Technologies and development tools
As a dynamically typed language, Python is really flexible. This means there are no hard rules on how to build features, and you'll have more flexibility solving problems using different methods (though the Python philosophy encourages using the obvious way to solve things). Furthermore, Python is also more forgiving of errors, so you'll still be able to compile and run your program until you hit the problematic part.
Because Python is a dynamically typed language, the same thing can easily mean something different depending on the context. As a Python app grows larger and more complex, this may get difficult to maintain as errors will become difficult to track down and fix, so it will take experience and insight to know how to design your code or write unit tests to ease maintainability.
As a dynamically typed language, Python is slow because it is too flexible and the machine would need to do a lot of referencing to make sure what the definition of something is, and this slows Python performance down.
At any rate, there are alternatives such as PyPy that are faster implementations of Python. While they might still not be as fast as Java, for example, it certainly improves the speed greatly.
Python's ease of use and compatibility across a variety of operating systems makes it an ideal language for a number of uses. Many complex websites either currently or historically have used Python to power their back ends, from YouTube to Instagram to Reddit, and thousands of other well-known examples. But Python isn't only a web language.
Python is the primary language used for the massive cloud computing project OpenStack, powering private and public clouds in data centers all over the world. It's also used to write desktop software, like Calibre, OpenShot, and the original client for BitTorrent. Many application written in other languages, such as Blender, allow for scripting by users in Python. It's also a popular language for machine learning, scientific, statistical, mathematical, and other types of specialized computing.
Even the Raspberry Pi gained its name from the founders plan to use the platform for teaching Python.
The Python language itself is managed by the Python Software Foundation, who offer a reference implementation of Python, called, CPython, under an open source license. You can even download the Python source code, here.
Besides the Python implementation itself being open source, many open source projects make use of Python, and Python has many libraries available for developers under open source licenses.
Python was designed for readability, and has some similarities to the English language with influence from mathematics. Python uses new lines to complete a command, as opposed to other programming languages which often use semicolons or parentheses. Python relies on indentation, using whitespace, to define scope; such as the scope of loops, functions and classes. Other programming languages often use curly-brackets for this purpose.
Flask is a micro web framework written in Python. It is classified as a microframework because it does not require particular tools or libraries. It has no database abstraction layer, form validation, or any other components where pre-existing third-party libraries provide common functions. However, Flask supports extensions that can add application features as if they were implemented in Flask itself. Extensions exist for object-relational mappers, form validation, upload handling, various open authentication technologies and several common framework related tools. Extensions are updated far more regularly than the core Flask program.
Applications that use the Flask framework include Pinterest, LinkedIn, and the community web page for Flask itself.
Flask was created by Armin Ronacher of Pocoo, an international group of Python enthusiasts formed in 2004. According to Ronacher, the idea was originally an April Fool's joke that was popular enough to make into a serious application.
When Ronacher and Georg Brandl created a bulletin board system written in Python, the Pocoo projects Werkzeug and Jinja were developed.
Despite the lack of a major release, Flask has become popular among Python enthusiasts. As of mid 2016, it was the most popular Python web development framework on GitHub.
What is PIP install in Python? pip (package manager) pip is a package-management system used to install and manage software packages written in Python. Many packages can be found in the default source for packages and their dependencies — Python Package Index (PyPI).
Pip is a tool for installing packages from the Python Package Index. virtualenv is a tool for creating isolated Python environments containing their own copy of python , pip , and their own place to keep libraries installed from PyPI.
MongoDB is a cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with schemata. MongoDB is developed by MongoDB Inc. and licensed under the Server Side Public License (SSPL). 10gen software company began developing MongoDB in 2007 as a component of a planned platform as a service product. In 2009, the company shifted to an open source development model, with the company offering commercial support and other services. In 2013, 10gen changed its name to MongoDB Inc.
MongoDB supports field, range query, and regular expression searches. Queries can return specific fields of documents and also include user-defined JavaScript functions. Queries can also be configured to return a random sample of results of a given size. Indexing
Fields in a MongoDB document can be indexed with primary and secondary indices.
MongoDB provides high availability with replica sets. A replica set consists of two or more copies of the data. Each replica set member may act in the role of primary or secondary replica at any time. All writes and reads are done on the primary replica by default. Secondary replicas maintain a copy of the data of the primary using built-in replication. When a primary replica fails, the replica set automatically conducts an election process to determine which secondary should become the primary. Secondaries can optionally serve read operations, but that data is only eventually consistent by default. Load balancing
MongoDB scales horizontally using sharding The user chooses a shard key, which determines how the data in a collection will be distributed. The data is split into ranges (based on the shard key) and distributed across multiple shards. (A shard is a master with one or more replicas.). Alternatively, the shard key can be hashed to map to a shard – enabling an even data distribution.
