Gemini (protocol)

Last updated
Gemini
Developed bySolderpunk et al.
IntroducedJune 2019 (2019-06)
Website geminiprotocol.net
Gemtext
Filename extension
.gmi, .gmni, .gemini
Internet media type text/gemini (unofficial)
Type code TEXT
Developed bySolderpunk et al.
Latest release
0.16.1
30 January 2022;2 years ago (2022-01-30)
Type of format Markup language
Open format?Yes
Website geminiprotocol.net/docs/specification.gmi

Gemini is an application-layer internet communication protocol for accessing remote documents, similar to HTTP (Hypertext Transfer Protocol) and Gopher. It comes with a special document format, commonly referred to as "gemtext", which allows linking to other documents. Started by a pseudonymous person known as Solderpunk, the protocol is being finalized collaboratively and as of October 2022, has not been submitted to the IETF organization for standardization.

Contents

History

The Gemini project was started in June 2019 by Solderpunk. Additional work has been done by an informal community of users. According to Solderpunk's FAQ, Gemini is not intended to replace Gopher or HTTP, but to co-exist with them. [1] Much of the development happened on the Gemini mailing list until the list disappeared at the end of 2021 due to a hardware issue. [2] The creation of the Usenet newsgroup comp.infosystems.gemini in October 2021 was the first new newsgroup in the Big Eight hierarchy in eight years. [3]

Design

The Gemini specification defines both the Gemini protocol and a native file format for that protocol, analogous to HTML for HTTP, known as "gemtext". The design is inspired by Gopher, but with modernisation such as mandatory use of Transport Layer Security (TLS) for connections and a hypertext format as native content type. [4]

The design is deliberately not easily extensible, in order to meet a project goal of simplicity. [5]

Protocol

Gemini is designed within the framework of the Internet protocol suite and like HTTP/S, Gemini functions as a request–response protocol in the client–server computing model. A Gemini server should listen on TCP port 1965. A Gemini browser, for example, may be the client and an application running on a computer hosting a Gemini site may be the server. The client sends a Gemini request message to the server, and the server sends back a response message. Gemini uses a separate connection to the same server for every resource request. [6]

Gemini mandates the use of TLS with privacy-related features and trust on first use (TOFU) verification being strongly suggested. [7]

Gemini resources are identified and located on the network by Uniform Resource Locators (URLs), using the URI scheme gemini://. A Gemini request consists only of such a URL, terminated by CRLF; the header of a Gemini response consists of a two-digit status code, a space, and a "meta" field, also terminated by CRLF. If the server is successful in finding the requested file, the "meta" field is the MIME type of the returned file and after the header follows the file data.

Example session
Client
gemini://example.com/
Server
20 text/gemini # Example Title Welcome to my Gemini capsule. * Example list item => gemini://link.to/another/resource Link text

Gemtext format

Gemtext format is line-oriented and the first three characters of a line determine its type. The syntax includes markup for headlines, flat list items, pre-formatted text, quotes and link lines. As with HTTP hypertext, URIs are encoded as hyperlinks to form interlinked hypertext documents in the Gemini "web", which users refer to as Geminispace . [1]

Geminispace

"Geminispace" denotes the whole of the public resources that are published on the Internet by the Gemini community via the Gemini protocol. Thus, Gemini spans an alternative communication web, with hypertext documents, including hyperlinks to other resources easily accessible to the user. [1]

As of February 2023, Geminispace consists of around 2300 online known Gemini appearances ("capsules") identified by crawling over 490,000 URIs. [8]

Software

Amfora - Gemini client Screenshot of Amfora.png
Amfora - Gemini client
AmiGemini - Gemini client AmiGemini.png
AmiGemini - Gemini client
Gemini clients include:
NamePlatformLicenseWritten in
Amfora Terminal (TUI)GPL 3.0 Go
AmiGemini GUI (Intuition)MIT C, Intuition
astro Terminal (TUI)MIT Shell script
asuka Terminal (TUI)MIT Rust, ncurses
AV-98 Terminal (CLI)2 Clause BSD Python
Bollux TerminalMIT Bash
Bombadillo TerminalGPL 3.0 Go
Buran App (Android)GPL 3.0 Kotlin
Castor GUI (GTK)MIT Rust, GTK
Castor9 GUI (Plan 9) C
Deedum App (Android and iOS)GPL 3.0 Flutter, Dart
Diohsc Terminal (CLI)GPL 3.0 Haskell
dillo-gemini Plugin (Dillo) FSFAP Shell
Elaho (gemini-ios) App (iOS)MPL 2.0 Swift
Elpher GUI (Emacs)GPL 3.0 Emacs Lisp
Eva GUI (GTK)MIT Rust, GTK
Fafi GUIMIT Racket
GemiNaut GUI (Windows)GPL 3.0 C# for Microsoft Windows
gemini.filter.dpi Plugin (Dillo)MIT Go
Geopard GUI (GTK)GPL 3.0 Rust, GTK
gmni Terminal (CLI)GPL 3.0 C
gplaces Terminal (CLI)GPL 3.0 or later C
Jimmy App (macOS)MIT Swift
Kristall GUI (Qt)GPL 2.0 C++, Qt
Lagrange GUI (Windows, macOS, Linux)2 Clause BSD C, SDL
Moonlander GUI (GTK)MIT Rust, GTK
Offpunk Terminal (CLI)2 Clause BSD Python
Rocketeer App (iOS, macOS) Swift
Rosy Crow App (Android)MIT C#, MAUI
Seren App (Android) Kotlin
Starfish GUI (elementary OS/Linux)GPL 3.0 Vala, GTK
Tinmop Terminal (TUI) or GUIGPL 3.0+ Common lisp
Telescope Terminal (TUI)ISC C
Twin Peaks GUI (Windows)GPL 3.0 C#
VIRGIL99 Terminal (TI-99) Assembly language

