Package: zenoh-backend-rocksdb
Version: 1.2.1
Architecture: amd64
Maintainer: zenoh-dev@eclipse.org
Installed-Size: 20233
Depends: zenoh-plugin-storage-manager (=1.2.1)
Filename: 1.2.1/zenoh-backend-rocksdb_1.2.1_amd64.deb
Size: 4504364
MD5sum: e22187af6ba6dc47dc8b09b35d4418b3
SHA1: ef6eb99827527d71473d0b01c41042db79929993
SHA256: e2c1a2a1b14f2391f7c711dc4eefbf13bf627f43f444d7aa3445c5becc02866a
Section: net
Priority: optional
Homepage: http://zenoh.io
Description: Backend for Zenoh using RocksDB
.
[](https://github.com/eclipse-zenoh/zenoh-backend-rocksdb/actions?query=workflow%3A%22CI%22)
[](https://github.com/eclipse-zenoh/roadmap/discussions)
[](https://discord.gg/2GJ958VuHs)
[](https://choosealicense.com/licenses/epl-2.0/)
[](https://opensource.org/licenses/Apache-2.0)
.
# Eclipse Zenoh
.
The Eclipse Zenoh: Zero Overhead Pub/sub, Store/Query and Compute.
.
Zenoh (pronounce _/zeno/_) unifies data in motion, 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](http://zenoh.io) and the
[roadmap](https://github.com/eclipse-zenoh/roadmap) for more detailed
information.
.
-------------------------------
.
# RocksDB backend
.
In zenoh a backend is a storage technology (such as DBMS, time-series database,
file system...) alowing to store the
keys/values publications made via zenoh and return them on queries.
See the [zenoh documentation](http://zenoh.io/docs/manual/backends/) for more
details.
.
This backend relies on [RocksDB](https://rocksdb.org/) to implement the
storages.
Its library name (without OS specific prefix and extension) that zenoh will
rely on to find it and load it is **`zenoh_backend_rocksdb`**.
.
:point_right: **Install latest release:** see [below](#how-to-install-it)
.
:point_right: **Build "main" branch:** see [below](#how-to-build-it)
.
-------------------------------
.
## **Examples of usage**
.
Prerequisites:
.
- You have a zenoh router (`zenohd`) installed, and the `zenoh_backend_rocksdb`
library file is available in `~/.zenoh/lib`.
- Declare the `ZENOH_BACKEND_ROCKSDB_ROOT` environment variable to the
directory where you want the RocksDB databases
to be stored. If you don't declare it, the `~/.zenoh/zenoh_backend_rocksdb`
directory will be used.
.
You can setup storages either at zenoh router startup via a configuration file,
either at runtime via the zenoh admin space, using for instance the REST API.
.
### **Setup via a JSON5 configuration file**
.
- Create a `zenoh.json5` configuration file containing:
.
```json5
{
plugins: {
// configuration of "storages" plugin:
storage_manager: {
volumes: {
// configuration of a "rocksdb" volume (the "zenoh_backend_rocksdb"
backend library will be loaded at startup)
rocksdb: {}
},
storages: {
// configuration of a "demo" storage using the "rocksdb" volume
demo: {
// the key expression this storage will subscribes to
key_expr: "demo/example/**",
// this prefix will be stripped from the received key when
converting to database key.
// i.e.: "demo/example/a/b" will be stored as "a/b"
strip_prefix: "demo/example",
volume: {
id: "rocksdb",
// the RocksDB database will be stored in this directory
(relative to ${ZENOH_BACKEND_ROCKSDB_ROOT})
dir: "example",
// create the RocksDB database if not already existing
create_db: true
}
}
}
},
// Optionally, add the REST plugin
rest: { http_port: 8000 }
}
}
```
.
- Run the zenoh router with:
`zenohd -c zenoh.json5`
.
### **Setup at runtime via `curl` commands on the admin space**
.
- Run the zenoh router, with write permissions to its admin space and with the
REST plugin:
`zenohd --adminspace-permissions=rw --rest-http-port=8000`
- Add the "rocksdb" backend (the "zenoh_backend_rocksdb" library will be
loaded):
`curl -X PUT -H 'content-type:application/json' -d '{}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/volumes/rocksdb`
- Add the "demo" storage using the "rocksdb" backend:
`curl -X PUT -H 'content-type:application/json' -d
'{key_expr:"demo/example/**",strip_prefix:"demo/example",volume: {id:
"rocksdb",dir: "example",create_db: true}}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/storages/demo`
.
### **Tests using the REST API**
.
Using `curl` to publish and query keys/values, you can:
.
```bash
# Put values that will be stored in the RocksDB database
curl -X PUT -d "TEST-1" http://localhost:8000/demo/example/test-1
curl -X PUT -d "B" http://localhost:8000/demo/example/a/b
.
# Retrive the values
curl http://localhost:8000/demo/example/**
```
.
-------------------------------
.
## Volume-specific storage configuration
.
Storages relying on a RocksDB-backed volume must specify some additional
configuration as shown [above](#setup-via-a-json5-configuration-file):
.
- **`"dir"`** (**required**, string) : The name of directory where the RocksDB
database is stored.
The absolute path will be `${ZENOH_BACKEND_ROCKSDB_ROOT}/`.
.
- **`"create_db"`** (optional, boolean) : create the RocksDB database if not
already existing. Not set by default.
_(the value doesn't matter, only the property existence is checked)_
.
