| ## Inter-process communication |
| |
| Since processes are isolated by default, the kernel needs to provide a way for |
| them to securely communicate with each other. Zircon includes the following |
| kernel object types for inter-process communication (IPC): |
| |
| * [Event](/docs/reference/kernel_objects/event.md): |
| Signaling interface between two processes. |
| * [Socket](/docs/reference/kernel_objects/socket.md): |
| Streaming data transport, similar to a pipe. |
| * [Stream](/docs/reference/kernel_objects/stream.md): |
| Streaming data transport that is seekable, like a file. |
| * [Channel](/docs/reference/kernel_objects/channel.md): |
| Message-based transport capable of passing both data and a set of handles. |
| * [FIFO](/docs/reference/kernel_objects/fifo.md): |
| Control plane for shared memory access, optimized for small data payloads. |
| |
| Among these objects, channels are uniquely suited to assist in launching new |
| processes because they are capable of transferring handles (and therefore, |
| capabilities) across to another process. |
| |
| Channels have exactly two endpoint handles, each owned by a separate process. |
| Only the owners may read or write messages, but ownership of an endpoint may |
| be transferred from one process to another. When handles are written into a |
| channel, they are removed from the sending process. When a message with handles |
| is read from a channel, the handles are added to the receiving process. |
| |
| {: width="582"} |
| |
| Note: You can find more of Zircon's deep technical details in the |
| [kernel documentation](/docs/concepts/kernel/README.md). |
| |
| Zircon channels are the basis for service-level IPC protocols described by |
| the [Fuchsia Interface Definition Language (FIDL)][glossary.FIDL]. FIDL |
| protocols are the primary method of IPC used by Fuchsia programs. You will |
| explore creating and consuming FIDL protocols in more detail later on. |
| |
| |
| [glossary.FIDL]: /docs/glossary/README.md#FIDL |
