C interface

The interface, defined at a level that depends on the variant of C standardized by ANSI.


The part of the DUA that implements the connection with the communications network.


CDS: The information that a CDS clerk stores locally to optimize name lookups. The cache contains attribute values resulting from previous lookups, as well as information about other clearinghouses and namespaces. The cache is written to disk periodically so that it can survive a system reboot. See also copy.

DFS: A reserved amount of disk or memory space on a DFS client machine. The DFS Cache Manager uses the cache to temporarily store files or parts of files retrieved from DFS File Server machines so that future access time and network load are reduced. DFS uses a cache-consistency mechanism (token- passing) to guarantee that the source and cached data are consistent. See also caching.

cache manager

DFS: The portion of a DFS client machine's kernel that communicates with DFS server processes by translating local file requests into RPCs (if needed). It stores the requested files in a local disk or memory cache, from which it makes the files available to users on that machine.


DFS: The technique of copying a file from a File Server machine (its central storage place) to a client machine's local disk or memory; users then access the copy locally. Caching reduces network load because a file does not have to be fetched across the network more than once (unless the central copy changes).

caching layer

DFS: The part of the DFS cache manager that manages the cached data, performing fetches and stores and answering status requests.

call chain

The chain of operations (RPC calls) leading from the delegation initiator to the final target.

call queue

RPC: A first-in, first-out queue used by an RPC server to hold incoming calls when the server is already executing its maximum number of concurrent calls.

call thread

RPC: A thread created by a server's RPC runtime to execute remote procedures. When engaged by a remote procedure call, a call thread temporarily forms part of the RPC thread of the call. See also application thread, RPC thread.


DFS: A procedure that is registered with a token to be called automatically if the token is revoked. The act of revoking a token is also referred to as a callback.


Threads: A mechanism by which a thread informs either itself or another thread to terminate as soon as possible. If a cancel arrives during an important operation, the canceled thread may continue until it can terminate in a controlled manner.

RPC: A mechanism by which a client thread notifies a server thread (the canceled thread) to terminate as soon as possible. See also thread.


See DCE Cell Directory Service.

CDS control program (cdscp)

A command interface that CDS managers use to control CDS servers and clerks and manage the namespace and its contents.

CDS-defined attribute

A standard attribute that CDS associates with names. A specific CDS-defined attribute has the same meaning no matter what type of entry (clearinghouse, directory, object) it is associated with. However, different types of entries can have different CDS-defined attributes. For example, every CDS name has the CDS-defined attributes of Creation Timestamp (CDS CTS), Update Timestamp (CDS UTS), and Access Control Set (CDS ACS). In addition to those attributes, a soft link has unique CDS-defined attributes containing its expiration time and the name it points to.


See CDS control program.


1. The basic unit of operation in DCE. A cell is a group of users, systems, and resources that are typically centered around a common purpose and that share common DCE services. At a minimum, a cell configuration includes one Cell Directory Server, one Security Server, and one Distributed Time Server. A cell can consist of from one system to as many as several thousand systems. Systems in the cell can be in the same geographic area (for example, on the same LAN), but geography does not necessarily determine a cell's boundaries. The boundaries of a cell are typically influenced by its purpose, as well as by security, administrative, and performance considerations. With respect to individual DCE technologies, a cell represents the following definitions.

2. CDS: A unified naming environment consisting of CDS clerks and servers.

3. DFS: An administratively independent installation of server and client machines.

4. Security: The set of principals that share their secret keys with the same Authentication Service.

cell alias

DFS: An additional global name given to a cell.

cell module

DFS: The part of the DFS Cache Manager that maintains a list of cells that have been contacted.

cell-relative name

See local name.

central audit trail file

The audit trail file that is maintained by the audit daemon. This is created and used if the user does not specify an audit trail file when starting the audit daemon.


A mode of interaction optionally used by a DSA that cannot perform an operation itself. The DSA chains by invoking an operation of another DSA and then relaying the outcome to the original requester.

character set

A group of characters, such as the English alphabet, Japanese Kanji, and the European character set.

characteristic attribute

A type of attribute that reflects or affects the behavior of a software entity. You generally can set or change characteristic attributes.

child cell

A cell whose name is stored in the CDS server of another cell (its parent cell) and includes its parent cell's name as a prefix to its own name.

child directory

A CDS directory that has a directory above it is considered a child of the directory immediately above it.

child pointer

A pointer that connects a directory to a directory immediately below it in a namespace. You do not explicitly create child pointers; CDS creates them for you when you create a new directory. CDS stores the child pointer in the directory that is the parent of the new directory.


