Zenoh Tutorial
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This document provides an overview of Zenoh, an open-source distributed data-centric middleware. It summarizes Zenoh's key features including pub/sub, storage/query, compute capabilities and how these can be used in peer-to-peer, routed, and geo-distributed communication patterns. It also describes how to install and use Zenoh in Python and Docker, configure routers and backends, and interact with the system using its REST API.
![Value types and encodings
zenoh supports different value types.
Each has an encoding described by its mime-type:
from zenoh import Zenoh
import json
z = Zenoh({})
workspace = z.workspace()
# - String
workspace.put('/demo/example/String', 'Hello World!')
# - Integer
workspace.put('/demo/example/Integer', 3)
# - Float
workspace.put('/demo/example/Float', 3.14)
# - Properties (as a Dictionary with str only)
workspace.put('/demo/example/Properties', {'p1': 'v1', 'p2': 'v2'})
# - Json (str format)
workspace.put('/demo/example/Json',
Value.Json(json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}])))
# - Raw ('application/octet-stream' encoding by default)
workspace.put('/demo/example/Raw', b'x48x69x21')
# - Custom
workspace.put('/demo/example/Custom',
Value.Custom('my_encoding', b'x48x69x21'))](https://image.slidesharecdn.com/2021-210212163031/85/Zenoh-Tutorial-14-320.jpg)
Zenoh Tutorial
- 1. Zero Overhead Pub/Sub Store/Query Compute Advanced Technology Office Angelo Corsaro, PhD Chief Technology Officer Luca Cominardi, PhD Senior Technologist Gabriele Baldoni Technologist Julien Enoch Senior Technologist Olivier Hecart Senior Technologist
- 2. installation
- 3. in Python Requires Python 3.6 minimum. Latest version (stable): • Available on pypi.org (https://pypi.org/project/eclipse-zenoh) • Binary wheels for x86_64, i686 and aarch64 • For other platforms: source distribution requiring Rust toolchain (https://www.rust-lang.org/tools/install) pip install eclipse-zenoh Version in development (master): • https://github.com/eclipse-zenoh/zenoh-python • Requires Rust toolchain (https://www.rust-lang.org/tools/install) pip install https://github.com/eclipse-zenoh/zenoh-python/zipball/master Code examples: • https://github.com/eclipse-zenoh/zenoh-python/tree/master/examples/zenoh
- 4. router - in Docker Latest version (stable): docker pull eclipse/zenoh:latest Version in development (master): docker pull eclipse/zenoh:master Usage: docker run --init eclipse/zenoh --help docker run --init -p 7447:7447/tcp -p 7447:7447/udp -p 8000:8000/tcp eclipse/zenoh
- 5. router - native Latest version (stable): • https://download.eclipse.org/zenoh/zenoh/latest • Files: eclipse-zenoh-<version>-<platform>.tgz (or .zip) Version in development (master): • https://download.eclipse.org/zenoh/zenoh/master • Files: eclipse-zenoh-<version>-<platform>.tgz (or .zip) zenohd --help RUST_LOG=info zenohd Usage:
- 7. Peer-to-peer Peer Peer Peer Peer Peer • Multicast discovery • Unicast “neighbour to neighbour” discovery • Unicast “reference point” discovery from zenoh import Zenoh z = Zenoh({"mode": "peer"}) Clique Peer Peer Peer Peer Peer Available soon !!! Mesh Peer init in Python:
- 8. Routed communication Client Client Client Client Router from zenoh import Zenoh z = Zenoh({ "mode": "client", "peer": "tcp/127.0.0.1:7447" }) Client init in Python: zenohd Single router startup:
- 10. Routers network Clique Mesh Available soon !!! Router Router Router Router Router Router Router Router Router Router zenohd -e tcp/<host1>:7447 -e tcp/<host2>:7447 ... Connected router startup:
- 11. Full picture Peer Peer Peer Peer Peer Peer Peer Peer Peer Peer Client Client Client Router Router Router
- 12. pub/sub
