Appendix: Container Communication
This section describes supported communication mechanisms for processes running in a container.
External Communication
For communication between container processes and external processes (not running on host), only TCP/IP is supported.
Internal Communication
For communication between container processes and other internal processes
(running on host or in another container),
the following standard QNX communication mechanisms are supported (with exceptions):
- Sockets (TCP/IP)
- Shared memory
- Message queues
- Semaphores
- Channels (QNX message passing)
Due to limitations in how pathname space mapping is currently handled within a chroot'ed environment, there are some exceptions in container-to-container and host-to-container communication as listed in the table below.
| Methods | Container-to-Container | Container-to-Host | Host-to-Container |
|---|---|---|---|
| TCP/IP | Yes | Yes | Yes |
| Shared Memory | Yes (fd only) | Yes (name, fd) | Yes (fd only) |
| Message Queue | No | Yes | No |
| Semaphores | No | Yes | No |
| Channels | Yes (name, chid only) | Yes (resmgr, name, chid) | Yes (name, chid only) |
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