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.)

Chapter TOC

• 2.1. Introduction to the EPP
  • 2.1.1. Service aspects
  • 2.1.2. Protocol characteristics
  • 2.1.3. Normal communication
  • 2.1.4. Use of the extension framework in FRED EPP
• 2.2. Generic message structure
• 2.3. Service discovery
  • 2.3.1. Hello element structure
  • 2.3.2. Greeting element structure
• 2.4. Commands & responses
  • 2.4.1. Implemented standard commands
  • 2.4.2. Transaction identification
  • 2.4.3. Command element structure
  • 2.4.4. Response element structure
  • 2.4.5. Success or failure of a command
• 2.5. FRED protocol extension
• 2.6. FRED command & response extensions
  • 2.6.1. Command extensions
  • 2.6.2. Response extensions