- **`"read_only"`** (optional, boolean) : the storage will only answer to GET
queries. It will not accept any PUT or DELETE message, and won't put anything
in RocksDB database. Not set by default. _(the value doesn't matter, only the
property existence is checked)_
.
- **`"on_closure"`** (optional, string) : the strategy to use when the Storage
is removed. There are 2 options:
- _unset_: the database remains untouched (this is the default behaviour)
- `"destroy_db"`: the database is destroyed (i.e. removed)
.
-------------------------------
.
## **Behaviour of the backend**
.
### Mapping to RocksDB database
.
Each **storage** will map to a RocksDB database stored in directory:
`${ZENOH_BACKEND_ROCKSDB_ROOT}/`, where:
.
- `${ZENOH_BACKEND_ROCKSDB_ROOT}` is an environment variable that could be
specified before zenoh router startup.
If this variable is not specified `${ZENOH_HOME}/zenoh_backend_rocksdb` will
be used
(where the default value of `${ZENOH_HOME}` is `~/.zenoh`).
- `` is the `"dir"` property specified at storage creation.
ch zenoh **key/value** put into the storage will map to 2 **key/values** in the
database:
- For both, the database key is the zenoh key, stripped from the
`"strip_prefix"` property specified at storage creation.
- In the `"default"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with the zenoh encoded value as a value.
- In the `"data_info"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with a bytes buffer encoded in this order:
- the Timestamp encoded as: 8 bytes for the time + 16 bytes for the HLC ID
- a "is deleted" flag encoded as a boolean on 1 byte
- the encoding prefix flag encoded as a ZInt (variable length)
- the encoding suffix encoded as a String (string length as a ZInt + string
bytes without ending `\0`)
.
### Behaviour on deletion
.
On deletion of a key, the corresponding key is removed from the `"default"`
Column Family. An entry with the
"deletion" flag set to true and the deletion timestamp is inserted in the
`"data-info"` Column Family
(to avoid re-insertion of points with an older timestamp in case of un-ordered
messages).
At regular interval, a task cleans-up the `"data-info"` Column Family from
entries with old timestamps and
the "deletion" flag set to true
.
### Behaviour on GET
.
On GET operations:
.
- if the selector is a unique key (i.e. not containing any `'*'`): the value
and its encoding and timestamp
for the corresponding key are directly retrieved from the 2 Column Families
using `get` RocksDB operation.
- if the selector is a key expression: the storage searches for matching keys,
leveraging RocksDB's [Prefix
Seek](https://github.com/facebook/rocksdb/wiki/Prefix-Seek) if possible to
minimize the number of entries to check.
.
-------------------------------
.
## How to install it
.
To install the latest release of this backend library, you can do as follows:
.
### Manual installation (all platforms)
.
All release packages can be downloaded from:
.
-
[https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/](https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/)
.
Each subdirectory has the name of the Rust target. See the platforms each
target corresponds to on
[https://doc.rust-lang.org/stable/rustc/platform-support.html](https://doc.rust-lang.org/stable/rustc/platform-support.html)
.
Choose your platform and download the `.zip` file.
Unzip it in the same directory than `zenohd` or to any directory where it can
find the backend library (e.g. /usr/lib or ~/.zenoh/lib)
.
### Linux Debian
.
Add Eclipse Zenoh private repository to the sources list, and install the
`zenoh-backend-rocksdb` package:
.
```bash
echo "deb [trusted=yes] https://download.eclipse.org/zenoh/debian-repo/ /" |
sudo tee -a /etc/apt/sources.list.d/zenoh.list > /dev/null
sudo apt update
sudo apt install zenoh-backend-rocksdb
```
.
-------------------------------
.
## How to build it
.
> :warning: **WARNING** :warning: : Zenoh and its ecosystem are under active
development. When you build from git, make sure you also build from git any
other Zenoh repository you plan to use (e.g. binding, plugin, backend, etc.).
It may happen that some changes in git are not compatible with the most recent
packaged Zenoh release (e.g. deb, docker, pip). We put particular effort in
mantaining compatibility between the various git repositories in the Zenoh
project.
.
At first, install [Clang](https://clang.llvm.org/) and [Cargo and
Rust](https://doc.rust-lang.org/cargo/getting-started/installation.html). If
you already have the Rust toolchain installed, make sure it is up-to-date with:
.
```bash
rustup update
```
.
> :warning: **WARNING** :warning: : As Rust doesn't have a stable ABI, the
backend library should be
built with the exact same Rust version than `zenohd`, and using for `zenoh`
dependency the same version (or commit number) than 'zenohd'.
Otherwise, incompatibilities in memory mapping of shared types between `zenohd`
and the library can lead to a `"SIGSEV"` crash.
.
To know the Rust version you're `zenohd` has been built with, use the
`--version` option.
Example:
.
```bash
$ zenohd --version
The zenoh router v0.6.0-beta.1 built with rustc 1.64.0 (a55dd71d5 2022-09-19)
```
.
Here, `zenohd` has been built with the rustc version `1.64.0`.
Install and use this toolchain with the following command:
.
```bash
rustup default 1.64.0
```
.
And `zenohd` version corresponds to an un-released commit with id `1f20c86`.
Update the `zenoh` dependency in Cargo.lock with this command:
.
```bash
cargo update -p zenoh --precise 1f20c86
```
.
Then build the backend with:
.
