examples

Zenoh Kotlin examples

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Start instructions

For running the examples, there are two approaches. Either you run the gradle example task with the syntax gradle <example> --args="<arguments>" or you can build fat JARs the examples through the task gradle buildExamples.

While both are valid, in this document we'll follow the second approach; when running gradle buildExamples, all the JARs will be located under /examples/build/libs, which can later be executed

java -jar <Example>.jar <arguments>

for instance

java -jar ZPub.jar -h

will return

Usage: zpub [<options>]

  Zenoh Pub example

Options:
  -k, --key=<key>          The key expression to write to [default: demo/example/zenoh-kotlin-pub]
  -c, --config=<config>    A configuration file.
  -e, --connect=<connect>  Endpoints to connect to.
  -l, --listen=<listen>    Endpoints to listen on.
  -m, --mode=<mode>        The session mode. Default: peer. Possible values: [peer, client, router]
  -v, --value=<value>      The value to write. [Default: "Pub from Kotlin!"]
  -a, --attach=<attach>    The attachments to add to each put. The key-value pairs are &-separated, and = serves as the separator between key and value.
  --no-multicast-scouting  Disable the multicast-based scouting mechanism.
  -h, --help               Show this message and exit

The connect and listen parameters (that are common to all the examples) accept multiple repeated inputs. For instance:

java -jar ZPub.jar -l tcp/localhost:7447 -l tcp/localhost:7448 -l tcp/localhost:7449

There is the possibility to provide a Zenoh config file as follows

java -jar ZPub.jar -c path/to/config.json5

In that case, any other provided configuration parameters through the command line interface will not be taken into consideration.

One last comment regarding Zenoh logging for the examples, logs from the native library can be enabled through the environment variable RUST_LOG as follows:

RUST_LOG=<level> java -jar ZPub.jar

where <level> is the log filter (for instance debug, warn, error... (see the Rust documentation)).

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Examples description

ZPub

Declares a resource with a path and a publisher on this resource. Then puts a value using the numerical resource id. The path/value will be received by all matching subscribers, for instance the ZSub example.

Usage:

java -jar ZPub.jar

or

java -jar ZPub.jar -k demo/example/test -v "hello world"

ZSub

Creates a subscriber with a key expression. The subscriber will be notified of each put made on any key expression matching the subscriber's key expression, and will print this notification.

Usage:

java -jar ZSub.jar

or

java -jar ZSub.jar -k demo/example/test

ZGet

Sends a query message for a selector. The queryables with a matching path or selector (for instance ZQueryable) will receive this query and reply with paths/values that will be received by the query callback.

java -jar ZGet.jar

or

java -jar ZGet.jar -s demo/example/get

ZPut

Puts a path/value into Zenoh. The path/value will be received by all matching subscribers, for instance the ZSub.

Usage:

java -jar ZPut.jar

or

java -jar ZPut.jar -k demo/example/put -v 'Put from Kotlin!'

ZDelete

Performs a Delete operation into a path/value into Zenoh.

Usage:

java -jar ZDelete.jar

or

java -jar ZDelete.jar -k demo/example/delete

ZQueryable

Creates a queryable function with a key expression. This queryable function will be triggered by each call to a get operation on zenoh with a selector that matches the key expression, and will return a value to the querier.

Usage:

java -jar ZQueryable.jar

or

java -jar ZQueryable.jar -k demo/example/query

ZPubThr & ZSubThr

Pub/Sub throughput test. This example allows to perform throughput measurements between a publisher performing put operations and a subscriber receiving notifications of those puts.

Subscriber usage:

java -jar ZSubThr.jar

Publisher usage:

java -jar ZPubThr.jar <payload_size>

ZPing & ZPong

Latency tests

java -jar ZPing.jar

java -jar ZPong.jar

ZScout

A scouting example. Will show information from other nodes in the Zenoh network.

java -jar ZScout.jar

Liveliness examples

ZLiveliness

The ZLiveliness example, it just announces itself to the Zenoh network by default to the key expression group1/zenoh-kotlin.

Usage:

java -jar ZLiveliness

It can be used along with the following liveliness examples:

ZGetLiveliness

Gets the liveliness tokens, by default to group1/zenoh-kotlin.

Usage:

java -jar ZGetLiveliness

ZSubLiveliness

Subscribes to liveliness events:

java -jar ZSubLiveliness