OLA ArtNet Roadmap

This describes proposed changes to the OLA ArtNet plugin to make it more usable. Some of the use cases that have been requested include:

• Receiving broadcast ArtNet data and unicasting to a static list of destinations
• Converting many universes (10s, 100s?) from ArtNet to E1.31 and visa versa.

Requirements

• Support multiple ArtNet Devices, one per logical network interface.
• Support unicasting data to a static list of IPv4 addresses.
• Support more than 4 ports in both directions
• De-couple the ArtNet universe from the OLA universe number to support any-way patching. i.e. patch ArtNet universe 5 to OLA universe 3.

Proposed Changes

Investigate Optimizing the Send Path

The sendmmsg syscall was added in Linux 3.0. It allows multiple datagrams to be sent with a single syscall. sendmmsg would allos us to reduce the number of syscalls required for each ArtNet packet when unicasting. This scope of this change is to make the required changes and then benchmark the performance.

Steps:

• Detect support for sendmmsg in configure.ac
• Add a method to the UDPSocket class to enable a single data message to be sent to many addresses
• Modify the ArtNetNode::SendDMX method to use the new UDPSocket method

Multiple ArtNet Devices

Right now only a single ArtNet Device is created. This should be changed so that OLA creates one device per logical interface.

Currently the ArtNetNode object binds to the wildcard address (code) which means trying to create a second instance will fail.

We need some research into how broadcast traffic is handled with multiple interfaces. Ideally each instance should bind to the broadcast addresses for the specified logical interface.