Crate zenoh

Zenoh /zeno/ is a stack that unifies data in motion, data at rest and computations. It elegantly blends traditional pub/sub with geo distributed storage, queries and computations, while retaining a level of time and space efficiency that is well beyond any of the mainstream stacks.

Before delving into the examples, we need to introduce few Zenoh concepts. First off, in Zenoh you will deal with Resources, where a resource is made up of a key and a value. The other concept you’ll have to familiarize yourself with are key expressions, such as robot/sensor/temp, robot/sensor/*, robot/**, etc. As you can gather, the above key expression denotes set of keys, while the * and ** are wildcards representing respectively (1) an arbitrary string of characters, with the exclusion of the / separator, and (2) an arbitrary sequence of characters including separators.

Below are some examples that highlight these key concepts and show how easy it is to get started with.

Examples

Publishing Data

The example below shows how to produce a value for a key expression.

use zenoh::prelude::r#async::*;

#[tokio::main]
async fn main() {
    let session = zenoh::open(config::default()).res().await.unwrap();
    session.put("key/expression", "value").res().await.unwrap();
    session.close().res().await.unwrap();
}

Subscribe

The example below shows how to consume values for a key expresison.

use futures::prelude::*;
use zenoh::prelude::r#async::*;

#[tokio::main]
async fn main() {
    let session = zenoh::open(config::default()).res().await.unwrap();
    let subscriber = session.declare_subscriber("key/expression").res().await.unwrap();
    while let Ok(sample) = subscriber.recv_async().await {
        println!("Received: {}", sample);
    };
}

Query

The example below shows how to make a distributed query to collect the values associated with the resources whose key match the given key expression.

use futures::prelude::*;
use zenoh::prelude::r#async::*;

#[tokio::main]
async fn main() {
    let session = zenoh::open(config::default()).res().await.unwrap();
    let replies = session.get("key/expression").res().await.unwrap();
    while let Ok(reply) = replies.recv_async().await {
        println!(">> Received {:?}", reply.sample);
    }
}

Re-exports

• pub use zenoh_config as config;
• pub use zenoh_buffers as buffers;

Modules

• handlers
  Callback handler trait.
• info
  Tools to access information about the current zenoh Session.
• key_expr
  Key expression are Zenoh’s address space.
• liveliness
  Liveliness primitives.
• prelude
  A “prelude” for crates using the zenoh crate.
• properties
  A map of key/value (String,String) properties.
• publication
  Publishing primitives.
• query
  Query primitives.
• queryable
  Queryable primitives.
• sample
  Sample primitives
• scouting
  Scouting primitives.
• selector
  Selector to issue queries
• subscriber
  Subscribing primitives.
• time
  Time related types and functions.
• value
  Value primitives.

Macros

• ke
  Equivalent to keyexpr::new, but the check is run at compile-time and will throw a compile error in case of failure.
• kedefine
  Create format modules from a format specification.
• keformat
  Write a set of values into a Formatter and then builds it into an OwnedKeyExpr, stopping as soon as a value doesn’t fit the specification for its field.
• kewrite
  Write a set of values into a Formatter, stopping as soon as a value doesn’t fit the specification for its field. Contrary to keformat doesn’t build the Formatter into a Key Expression.

Structs

• OpenBuilder
  A builder returned by open used to open a zenoh Session.
• Session
  A zenoh session.

Enums

• SessionRef

Constants

• FEATURES

Traits

• SessionDeclarations
  Functions to create zenoh entities
• Undeclarable
  A trait implemented by types that can be undeclared.

Functions

• open
  Open a zenoh Session.
• scout
  Scout for routers and/or peers.

Type Aliases

• Error
  A zenoh error.
• Result
  A zenoh result.