The output of an encryption function. Encryption transforms plaintext into ciphertext.


A category into which objects are placed on the basis of both their purpose and their internal structure. See also object class, OM class.


A component of the event class number, which identifies the event class within the set of event classes.

class-specific attribute

CDS: An attribute that has meaning only to a particular class of object and to the application using that object class. A CDS object's class can be defined in an attribute named CDS_Class. Programmers who write applications that use CDS can define their own object classes and class- specific attributes.


A collection of directory replicas on one CDS server. A clearinghouse takes the form of a database file. It can exist only on a CDS server node; it cannot exist on a node running only CDS clerk software. Usually only one clearinghouse exists on a server node, but there may be special cases when more than one exists.

clearinghouse object entry

A special class of object entry that describes a clearinghouse. The clearinghouse object entry is a pointer to the network address of an actual clearinghouse. This pointer enables CDS to find a clearinghouse and use and manage its contents. A clearinghouse modifies and manages its own object entry when necessary; normally CDS managers do not need to maintain it. The clearinghouse object entry has the same name as the clearinghouse.


CDS: The software that provides an interface between client applications and CDS servers. The clerk receives a request from an application, sends the request to a CDS server, and returns any resulting information to the application. The clerk saves (caches) the results of lookups so that it does not have to repeatedly go to a CDS server for the same information.

DTS: A software component that synchronizes the clock for its client system by requesting time values from servers, computing a new time from the values, and supplying the computed time to client applications.


CDS: Any application that interacts with a CDS server through the CDS clerk.

DTS: Any application that interacts with a DTS server through the DTS clerk.

RPC: The party that initiates a remote procedure call. Some applications act as both an RPC client and an RPC server. See also server.

DFS: A consumer of resources or services. See also server.

GDS: Consists of an application that links the DUA library, the C-stub that handles the connection over the communications network for accessing a remote server, and the DUA cache.

client application thread

RPC: A thread that is executing client application code that makes one or more remote procedure calls. See also application thread, local application thread, RPC thread, server application thread.

client binding information

RPC: Information about a calling client provided by the client runtime to the server runtime, including the address where the call originated, the RPC protocol used for the call, the requested object UUID, and any client authentication information. See also binding information, server binding information .

client context

RPC: The state in an RPC server's address space generated by a set of remote procedures (manager) and maintained across a series of calls for a particular client. See also manager, context handle.

client machine

DFS: A machine whose kernel includes the DFS Cache Manager. A client machine is capable of requesting data from remote File Exporters and caching the data locally. See also server machine.

client portion of update server

See upclient.

client stub

RPC: The surrogate code for an RPC interface that is linked with and called by the client application code. In addition to general operations such as marshalling data, a client stub calls the RPC runtime to perform remote procedure calls and, optionally, manages bindings. See also server stub, stub.


The combined hardware interrupt timer and software register that maintain the system time. In many systems, the hardware timer sends interrupts to the operating system; at each interrupt, the operating system adds an increment to a software register that contains the time value.

clock adjustment

DTS: Process of changing the system clock time by modifying the incremental value that is added to the clock's software register for a specified duration.


DFS: A backup or read-only copy of a fileset created by copying only the read/write (source) fileset's header rather than the data it contains. The clone preserves pointers to fileset data that existed when the clone was made; it therefore must exist on the same aggregate as the source. Cloning a fileset also refers to making a copy of it with the proper fts commands for later use with the DFS Backup System. See also replica.

clone ID number

DFS: The fileset ID number of the last clone made from the fileset's read/write source for the purpose of replication.

code point

Location in the distributed application code that designates the operations in the application where logging of audit records may be required. The DCE audit APIs are called in the application's code points.

code set

The mapping of the members of a character set to specific numeric code values. Examples of code sets include ASCII, JIS X0208, and ISO 8859-1.

code set registry

A per-host file that contains, for each code set supported on the host, a mapping between a string name for the code set (which is the name used on the host to refer to the code set) and the unique identifier that has been assigned (by OSF or by the site) to the code set.


