URI scheme

A Uniform Resource Identifier (URI) scheme is a component of the URI that defines a specific protocol or method used to access a resource on the Internet. URI schemes are essential for the functioning of the web, as they specify how resources can be retrieved or interacted with.

Overview

A URI is a string of characters used to identify a resource on the Internet. The URI scheme is the initial part of the URI, preceding the colon, and it indicates the protocol or method to be used. For example, in the URI `http://www.example.com`, `http` is the scheme.

URI schemes are defined by the Internet Assigned Numbers Authority (IANA) and are standardized by the Internet Engineering Task Force (IETF). They are a critical part of the Uniform Resource Locator (URL) and Uniform Resource Name (URN) systems.

Common URI Schemes

Some of the most common URI schemes include:

• http: Used for accessing resources via the Hypertext Transfer Protocol.
• https: Similar to http, but with added security through Transport Layer Security (TLS).
• ftp: Used for accessing resources via the File Transfer Protocol.
• mailto: Used for email addresses, allowing users to send emails directly from a link.
• file: Used to access files on a local or networked file system.

Structure of a URI

A typical URI is structured as follows:

``` <scheme>://<authority>/<path>?<query>#<fragment> ```

• Scheme: The protocol or method used to access the resource.
• Authority: The domain name or IP address of the server hosting the resource.
• Path: The specific location of the resource on the server.
• Query: Optional parameters that provide additional instructions for accessing the resource.
• Fragment: An optional identifier that points to a specific part of the resource.

Registration of URI Schemes

The registration of URI schemes is managed by the IANA. New schemes can be proposed and registered through a formal process, which involves submitting a specification to the IETF for review and approval.

Security Considerations

URI schemes can have security implications, especially when they involve the transfer of sensitive data. It is important to use secure schemes, such as `https`, to protect data integrity and confidentiality.

Also see

• Uniform Resource Locator (URL)
• Uniform Resource Name (URN)
• Internet Assigned Numbers Authority (IANA)
• Internet Engineering Task Force (IETF)
• Hypertext Transfer Protocol (HTTP)