```bash
cargo build --release --all-targets
```
Package: zenoh-backend-rocksdb
Version: 1.2.1
Architecture: armhf
Maintainer: zenoh-dev@eclipse.org
Installed-Size: 13990
Depends: zenoh-plugin-storage-manager (=1.2.1)
Filename: 1.2.1/zenoh-backend-rocksdb_1.2.1_armhf.deb
Size: 3948536
MD5sum: 0f4cad0fc7b9789b02a9ce3a901d9b28
SHA1: b4576c359170372ce4c7516e46a8424f39118b57
SHA256: 2225c74080d840060261e825bc40919a2db002711997f88371cb422eec81f096
Section: net
Priority: optional
Homepage: http://zenoh.io
Description: Backend for Zenoh using RocksDB
.
[](https://github.com/eclipse-zenoh/zenoh-backend-rocksdb/actions?query=workflow%3A%22CI%22)
[](https://github.com/eclipse-zenoh/roadmap/discussions)
[](https://discord.gg/2GJ958VuHs)
[](https://choosealicense.com/licenses/epl-2.0/)
[](https://opensource.org/licenses/Apache-2.0)
.
# Eclipse Zenoh
.
The Eclipse Zenoh: Zero Overhead Pub/sub, Store/Query and Compute.
.
Zenoh (pronounce _/zeno/_) unifies data in motion, 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](http://zenoh.io) and the
[roadmap](https://github.com/eclipse-zenoh/roadmap) for more detailed
information.
.
-------------------------------
.
# RocksDB backend
.
In zenoh a backend is a storage technology (such as DBMS, time-series database,
file system...) alowing to store the
keys/values publications made via zenoh and return them on queries.
See the [zenoh documentation](http://zenoh.io/docs/manual/backends/) for more
details.
.
This backend relies on [RocksDB](https://rocksdb.org/) to implement the
storages.
Its library name (without OS specific prefix and extension) that zenoh will
rely on to find it and load it is **`zenoh_backend_rocksdb`**.
.
:point_right: **Install latest release:** see [below](#how-to-install-it)
.
:point_right: **Build "main" branch:** see [below](#how-to-build-it)
.
-------------------------------
.
## **Examples of usage**
.
Prerequisites:
.
- You have a zenoh router (`zenohd`) installed, and the `zenoh_backend_rocksdb`
library file is available in `~/.zenoh/lib`.
- Declare the `ZENOH_BACKEND_ROCKSDB_ROOT` environment variable to the
directory where you want the RocksDB databases
to be stored. If you don't declare it, the `~/.zenoh/zenoh_backend_rocksdb`
directory will be used.
.
You can setup storages either at zenoh router startup via a configuration file,
either at runtime via the zenoh admin space, using for instance the REST API.
.
### **Setup via a JSON5 configuration file**
.
- Create a `zenoh.json5` configuration file containing:
.
```json5
{
plugins: {
// configuration of "storages" plugin:
storage_manager: {
volumes: {
// configuration of a "rocksdb" volume (the "zenoh_backend_rocksdb"
backend library will be loaded at startup)
rocksdb: {}
},
storages: {
// configuration of a "demo" storage using the "rocksdb" volume
demo: {
// the key expression this storage will subscribes to
key_expr: "demo/example/**",
// this prefix will be stripped from the received key when
converting to database key.
// i.e.: "demo/example/a/b" will be stored as "a/b"
strip_prefix: "demo/example",
volume: {
id: "rocksdb",
// the RocksDB database will be stored in this directory
(relative to ${ZENOH_BACKEND_ROCKSDB_ROOT})
dir: "example",
// create the RocksDB database if not already existing
create_db: true
}
}
}
},
// Optionally, add the REST plugin
rest: { http_port: 8000 }
}
}
```
.
- Run the zenoh router with:
`zenohd -c zenoh.json5`
.
### **Setup at runtime via `curl` commands on the admin space**
.
- Run the zenoh router, with write permissions to its admin space and with the
REST plugin:
`zenohd --adminspace-permissions=rw --rest-http-port=8000`
- Add the "rocksdb" backend (the "zenoh_backend_rocksdb" library will be
loaded):
`curl -X PUT -H 'content-type:application/json' -d '{}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/volumes/rocksdb`
- Add the "demo" storage using the "rocksdb" backend:
`curl -X PUT -H 'content-type:application/json' -d
'{key_expr:"demo/example/**",strip_prefix:"demo/example",volume: {id:
"rocksdb",dir: "example",create_db: true}}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/storages/demo`
.
### **Tests using the REST API**
.
Using `curl` to publish and query keys/values, you can:
.
```bash
# Put values that will be stored in the RocksDB database
curl -X PUT -d "TEST-1" http://localhost:8000/demo/example/test-1
curl -X PUT -d "B" http://localhost:8000/demo/example/a/b
.
# Retrive the values
curl http://localhost:8000/demo/example/**
```
.
-------------------------------
.
## Volume-specific storage configuration
.
Storages relying on a RocksDB-backed volume must specify some additional
configuration as shown [above](#setup-via-a-json5-configuration-file):
.
- **`"dir"`** (**required**, string) : The name of directory where the RocksDB
database is stored.
The absolute path will be `${ZENOH_BACKEND_ROCKSDB_ROOT}/`.
.
- **`"create_db"`** (optional, boolean) : create the RocksDB database if not
already existing. Not set by default.
_(the value doesn't matter, only the property existence is checked)_
.