- 13. pub/sub in Python Publications are made via the put() operation: • See https://github.com/eclipse-zenoh/zenoh-python/blob/master/examples/zenoh/z_put.py from zenoh import Zenoh z = Zenoh({}) workspace = z.workspace() workspace.put("/demo/example/hi", "Hello World!") Subscriptions are made via the subscribe() operation: • See https://github.com/eclipse-zenoh/zenoh-python/blob/master/examples/zenoh/z_sub.py from zenoh import Zenoh, ChangeKind def listener(change): print("{} : {} (encoding: {} , timestamp: {})".format(change.path, "DELETED" if change.kind == ChangeKind.DELETE else change.value.get_content(), "none" if change.kind == ChangeKind.DELETE else change.value.encoding_descr(), change.timestamp)) z = Zenoh({}) workspace = z.workspace() workspace.subscribe("/demo/example/**", listener)
- 14. Value types and encodings zenoh supports different value types. Each has an encoding described by its mime-type: from zenoh import Zenoh import json z = Zenoh({}) workspace = z.workspace() # - String workspace.put('/demo/example/String', 'Hello World!') # - Integer workspace.put('/demo/example/Integer', 3) # - Float workspace.put('/demo/example/Float', 3.14) # - Properties (as a Dictionary with str only) workspace.put('/demo/example/Properties', {'p1': 'v1', 'p2': 'v2'}) # - Json (str format) workspace.put('/demo/example/Json', Value.Json(json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}]))) # - Raw ('application/octet-stream' encoding by default) workspace.put('/demo/example/Raw', b'x48x69x21') # - Custom workspace.put('/demo/example/Custom', Value.Custom('my_encoding', b'x48x69x21'))
- 15. store/query
- 16. Storages Peer Peer Peer Peer Peer Client Client Client Router Router Router zenohd --mem-storage '/a/b/**' --mem-storage '/x/y/**' ... Router with in-memory storages: • Deployed in router • Store publications matching its selector • Replies to queries /a/b/** /x/y/** put(/x/y/1) put(/a/b/2) get(a/b/*) g e t ( / x / y / * )
- 17. pub/store/query in Python Deletions from storage are made via the delete() operation: • See https://github.com/eclipse-zenoh/zenoh-python/blob/master/examples/zenoh/z_delete.py from zenoh import Zenoh z = Zenoh({}) workspace = z.workspace() workspace.delete("/demo/example/hi") Publications are made via the put() operation (seen previously). Queries are made via the get() operation: • See https://github.com/eclipse-zenoh/zenoh-python/blob/master/examples/zenoh/z_get.py from zenoh import Zenoh z = Zenoh({}) workspace = z.workspace() for data in workspace.get("/demo/example/**"): print("{} : {} (encoding: {} , timestamp: {})".format( data.path, data.value.get_content(), data.value.encoding_descr(), data.timestamp))
- 18. compute/query
- 19. Compute Peer Peer Peer Peer Peer Client Client Client Router Router Router • Eval function declared by zenoh applications that compute a value on demand • Called by queries register_eval(/x/y/z) get(a/b/*) g e t ( / x / y / * ) register_eval(/a/b/c)
- 20. Compute/query in Python Queries are made via the get() operation (seen previously). Compute are declared via the register_eval() operation: • See https://github.com/eclipse-zenoh/zenoh-python/blob/master/examples/zenoh/z_eval.py import datetime from zenoh import Zenoh def eval_callback(get_request): get_request.reply("/demo/example/eval", "It's {}".format(datetime.datetime.now().time())) z = Zenoh({}) workspace = z.workspace() workspace.register_eval("/demo/example/eval", eval_callback)
- 21. REST API
- 22. REST API Implemented as a plugin. Default port: 8080. The zenoh put/get/delete operations map to the PUT/GET/DELETE HTTP methods. Example using the curl command: # Put a string value in /demo/example/test curl -X PUT -d 'Hello World!' http://localhost:8000/demo/example/test # Put a JSON value in /demo/example/json curl -X PUT -H "Content-Type: application/json" -d '{"value": "Hello World!"}' http://localhost:8000/demo/example/test # Put a Properties value in /demo/example/props curl -X PUT -H 'content-type:application/properties' -d 'k1=v1;k2=v2' http://localhost:8000/demo/example/props # Get the keys/values matching /demo/** curl http://localhost:8000/demo/** # Get the keys/values matching /demo/example/*eval (i.e. the zenoh eval examples) # with property name=Bob curl http://localhost:8000/demo/example/*eval?(name=Bob) # Delete key/value /demo/example/test curl -X DELETE http://localhost:8000/demo/example/test