MongoDB can run over multiple servers, balancing the load or duplicating data to keep the system up and running in case of hardware failure. File storage
MongoDB can be used as a file system, called GridFS, with load balancing and data replication features over multiple machines for storing files.
This function, called grid file system, is included with MongoDB drivers. MongoDB exposes functions for file manipulation and content to developers. GridFS can be accessed using mongofiles utility or plugins for Nginx and lighttpd. GridFS divides a file into parts, or chunks, and stores each of those chunks as a separate document
MongoDB provides three ways to perform aggregation: the aggregation pipeline, the map-reduce function, and single-purpose aggregation methods.
Map-reduce can be used for batch processing of data and aggregation operations. But according to MongoDB's documentation, the Aggregation Pipeline provides better performance for most aggregation operations.
The aggregation framework enables users to obtain the kind of results for which the SQL GROUP BY clause is used. Aggregation operators can be strung together to form a pipeline – analogous to Unix pipes. The aggregation framework includes the $lookup operator which can join documents from multiple documents, as well as statistical operators such as standard deviation.
JavaScript can be used in queries, aggregation functions (such as MapReduce), and sent directly to the database to be executed.
MongoDB supports fixed-size collections called capped collections. This type of collection maintains insertion order and, once the specified size has been reached, behaves like a circular queue. Transactions
Support for multi-document ACID transactions was added to MongoDB with the General Availability of the 4.0 release in June 2018.
As of October 2018, MongoDB is released under the Server Side Public License (SSPL), a license developed by the project. It replaces the GNU Affero General Public License, and is nearly identical to the GNU General Public License version 3, but requires that those making the software publicly available as part of a "service" must make the service's entire source code available under this license. The SSPL was submitted for certification to the Open Source Initiative but later withdrawn. The language drivers are available under an Apache License. In addition, MongoDB Inc. offers proprietary licenses for MongoDB. The last versions licensed as AGPL version 3 are 4.0.3 (stable) and 4.1.4.
MongoDB has been dropped from the Debian, Fedora and Red Hat Enterprise Linux distributions due to the licensing change. Fedora determined that the SSPL version 1 is not a free software license because it is "intentionally crafted to be aggressively discriminatory" towards commercial users.
Due to the default security configuration of MongoDB, allowing anyone to have full access to the database, data from tens of thousands of MongoDB installations has been stolen. Furthermore, many MongoDB servers have been held for ransom.
From the MongoDB 2.6 release onwards, the binaries from the official MongoDB RPM and DEB packages bind to localhost by default. From MongoDB 3.6, this default behavior was extended to all MongoDB packages across all platforms. As a result, all networked connections to the database will be denied unless explicitly configured by an administrator.
In some failure scenarios where an application can access two distinct MongoDB processes, but these processes cannot access each other, it is possible for MongoDB to return stale reads. In this scenario it is also possible for MongoDB to roll back writes that have been acknowledged. This issue was addressed since version 3.4.0 released in November 2016 (and back-ported to v3.2.12).
Before version 2.2, locks were implemented on a per-server process basis. With version 2.2, locks were implemented at the database level. Since version 3.0, pluggable storage engines were introduced, and each storage engine may implement locks differently. With MongoDB 3.0 locks are implemented at the collection level for the MMAPv1 storage engine, while the WiredTiger storage engine uses an optimistic concurrency protocol that effectively provides document-level locking. Even with versions prior to 3.0, one approach to increase concurrency is to use sharding. In some situations, reads and writes will yield their locks. If MongoDB predicts a page is unlikely to be in memory, operations will yield their lock while the pages load. The use of lock yielding expanded greatly in 2.2.
Up until version 3.3.11, MongoDB could not do collation-based sorting and was limited to byte-wise comparison via memcmp which would not provide correct ordering for many non-English languages when used with a Unicode encoding. The issue was fixed on August 23, 2016.
With storage engine MMAPv1, MongoDB queries against an index are not atomic and can miss documents which are being updated while the query is running and match the query both before and after an update. Prior to MongoDB 4.0 queries against an index were not atomic and could miss documents which were being updated while the query was running and match the query both before and after an update. The introduction of the snapshot read concern in MongoDB 4.0 eliminated this phenomenon.