- **`"read_only"`** (optional, boolean) : the storage will only answer to GET
queries. It will not accept any PUT or DELETE message, and won't put anything
in RocksDB database. Not set by default. _(the value doesn't matter, only the
property existence is checked)_
.
- **`"on_closure"`** (optional, string) : the strategy to use when the Storage
is removed. There are 2 options:
- _unset_: the database remains untouched (this is the default behaviour)
- `"destroy_db"`: the database is destroyed (i.e. removed)
.
-------------------------------
.
## **Behaviour of the backend**
.
### Mapping to RocksDB database
.
Each **storage** will map to a RocksDB database stored in directory:
`${ZENOH_BACKEND_ROCKSDB_ROOT}/`, where:
.
- `${ZENOH_BACKEND_ROCKSDB_ROOT}` is an environment variable that could be
specified before zenoh router startup.
If this variable is not specified `${ZENOH_HOME}/zenoh_backend_rocksdb` will
be used
(where the default value of `${ZENOH_HOME}` is `~/.zenoh`).
- `` is the `"dir"` property specified at storage creation.
ch zenoh **key/value** put into the storage will map to 2 **key/values** in the
database:
- For both, the database key is the zenoh key, stripped from the
`"strip_prefix"` property specified at storage creation.
- In the `"default"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with the zenoh encoded value as a value.
- In the `"data_info"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with a bytes buffer encoded in this order:
- the Timestamp encoded as: 8 bytes for the time + 16 bytes for the HLC ID
- a "is deleted" flag encoded as a boolean on 1 byte
- the encoding prefix flag encoded as a ZInt (variable length)
- the encoding suffix encoded as a String (string length as a ZInt + string
bytes without ending `\0`)
.
### Behaviour on deletion
.
On deletion of a key, the corresponding key is removed from the `"default"`
Column Family. An entry with the
"deletion" flag set to true and the deletion timestamp is inserted in the
`"data-info"` Column Family
(to avoid re-insertion of points with an older timestamp in case of un-ordered
messages).
At regular interval, a task cleans-up the `"data-info"` Column Family from
entries with old timestamps and
the "deletion" flag set to true
.
### Behaviour on GET
.
On GET operations:
.
- if the selector is a unique key (i.e. not containing any `'*'`): the value
and its encoding and timestamp
for the corresponding key are directly retrieved from the 2 Column Families
using `get` RocksDB operation.
- if the selector is a key expression: the storage searches for matching keys,
leveraging RocksDB's [Prefix
Seek](https://github.com/facebook/rocksdb/wiki/Prefix-Seek) if possible to
minimize the number of entries to check.
.
-------------------------------
.
## How to install it
.
To install the latest release of this backend library, you can do as follows:
.
### Manual installation (all platforms)
.
All release packages can be downloaded from:
.
-
[https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/](https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/)
.
Each subdirectory has the name of the Rust target. See the platforms each
target corresponds to on
[https://doc.rust-lang.org/stable/rustc/platform-support.html](https://doc.rust-lang.org/stable/rustc/platform-support.html)
.
Choose your platform and download the `.zip` file.
Unzip it in the same directory than `zenohd` or to any directory where it can
find the backend library (e.g. /usr/lib or ~/.zenoh/lib)
.
### Linux Debian
.
Add Eclipse Zenoh private repository to the sources list, and install the
`zenoh-backend-rocksdb` package:
.
```bash
echo "deb [trusted=yes] https://download.eclipse.org/zenoh/debian-repo/ /" |
sudo tee -a /etc/apt/sources.list.d/zenoh.list > /dev/null
sudo apt update
sudo apt install zenoh-backend-rocksdb
```
.
-------------------------------
.
## How to build it
.
> :warning: **WARNING** :warning: : Zenoh and its ecosystem are under active
development. When you build from git, make sure you also build from git any
other Zenoh repository you plan to use (e.g. binding, plugin, backend, etc.).
It may happen that some changes in git are not compatible with the most recent
packaged Zenoh release (e.g. deb, docker, pip). We put particular effort in
mantaining compatibility between the various git repositories in the Zenoh
project.
.
At first, install [Clang](https://clang.llvm.org/) and [Cargo and
Rust](https://doc.rust-lang.org/cargo/getting-started/installation.html). If
you already have the Rust toolchain installed, make sure it is up-to-date with:
.
```bash
rustup update
```
.
> :warning: **WARNING** :warning: : As Rust doesn't have a stable ABI, the
backend library should be
built with the exact same Rust version than `zenohd`, and using for `zenoh`
dependency the same version (or commit number) than 'zenohd'.
Otherwise, incompatibilities in memory mapping of shared types between `zenohd`
and the library can lead to a `"SIGSEV"` crash.
.
To know the Rust version you're `zenohd` has been built with, use the
`--version` option.
Example:
.
```bash
$ zenohd --version
The zenoh router v0.6.0-beta.1 built with rustc 1.64.0 (a55dd71d5 2022-09-19)
```
.
Here, `zenohd` has been built with the rustc version `1.64.0`.
Install and use this toolchain with the following command:
.
```bash
rustup default 1.64.0
```
.
And `zenohd` version corresponds to an un-released commit with id `1f20c86`.
Update the `zenoh` dependency in Cargo.lock with this command:
.
```bash
cargo update -p zenoh --precise 1f20c86
```
.
Then build the backend with:
.
