Gemini is an

application-layer An application layer is an abstraction layer that specifies the shared communication protocols and interface methods used by hosts in a communications network. An ''application layer'' abstraction is specified in both the Internet Protocol Sui ...

internet communication protocol for accessing remote documents, similar to

HTTP HTTP (Hypertext Transfer Protocol) 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, wher ...

and

Gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They ar ...

. 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 , has not been submitted to the

IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster ...

organization for

standardization Standardization (American English) or standardisation (British English) is the process of implementing and developing technical standards based on the consensus of different parties that include firms, users, interest groups, standards organiza ...

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

, but to co-exist with them. Much of the development happened on the Gemini mailing list until the list disappeared at the end of 2021 due to a hardware issue. The creation of the

Usenet Usenet (), a portmanteau of User's Network, is a worldwide distributed discussion system available on computers. It was developed from the general-purpose UUCP, Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Elli ...

newsgroup ''comp.infosystems.gemini'' in October 2021 was the first new newsgroup in the Big Eight hierarchy in eight years.

Design

The Gemini specification defines both the Gemini protocol and a native file format for that protocol, analogous to

HTML Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It defines the content and structure of web content. It is often assisted by technologies such as Cascading Style Sheets ( ...

for HTTP, known as "gemtext". The design is inspired by

, but with modernisation such as mandatory use of

Transport Layer Security Transport Layer Security (TLS) is a cryptographic protocol designed to provide communications security over a computer network, such as the Internet. The protocol is widely used in applications such as email, instant messaging, and voice over ...

(TLS) for connections and a

hypertext Hypertext is E-text, text displayed on a computer display or other electronic devices with references (hyperlinks) to other text that the reader can immediately access. Hypertext documents are interconnected by hyperlinks, which are typic ...

format as native content type. The design is deliberately not easily extensible, in order to meet a project goal of simplicity.

Protocol

Gemini is designed within the framework of the

Internet protocol suite The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...

. Like HTTP/S, Gemini functions as a

request–response In computer science, request–response or request–reply is one of the basic methods computers use to communicate with each other in a network, in which the first computer sends a ''request'' for some data and the second ''responds'' to the req ...

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. Gemini mandates the use of TLS with privacy-related features and trust on first use (TOFU) verification being strongly suggested. Gemini resources are identified and located on the network by

Uniform Resource Locator A uniform resource locator (URL), colloquially known as an address on the World Wide Web, Web, is a reference to a web resource, resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific t ...

s (URLs), using the

URI scheme A Uniform Resource Identifier (URI), formerly Universal Resource Identifier, is a unique sequence of characters that identifies an abstract or physical resource, such as resources on a webpage, mail address, phone number, books, real-world obje ...

''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.

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

hyperlink In computing, a hyperlink, or simply a link, is a digital reference providing direct access to Data (computing), data by a user (computing), user's point and click, clicking or touchscreen, tapping. A hyperlink points to a whole document or to ...

s to form interlinked hypertext documents in the Gemini "web", which users refer to as ''Geminispace''.

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. Geminispace consists of around 3900 online known Gemini appearances ("capsules") identified by crawling over 600,000 URIs.

Software

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

Reception

Gemini is praised for its simplicity but criticized for "excluding people who use ordinary web browsers". Gemini's usefulness has been said to be "dependent on the kinds of content available on Gemini and whether it appeals or not". Stéphane Bortzmeyer has said Gemini is retro but with modern features.

References

External links

Official website

Project Gemini FAQ

Gopher, Gemini, and the rise of the small Internet: Beyond the Web
in

Linux Magazine ''Linux Magazine'' is an international magazine for Linux software enthusiasts and professionals. It is published by Computec Media GmbH in German-speaking countries and Linux New Media USA, LLC. for English edition. The magazine was first publ ...

Mozz.us Gemini-to-HTTP proxy
{{URI scheme Application layer protocols Internet protocols Network protocols Accessible information Hypertext Internet properties established in 2019