1.1 Glossary

This document uses the following terms:

activation: In the DCOM protocol, a mechanism by which a client provides the CLSID of an object class and obtains an object, either from that object class or a class factory that is able to create such objects. For more information, see [MS-DCOM].

authentication level: A numeric value indicating the level of authentication or message protection that remote procedure call (RPC) will apply to a specific message exchange. For more information, see [C706] section 13.1.2.1 and [MS-RPCE].

causality identifier (CID): A GUID that is passed as part of an ORPC call to identify a chain of calls that are causally related.

class factory: An object (3 or 4) whose purpose is to create objects (3 or 4) from a specific object class (3 or 4).

class identifier (CLSID): A GUID that identifies a software component; for instance, a DCOM object class or a COM class.

client: A computer on which the remote procedure call (RPC) client is executing.

client context: A context describing an execution environment from which an activation request has originated.

Component Object Model (COM): An object-oriented programming model that defines how objects interact within a single process or between processes. In COM, clients have access to an object through interfaces implemented on the object. For more information, see [MS-DCOM].

context: (1) A collection of context properties that describe an execution environment.

(2) An abstract concept that represents an association between a resource and a set of messages that are exchanged between a client and a server. A context is uniquely identified by a context identifier.

context identifier: A GUID that identifies a context.

context property: An attribute of an execution environment.

context property identifier: A GUID that identifies a context property.

Distributed Component Object Model (DCOM): The Microsoft Component Object Model (COM) specification that defines how components communicate over networks, as specified in [MS-DCOM].

dynamic endpoint: A network-specific server address that is requested and assigned at run time. For more information, see [C706].

endpoint: A network-specific address of a remote procedure call (RPC) server process for remote procedure calls. The actual name and type of the endpoint depends on the RPC protocol sequence that is being used. For example, for RPC over TCP (RPC Protocol Sequence ncacn_ip_tcp), an endpoint might be TCP port 1025. For RPC over Server Message Block (RPC Protocol Sequence ncacn_np), an endpoint might be the name of a named pipe. For more information, see [C706].

envoy context: A context that is marshaled and returned to a client as a result of obtaining an object reference.

fully qualified domain name (FQDN): An unambiguous domain name that gives an absolute location in the Domain Name System's (DNS) hierarchy tree, as defined in [RFC1035] section 3.1 and [RFC2181] section 11.

garbage collection: The process of identifying logically deleted objects (also known as tombstones) and link values that have passed their tombstone lifetime, and then permanently removing these objects from a naming context (NC) replica. Garbage collection does not generate replication traffic.

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] have to be used for generating the GUID. See also universally unique identifier (UUID).

interface: A specification in a Component Object Model (COM) server that describes how to access the methods of a class. For more information, see [MS-DCOM].

Interface Definition Language (IDL): The International Standards Organization (ISO) standard language for specifying the interface for remote procedure calls. For more information, see [C706] section 4.

interface identifier (IID): A GUID that identifies an interface.

interface pointer identifier (IPID): A 128-bit number that uniquely identifies an interface on an object within an object exporter.

little-endian: Multiple-byte values that are byte-ordered with the least significant byte stored in the memory location with the lowest address.

NetBIOS name: A 16-byte address that is used to identify a NetBIOS resource on the network. For more information, see [RFC1001] and [RFC1002].

Network Data Representation (NDR): A specification that defines a mapping from Interface Definition Language (IDL) data types onto octet streams. NDR also refers to the runtime environment that implements the mapping facilities (for example, data provided to NDR). For more information, see [MS-RPCE] and [C706] section 14.

object: In the DCOM protocol, a software entity that implements one or more object remote protocol (ORPC) interfaces and which is uniquely identified, within the scope of an object exporter, by an object identifier (OID). For more information, see [MS-DCOM].

object class: In the DCOM protocol, a category of objects identified by a CLSID, members of which can be obtained through activation of the CLSID. An object class is typically associated with a common set of interfaces that are implemented by all objects in the object class.

object exporter: An object container (for example, process, machine, thread) in an object server. Object exporters are callable using RPC interfaces, and they are responsible for dispatching calls to the objects they contain.

object exporter identifier (OXID): A 64-bit number that uniquely identifies an object exporter within an object server.

object identifier (OID): In the context of an object server, a 64-bit number that uniquely identifies an object.

object reference: In the DCOM protocol, a reference to an object, represented on the wire as an OBJREF. An object reference enables the object to be reached by entities outside the object's object exporter.

object remote procedure call (ORPC): A remote procedure call whose target is an interface on an object. The target interface (and therefore the object) is identified by an interface pointer identifier (IPID).

object resolver: A service in an object server that supports instantiating objects, obtaining remote procedure call (RPC) binding information for object exporters, and managing object lifetimes. Object resolvers can be reachable via well-known or dynamic RPC endpoints.

object server: An execution environment that contains a particular object resolver service and its associated object exporters.

object UUID: A UUID that is used to represent a resource available on the remote procedure call (RPC) servers. For more information, see [C706].

