Understanding SQL*Net

GLOSSARY

address: A unique network location used to identify a network object, such as a database server, client, MultiProtocol Interchange, or Names Server. TNS addresses have a specific format. Addresses must be unique. See TNS address.

administrative region: An organizational entity for administering SQL*Net network components.

alias: An alternative name for an existing network object.

ASCII character set: Stands for American Standard Code for Information Interchange character set, a convention for representing alphanumeric information using digital data. The collation sequence used by most computers with the exception of IBM and IBM-compatible computers. Contrast with EBCDIC character set.

buffer: (1) A temporary storage area for data. (2) In SQL*Net, an area of memory used by the network driver to pass data between two points on the network. (3) In SQL*Plus, an area where the user's SQL statements or PL/SQL blocks are temporarily stored. SQL*Plus buffers are supplied for users' convenience in working with multiple statements. The SQL buffer is the default buffer. You can use multiple buffers.

cache: The in-memory database within a Names Server where all data is stored.

central administration: A SQL*Net network in which all data is administered in one administrative region.

client: A user, software application, or computer that requests the services, data, or processing of another application or computer. In a two-task environment, the client is the user process. In a network environment, the client is the local user process and the server may be local or remote.

client profile: The properties of a client, often shared by many clients. Includes the protocols used, preferred Interchanges, and preferred Names Servers. Also called client type.

client type: See client profile.

client-server architecture: Software architecture based on a separation of processing between two CPUs, one acting as the client in the transaction, requesting and receiving services, and the other as the server that provides services in a transaction.

community: A group of network clients and servers using TNS-based software that can communicate using the same industry-standard protocol.

community cost: A number assigned to a community to reflect its relative communications speed and throughput. The network administrator assigns costs in the file TNSNET.ORA. The cost is used by the Navigator when selecting the best path to a destination.

community name: A unique name used to identify a TNS community in a TNS network.

configuration files: Files that are used to identify and characterize the components of a network. Configuration is largely a process of naming network components and identifying relationships among those components.

CONNECT DATA: A portion of the connect descriptor, introduced by the keyword CONNECT DATA, that specifies the application to which the connection is to be made. The CONNECT DATA section of the connect descriptor includes the Oracle System Identifier (SID).

connect descriptor: A specially formatted description of the destination for a network connection. Connect descriptors are constructed using a set of keywords and values. They are mapped to service names to provide more convenient reference.

connection: An interaction between two clients on a network. TNS connections are originated by an initiator (client), who requests a connection with a destination (server).

Connection Manager: The component of the MultiProtocol Interchange that detects, establishes, and maintains data connections over a TNS network. The Connection Manager contains a listener and multiple data pumps.

connection request: A notification sent by an initiator and received by a listener that indicates that the initiator wants to start a TNS connection.

cost: See community cost.

database administrator (DBA): (1) A person responsible for operating and maintaining an Oracle Server or a database application. (2) An Oracle username that has been given DBA privileges and can perform database administration functions. Usually the two meanings coincide. Many sites have multiple DBAs.

database link: A network object stored in the local database or in the network definition that identifies a remote database, a communication path to that database, and optionally, a username and password. Once defined, the database link is used to access the remote database. Also called DBlink.

A public or private database link from one database to another is created on the local database by a DBA or user.

A global database link is created automatically from each database to every other database in a network with Oracle Names. Global database links are stored in the network definition.

database service name

See service name.

default domain: The domain within which most client requests take place. It could be the domain where the client resides, or it could be a domain from which the client requests network services often. Default domain is also the client configuration parameter that determines what domain should be appended to unqualified network name requests. A name request is unqualified if it does not have a "." character within it.

delegated administration: A SQL*Net network where network management is delegated to one or more administrative regions below the root administrative region. Each region is administered through an installation of Oracle Network Manager. Also referred to as distributed or decentralized administration.

delegated administrative region: A region hierarchically below the root administrative region. Any region other than the root administrative region.

