Transparent Distributed Processing Using Qnet

Transparent Distributed Processing (TDP) allows you to leverage the processing power of your entire network by sharing resources and services transparently over the network. TDP uses Neutrino native network protocol Qnet to link the devices in your network.

What is Qnet?
Qnet is Neutrino's protocol for distributed networking. Using Qnet, you can build a transparent distributed-processing platform that is fast and scalable. This is accomplished by extending the Neutrino message passing architecture over a network. This creates a group of tightly integrated Neutrino nodes (systems) or CPUs—a Neutrino native network.
Benefits of Qnet
The Qnet protocol extends interprocess communication (IPC) transparently over a network of microkernels. This is done by taking advantage of the Neutrino's message-passing paradigm. Message passing is the central theme of Neutrino that manages a group of cooperating processes by routing messages. This enhances the efficiency of all transactions among all processes throughout the system.
How does it work?
As explained in the System Architecture guide, Neutrino client and server applications communicate by Neutrino message passing.
Locating services using GNS
You use gns, the Global Name Service or GNS manager to locate services. GNS is a standalone resource manager. With the help of this utility, an application can advertise, look up, and use (connect to) a service across Qnet network, without knowing the details of where the service is, or who the provider is.
Quality of Service (QoS) and multiple paths
Quality of Service (QoS) is an issue that often arises in high-availability networks as well as realtime control systems. In the Qnet context, QoS really boils down to transmission media selection — in a system with two or more network interfaces, Qnet chooses which one to use, according to the policy you specify.
Designing a system using Qnet
Autodiscovery vs static
When you're creating a network of Neutrino hosts via Qnet, one thing you must consider is how they locate and address each other. This falls into two categories: autodiscovery and static mappings.
When should you use Qnet, TCP/IP, or NFS?
In your network design, when should you use Qnet, TCP/IP, or NFS? The decision depends on what your intended application is and what machines you need to connect.
Drivers for Qnet
You don't need a specific driver for your hardware, for example, for implementing a local area network using Ethernet hardware or for implementing TCP/IP networking that require IP encapsulation. In these cases, the underlying io-pkt* and TCP/IP layer is sufficient to interface with the Qnet layer for transmitting and receiving packets. You use standard Neutrino drivers to implement Qnet over a local area network or to encapsulate Qnet messages in IP (TCP/IP) to allow Qnet to be routed to remote networks.

Related concepts

Native Networking: Qnet (System Architecture)

Using Qnet for Transparent Distributed Processing (QNX Neutrino User's Guide)

Message passing over a network (Getting Started with QNX Neutrino)

Related reference

io-pkt-v4, io-pkt-v4-hc, io-pkt-v6-hc

lsm-qnet.so