Redis (Remote Dictionary Server) is an in-memory data structure project implementing a distributed, in-memory key-value database with optional durability. Redis supports different kinds of abstract data structures, such as strings, lists, maps, sets, sorted sets, HyperLogLogs, bitmaps, streams, and spatial indexes. The project is mainly developed by Salvatore Sanfilippo and as of 2019, is sponsored by Redis Labs. It is open-source software released under a BSD 3-clause license.
Redis made popular the idea of a system that can be considered at the same time a store and a cache, using a design where data is always modified and read from the main computer memory, but also stored on disk in a format that is unsuitable for random access of data, but only to reconstruct the data back in memory once the system restarts. At the same time, Redis provides a data model that is very unusual compared to relational database management system (RDBMS), as user commands do not describe a query to be executed by the database engine, but specific operations that are performed on given abstract data types, hence data must be stored in a way which is suitable later for fast retrieval, without help from the database system in form of secondary indexes, aggregations or other common features of traditional RDBMS. The Redis implementation makes heavy use of the Fork (system call), to duplicate the process holding the data, so that the parent process continues to serve clients, while the child process creates a copy of the data on disk.
Since version 2.6, Redis features server-side scripting in the language Lua.
Many programming languages have Redis language bindings on the client side, including: ActionScript, C, C++, C#, Chicken, Clojure, Common Lisp, Crystal, D, Dart, Elixir, Erlang, Go, Haskell, Haxe, Io, Java, JavaScript (Node.js), Julia, Lua, Objective-C, OCaml, Perl, PHP, Pure Data, Python, R, Racket, Ruby, Rust, Scala, Smalltalk, Swift, and Tcl. Several client software programs exist in these languages.
Redis maps keys to types of values. An important difference between Redis and other structured storage systems is that Redis supports not only strings, but also abstract data types:
Lists of strings
Sets of strings (collections of non-repeating unsorted elements)
Sorted sets of strings (collections of non-repeating elements ordered by a floating-point number called score)
Hash tables where keys and values are strings
HyperLogLogs used for approximated set cardinality size estimation, available since Redis 2.8.9 in April 2014.
Stream of entries with consumer groups, allows you to store multiple fields and string values with an automatic, time-based sequence at a single key, available since Redis 5.0 in October 2018
Geospatial data through the implementation of the geohash technique, available since Redis 3.2.
The type of a value determines what operations (called commands) are available for the value. Redis supports high-level, atomic, server-side operations like intersection, union, and difference between sets and sorting of lists, sets and sorted sets.
The Redis module ReJSON implements ECMA-404 (the JavaScript Object Notation (JSON) Data Interchange Standard) as a native data type.
Redis typically holds the whole dataset in memory. Versions up to 2.4 could be configured to use what they refer to as virtual memory in which some of the dataset is stored on disk, but this feature is deprecated. Persistence is now achieved in two different ways: one is called snapshotting, and is a semi-persistent durability mode where the dataset is asynchronously transferred from memory to disk from time to time, written in RDB dump format. Since version 1.1 the safer alternative is an append-only file (AOF), a journal that is written as operations modifying the dataset in memory are processed. Redis can rewrite the append-only file in the background to avoid an indefinite growth of the journal.
By default, Redis writes data to a file system at least every 2 seconds, with more or less robust options available if needed. In the case of a complete system failure on default settings, only a few seconds of data would be lost.
Redis supports master-replica replication. Data from any Redis server can replicate to any number of replicas. A replica may be a master to another replica. This allows Redis to implement a single-rooted replication tree. Redis replicas can be configured to accept writes, permitting intentional and unintentional inconsistency between instances. The publish/subscribe feature is fully implemented, so a client of a replica may subscribe to a channel and receive a full feed of messages published to the master, anywhere up the replication tree. Replication is useful for read (but not write) scalability or data redundancy.
When the durability of data is not needed, the in-memory nature of Redis allows it to perform well compared to database systems that write every change to disk before considering a transaction committed. Redis operates as a single process and is single-threaded or double-threaded when it rewrites the AOF (append-only file). Thus, a single Redis instance cannot use parallel execution of tasks such as stored procedures.
Redis introduced clustering in April 2015 with the release of version 3.0. The cluster specification implements a subset of Redis commands: all single-key commands are available, multi-key operations (commands related to unions and intersections) are restricted to keys belonging to the same node, and commands related to database selection operations are unavailable. A Redis cluster can scale up to 1,000 nodes, achieve "acceptable" write safety and to continue operations when some nodes fail.
Due to the nature of the database design, typical use cases are session caching, full page cache, message queue applications, leaderboards and counting among others. Large companies such as Twitter are using Redis, Amazon Web Services is offering Redis in its portfolio, and Microsoft is offering the Redis Cache in Azure.
Ionic is a complete open-source SDK for hybrid mobile app development created by Max Lynch, Ben Sperry and Adam Bradley of Drifty Co. in 2013. The original version was released in 2013 and built on top of AngularJS and Apache Cordova. However, The latest release was re-built as a set of Web Components, allowing the user to choose any user interface framework, such as Angular, React or Vue.js. It also allows the use of Ionic components with no user interface framework at all. Ionic provides tools and services for developing hybrid mobile, desktop, and Progressive Web Apps based on modern web development technologies and practices, using Web technologies like CSS, HTML5, and Sass. In particular, mobile apps can be built with these Web technologies and then distributed through native app stores to be installed on devices by utilizing Cordova or Capacitor.
Ionic uses Cordova and, more recently, Capacitor plugins to gain access to host operating systems features such as Camera, GPS, Flashlight, etc. Users can build their apps, and they can then be customized for Android, iOS, Windows, Desktop (with Electron_(software_framework) or modern browsers. Ionic allows app building and deployment by wrapping around the build tool Cordova or Capacitor with a simplified 'ionic' command line tool.
Ionic includes mobile components, typography, interactive paradigms, and an extensible base theme.
Using Web Components, Ionic provides custom components and methods for interacting with them. One such component, virtual scroll, allows users to scroll through a list of thousands of items without any performance hits. Another component, tabs, creates a tabbed interface with support for native-style navigation and history state management.
Besides the SDK, Ionic also provides services that developers can use to enable features, such as code deploys, automated builds. Ionic also provides its own Integrated_development_environment known as Ionic Studio.
Ionic also provides a command-line interface (CLI) to create projects. The CLI also allows developers to add Cordova plugins and additional front-end packages, enable push notifications, generate app Icons and Splash screens, and build native binaries.
For Android, Ionic supports Android 4.1 and up. For iOS, Ionic supports iOS 9 and up. Ionic 2 supports the Universal Windows Platform for building Windows 10 apps. Ionic Framework, based on Angular.js, supports BlackBerry 10 apps.
Ionic apps run with a mixture of native code and web code, providing full access to native functionality if necessary, with the bulk of the UI of the app built with standard web technology. Ionic utilizes native hardware acceleration features available in the browser (such as CSS animations), and optimizes rendering (avoiding expensive DOM manipulation). Ionic leverages CSS transitions and transforms for animation as a way to leverage the GPU and maximize available processor time.
Angular (commonly referred to as "Angular 2+" or "Angular v2 and above") is a TypeScript-based open-source web application framework led by the Angular Team at Google and by a community of individuals and corporations. Angular is a complete rewrite from the same team that built AngularJS.
TypeScript is an open-source programming language developed and maintained by Microsoft. It is a strict syntactical superset of JavaScript, and adds optional static typing to the language.
TypeScript is designed for development of large applications and transcompiles to JavaScript. As TypeScript is a superset of JavaScript, existing JavaScript programs are also valid TypeScript programs. TypeScript may be used to develop JavaScript applications for both client-side and server-side (Node.js) execution.
There are multiple options available for transcompilation. Either the default TypeScript Checker can be used, or the Babel compiler can be invoked to convert TypeScript to JavaScript.
TypeScript supports definition files that can contain type information of existing JavaScript libraries, much like C++ header files can describe the structure of existing object files. This enables other programs to use the values defined in the files as if they were statically typed TypeScript entities. There are third-party header files for popular libraries such as jQuery, MongoDB, and D3.js. TypeScript headers for the Node.js basic modules are also available, allowing development of Node.js programs within TypeScript.
The TypeScript compiler is itself written in TypeScript and compiled to JavaScript. It is licensed under the Apache 2.0 License.
TypeScript is included as a first-class programming language in Microsoft Visual Studio 2013 Update 2 and later, beside C# and other Microsoft languages. An official extension allows Visual Studio 2012 to support TypeScript as well.
TypeScript originated from the shortcomings of JavaScript for the development of large-scale applications both at Microsoft and among their external customers. Challenges with dealing with complex JavaScript code led to demand for custom tooling to ease developing of components in the language.