The Gemini software list covers client, server, libraries, and tools. [9]
Gemini-to-HTTP proxy server gateways such as Mozz.us can be used by web browsers lacking Gemini support. [10]

See also

Related Research Articles

The Gopher protocol is a communication protocol designed for distributing, searching, and retrieving documents in Internet Protocol networks. The design of the Gopher protocol and user interface is menu-driven, and presented an alternative to the World Wide Web in its early stages, but ultimately fell into disfavor, yielding to HTTP. The Gopher ecosystem is often regarded as the effective predecessor of the World Wide Web.

<span class="mw-page-title-main">HTTP</span> Application protocol for distributed, collaborative, hypermedia information systems

The Hypertext Transfer Protocol (HTTP) is an application layer protocol in the Internet protocol suite model for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web, where hypertext documents include hyperlinks to other resources that the user can easily access, for example by a mouse click or by tapping the screen in a web browser.

<span class="mw-page-title-main">HTTPS</span> Extension of the HTTP communications protocol to support TLS encryption

Hypertext Transfer Protocol Secure (HTTPS) is an extension of the Hypertext Transfer Protocol (HTTP). It uses encryption for secure communication over a computer network, and is widely used on the Internet. In HTTPS, the communication protocol is encrypted using Transport Layer Security (TLS) or, formerly, Secure Sockets Layer (SSL). The protocol is therefore also referred to as HTTP over TLS, or HTTP over SSL.

The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telephone systems, as well as mobile phone calling over LTE (VoLTE).

<span class="mw-page-title-main">World Wide Web</span> Linked hypertext system on the Internet

The World Wide Web is an information system that enables content sharing over the Internet through user-friendly ways meant to appeal to users beyond IT specialists and hobbyists. It allows documents and other web resources to be accessed over the Internet according to specific rules of the Hypertext Transfer Protocol (HTTP).

<span class="mw-page-title-main">Proxy server</span> Computer server that makes and receives requests on behalf of a user

In computer networking, a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource. It improves privacy, security, and performance in the process.

WebDAV is a set of extensions to the Hypertext Transfer Protocol (HTTP), which allows user agents to collaboratively author contents directly in an HTTP web server by providing facilities for concurrency control and namespace operations, thus allowing Web to be viewed as a writeable, collaborative medium and not just a read-only medium. WebDAV is defined in RFC 4918 by a working group of the Internet Engineering Task Force (IETF).

<span class="mw-page-title-main">Squid (software)</span> Caching and forwarding HTTP web proxy

Squid is a caching and forwarding HTTP proxy. It has a wide variety of uses, including speeding up a web server by caching repeated requests, caching World Wide Web (WWW), Domain Name System (DNS), and other lookups for a group of people sharing network resources, and aiding security by filtering traffic. Although used for mainly HTTP and File Transfer Protocol (FTP), Squid includes limited support for several other protocols including Internet Gopher, Secure Sockets Layer (SSL), Transport Layer Security (TLS), and Hypertext Transfer Protocol Secure (HTTPS). Squid does not support the SOCKS protocol, unlike Privoxy, with which Squid can be used in order to provide SOCKS support.

The Internet Printing Protocol (IPP) is a specialized communication protocol for communication between client devices and printers. It allows clients to submit one or more print jobs to the network-attached printer or print server, and perform tasks such as querying the status of a printer, obtaining the status of print jobs, or cancelling individual print jobs.

Web Services Security is an extension to SOAP to apply security to Web services. It is a member of the Web service specifications and was published by OASIS.

REST is a software architectural style that was created to guide the design and development of the architecture for the World Wide Web. REST defines a set of constraints for how the architecture of a distributed, Internet-scale hypermedia system, such as the Web, should behave. The REST architectural style emphasises uniform interfaces, independent deployment of components, the scalability of interactions between them, and creating a layered architecture to promote caching to reduce user-perceived latency, enforce security, and encapsulate legacy systems.