OBJREF: The marshaled form of an object reference.

opnum: An operation number or numeric identifier that is used to identify a specific remote procedure call (RPC) method or a method in an interface. For more information, see [C706] section 12.5.2.12 or [MS-RPCE].

ORPC extension: An out-of-band (not part of the explicit method signature), GUID-tagged binary large object (BLOB) of data that is sent or received in an object remote procedure call (ORPC) call.

OXID resolution: The process of obtaining the remote procedure call (RPC) binding information that is required to communicate with the object exporter.

ping: In the Domain Controller (DC) Locator Protocol, a client sends a ping request to a DC to determine its responsiveness. When a client is actively soliciting the attention of a DC, it is said to be pinging the DC.

ping set: A set of DCOM objects on a particular object server in use by a particular client. The set is grouped in order to maintain the lifetimes of object references collectively for the set rather than individually for each object.

ping set identifier (SETID): A 64-bit number that uniquely identifies a ping set within an object server.

pinging: The process by which a client periodically contacts an object server to maintain the lifetime of its references to objects on that object server.

protocol sequence identifier: A numeric value that uniquely identifies an RPC transport protocol when describing a protocol in the context of a protocol tower. For more details, see [C706] Appendix I.

prototype context: A context that is sent as part of an activation request.

reference count: An integer value that is used to keep track of a Component Object Model (COM) object. When an object is created, its reference count is set to 1. Every time an interface is bound to the object, its reference count is incremented; when the interface connection is destroyed, the reference count is decremented. The object is destroyed when the reference count reaches zero. All interfaces to that object are then invalid.

remote procedure call (RPC): A communication protocol used primarily between client and server. The term has three definitions that are often used interchangeably: a runtime environment providing for communication facilities between computers (the RPC runtime); a set of request-and-response message exchanges between computers (the RPC exchange); and the single message from an RPC exchange (the RPC message).  For more information, see [C706].

remote server name: A null-terminated Unicode string, supplied by an application, which in conjunction with an RPC protocol sequence is used to initiate communication with an object server.

remote unknown: An object exporter's remotely accessible implementation of the IUnknown interface. Each object exporter has exactly one such remotely accessible IUnknown implementation, which is responsible for handling all IUnknown invocations from clients.

RPC endpoint: A network-specific address of a server process for remote procedure calls (RPCs). The actual name of the RPC endpoint depends on the RPC protocol sequence being used. For example, for the NCACN_IP_TCP RPC protocol sequence an RPC endpoint might be TCP port 1025. For more information, see [C706].

RPC protocol sequence: A character string that represents a valid combination of a remote procedure call (RPC) protocol, a network layer protocol, and a transport layer protocol, as described in [C706] and [MS-RPCE].

RPC transport: The underlying network services used by the remote procedure call (RPC) runtime for communications between network nodes. For more information, see [C706] section 2.

security provider: A pluggable security module that is specified by the protocol layer above the remote procedure call (RPC) layer, and will cause the RPC layer to use this module to secure messages in a communication session with the server. The security provider is sometimes referred to as an authentication service. For more information, see [C706] and [MS-RPCE].

service principal name (SPN): The name a client uses to identify a service for mutual authentication. (For more information, see [RFC1964] section 2.1.1.) An SPN consists of either two parts or three parts, each separated by a forward slash ('/'). The first part is the service class, the second part is the host name, and the third part (if present) is the service name. For example, "ldap/dc-01.fabrikam.com/fabrikam.com" is a three-part SPN where "ldap" is the service class name, "dc-01.fabrikam.com" is the host name, and "fabrikam.com" is the service name. See [SPNNAMES] for more information about SPN format and composing a unique SPN.

universally unique identifier (UUID): A 128-bit value. UUIDs can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects in cross-process communication such as client and server interfaces, manager entry-point vectors, and RPC objects. UUIDs are highly likely to be unique. UUIDs are also known as globally unique identifiers (GUIDs) and these terms are used interchangeably in the Microsoft protocol technical documents (TDs). Interchanging the usage of these terms does not imply or require a specific algorithm or mechanism to generate the UUID. Specifically, the use of this term does not imply or require that the algorithms described in [RFC4122] or [C706] has to be used for generating the UUID.

well-known endpoint: A preassigned, network-specific, stable address for a particular client/server instance. For more information, see [C706].

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.