TypeScript developers sought a solution that would not break compatibility with the standard and its cross-platform support. Knowing that the current ECMAScript standard proposal promised future support for class-based programming, TypeScript was based on that proposal. That led to a JavaScript compiler with a set of syntactical language extensions, a superset based on the proposal, that transforms the extensions into regular JavaScript. In this sense TypeScript was a preview of what to expect of ECMAScript 2015. A unique aspect not in the proposal, but added to TypeScript, is optional static typing that enables static language analysis, which facilitates tooling and IDE support.
TypeScript is a strict superset of ECMAScript 2015, which is itself a superset of ECMAScript 5, commonly referred to as JavaScript. As such, a JavaScript program is also a valid TypeScript program, and a TypeScript program can seamlessly consume JavaScript. By default the compiler targets ECMAScript 5, the current prevailing standard, but is also able to generate constructs used in ECMAScript 3 or 2015.
With TypeScript, it is possible to use existing JavaScript code, incorporate popular JavaScript libraries, and call TypeScript-generated code from other JavaScript. Type declarations for these libraries are provided with the source code.
Microsoft provides a plug-in for Visual Studio 2012 and WebMatrix, full integrated support in Visual Studio 2013, Visual Studio 2015, and basic text editor support for Sublime Text, Emacs and Vim. Visual Studio Code is an open-source, cross-platform source code editor developed by Microsoft based on Electron. It supports TypeScript in addition to several other languages, and offers features like debugging and intelligent code completion alm.tools is an open source cloud IDE for TypeScript built using TypeScript, ReactJS and TypeStyle. JetBrains supports TypeScript with code completion, refactoring and debugging in its IDEs built on IntelliJ platform, such as PhpStorm 6, WebStorm 6, and IntelliJ IDEA, as well as their Visual Studio Add-in and extension, ReSharper 8.1. Atom has a TypeScript Plugin by Basarat with support for code completion, navigation, formatting, and fast compilation. The online Cloud9 IDE and Codenvy support TypeScript. A plugin is available for the NetBeans IDE. A plugin is available for the Eclipse IDE (version Kepler) TypEcs is available for the Eclipse IDE. Microsoft provides a TypeScript Plugin for Sublime Text. The Cross Platform Cloud IDE Codeanywhere supports TypeScript. Webclipse An Eclipse plugin designed to develop TypeScript and Angular 2. Angular IDE A standalone IDE available via npm to develop TypeScript and Angular 2 applications, with integrated terminal support. Tide — TypeScript Interactive Development Environment for Emacs. Tsuquyomi - a Vim plugin which uses TSServer and provides features like code completion, navigation and syntax and semantic error checking.
JWt (pronounced "jay-witty") is an open-source widget-centric web application framework for the Java programming language developed by Emweb. It has an API that uses established GUI application development patterns. The programming model is component-based and event-driven, similar to Swing.
The goal of the library is to benefit from the stateful component model used in desktop applications APIs, applied to web development, instead of the traditional model–view–controller (MVC) model. Rather than using MVC at the level of a page, MVC is pushed to the level of individual components.
While the library uses a desktop application development model, it does support web-specific features including semantic URLs, browser history navigation support, internationalization, themes and styling, ...
A unique feature of the library is its abstraction layer of the browser rendering model. The library uses Ajax for communicating with Ajax-capable browsers, while using plain HTML form post-backs for other user agents (for accessibility and search engines). Using a progressive bootstrap method, the user interface is initially rendered as plain HTML, and for Ajax-capable browsers, it is automatically upgraded to use Ajax for increased interactivity. In this way, it is the only server-side framework that implements progressive enhancement automatically, and the only Ajax framework with search engine optimization (SEO) qualities.
JWt is distributed as a jar file. A JWt application is a war file that is deployed in a standards-compliant servlet container.
See the feature list on the project homepage for a more detailed overview.
Automatic graceful degradation and progressive enhancement On all modern browsers, a JWt application is a Single Page Application, with full support for forward/back and bookmark navigation, but still fully SEO. Supports server-initiated events (Comet), and uses Asynchronous I/O when deployed within a Servlet 3.0 container. A unified 2D rendering API (SVG/HTML5 canvas/VML/PDF) with java.awt.Graphics2D compatibility Integrated PDF rendering for Widgets, Graphics (Charts) and HTML/CSS, to generate reports Both client-side and server-side validation Various automatic built-in security features to avoid Cross-site scripting and CSRF vulnerabilities. Theme support through CSS or Twitter Bootstrap Available widgets are demonstrated in the widget gallery A 3D painting API for WebGL rendering, with fallback to server-side GPU accelerated rendering A 3D chart API (surfaces, points, bar charts, ...) supporting selection, intersection highlighting, height maps, isolines, ...