<span class="mw-page-title-main">Line Mode Browser</span> Command-line web browser

The Line Mode Browser is the second web browser ever created. The browser was the first demonstrated to be portable to several different operating systems. Operated from a simple command-line interface, it could be widely used on many computers and computer terminals throughout the Internet. The browser was developed starting in 1990, and then supported by the World Wide Web Consortium (W3C) as an example and test application for the libwww library.

<span class="mw-page-title-main">Secure Hypertext Transfer Protocol</span> Web encryption method similar to HTTPS

Secure Hypertext Transfer Protocol (S-HTTP) is an obsolete alternative to the HTTPS protocol for encrypting web communications carried over the Internet. It was developed by Eric Rescorla and Allan M. Schiffman at EIT in 1994 and published in 1999 as RFC 2660.

<span class="mw-page-title-main">HTTP compression</span> Capability that can be built into web servers and web clients

HTTP compression is a capability that can be built into web servers and web clients to improve transfer speed and bandwidth utilization.

<span class="mw-page-title-main">HTTP referer</span> HTTP header field

In HTTP, "Referer" is an optional HTTP header field that identifies the address of the web page, from which the resource has been requested. By checking the referrer, the server providing the new web page can see where the request originated.

<span class="mw-page-title-main">WebSocket</span> Computer network protocol

WebSocket is a computer communications protocol, providing simultaneous two-way communication channels over a single Transmission Control Protocol (TCP) connection. The WebSocket protocol was standardized by the IETF as RFC 6455 in 2011. The current specification allowing web applications to use this protocol is known as WebSockets. It is a living standard maintained by the WHATWG and a successor to The WebSocket API from the W3C.

<span class="mw-page-title-main">HTTP/1.1 Upgrade header</span> HTTP header field introduced in HTTP/1.1

The Upgrade header field is an HTTP header field introduced in HTTP/1.1. In the exchange, the client begins by making a cleartext request, which is later upgraded to a newer HTTP protocol version or switched to a different protocol. A connection upgrade must be requested by the client; if the server wants to enforce an upgrade it may send a 426 Upgrade Required response. The client can then send a new request with the appropriate upgrade headers while keeping the connection open.

HTTP/2 is a major revision of the HTTP network protocol used by the World Wide Web. It was derived from the earlier experimental SPDY protocol, originally developed by Google. HTTP/2 was developed by the HTTP Working Group of the Internet Engineering Task Force (IETF). HTTP/2 is the first new version of HTTP since HTTP/1.1, which was standardized in RFC 2068 in 1997. The Working Group presented HTTP/2 to the Internet Engineering Steering Group (IESG) for consideration as a Proposed Standard in December 2014, and IESG approved it to publish as Proposed Standard on February 17, 2015. The HTTP/2 specification was published as RFC 7540 on May 14, 2015.

<span class="mw-page-title-main">Automatic Certificate Management Environment</span> Communications protocol for automating interactions between certificate authorities and web servers

The Automatic Certificate Management Environment (ACME) protocol is a communications protocol for automating interactions between certificate authorities and their users' servers, allowing the automated deployment of public key infrastructure at very low cost. It was designed by the Internet Security Research Group (ISRG) for their Let's Encrypt service.

References

  1. 1 2 3 "Project Gemini FAQ". Archived from the original on 27 September 2023. Retrieved 27 September 2023.
  2. "Gemini Info Page". Archived from the original on 2021-10-20. Retrieved 2021-10-20.
  3. "Gemini Usenet Newsgroup". Archived from the original on 2021-10-26. Retrieved 2021-10-26.
  4. "Project Gemini Speculative Specification v0.16.1". gemini.circumlunar.space. 2023-03-23. 5 The text/gemini media type. Response bodies of type "text/gemini" are a kind of lightweight hypertext format, which takes inspiration from gophermaps and from Markdown.
  5. Edge, Jake (2021-02-10). "Visiting another world". lwn.net. Retrieved 2021-02-19.
  6. "Project Gemini Speculative Specification v0.16.1". gemini.circumlunar.space. 2023-03-23. 1 Overview. Connections are closed at the end of a single transaction and cannot be reused.
  7. "Project Gemini Speculative Specification". gemini.circumlunar.space. 2020-11-29. Archived from the original on 2021-05-12. Retrieved 2021-06-25. 4.2 Server certificate validation. Clients can validate TLS connections however they like (including not at all) but the strongly recommended approach is to implement a lightweight "TOFU" certificate-pinning system which treats self-signed certificates as first-class citizens.
  8. "Statistics on the Gemini space". Proxied gemini://gemini.bortzmeyer.org/software/lupa/stats.gmi
  9. "Gemini software".
  10. "About Mozz.us".