1.1 Glossary

This document uses the following terms:

block: A chunk of content that composes a segment. Each segment is divided into one or more blocks. Every block belongs to a specific segment, and within a segment, blocks are identified by their progressive index. (Block 0 is the first block in the segment, block 1 is the second, and so on.) See [MS-PCCRC] for more details.

client: For the Peer Content Caching and Retrieval Framework, a client is a client-role peer; that is, a peer that is searching for content, either from the server or from other peers or hosted cashes. In the context of the Retrieval Protocol, a client is a peer that requests a block-range from a server_role_peer. It acts as a Web Services Dynamic Discovery (WS-Discovery) [WS-Discovery] client.

client-role peer: A peer that is looking for content, either from the server or from other peers or hosted caches.

content: Items that correspond to a file that an application attempts to access. Examples of content include web pages and documents stored on either HTTP servers or SMB file servers. Each content item consists of an ordered collection of one or more segments.

Coordinated Universal Time (UTC): A high-precision atomic time standard that approximately tracks Universal Time (UT). It is the basis for legal, civil time all over the Earth. Time zones around the world are expressed as positive and negative offsets from UTC. In this role, it is also referred to as Zulu time (Z) and Greenwich Mean Time (GMT). In these specifications, all references to UTC refer to the time at UTC-0 (or GMT).

globally unique identifier (GUID): A term used interchangeably with universally unique identifier (UUID) in Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the value. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] must be used for generating the GUID. See also universally unique identifier (UUID).

hash: A hash, such as SHA-1, on the content or content block.

higher-layer application: An application that uses the Peer Content Caching and Retrieval: Retrieval Protocol, either by itself or as part of the Peer Content Caching and Retrieval Framework or other applications.

HoHoDk: A hash that represents the content-specific label or public identifier that is used to discover content from other peers or from the hosted cache. This identifier is disclosed freely in broadcast messages. Knowledge of this identifier does not prove authorization to access the actual content.

multicast: A style of resource location or a data transmission in which a client makes a request to specific parties on a network simultaneously.

network byte order: The order in which the bytes of a multiple-byte number are transmitted on a network, most significant byte first (in big-endian storage). This may or may not match the order in which numbers are normally stored in memory for a particular processor.

peer: A node participating in the content caching and retrieval system. A peer is a node that both accesses the content and serves the content it caches for other peers.

peer-to-peer (P2P): An Internet-based networking option in which two or more computers connect directly to each other in order to communicate.

probe: The Web Services Dynamic Discovery (WS-Discovery) protocol message sent by a client to discover content, as defined in [WS-Discovery1.1].

ProbeMatch: The WSD protocol message sent by a server peer to the requesting client when it has the content the client is looking for.

segment: A unit of content for discovery purposes. A segment is identified on the network by its public identifier, also known as segment ID or HoHoDk. A segment does not belong to any particular content; it can be shared by many content items if all those content items have an identical segment-sized portion at some offset.

segment ID (HoHoDk): A hash that represents the content-specific label or public identifier that is used to discover content from other peers or from the hosted cache. This identifier is disclosed freely in broadcast messages. Knowledge of this identifier does not prove authorization to access the actual content.

server peer: A peer that has the content in its local cache and that will serve the content to other peers requesting it. A server peer is acting as a WSD server or service target in the Discovery Protocol.

SOAP: A lightweight protocol for exchanging structured information in a decentralized, distributed environment. SOAP uses XML technologies to define an extensible messaging framework, which provides a message construct that can be exchanged over a variety of underlying protocols. The framework has been designed to be independent of any particular programming model and other implementation-specific semantics. SOAP 1.2 supersedes SOAP 1.1. See [SOAP1.2-1/2003].

Uniform Resource Identifier (URI): A string that identifies a resource. The URI is an addressing mechanism defined in Internet Engineering Task Force (IETF) Uniform Resource Identifier (URI): Generic Syntax [RFC3986].

User Datagram Protocol (UDP): The connectionless protocol within TCP/IP that corresponds to the transport layer in the ISO/OSI reference model.

UTF-8: A byte-oriented standard for encoding Unicode characters, defined in the Unicode standard. Unless specified otherwise, this term refers to the UTF-8 encoding form specified in [UNICODE5.0.0/2007] section 3.9.

Web Services Description Language (WSDL): An XML format for describing network services as a set of endpoints that operate on messages that contain either document-oriented or procedure-oriented information. The operations and messages are described abstractly and are bound to a concrete network protocol and message format in order to define an endpoint. Related concrete endpoints are combined into abstract endpoints, which describe a network service. WSDL is extensible, which allows the description of endpoints and their messages regardless of the message formats or network protocols that are used.

WS-Discovery: This term refers to the specific version of the WS-Discovery protocol that the implementer is taking a dependency on. This term can refer to any of the supported protocol versions that are specified in section 1.7.

WSDL message: An abstract, typed definition of the data that is communicated during a WSDL operation [WSDL]. Also, an element that describes the data being exchanged between web service providers and clients.

WSDL operation: A single action or function of a web service. The execution of a WSDL operation typically requires the exchange of messages between the service requestor and the service provider.

XML namespace: A collection of names that is used to identify elements, types, and attributes in XML documents identified in a URI reference [RFC3986]. A combination of XML namespace and local name allows XML documents to use elements, types, and attributes that have the same names but come from different sources. For more information, see [XMLNS-2ED].

XML schema: A description of a type of XML document that is typically expressed in terms of constraints on the structure and content of documents of that type, in addition to the basic syntax constraints that are imposed by XML itself. An XML schema provides a view of a document type at a relatively high level of abstraction.

XML Schema (XSD): A language that defines the elements, attributes, namespaces, and data types for XML documents as defined by [XMLSCHEMA1/2] and [XMLSCHEMA2/2] standards. An XML schema uses XML syntax for its language.

MAY, SHOULD, MUST, SHOULD NOT, MUST NOT: These terms (in all caps) are used as defined in [RFC2119]. All statements of optional behavior use either MAY, SHOULD, or SHOULD NOT.