groovy 1.0 was released on January 2, 2007, and Groovy 2.0 in July, 2012. Since version 2, Groovy can be compiled statically, offering type inference and performance near that of Java. Groovy 2.4 was the last major release under Pivotal Software's sponsorship which ended in March 2015. Groovy has since changed its governance structure to a Project Management Committee in the Apache Software Foundation.

Haxe is an open-source high-level cross-platform programming language and compiler that can produce applications and source code, for many different computing platforms from one code-base. It is free and open-source software, released under the MIT License. The compiler, written in OCaml, is released under the GNU General Public License (GPL) version 2.

Haxe includes a set of features and a standard library supported across all platforms, like numeric data types, strings, arrays, maps, binary, reflection, math, http, file system and common file formats. Haxe also includes platform-specific APIs for each compiler target. Kha, OpenFL and Heaps.io are popular Haxe frameworks that enable creating multi-platform content from one codebase.

Haxe originated with the idea of supporting client-side and server-side programming in one language and simplifying the communication logic between them. Code written in the Haxe language can be compiled into JavaScript, C++, Java, JVM, PHP, C#, Python, Lua and Node.js. Haxe can also directly compile SWF, HashLink and Neko, bytecode and also runs in interpreted mode.

Haxe supports externs (definition files) that can contain type information of existing libraries to describe target-specific interaction in a type-safe manner, like C++ header files can describe the structure of existing object files. This enables it to use the values defined in the files as if they were statically typed Haxe entities. Besides externs, other solutions exist to access each platform's native capabilities.

Many popular IDEs and source code editors have support available for Haxe development. No particular development environment or tool set is officially recommended by the Haxe Foundation, although VSCode, IntelliJ IDEA and HaxeDevelop have the most support for Haxe development. The core functionalities of syntax highlighting, code completion, refactoring, debugging, etc. are available in various degrees.

Julia is a high-level, high-performance, dynamic programming language. While it is a general-purpose language and can be used to write any application, many of its features are well suited for numerical analysis and computational science.

Lua, is a lightweight, high-level, multi-paradigm programming language designed primarily for embedded use in applications. Lua is cross-platform, since the interpreter of compiled bytecode is written in ANSI C, and Lua has a relatively simple C API to embed it into applications.

Lua was originally designed in 1993 as a language for extending software applications to meet the increasing demand for customization at the time. It provided the basic facilities of most procedural programming languages, but more complicated or domain-specific features were not included; rather, it included mechanisms for extending the language, allowing programmers to implement such features. As Lua was intended to be a general embeddable extension language, the designers of Lua focused on improving its speed, portability, extensibility, and ease-of-use in development.

Mono is a free and open-source project to create an Ecma standard-compliant .NET Framework-compatible software framework, including a C# compiler and a Common Language Runtime. Originally by Ximian, it was later acquired by Novell, and is now being led by Xamarin, a subsidiary of Microsoft and the .NET Foundation. The stated purpose of Mono is not only to be able to run Microsoft .NET applications cross-platform but also to bring better development tools to Linux developers. Mono can be run on many software systems including Android, most Linux distributions, BSD, macOS, Windows, Solaris, and even some game consoles such as PlayStation 3, Wii, and Xbox 360.

The Mono project has been controversial within the open-source community, as it implements portions of .NET Framework that may be covered by Microsoft patents. Although standardized portions of .NET Framework are covered under Microsoft Open Specification Promise—a covenant stating that Microsoft will not assert its patents against implementations of its specifications under certain conditions—other portions are not, which led to concerns that the Mono project could become the target of patent infringement lawsuits. Following Microsoft's open-sourcing of several core .NET technologies since 2014 and its acquisition of Xamarin at the beginning of 2016, an updated patent promise has been issued for the Mono project.

The logo of Mono is a stylized monkey's face, mono being Spanish for monkey.

OpenJDK (Open Java Development Kit) is a free and open-source implementation of the Java Platform, Standard Edition (Java SE). It is the result of an effort Sun Microsystems began in 2006. The implementation is licensed under the GNU General Public License (GNU GPL) version 2 with a linking exception. Were it not for the GPL linking exception, components that linked to the Java class library would be subject to the terms of the GPL license. OpenJDK is the official reference implementation of Java SE since version 7.

Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it also referred to its redesigned "sister language", Perl 6, before the latter's name was officially changed to Raku in October 2019.

Though Perl is not officially an acronym, there are various backronyms in use, including "Practical Extraction and Reporting Language". Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions. Raku, which began as a redesign of Perl 5 in 2000, eventually evolved into a separate language. Both languages continue to be developed independently by different development teams and liberally borrow ideas from one another.

The Perl languages borrow features from other programming languages including C, shell script (sh), AWK, and sed; Wall also alludes to BASIC and Lisp in the introduction to Learning Perl (Schwartz & Christiansen) and so on. They provide text processing facilities without the arbitrary data length limits of many contemporary Unix command-line tools, facilitating the manipulation of text files. Perl 5 gained widespread popularity in the late 1990s as a CGI scripting language, in part due to its unsurpassed regular expression and string parsing abilities.