destination: The client that is the endpoint of a TNS connection. The initiator of the connection requires some data or service of the destination.

distributed architecture: A blueprint or specification that allows applications to access data on more than one CPU (and often many types of computers ranging from PCs to mainframes) within a computer system or network.

distributed database: One logical database whose data is spread across two or more computers. Users interact with the single, logical database, not the individual pieces. See also distributed processing.

distributed processing: Division of front-end and back-end processing to different computers. SQL*Net supports distributed processing by transparently connecting applications to remote databases.

distributed query: A query that selects data from multiple databases, using, for example, joins, nested queries, or views. See also distributed database.

domain: A grouping of network objects, such as databases, that simplifies the naming of network services. Within a domain, all the names must be unique.

domestic domains: The set of domains that are managed within a given administrative region. Domains are only domestic relative to a region; they are not domestic in any absolute sense. Also referred to as local domains.

Dynamic Discovery Option
An optional feature of Oracle Names version 2.0 that enables services to register themselves with well-known Names Servers on startup, enables clients to find well-known Names Servers without configuration, and enables well-known Names Servers to automatically replicate their data to each other.

error message: A message from a computer program informing you of a potential problem or condition preventing program or command execution.

flat naming model: An Oracle Names infrastructure in which there is only one domain, WORLD. All names must be unique within the WORLD domain.

foreign domains: The set of domains not managed within a given administrative region. Domains are only foreign relative to a region; they are not foreign in any absolute sense.

global database link: A database link created automatically by Network Manager for use with Oracle Names that links each database in a network to all other databases.

global database name: A unique name that identifies a database in a network. It consists of a database name and its network domain.

hierarchical naming model: A network naming scheme in which names are divided into multiple hierarchically related domains.

hop: A portion of a connection path. It may be between two communities, between two Interchanges, or between an Interchange and the destination. Or, the path may simply have one hop, from the initiator directly to the destination.

initiator: The client that starts a TNS connection by sending a connection request. The initiator of the connection requires some data or service of the destination.

INTCHG.ORA file: A file maintained for each Interchange that defines the startup parameters of an Interchange.

Interchange Control Utility (INTCTL): A utility included with the MultiProtocol Interchange to control various functions, such as to start, stop, and gather statistics from the Interchange.

keyword-value pair: The combination of a standard TNS keyword and a value, used as the standard unit of information in connect descriptors and many configuration files. Keyword-value pairs may be nested; that is, a keyword may have another keyword-value pair as its value.

listener process: The server process that listens for and accepts incoming connection requests from client applications. Oracle listener processes start up Oracle database processes to handle subsequent communications with the client.

listener: See network listener

LISTENER.ORA

A configuration file that describes one or more TNS listeners on a server.

Listener Control Utility (LSNRCTL): A utility included with SQL*Net version 2 to control various functions, such as to start, stop, and get the status of the network listener.

logging: A feature in which errors, service activity, and statistics are written to a log file. See also tracing.

location transparency: A distributed database characteristic that allows applications to access data tables without knowing where they reside. All data tables appear to be in a single database, and the system determines the actual data location based on the table name. The user can reference data on multiple nodes in a single statement, and the system automatically and transparently routes (parts of) SQL statements to remote nodes for execution if needed. The data can move among nodes with no impact on the user or application.

multicommunity connection: A connection between an initiator and a destination that belong to different communities. The connection passes between at least two communities, by way of one or more Interchanges.

MultiProtocol Interchange: An Oracle networking product that allows applications in TNS networks to communicate across different protocols. For example, a TCP/IP client could connect through an Interchange to an Oracle7 server running only DECnet.

naming model: The set and structure of domains within which names can be allocated.

In a flat naming model, there is a single domain -- the WORLD domain. Examples of database service names in a flat naming model are SALES.WORLD or HR.WORLD.

