DQNET is a family of network connectivity products from CYNOSURE Computer Technologies Incorporated that allows DOS workstations, QNX2 networks and QNX4 networks to communicate with each other. DQNET consists of a network layer (DQnet), and higher level servers that provide specific networking features. The current servers are:
The foundation that supports all the DQNET products is a networking layer called DQnet. This layer provides for the exchange of messages across a network system. There is a version of DQnet for QNX2, QNX4 and DOS.
DQnet itself has two layers - the network manager layer and the driver layer. The network adapter layer accepts messages from the DQNET servers and dispatches them through the driver(s). Messages received from drivers are routed up to the appropriate server.
Drivers are available for Arcnet, Ethernet or high-speed serial connections, and for interfacing to QNX2/QNX4 Net tasks, Novell ODI and Lantastic Netbios drivers. This means that DQnet coexists with other networking protocols on existing networks.
As an example, a DOS computer may have an Ethernet adapter, and may be using the Ethernet to talk with other computers on a Novell network. The same Ethernet might also be used to connect several QNX4 systems via QNX Net. DQnet shares the Novell ODI driver on the DOS computer to send messages to the QNX computers, where DQnet shares the driver with the QNX Net task.
DQfs is a server that uses DQnet to provide remote file systems to DOS computers. In much the same way that Novell or Lantastic provide remote drives for a computer, DQnet provides remote drives for a DOS system. DOS users will run programs that attempt accesses to drives not physically present on the DOS computer, and DQFS redirects those file accesses to files on QNX systems. Each DOS remote drive is mapped to a specific directory on the QNX system.
The mappings of DOS remote drives to QNX directories is dynamic. That is, the system administrator can set up some default mappings for a particular DOS workstation, but a user at that workstation can change the mappings, provided the user has appropriate permissions. This is done through a login mechanism. The QNX security system prevents unauthorized access to files, even if those files appear in directories mapped to DOS remote drives.
DQFS handles the mapping of devices as well. QNX printers or spoolers can be made available as DOS printers.
DQsr allows QNX and DOS programs to communicate with each other using QNX-style Send()-Receive()-Reply() functions. DOS tasks may locate tasks running on QNX machines, then send messages to the located tasks. Similarly, QNX tasks can locate programs running on DOS machines and send messages to those programs.
QNX tasks use the standard Send(), Receive(), and Reply() functions provided with the operating system. Programs written to communicate with other QNX tasks can be used to communicate with DOS programs without change.
A typical use of the DQSR package is in an application that may have a user interface program that runs under MS-Windows, but that wants to access data stored in a QNX-resident database. The DOS-MSWindows program could locate the QNX database manager task, and then send messages to retrieve or alter data stored in the database.
DQdde allows MS-Windows programs that use DDE messaging to exchange messages with QNX programs. Dynamic Data Exchange (DDE) is a protocol used by MS-Windows to handle the exchange of messages between MS-Windows tasks. DDE messaging is similar to, but not identical to, QNX message passing.
In a typical application, a network of computers running QNX may be handling real-time data collection and control. An engineer develops some Excel spreadsheets under MS-Windows to model the plant. The input data has to come from the QNX network. DQDDE allows the engineer to use Excel's DDE capability to link cells in the spreadsheet to messages that are sent to QNX data collection tasks. The engineer does not have to copy data from a QNX screen or a printed report; the MS-Windows application can access the latest data in real time.
DQinet allows multiple QNX2 and/or QNX4 networks to be connected on an internetwork for purposes of file transfer, printer sharing, etc.
DQINET works on a separate backbone to connect several QNX networks together. That is, each of the QNX networks has one computer that acts as a gateway between its network and the DQINET.
DQINET provides several utility programs to allow file manipulation across the various QNX networks. Programs on one node of one QNX system can exchange data with a node on a different QNX network.
An example of the use of DQINET is a facility that uses a QNX network to connect several computers controlling a particular machine. A site may have several machines, and thus wish to connect those several QNX networks together. A DOS machine, running MS-Windows, may provide an operator interface to all the machines at a site. DQnet is used to provide the inter-QNX connectivity, and DQINET provides a file access mechanism between the networks. DQFS allows the DOS machine to share files with each of the QNX networks, and DQDDE allows an MS-Windows application on the DOS machine to fetch data from each of the QNX controllers on the machines.
There are two communications products that Cynosure continues to develop, sell and support:
DQBRIDGE connects a Windows (or DOS) computer to a QNX computer via serial port and transfers files between the systems. The file transfer is controlled by a script, and can be repeated periodically. DQBRIDGE is configurable, so that it can be used with QNX2, QNX4 or any other system that supports command-line access via serial port.
DQSTERM connects a Windows (or DOS) computer to a QNX computer via serial port, providing command-line access to the QNX computer. DQSTERM provides file transfer between the QNX and DOS system, as well as access to the local (DOS) command line interpreter (shell).
For more information, click on the following links: