The Eclipse zenoh: Zero Overhead Pub/sub, Store/Query and Compute.

Eclipse zenoh (pronounce /zeno/) unifies data in motion, data in-use, data at rest and computations. It carefully blends traditional pub/sub with geo-distributed storages, queries and computations, while retaining a level of time and space efficiency that is well beyond any of the mainstream stacks.

Check the website zenoh.io for more detailed information.

See our "Getting started" tour starting with the zenoh key concepts.

Install Cargo and Rust. Zenoh can be succesfully compiled with Rust stable (>= 1.5.1), so no special configuration is required from your side.
To build zenoh, just type the following command after having followed the previous instructions:

$ cargo build --release --all-targets

The zenoh router is built as target/release/zenohd. All the examples are built into the target/release/examples directory. They can all work in peer-to-peer, or interconnected via the zenoh router.

Peer-to-peer tests:

• pub/sub

  • run: ./target/release/examples/z_sub
  • in another shell run: ./target/release/examples/z_put
  • the subscriber should receive the publication.

• get/eval

  • run: ./target/release/examples/z_eval
  • in another shell run: ./target/release/examples/z_get
  • the eval should display the log in it's listener, and the get should receive the eval result.

Routed tests:

• put/store/get

  • run the zenoh router with a memory storage:
    ./target/release/zenohd --mem-storage '/demo/example/**'
  • in another shell run: ./target/release/examples/z_put
  • then run ./target/release/examples/z_get
  • the get should receive the stored publication.

• REST API using curl tool

  • run the zenoh router with a memory storage:
    ./target/release/zenohd --mem-storage '/demo/example/**'
  • in another shell, do a publication via the REST API:
    curl -X PUT -d 'Hello World!' http://localhost:8000/demo/example/test
  • get it back via the REST API:
    curl http://localhost:8000/demo/example/test

• router admin space via the REST API

  • run the zenoh router with a memory storage:
    ./target/release/zenohd --mem-storage '/demo/example/**'
  • in another shell, get info of the zenoh router via the zenoh admin space:
    curl http://localhost:8000/@/router/local
  • get the backends of the router (only memory by default):
    curl 'http://localhost:8000/@/router/local/**/backend/*'
  • get the storages of the local router (the memory storage configured at startup on '/demo/example/**' should be present):
    curl 'http://localhost:8000/@/router/local/**/storage/*'
  • add another memory storage on /demo/mystore/**:
    curl -X PUT -H 'content-type:application/properties' -d 'path_expr=/demo/mystore/**' http://localhost:8000/@/router/local/plugin/storages/backend/memory/storage/my-storage
  • check it has been created:
    curl 'http://localhost:8000/@/router/local/**/storage/*'

See other examples of zenoh usage:

• with the zenoh API in zenoh/examples/zenoh
• with the zenoh-net API in zenoh/examples/zenoh-net

zenohd accepts the following arguments:

• -c, --config <FILE>: a configuration file containing a list of properties with format <key>=<value> (1 per-line). The accepted property keys are the same than accepted by the zenoh API and are documented here.
• -l, --listener <LOCATOR>...: A locator on which this router will listen for incoming sessions. Repeat this option to open several listeners. By default tcp/0.0.0.0:7447 is used. The following locators are currently supported:
  • TCP: tcp/<host_name_or_IPv4>:<port>
  • UDP: udp/<host_name_or_IPv4>:<port>
  • TCP+TLS: tls/<host_name_or_IPv4>:<port>
  • QUIC: quic/<host_name_or_IPv4>:<port>
• -e, --peer <LOCATOR>...: A peer locator this router will try to connect to. Repeat this option to connect to several peers.
• --no-multicast-scouting: By default zenohd replies to multicast scouting messages for being discovered by peers and clients. This option disables this feature.
• -i, --id <hex_string>: The identifier (as an hexadecimal string - e.g.: 0A0B23...) that zenohd must use. WARNING: this identifier must be unique in the system! If not set, a random UUIDv4 will be used.
• --no-timestamp: By default zenohd adds a HLC-generated Timestamp to each routed Data if there isn't already one. This option disables this feature.
• --plugin-nolookup: When set, zenohd will not look for plugins nor try to load any plugin except the ones explicitely configured with -P or --plugin.
• -P, --plugin <PATH_TO_PLUGIN_LIB>...: A plugin that must be loaded. Repeat this option to load several plugins.
• --plugin-search-dir <DIRECTORY>...: A directory where to search for plugins libraries to load. Repeat this option to specify several search directories'. By default, the plugins libraries will be searched in: '/usr/local/lib:/usr/lib:~/.zenoh/lib:.'

By default the zenoh router is delivered or built with 2 plugins that will be loaded at start-up. Each accepts some extra command line arguments:

REST plugin (exposing a REST API):

• --rest-http-port <rest-http-port>: The REST plugin's http port [default: 8000]

Storages plugin (managing backends and storages)

• --no-backend: If true, no backend (and thus no storage) are created at startup. If false (default) the Memory backend it present at startup.
• --mem-storage <PATH_EXPR>...: A memory storage to be created at start-up. Repeat this option to created several storages
• --backend-search-dir <DIRECTORY>...: A directory where to search for backends libraries to load. Repeat this option to specify several search directories'. By default, the backends libraries will be searched in: '/usr/local/lib:/usr/lib:~/.zenoh/lib:.'

In case of troubles, please first check on this page if the trouble and cause are already known.
Otherwise, you can ask a question on the zenoh Gitter channel, or create an issue.