```bash
cargo build --release --all-targets
```
Package: zenoh-backend-rocksdb
Version: 1.2.1
Architecture: armel
Maintainer: zenoh-dev@eclipse.org
Installed-Size: 16097
Depends: zenoh-plugin-storage-manager (=1.2.1)
Filename: 1.2.1/zenoh-backend-rocksdb_1.2.1_armel.deb
Size: 3835932
MD5sum: 32cbfe7b58cecbee68b8cc28793132fe
SHA1: a459d433cbafb0eb9b3880d9935460e8368c42ca
SHA256: 60764020f69627f71ee0f72e72b8ba36ad6afe264a2cd8607528117dc873e9fc
Section: net
Priority: optional
Homepage: http://zenoh.io
Description: Backend for Zenoh using RocksDB
.
[](https://github.com/eclipse-zenoh/zenoh-backend-rocksdb/actions?query=workflow%3A%22CI%22)
[](https://github.com/eclipse-zenoh/roadmap/discussions)
[](https://discord.gg/2GJ958VuHs)
[](https://choosealicense.com/licenses/epl-2.0/)
[](https://opensource.org/licenses/Apache-2.0)
.
# Eclipse Zenoh
.
The Eclipse Zenoh: Zero Overhead Pub/sub, Store/Query and Compute.
.
Zenoh (pronounce _/zeno/_) unifies data in motion, 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](http://zenoh.io) and the
[roadmap](https://github.com/eclipse-zenoh/roadmap) for more detailed
information.
.
-------------------------------
.
# RocksDB backend
.
In zenoh a backend is a storage technology (such as DBMS, time-series database,
file system...) alowing to store the
keys/values publications made via zenoh and return them on queries.
See the [zenoh documentation](http://zenoh.io/docs/manual/backends/) for more
details.
.
This backend relies on [RocksDB](https://rocksdb.org/) to implement the
storages.
Its library name (without OS specific prefix and extension) that zenoh will
rely on to find it and load it is **`zenoh_backend_rocksdb`**.
.
:point_right: **Install latest release:** see [below](#how-to-install-it)
.
:point_right: **Build "main" branch:** see [below](#how-to-build-it)
.
-------------------------------
.
## **Examples of usage**
.
Prerequisites:
.
- You have a zenoh router (`zenohd`) installed, and the `zenoh_backend_rocksdb`
library file is available in `~/.zenoh/lib`.
- Declare the `ZENOH_BACKEND_ROCKSDB_ROOT` environment variable to the
directory where you want the RocksDB databases
to be stored. If you don't declare it, the `~/.zenoh/zenoh_backend_rocksdb`
directory will be used.
.
You can setup storages either at zenoh router startup via a configuration file,
either at runtime via the zenoh admin space, using for instance the REST API.
.
### **Setup via a JSON5 configuration file**
.
- Create a `zenoh.json5` configuration file containing:
.
```json5
{
plugins: {
// configuration of "storages" plugin:
storage_manager: {
volumes: {
// configuration of a "rocksdb" volume (the "zenoh_backend_rocksdb"
backend library will be loaded at startup)
rocksdb: {}
},
storages: {
// configuration of a "demo" storage using the "rocksdb" volume
demo: {
// the key expression this storage will subscribes to
key_expr: "demo/example/**",
// this prefix will be stripped from the received key when
converting to database key.
// i.e.: "demo/example/a/b" will be stored as "a/b"
strip_prefix: "demo/example",
volume: {
id: "rocksdb",
// the RocksDB database will be stored in this directory
(relative to ${ZENOH_BACKEND_ROCKSDB_ROOT})
dir: "example",
// create the RocksDB database if not already existing
create_db: true
}
}
}
},
// Optionally, add the REST plugin
rest: { http_port: 8000 }
}
}
```
.
- Run the zenoh router with:
`zenohd -c zenoh.json5`
.
### **Setup at runtime via `curl` commands on the admin space**
.
- Run the zenoh router, with write permissions to its admin space and with the
REST plugin:
`zenohd --adminspace-permissions=rw --rest-http-port=8000`
- Add the "rocksdb" backend (the "zenoh_backend_rocksdb" library will be
loaded):
`curl -X PUT -H 'content-type:application/json' -d '{}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/volumes/rocksdb`
- Add the "demo" storage using the "rocksdb" backend:
`curl -X PUT -H 'content-type:application/json' -d
'{key_expr:"demo/example/**",strip_prefix:"demo/example",volume: {id:
"rocksdb",dir: "example",create_db: true}}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/storages/demo`
.
### **Tests using the REST API**
.
Using `curl` to publish and query keys/values, you can:
.
```bash
# Put values that will be stored in the RocksDB database
curl -X PUT -d "TEST-1" http://localhost:8000/demo/example/test-1
curl -X PUT -d "B" http://localhost:8000/demo/example/a/b
.
# Retrive the values
curl http://localhost:8000/demo/example/**
```
.
-------------------------------
.
## Volume-specific storage configuration
.
Storages relying on a RocksDB-backed volume must specify some additional
configuration as shown [above](#setup-via-a-json5-configuration-file):
.
- **`"dir"`** (**required**, string) : The name of directory where the RocksDB
database is stored.
The absolute path will be `${ZENOH_BACKEND_ROCKSDB_ROOT}/`.
.
- **`"create_db"`** (optional, boolean) : create the RocksDB database if not
already existing. Not set by default.
_(the value doesn't matter, only the property existence is checked)_
.
- **`"read_only"`** (optional, boolean) : the storage will only answer to GET
queries. It will not accept any PUT or DELETE message, and won't put anything
in RocksDB database. Not set by default. _(the value doesn't matter, only the
property existence is checked)_
.