In a hierarchical naming model, the highest level is the root domain, and all other domains are hierarchically related. An example of a service name in a hierarchical naming model is HR.US.ORACLE.COM.

native naming adapters: Support for industry-standard name services such as Network Information Services (NIS), Distributed Computing Environment Cell Directory Service (DCE CDS), Banyan StreetTalk, and Novell's NetWare Directory Services (NDS) enables users to connect to Oracle services in various native naming environments.

Navigator: The component of an Interchange that chooses (navigates) the best connection path over a TNS network. In order to navigate, the Navigator refers to the file TNSNET.ORA.

negotiation: A communication between two processes in which they agree upon how they will communicate. In a TNS connection, a negotiation occurs between the initiator and the destination, and at every intermediate hop.

NetBIOS: Stands for Network Basic Input/Output System, a process-to-process communications protocol designed to provide virtual links between machines on a network.

NetWare: A network operating system produced by Novell.

network: A group of two or more computers linked together through hardware and software to allow the sharing of data and/or peripherals.

network administrator: The person who performs network management tasks such as installing, configuring, and testing network components. The administrator typically maintains the configuration files, TNS connect descriptors and service names, aliases, and public and global database links.

network character set: As defined by Oracle, the set of characters acceptable for use as values in keyword-value pairs (that is, in connect descriptors and configuration files). The set includes alphanumeric upper- and lowercase, and some special characters.

network data: Includes all communities and MultiProtocol Interchanges in the entire network, and all Names Servers in the root or central administrative region. Also called backbone data.

network definition: The network configuration created by Network Manager. When you enter and save information in Network Manager, it creates a network definition in an operating system file or a database. It generates configuration files from the network definition, and uses it as a data source for Oracle Names.

network listener: A listener on a server that listens for connection requests for one or more databases on one or more protocols.

Network Manager: The graphical tool for configuring and maintaining a SQL*Net network, including SQL*Net, the MultiProtocol Interchange, and Oracle Names.

network object: Any service that can be directly addressed on a network; for example, a listener, MultiProtocol Interchange, or Names Server.

network protocol: Any industry standard transport protocol, such as TCP/IP or APPC.

network service: In an Oracle application network, a service performs tasks for its service consumers; for example, a MultiProtocol Interchange provides protocol conversion services for clients, and a Names Server provides name resolution services for clients.

node: A computer or terminal that is part of a TNS network.

ORACLE _HOME: An alternate name for the top directory in the Oracle directory hierarchy on some directory-based operating systems.

Oracle Names: A name resolution product for Oracle7 Servers and SQL*Net networks.

Oracle Names Server (Names Server): The name resolution software for answering name requests.

Oracle Protocol Adapter: s A set of products in which each one maps the functions of a given network protocol into TNS, so that TNS can act as an interface among all protocols. For example, there is a TCP/IP protocol adapter and a DECnet adapter. SQL*Net version 2 requires protocol adapters; the equivalent in SQL*Net version 1 was the protocol driver component of SQL*Net.

Oracle System Identifier (SID): A unique name for an Oracle database instance. To switch between Oracle databases, users must specify the desired SID. The SID is included in the CONNECT DATA parts of the connect descriptors in a TNSNAMES.ORA file, and in the definition of the network listener in the LISTENER.ORA file.

parameter: Information passed to a program, command, or function, such as a file specification, a keyword, or a constant value.

password: A string (word or phrase) used for data security and known only to its owner. Passwords are entered in conjunction with an operating system login ID, Oracle username, or account name, in order to connect to an operating system or software application (such as the Oracle database). Whereas the username or ID is public, the secret password ensures that only the owner of the username can use that name, or access that data.

path: A series of nodes traversed by a TNS connection, to send data from one end of a connection to the other. A path is made up of hops, which are addresses of the next points on the path.

path correction: The process by which a Navigator determines that a particular connection is taking a less than optimal path, and so redirects the connection so that it follows the best path.

preferred Connection Manager: A Connection Manager, or Interchange, that has been identified by a particular TNS client as the best starting point for navigating to that client's destinations. Preferred Connection Managers are identified in each client's TNSNAV.ORA file.

