2. Protocol basics

Extensible Provisioning Protocol (EPP) is an application-layer client-server protocol which was designed for the provisioning and management of objects stored in a shared central repository. It is a standard (RFC 5730) that is usually chosen for communication between registrars (clients) and a domain registry (server). The standard allows the protocol to be extended by providing an extension framework which is used extensively in the FRED EPP implementation.

Communication between a client and the EPP server is performed as an exchange of XML documents (further referred to as messages) whose structure and content are defined by a series of schemas. EPP takes advantage of XML namespaces which make extensions easy.

A message sent from a client to the server is called a request message which the server answers with what is called a reply message.

XML messages are transported over the Transmission Control Protocol (TCP) with Transport Layer Security (TLS) using a client’s certificate. (See also RFC 5734.)

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