- **`"on_closure"`** (optional, string) : the strategy to use when the Storage
is removed. There are 2 options:
- _unset_: the database remains untouched (this is the default behaviour)
- `"destroy_db"`: the database is destroyed (i.e. removed)
.
-------------------------------
.
## **Behaviour of the backend**
.
### Mapping to RocksDB database
.
Each **storage** will map to a RocksDB database stored in directory:
`${ZENOH_BACKEND_ROCKSDB_ROOT}/`, where:
.
- `${ZENOH_BACKEND_ROCKSDB_ROOT}` is an environment variable that could be
specified before zenoh router startup.
If this variable is not specified `${ZENOH_HOME}/zenoh_backend_rocksdb` will
be used
(where the default value of `${ZENOH_HOME}` is `~/.zenoh`).
- `` is the `"dir"` property specified at storage creation.
ch zenoh **key/value** put into the storage will map to 2 **key/values** in the
database:
- For both, the database key is the zenoh key, stripped from the
`"strip_prefix"` property specified at storage creation.
- In the `"default"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with the zenoh encoded value as a value.
- In the `"data_info"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with a bytes buffer encoded in this order:
- the Timestamp encoded as: 8 bytes for the time + 16 bytes for the HLC ID
- a "is deleted" flag encoded as a boolean on 1 byte
- the encoding prefix flag encoded as a ZInt (variable length)
- the encoding suffix encoded as a String (string length as a ZInt + string
bytes without ending `\0`)
.
### Behaviour on deletion
.
On deletion of a key, the corresponding key is removed from the `"default"`
Column Family. An entry with the
"deletion" flag set to true and the deletion timestamp is inserted in the
`"data-info"` Column Family
(to avoid re-insertion of points with an older timestamp in case of un-ordered
messages).
At regular interval, a task cleans-up the `"data-info"` Column Family from
entries with old timestamps and
the "deletion" flag set to true
.
### Behaviour on GET
.
On GET operations:
.
- if the selector is a unique key (i.e. not containing any `'*'`): the value
and its encoding and timestamp
for the corresponding key are directly retrieved from the 2 Column Families
using `get` RocksDB operation.
- if the selector is a key expression: the storage searches for matching keys,
leveraging RocksDB's [Prefix
Seek](https://github.com/facebook/rocksdb/wiki/Prefix-Seek) if possible to
minimize the number of entries to check.
.
-------------------------------
.
## How to install it
.
To install the latest release of this backend library, you can do as follows:
.
### Manual installation (all platforms)
.
All release packages can be downloaded from:
.
-
[https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/](https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/)
.
Each subdirectory has the name of the Rust target. See the platforms each
target corresponds to on
[https://doc.rust-lang.org/stable/rustc/platform-support.html](https://doc.rust-lang.org/stable/rustc/platform-support.html)
.
Choose your platform and download the `.zip` file.
Unzip it in the same directory than `zenohd` or to any directory where it can
find the backend library (e.g. /usr/lib or ~/.zenoh/lib)
.
### Linux Debian
.
Add Eclipse Zenoh private repository to the sources list, and install the
`zenoh-backend-rocksdb` package:
.
```bash
echo "deb [trusted=yes] https://download.eclipse.org/zenoh/debian-repo/ /" |
sudo tee -a /etc/apt/sources.list.d/zenoh.list > /dev/null
sudo apt update
sudo apt install zenoh-backend-rocksdb
```
.
-------------------------------
.
## How to build it
.
> :warning: **WARNING** :warning: : Zenoh and its ecosystem are under active
development. When you build from git, make sure you also build from git any
other Zenoh repository you plan to use (e.g. binding, plugin, backend, etc.).
It may happen that some changes in git are not compatible with the most recent
packaged Zenoh release (e.g. deb, docker, pip). We put particular effort in
mantaining compatibility between the various git repositories in the Zenoh
project.
.
At first, install [Clang](https://clang.llvm.org/) and [Cargo and
Rust](https://doc.rust-lang.org/cargo/getting-started/installation.html). If
you already have the Rust toolchain installed, make sure it is up-to-date with:
.
```bash
rustup update
```
.
> :warning: **WARNING** :warning: : As Rust doesn't have a stable ABI, the
backend library should be
built with the exact same Rust version than `zenohd`, and using for `zenoh`
dependency the same version (or commit number) than 'zenohd'.
Otherwise, incompatibilities in memory mapping of shared types between `zenohd`
and the library can lead to a `"SIGSEV"` crash.
.
To know the Rust version you're `zenohd` has been built with, use the
`--version` option.
Example:
.
```bash
$ zenohd --version
The zenoh router v0.6.0-beta.1 built with rustc 1.64.0 (a55dd71d5 2022-09-19)
```
.
Here, `zenohd` has been built with the rustc version `1.64.0`.
Install and use this toolchain with the following command:
.
```bash
rustup default 1.64.0
```
.
And `zenohd` version corresponds to an un-released commit with id `1f20c86`.
Update the `zenoh` dependency in Cargo.lock with this command:
.
```bash
cargo update -p zenoh --precise 1f20c86
```
.
Then build the backend with:
.
