Galaxy Communicator Documentation:


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A server-to-server connection, unmediated by the Hub, through which typed data can be transmitted.

broker proxy

An encapsulation of the connection and type information associated with a broker.
call environment
A structure passed to every dispatch function which contains the environment of the invocation, such as the current session, the connection through which the message was received, and whether or not a response has been provided yet.
dispatch function
A procedure invoked in a server in response to a rule in a Hub program.
See call environment.
A general-purpose data object which is passed between servers and the Hub.  It consists of a frame type, a frame name, and a collection of attributes, or keys, and their associated values. See the frame documentation.

global variables, program file

See program file global variables.
An executable which controls the interaction among a number of servers, using a Hub script as its controller.
Hub script
Initialization file for the Hub which contains information about available servers (name, location, externally accessible operations), global variables, and possibly flow of control instructions.  Also known as a program file.
Hub program
A set of rules that describes a sequence of operations specifying the flow of control in the Hub.
initial token
A token specified in the program file which is executed immediately after the Hub contacts its servers.
key-value pair
An attribute and its associated value that describes some domain entity.  Sets of key-value pairs are stored in frames.
Text file containing logs of timestamped server operations and specified key values.
A frame used as a vehicle for communication to and from servers.  The key-value pairs which comprise the message sent to the server are drawn from the Hub program rules and the current state of the token.  The message causes a dispatch function to be invoked in the server. Any response from the dispatch function is used to update the token state.  See frame, token.
One of five types of frames comprising a memory state during the execution of a Hub program.
A dispatch function supported by a server, as viewed by a service type in a program file.
program, Hub
See Hub program.
program file
See Hub script.
program file global variables
Program file declarations used to set key-value pairs in the initial token and to set global information about the Hub.  Examples include DOMAIN:, USER_ID:,LOG_DIR:.
See service provider.
provider ID
A bracket-delimited string enclosing an integer or string which comprises the obligatory portion of a provider name.
provider name
A unique string, consisting of a provider ID and an optional service type, which names a service provider in a Hub script.
An element of a Hub program which specifies a condition for execution and instructions for constructing a message to a server and for updating the state of the token.
scripted interaction
A new incoming message which the Hub processes according to the instructions in a Hub program whose name matches that of the incoming message.
scriptless interaction
A new incoming message which the Hub processes by dispatching directly to a server which supports a dispatch function whose name matches that of the incoming message.
scripting module
A module compiled into the Communicator Hub which assumes responsibility for the processing of a subset of incoming new messages. MIT provides the default scripting module, which allows users to specify programs to implement this control.
An executable configured to accept messages from the Hub and respond to dispatch functions invoked by these messages.
server-to-server subdialogue
A call to GalSS_EnvDispatchFrame, which uses the Hub to invoke operations on another server or servers and retrieves the result. The Hub may retrieve this information via a Hub program, or it may relay the request directly to another server.
service provider
A specific process on a specific host which qualifies as an instance of a service type.
service type
A named collection of operations in a program file. Each operation is expected to correspond to a dispatch function implemented by any service provider which is an instance of this service type.
An instance of an interaction of a user with a Hub.
A frame which represents the evolving state of the execution of a Hub program.  A token is similar to the local memory state of a function or a procedure.  See also frame, message.
utterance ID
Internal counter maintained by the builtin server.  This counter can be updated only by calling builtin.increment_utterance. This counter cannot currently be accessed except by calling this builtin function.
A setting provided to a Hub or server which controls the amount of information printed out. Zero verbosity is silence; the highest level of verbosity is 6; the default is 3.

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Last updated August 13, 2002