Docker is a collection of interoperating software-as-a-service and platform-as-a-service offerings that employ operating-system-level virtualization to cultivate development and delivery of software inside standardized software packages called containers. The software that hosts the containers is called Docker Engine. It was first started in 2013 and is developed by Docker, Inc. The service has both free and premium tiers.
Containers are isolated from each other 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 are thus more lightweight than virtual machines. Containers are created from images that specify their precise contents. Images are often created by combining and modifying standard images downloaded from public repositories.
Docker is developed primarily for Linux, where it uses the resource isolation features of the Linux kernel such as cgroups and kernel namespaces, and a union-capable file system such as OverlayFS and others to allow independent containers to run within a single Linux instance, avoiding the overhead of starting and maintaining virtual machines (VMs). The Linux kernel's support for namespaces mostly isolates an application's view of the operating environment, including process trees, network, user IDs and mounted file systems, while the kernel's cgroups provide resource limiting for memory and CPU. Since version 0.9, Docker includes the libcontainer library as its own way to directly use virtualization facilities provided by the Linux kernel, in addition to using abstracted virtualization interfaces via libvirt, LXC and systemd-nspawn.
Building on top of facilities provided by the Linux kernel (primarily cgroups and namespaces), a Docker container, unlike a virtual machine, does not require or include a separate operating system. Instead, it relies on the kernel's functionality and uses resource isolation for CPU and memory, and separate namespaces to isolate the application's view of the operating system. Docker accesses the Linux kernel's virtualization features either directly using the libcontainer library, which is available as of Docker 0.9, or indirectly via libvirt, LXC (Linux Containers) or systemd-nspawn.
Socket.IO is a JavaScript library for realtime web applications. It enables realtime, bi-directional communication between web clients and servers. It has two parts: a client-side library that runs in the browser, and a server-side library for Node.js. Both components have a nearly identical API. Like Node.js, it is event-driven.
Socket.IO primarily uses the WebSocket protocol with polling as a fallback option, while providing the same interface. Although it can be used as simply a wrapper for WebSocket, it provides many more features, including broadcasting to multiple sockets, storing data associated with each client, and asynchronous I/O.
It can be installed with the npm tool.
Socket.IO provides the ability to implement real-time analytics, binary streaming, instant messaging, and document collaboration. Notable users include Microsoft Office, Yammer, and Zendesk.
Socket.IO handles the connection transparently. It will automatically upgrade to WebSocket if possible. This requires the programmer to only have Socket.IO knowledge.
Socket.IO is not a WebSocket library with fallback options to other realtime protocols. It is a custom realtime transport protocol implementation on top of other realtime protocols. A Socket.IO implementing server cannot connect to a non-Socket.IO WebSocket client. A Socket.IO implementing client cannot talk to a non-Socket.IO WebSocket or Long Polling Comet server. Socket.IO requires using the Socket.IO libraries on both client and server side.
As of version 2.0, Socket.IO makes use of µWebSockets as the underlying WebSocket library.
Docker Compose is a tool for defining and running multi-container Docker applications. It uses YAML files to configure the application's services and performs the creation and start-up process of all the containers with a single command. The docker-compose CLI utility allows users to run commands on multiple containers at once, for example, building images, scaling containers, running containers that were stopped, and more. Commands related to image manipulation, or user-interactive options, are not relevant in Docker Compose because they address one container. The docker-compose.yml file is used to define an application's services and includes various configuration options. For example, the build option defines configuration options such as the Dockerfile path, the command option allows one to override default Docker commands, and more. The first public version of Docker Compose (version 0.0.1) was released on December 21, 2013. The first production-ready version (1.0) was made available on October 16, 2014.
Docker Swarm provides native clustering functionality for Docker containers, which turns a group of Docker engines into a single virtual Docker engine. In Docker 1.12 and higher, Swarm mode is integrated with Docker Engine. The swarm CLI utility allows users to run Swarm containers, create discovery tokens, list nodes in the cluster, and more. The docker node CLI utility allows users to run various commands to manage nodes in a swarm, for example, listing the nodes in a swarm, updating nodes, and removing nodes from the swarm. Docker manages swarms using the Raft Consensus Algorithm. According to Raft, for an update to be performed, the majority of Swarm nodes need to agree on the update.