```bash
cargo build --release --all-targets
```
Package: zenoh-backend-rocksdb
Version: 1.2.1
Architecture: arm64
Maintainer: zenoh-dev@eclipse.org
Installed-Size: 18294
Depends: zenoh-plugin-storage-manager (=1.2.1)
Filename: 1.2.1/zenoh-backend-rocksdb_1.2.1_arm64.deb
Size: 4030324
MD5sum: 27e2fb1810d75a02a06105214d826dd6
SHA1: c1791cd20e0027c29bf999cd88710d1d9a95a029
SHA256: eba3c2694cdec99160d2cc993c0175749114e068c5c8923462ae50e2a0f076d8
Section: net
Priority: optional
Homepage: http://zenoh.io
Description: Backend for Zenoh using RocksDB
.
[](https://github.com/eclipse-zenoh/zenoh-backend-rocksdb/actions?query=workflow%3A%22CI%22)
[](https://github.com/eclipse-zenoh/roadmap/discussions)
[](https://discord.gg/2GJ958VuHs)
[](https://choosealicense.com/licenses/epl-2.0/)
[](https://opensource.org/licenses/Apache-2.0)
.
# Eclipse Zenoh
.
The Eclipse Zenoh: Zero Overhead Pub/sub, Store/Query and Compute.
.
Zenoh (pronounce _/zeno/_) unifies data in motion, 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](http://zenoh.io) and the
[roadmap](https://github.com/eclipse-zenoh/roadmap) for more detailed
information.
.
-------------------------------
.
# RocksDB backend
.
In zenoh a backend is a storage technology (such as DBMS, time-series database,
file system...) alowing to store the
keys/values publications made via zenoh and return them on queries.
See the [zenoh documentation](http://zenoh.io/docs/manual/backends/) for more
details.
.
This backend relies on [RocksDB](https://rocksdb.org/) to implement the
storages.
Its library name (without OS specific prefix and extension) that zenoh will
rely on to find it and load it is **`zenoh_backend_rocksdb`**.
.
:point_right: **Install latest release:** see [below](#how-to-install-it)
.
:point_right: **Build "main" branch:** see [below](#how-to-build-it)
.
-------------------------------
.
## **Examples of usage**
.
Prerequisites:
.
- You have a zenoh router (`zenohd`) installed, and the `zenoh_backend_rocksdb`
library file is available in `~/.zenoh/lib`.
- Declare the `ZENOH_BACKEND_ROCKSDB_ROOT` environment variable to the
directory where you want the RocksDB databases
to be stored. If you don't declare it, the `~/.zenoh/zenoh_backend_rocksdb`
directory will be used.
.
You can setup storages either at zenoh router startup via a configuration file,
either at runtime via the zenoh admin space, using for instance the REST API.
.
### **Setup via a JSON5 configuration file**
.
- Create a `zenoh.json5` configuration file containing:
.
```json5
{
plugins: {
// configuration of "storages" plugin:
storage_manager: {
volumes: {
// configuration of a "rocksdb" volume (the "zenoh_backend_rocksdb"
backend library will be loaded at startup)
rocksdb: {}
},
storages: {
// configuration of a "demo" storage using the "rocksdb" volume
demo: {
// the key expression this storage will subscribes to
key_expr: "demo/example/**",
// this prefix will be stripped from the received key when
converting to database key.
// i.e.: "demo/example/a/b" will be stored as "a/b"
strip_prefix: "demo/example",
volume: {
id: "rocksdb",
// the RocksDB database will be stored in this directory
(relative to ${ZENOH_BACKEND_ROCKSDB_ROOT})
dir: "example",
// create the RocksDB database if not already existing
create_db: true
}
}
}
},
// Optionally, add the REST plugin
rest: { http_port: 8000 }
}
}
```
.
- Run the zenoh router with:
`zenohd -c zenoh.json5`
.
### **Setup at runtime via `curl` commands on the admin space**
.
- Run the zenoh router, with write permissions to its admin space and with the
REST plugin:
`zenohd --adminspace-permissions=rw --rest-http-port=8000`
- Add the "rocksdb" backend (the "zenoh_backend_rocksdb" library will be
loaded):
`curl -X PUT -H 'content-type:application/json' -d '{}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/volumes/rocksdb`
- Add the "demo" storage using the "rocksdb" backend:
`curl -X PUT -H 'content-type:application/json' -d
'{key_expr:"demo/example/**",strip_prefix:"demo/example",volume: {id:
"rocksdb",dir: "example",create_db: true}}'
http://localhost:8000/@/router/local/config/plugins/storage_manager/storages/demo`
.
### **Tests using the REST API**
.
Using `curl` to publish and query keys/values, you can:
.
```bash
# Put values that will be stored in the RocksDB database
curl -X PUT -d "TEST-1" http://localhost:8000/demo/example/test-1
curl -X PUT -d "B" http://localhost:8000/demo/example/a/b
.
# Retrive the values
curl http://localhost:8000/demo/example/**
```
.
-------------------------------
.
## Volume-specific storage configuration
.
Storages relying on a RocksDB-backed volume must specify some additional
configuration as shown [above](#setup-via-a-json5-configuration-file):
.
- **`"dir"`** (**required**, string) : The name of directory where the RocksDB
database is stored.
The absolute path will be `${ZENOH_BACKEND_ROCKSDB_ROOT}/`.
.
- **`"create_db"`** (optional, boolean) : create the RocksDB database if not
already existing. Not set by default.
_(the value doesn't matter, only the property existence is checked)_
.
- **`"read_only"`** (optional, boolean) : the storage will only answer to GET
queries. It will not accept any PUT or DELETE message, and won't put anything
in RocksDB database. Not set by default. _(the value doesn't matter, only the
property existence is checked)_
.