To remove the contents of a directory from the display (close it) via the CDS Browser. To collapse an open directory, you double-click on its icon. Double-clicking on a closed directory expands it.

command suite

DFS: The DFS command suites are bak, bos, cm, dfsgw, dfstrace, and fts.


DFS: An indication that all of the actions associated with a specific transaction have been written to the log. Once a transaction has committed, its actions are permanent. In the event of system problems, those actions are repeated when the system's recovery mechanism replays the log.

communications link

RPC: A network pathway between an RPC client and server that uses a valid combination of transport and network protocols that are available to both the client and server RPC runtimes.

compatible server

RPC: A server that offers the requested RPC interface and RPC object and that is available over a valid combination of network and transport protocols that are supported by both the client and server RPC runtimes.

computed time

The result of the synchronization process - the time value that the clerk or server process computes according to the values it receives from several servers.

concrete class

An OM class of which instances are permitted.

condition variable

A synchronization object used in conjunction with a mutex. A condition variable allows a thread to block until some event happens.

configuration of directory service

GDS can be configured as a client system or a client/server system. In a client system, a DUA either accesses the local DUA cache or a remote server over the communications network. In a client/server system, a DUA either accesses a local server or a remote server over the communications network. The local server is also accessible from a remote client or server.

conformant array

RPC: An array whose size is determined at runtime. A structure containing a conformant array as a field is a conformant structure.

connection-oriented protocol

A connection-based, reliable, virtual-circuit transport protocol, such as TCP; an RPC protocol that runs over a connection-based transport protocol.


Containers are objects that hold other objects. The objects they hold can themselves be either simple objects or container objects. Simple objects do not hold other objects. Files are simple objects, and directories are containers. The directories can hold simple objects (files) and other containers (subdirectories). See also container object , simple object.

container object

An object that can hold another object. For example, a directory is a container object since it can hold files. See also simple object.

context handle

RPC: A reference to the state (client context) maintained across remote procedure calls by a server on behalf of a client. See also client context.

continuation reference

Describes how the performance of all or part of an operation can be continued at a different DSA or DSAs. See also referral.

control access

CDS: An access right that grants users the ability to change the access control on a name and do other powerful management tasks, such as replicate a directory or move a clearinghouse.


The degree to which CDS attempts to keep all replicas of a directory consistent. Two factors control the persistence and speed at which CDS keeps directory replicas up to date: the setting of a directory's CDS_Convergence attribute and the background skulk time. You can set the CDS_Convergence attribute to high, medium, or low. By default, every directory inherits the convergence setting of its parent. See also background skulk.

conversation key

A short-lived encryption key provided by the authentication service to two principals for the purpose of ensuring secure communications between them.

Coordinated Universal Time (UTC)

An international time standard that DTS uses. The zero hour of Coordinated Universal Time is based on the zero hour of Greenwich (England) Mean Time.


GDS: Either a copy of an entry stored in other DSAs or a locally and dynamically stored copy of an entry resulting from a request (a cache copy).

core leak

DFS: A situation that can develop as a process allocates virtual memory but does not free it again. When memory is completely exhausted, the machine crashes. The BOS server can be configured to restart all processes on a file server machine once a week to reduce the likelihood of core leaks.


DTS: A local server that requests a time value from a randomly selected global server each time it synchronizes.

Creation Timestamp (CTS)

An attribute of all CDS clearinghouses, directories, soft links, child pointers, and object entries that contains a unique value reflecting the date and time the name was created. The timestamp actually consists of two parts: a time portion, and a portion containing the system identifier of the node on which the name was created. This guarantees uniqueness among timestamps generated on different nodes.


A general term for privilege attribute data that has been certified by a trusted privilege certification authority. The DCE authorization protocol implements credentials as Privilege Attribute Certificates (PACs).

cron bnode

DFS: A bnode that manages a single process that is to be run either exactly once or periodically. See also basic overseer server , bnode.

cron process

DFS: A type of process defined in a server machine's BosConfig file. It executes weekly or daily at a defined time rather than running continuously. See also cron bnode, simple process.


See Creation Timestamp.

customized binding handle

RPC: A user-defined data structure from which a primitive binding handle can be derived by user- defined routines in application code. See also primitive binding handle.