In addition to CGI, Perl 5 is used for system administration, network programming, finance, bioinformatics, and other applications, such as for GUIs. It has been nicknamed "the Swiss Army chainsaw of scripting languages" because of its flexibility and power, and also its ugliness. In 1998, it was also referred to as the "duct tape that holds the Internet together," in reference to both its ubiquitous use as a glue language and its perceived inelegance.

Perl is a highly expressive programming language: source code for a given algorithm can be short and highly compressible.

PHP is a general-purpose scripting language especially suited to web development. It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1994. The PHP reference implementation is now produced by The PHP Group. PHP originally stood for Personal Home Page, but it now stands for the recursive initialism PHP: Hypertext Preprocessor.

PHP code is usually processed on a web server by a PHP interpreter implemented as a module, a daemon or as a Common Gateway Interface (CGI) executable. On a web server, the result of the interpreted and executed PHP code – which may be any type of data, such as generated HTML or binary image data – would form the whole or part of an HTTP response. Various web template systems, web content management systems, and web frameworks exist which can be employed to orchestrate or facilitate the generation of that response. Additionally, PHP can be used for many programming tasks outside of the web context, such as standalone graphical applications and robotic drone control. Arbitrary PHP code can also be interpreted and executed via the command-line interface (CLI).

The standard PHP interpreter, powered by the Zend Engine, is free software released under the PHP License. PHP has been widely ported and can be deployed on most web servers on almost every operating system and platform, free of charge.

The PHP language evolved without a written formal specification or standard until 2014, with the original implementation acting as the de facto standard which other implementations aimed to follow. Since 2014, work has gone on to create a formal PHP specification.

By September 2020, two out of every three websites using PHP are still on discontinued PHP versions, and almost half of all PHP websites use version 5.6 or older, that not even Debian supports (while Debian 9 still supports version 7.0 and 7.1, those versions are unsupported by The PHP Development Team). In addition, PHP version 7.2, the most popular supported PHP version, will stop getting security updates on November 30, 2020, in less than two months, and therefore, unless PHP websites are upgraded to version 7.3 (or newer), 84% of PHP websites will thus use discontinued versions.

PyPy is an alternative implementation of the Python programming language to CPython (which is the standard implementation). PyPy often runs faster than CPython because PyPy is a just-in-time compiler while CPython is an interpreter. Most Python code runs well on PyPy except for code that depends on CPython extensions, which either doesn't work or incurs some overhead when run in PyPy. Internally, PyPy uses a technique known as meta-tracing, which transforms an interpreter into a tracing just-in-time compiler. Since interpreters are usually easier to write than compilers, but run slower, this technique can make it easier to produce efficient implementations of programming languages. PyPy's meta-tracing toolchain is called RPython.

Python is an interpreted, high-level and general-purpose programming language. Created by Guido van Rossum and first released in 1991, Python's design philosophy emphasizes code readability with its notable use of significant whitespace. Its language constructs and object-oriented approach aim to help programmers write clear, logical code for small and large-scale projects.Python is dynamically typed and garbage-collected. It supports multiple programming paradigms, including structured (particularly, procedural), object-oriented, and functional programming. Python is often described as a "batteries included" language due to its comprehensive standard library. Python was created in the late 1980s as a successor to the ABC language. Python 2.0, released in 2000, introduced features like list comprehensions and a garbage collection system with reference counting.

Python 3.0, released in 2008, was a major revision of the language that is not completely backwards-compatible, and much Python 2 code does not run unmodified on Python 3.

The Python 2 language was officially discontinued in 2020 (first planned for 2015), and "Python 2.7.18 is the last Python 2.7 release and therefore the last Python 2 release." No more security patches or other improvements will be released for it. With Python 2's end-of-life, only Python 3.6.x and later are supported.

Python interpreters are available for many operating systems. A global community of programmers develops and maintains CPython, a free and open-source reference implementation. A non-profit organization, the Python Software Foundation, manages and directs resources for Python and CPython development.

R is a programming language and free software environment for statistical computing and graphics supported by the R Foundation for Statistical Computing. The R language is widely used among statisticians and data miners for developing statistical software and data analysis.

Ruby is an interpreted, high-level, general-purpose programming language. It was designed and developed in the mid-1990s by Yukihiro "Matz" Matsumoto in Japan.

Ruby is dynamically typed and uses garbage collection. It supports multiple programming paradigms, including procedural, object-oriented, and functional programming. According to the creator, Ruby was influenced by Perl, Smalltalk, Eiffel, Ada, BASIC, and Lisp.

Rust is a multi-paradigm programming language focused on performance and safety, especially safe concurrency. Rust is syntactically similar to C++, but can guarantee memory safety by using a borrow checker to validate references. Unlike other "safe" programming languages, Rust does not use garbage collection.

Rust was originally designed by Graydon Hoare at Mozilla Research, with contributions from Dave Herman, Brendan Eich, and others. The designers refined the language while writing the Servo layout or browser engine, and the Rust compiler. It has gained increasing use in the industry, and Microsoft has been experimenting with the language for secure and safety-critical software components.

Rust has been named the "most loved programming language" in the Stack Overflow Developer Survey every year since 2016.