- 24. Backends A zenoh backend is: • a library, loaded on demand by the zenoh router (name: libzbackend_<id>.so) • a factory for zenoh storages • leveraging a speci fi c technology to implement storages Existing backends: • In-memory: built-in in zenoh router • File system: • https://github.com/eclipse-zenoh/zenoh-backend- fi lesystem • RocksDB: • https://github.com/eclipse-zenoh/zenoh-backend-rocksdb • In fl uxDB: • https://github.com/eclipse-zenoh/zenoh-backend-in fl uxdb
- 25. Admin space zenoh admin space: •A zenoh key/value space with under /@/** •Addressable via zenoh APIs using put/get/delete operations •Each router addressable via its ID, or the "local" keyword for the router an API is connected to /@/router/1a2b3c.../plugin/storages /backend /memory /rocksdb /<beid> /storage /storage /s2 /s1 ... ... /storage /db2 /db1 ... # Get local router's info curl http://localhost:8000/@/router/local # Get all routers' of the system curl http://localhost:8000/@/router/* # Get local router's storages info curl http://localhost:8000/@/router/local/**/storages/** Examples using the REST API:
- 26. Backends/storages management Examples using the REST API: # Add a memory storage curl -X PUT -H 'content-type:application/properties' -d 'path_expr=/demo/test/**' http://localhost:8000/@/router/local/plugin/storages/backend/memory/storage/my-test # Add a FileSystem backend (assuming libzbackend_fs.so is available) curl -X PUT -H 'content-type:application/properties' http://localhost:8000/@/router/local/plugin/storages/backend/fs # Add a FileSystem storage curl -X PUT -H 'content-type:application/properties' -d 'path_expr=/demo/example/**;path_prefix=/demo/example;dir=test' http://localhost:8000/@/router/local/plugin/storages/backend/fs/storage/my-test # Add an InfluxDB backend (assuming libzbackend_influxdb.so is available and InfluxDB running at http://localhost:8086) curl -X PUT -H 'content-type:application/properties' -d 'url=http://localhost:8086' http://localhost:8000/@/router/local/plugin/storages/backend/influxdb # Add an InfluxDB storage using the database named "zenoh-example" curl -X PUT -H 'content-type:application/properties' -d 'path_expr=/demo/example/**;db=zenoh-example' http://localhost:8000/@/router/local/plugin/storages/backend/influxdb/storage/my-test
- 27. plugins
- 28. Plugins A zenoh plugin is • a library, loaded at start-up by the zenoh router (name: libzplugin_<id>.so) • similar to zenoh application using the zenoh APIs (in RUST) • using the router's runtime => no transport overhead Existing plugins: • REST plugin (packaged with zenoh deliverable) • Storages plugin (packaged with zenoh deliverable) • WebServer plugin: • https://github.com/eclipse-zenoh/zenoh-plugin-webserver • DDS plugin: • https://github.com/eclipse-zenoh/zenoh-plugin-dds
- 29. Live Demo zenoh
- 30. us-west.zenoh.io /demo/us-west/** us-east.zenoh.io /demo/us-east/** eu.zenoh.io /demo/eu/** ap.zenoh.io /demo/ap/** Example: • Put data: curl -X PUT -d 'Hello World!' http://us-west.zenoh.io:8000/demo/eu/test • Get data: curl http://ap.zenoh.io:8000/demo/*/test
- 31. us-west.zenoh.io /demo/us-west/** us-east.zenoh.io /demo/us-east/** eu.zenoh.io /demo/eu/** ap.zenoh.io /demo/ap/** Example: • Get time series: curl http://us-west.zenoh.io:8000/demo/influxdb/**?(stoptime=now()) • Browse /public/**: http://eu.zenoh.io:8080/public File system storage /public/** File system storage /public/** InfluxDB storage /demo/influxdb/** RocksDB storage /demo/rocksdb/** After addition of backends/storages:
- 32. References