Cascade DataHub™ for Linux and QNX

Version 6.4

March 27, 2008

A memory resident real-time database that acts as a hub, providing fast and efficient concentration and distribution of data for QNX and Linux applications.

Cogent software is source-code compatible among the Linux, QNX 6, and QNX 4 operating systems.
Go to the Cogent Web Site.
Copyright, trademark, and software license information.

Table of Contents

1. Introduction
1.1. What is the Cascade DataHub?
1.2. A note about the Cascade DataHub API
1.3. System Requirements
1.4. Download and Installation
1.4.1. QNX 4
1.4.2. QNX 6
1.4.3. Linux
1.4.4. Installed file locations
1.4.5. Installing licenses
1.5. Quick Start
1.6. Cogent Product Integration
1.7. Where can I get help?

2. Using the Cascade DataHub
2.1. Starting up and shutting down.
2.2. Testing the installation
2.3. Configuration
2.3.1. Using a Configuration File at Startup
2.3.2. Dynamic Run-Time Configuration
2.4. Working with Data
2.4.1. Data Points
2.4.2. Registering for Exceptions
2.4.3. Domains and Names
2.4.4. Assemblies, Subassemblies, Attributes, and Properties
2.4.5. Attributes and Types
2.5. Mirroring Data to Windows or other nodes in Linux or QNX
2.5.1. Exchanging data between Windows and Linux/QNX
2.5.2. Exchanging data between Linux/QNX and Linux/QNX
2.5.3. Mirroring Master Setup - Linux or QNX
2.5.4. Mirroring Slave Setup - Linux or QNX
2.5.5. Mirroring Master Setup - Windows
2.5.6. Mirroring Slave Setup - Windows
2.6. Viewing Data
2.6.1. Console Mode
2.6.2. QNX Photon Mode
2.6.3. X Windows Mode
2.7. Features
2.7.1. Exceptions and Echoes
2.7.2. Asynchronous Messages
2.7.3. Network Access in QNX 4
2.7.4. Confidence Factors
2.7.5. Security and Point Locking
2.7.6. Unlimited Point Count
2.7.7. Cascade DataHub performance

3. Data Transmission
3.1. Synchronous data transmission
3.2. Asynchronous data transmission
3.3. Cascade DataHub data transmission

A. GNU General Public License
B. GNU Lesser General Public License

I. Utilities
datahub - starts the Cascade DataHub.
dhview - a console-based viewer for the Cascade DataHub.dhview
phdhview - a Photon-based viewer for the Cascade DataHub.
readpt - reads a point from the Cascade DataHub.
waiter - registers for exceptions with a Cascade DataHub and displays values as updates are received.
writept - writes a point to the Cascade DataHub.
xdhview - an X Windows-based viewer for the Cascade DataHub.

II. Cascade DataHub Command Set
acksuccess - tells the DataHub to return success messages.
add - adds a value to a point.
alias - creates an alias point for an existing point.
alive - tells the Cascade DataHub that the client is running.
append - appends a string to the value of a point.
assembly - creates an assembly.
asyncsocket - sets up asynchronous communication on a socket.
attribute - creates an attribute.
auth - requests authentication for a client.
authgroup - creates a new authentication group.
authuser - creates a new user.
auto_create_domains - automatically adds domains requested by clients.
auto_timestamp - adds timestamps to unstamped changes.
bridge - creates a bridge between two points.
bridge_remove - deletes a bridge.
bridge_transform - modifies an existing bridge.
cforce - creates a point and forces a value to be written to it.
cread - creates and reads a point.
create - creates a new point.
create_domain - creates a new domain.
creport - creates a point and requests notification of changes.
cset - creates a point and assigns it a value.
cwrite - creates a point and writes information to it.
debug - sets the debug level.
defaultprop - sets a default type for a property.
delete - deletes a point—use with caution.
deleted - checks if a point has been deleted.
div - does division on the value of a point.
domain - identifies the client domain name.
domains - lists all domains in the DataHub.
dump - writes the entire content of the DataHub to a file.
enable_bridging - enables or disables bridging capabilities
enable_dde_client - enables or disables DDE client capabilities.
enable_dde_server - enables or disables DDE server capabilities.
enable_mirror_master - enables or disables mirror master capabilities.
enable_mirror_slave - enables or disables mirror slave capabilities.
enable_scripting - enables or disables scripting capabilities
enable_tcp_server - enables or disables TCP server capabilities.
error - sends an error with an error string.
exit - shuts down the DataHub.
flush - flushes output to a terminal (Linux).
flush_log - forces an immediate update of the Script Log (Windows).
force - forces a write to a point.
format - is an efficiency enhancement for Linux.
heartbeat - establishes a heartbeat message.
ignore - ignores a given point.
ignore_old_data - ignores changes with an old timestamp.
include - includes a file in with configuration files.
instance - creates an instance of a data organization model.
load_config_files - loads configuration files.
load_plugin - loads a specified plugin. (experimental)
load_scripts - loads scripts.
lock - locks and unlocks points.
log_file - sets up a log file.
log_to_file - starts or stops logging to a file.
mirror_master - sets up a mirroring master.
mirror_master_2 - sets up a secure mirroring master.
mult - multiplies the value of a point.
private_attribute - creates a private attribute.
property - creates a property for an assembly.
quality - assigns a quality to a point.
read - reads a complete point definition.
report - requests notification of changes to a data point.
report_domain - registers points and requests information on a whole domain.
report_errors - controls the reporting of errors.
request_initial_data - gets current data when client connection is made.
save_config - forces the DataHub to save its configuration.
secure - adjusts the security level of a point.
set - sets the value of a point.
set_canonical - sets the type of a point.
subassembly - creates a subassembly.
success - sets up a success message.
tcp_service - sets a TCP service name or port number for incoming slave connections.
timeout - suspends data flow.
transmit_insignificant - permits transmission of insignificant changes.
type - creates a type.
unload_plugin - unloads a plugin. (experimental)
unreport - allows a client to stop receiving data value changes to a point.
version - returns the current version number.
write - writes information to a point.

III. Obsolete and Unused Commands
bandwidth_reduce - is for internal use only.
drop_license - is for internal use only.
echo - is for internal use.
enable_connect_server - is deprecated.
EnableDDEServer - is for internal use only.
exception_buffer - is deprecated.
failed_license - is for internal use only.
master_host - is deprecated in favor of mirror_master.
master_service - is deprecated in favor of mirror_master.
on_change - is for internal use only.
point - is used internally.
qnx_name_attach - does nothing.
qnx_receiver - does nothing.
readid - should not be used.
register_datahub - replaced by report_domain.
report_all - replaced by report_domain.
report_datahubs - does nothing.
request - replaced by report_domain.
run - does nothing.
script_register - is for internal use only.
script_symbol - is for internal use only.
slave - is for internal use only.
sync - is for internal use only.
taskdied - is for internal use.
taskstarted - is for internal use.
using_license - is for internal use only.
warn_of_license_expiry - is deprecated.

List of Figures

2.1. The Cascade DataHub Viewer in Console Mode
2.2. The Cascade DataHub Viewer for QNX Photon
2.3. The Cascade DataHub Viewer for X Windows
2.4. Exceptions and Echoes
2.5. Asynchronous Messages
3.1. Synchronous data transmission
3.2. Asynchronous data transmission
3.3. Cascade DataHub Data Transmission

List of Tables

2.1. Memory Usage