- **`"on_closure"`** (optional, string) : the strategy to use when the Storage
is removed. There are 2 options:
- _unset_: the database remains untouched (this is the default behaviour)
- `"destroy_db"`: the database is destroyed (i.e. removed)
.
-------------------------------
.
## **Behaviour of the backend**
.
### Mapping to RocksDB database
.
Each **storage** will map to a RocksDB database stored in directory:
`${ZENOH_BACKEND_ROCKSDB_ROOT}/`, where:
.
- `${ZENOH_BACKEND_ROCKSDB_ROOT}` is an environment variable that could be
specified before zenoh router startup.
If this variable is not specified `${ZENOH_HOME}/zenoh_backend_rocksdb` will
be used
(where the default value of `${ZENOH_HOME}` is `~/.zenoh`).
- `` is the `"dir"` property specified at storage creation.
ch zenoh **key/value** put into the storage will map to 2 **key/values** in the
database:
- For both, the database key is the zenoh key, stripped from the
`"strip_prefix"` property specified at storage creation.
- In the `"default"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with the zenoh encoded value as a value.
- In the `"data_info"` [Column
Family](https://github.com/facebook/rocksdb/wiki/Column-Families) the key is
put with a bytes buffer encoded in this order:
- the Timestamp encoded as: 8 bytes for the time + 16 bytes for the HLC ID
- a "is deleted" flag encoded as a boolean on 1 byte
- the encoding prefix flag encoded as a ZInt (variable length)
- the encoding suffix encoded as a String (string length as a ZInt + string
bytes without ending `\0`)
.
### Behaviour on deletion
.
On deletion of a key, the corresponding key is removed from the `"default"`
Column Family. An entry with the
"deletion" flag set to true and the deletion timestamp is inserted in the
`"data-info"` Column Family
(to avoid re-insertion of points with an older timestamp in case of un-ordered
messages).
At regular interval, a task cleans-up the `"data-info"` Column Family from
entries with old timestamps and
the "deletion" flag set to true
.
### Behaviour on GET
.
On GET operations:
.
- if the selector is a unique key (i.e. not containing any `'*'`): the value
and its encoding and timestamp
for the corresponding key are directly retrieved from the 2 Column Families
using `get` RocksDB operation.
- if the selector is a key expression: the storage searches for matching keys,
leveraging RocksDB's [Prefix
Seek](https://github.com/facebook/rocksdb/wiki/Prefix-Seek) if possible to
minimize the number of entries to check.
.
-------------------------------
.
## How to install it
.
To install the latest release of this backend library, you can do as follows:
.
### Manual installation (all platforms)
.
All release packages can be downloaded from:
.
-
[https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/](https://download.eclipse.org/zenoh/zenoh-backend-rocksdb/latest/)
.
Each subdirectory has the name of the Rust target. See the platforms each
target corresponds to on
[https://doc.rust-lang.org/stable/rustc/platform-support.html](https://doc.rust-lang.org/stable/rustc/platform-support.html)
.
Choose your platform and download the `.zip` file.
Unzip it in the same directory than `zenohd` or to any directory where it can
find the backend library (e.g. /usr/lib or ~/.zenoh/lib)
.
### Linux Debian
.
Add Eclipse Zenoh private repository to the sources list, and install the
`zenoh-backend-rocksdb` package:
.
```bash
echo "deb [trusted=yes] https://download.eclipse.org/zenoh/debian-repo/ /" |
sudo tee -a /etc/apt/sources.list.d/zenoh.list > /dev/null
sudo apt update
sudo apt install zenoh-backend-rocksdb
```
.
-------------------------------
.
## How to build it
.
> :warning: **WARNING** :warning: : Zenoh and its ecosystem are under active
development. When you build from git, make sure you also build from git any
other Zenoh repository you plan to use (e.g. binding, plugin, backend, etc.).
It may happen that some changes in git are not compatible with the most recent
packaged Zenoh release (e.g. deb, docker, pip). We put particular effort in
mantaining compatibility between the various git repositories in the Zenoh
project.
.
At first, install [Clang](https://clang.llvm.org/) and [Cargo and
Rust](https://doc.rust-lang.org/cargo/getting-started/installation.html). If
you already have the Rust toolchain installed, make sure it is up-to-date with:
.
```bash
rustup update
```
.
> :warning: **WARNING** :warning: : As Rust doesn't have a stable ABI, the
backend library should be
built with the exact same Rust version than `zenohd`, and using for `zenoh`
dependency the same version (or commit number) than 'zenohd'.
Otherwise, incompatibilities in memory mapping of shared types between `zenohd`
and the library can lead to a `"SIGSEV"` crash.
.
To know the Rust version you're `zenohd` has been built with, use the
`--version` option.
Example:
.
```bash
$ zenohd --version
The zenoh router v0.6.0-beta.1 built with rustc 1.64.0 (a55dd71d5 2022-09-19)
```
.
Here, `zenohd` has been built with the rustc version `1.64.0`.
Install and use this toolchain with the following command:
.
```bash
rustup default 1.64.0
```
.
And `zenohd` version corresponds to an un-released commit with id `1f20c86`.
Update the `zenoh` dependency in Cargo.lock with this command:
.
```bash
cargo update -p zenoh --precise 1f20c86
```
.
Then build the backend with:
.
```bash
cargo build --release --all-targets
```