preferred Names Server: The Names Server preferred by a client for names resolution.

prespawned dedicated server process: Prespawned dedicated server processes are prestarted by the SQL*Net listener before any incoming connection request. They improve the time it takes to establish a connection on servers where the MultiThreaded Server is not used or not supported on a given machine. They also use allocated memory and system resources better by recycling server processes for use by other connections with shutting down and recreating a server. The ability to prespawn dedicated servers requires Oracle7 Server release 7.1 and SQL*Net release 2.1 or later.

private database link: A DBlink created by one user for his or her exclusive use. See also database link.

protocol adapter: See Oracle Protocol Adapters.

public database link: A database link created by a database administrator on a local database which is accessible to all users on that database. See also database link.

pump: The Interchange component responsible for transferring data between two communities as a part of a TNS connection. The Interchange's Connection Manager controls several data pumps, starting them as required.

root domain: The highest level domain in a hierarchical naming model.

root administrative region: The highest level administrative region in a distributed installation. The root administrative region contains the root domain.

service name: A name for a TNS connect descriptor that is easy to use and remember. End users need only know the appropriate service name to make a TNS connection. Each connect descriptor is assigned a service name in the network definition. The service name for a database must be the same as the global database name.

SID: See Oracle System Identifier.

single community connection: A connection between an initiator and a destination that belong to the same community. The connection is confined to one community and thus a single network protocol.

SPX: Stands for Sequenced Packet Exchange, a network protocol known for high performance and acceptance among many major network management systems, in particular, Novell Advanced NetWare.

SQL*Net: An Oracle product that works with the Oracle Server and enables two or more computers that run the Oracle RDBMS or Oracle tools such as SQL*Forms to exchange data through a third-party network. SQL*Net supports distributed processing and distributed database capability. SQL*Net runs over many communications protocols.

SQL*Net OPEN: An application program interface (API) to SQL*Net, which enables programmers to develop non-database applications that can use the SQL*Net network.

TNS: See Transparent Network Substrate.

TNS address: An address of a client or network service in a TNS network, which identifies the community to which it belongs, the protocol used by that community, and some protocol specific values. One TNS client or network service may have multiple TNS addresses if it resides in multiple communities.

TNS client: A client node that is a member of one or more TNS communities and is running software based on TNS. A TNS client can be either a client, a server, or both.

TNS community: See community.

TNS connection: A connection initiated by a TNS client using a connect descriptor, and maintained by TNS and, optionally, a MultiProtocol Interchange.

TNSNAMES.ORA file: A file that contains connect descriptors mapped to service names. The file may be maintained centrally or locally, for use by all or individual clients.

TNSNAV.ORA file: There are two versions of this file. The TNSNAV.ORA file for a client specifies that client's preferred Connection Managers. Clients can share the file if they have identical network requirements (that is, if they are the same client profile). The TNSNAV.ORA file for an Interchange lists the communities of which that Interchange is a member. Each Interchange in a network must have its own TNSNAV.ORA file.

TNSNET.ORA file: A file that includes a list of every Interchange on the network and the communities they connect. The file is used by Navigators to navigate connection paths. It is maintained centrally and copied as necessary. Every Interchange must be able to access this file.

TNS network: A network composed of one or more TNS communities. Many TNS networks have one or more MultiProtocol Interchanges to connect communities based on different network protocols.

tracing: A facility that writes detailed information about an operation to an output file. The trace facility produces a detailed sequence of statements that describe the events of an operation as they are executed. Administrators use the trace facility for diagnosing an abnormal condition; it is not normally turned on.

Transparent Network Substrate (TNS): A foundation technology, built into SQL*Net version 2, the MultiProtocol Interchange, and Oracle Names, that works with any standard network transport protocol.

username The name by which a user is known to the Oracle Server and to other users. Every username is associated with a password, and both must be entered to connect to an Oracle database.