118 releases (73 stable)
4.9.0-rc.2 | Oct 29, 2024 |
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4.8.2 | Sep 25, 2024 |
4.8.0-rc.1 | Jul 11, 2024 |
4.7.0-rc.3 | Mar 27, 2024 |
1.0.0-alpha9 | Mar 24, 2021 |
#9 in Database implementations
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What is Ditto?
Ditto is a cross-platform, peer-to-peer database that allows apps to sync with and without internet connectivity.
Install Ditto into your application, then use the APIs to read and write data into its storage system, and it will then automatically sync any changes to other devices.
Unlike other synchronization solutions, Ditto is designed for "peer-to-peer" scenarios where it can directly communicate with other devices even without an Internet connection.
Additionally, Ditto automatically manages the complexity of using multiple network transports, like Bluetooth, P2P Wi-Fi, and Local Area Network, to find and connect to other devices and then synchronize any changes.
Ditto Platform Docs
Visit https://docs.ditto.live to learn about the full Ditto platform, including multi-language SDKs, the Ditto Cloud offering, and more.
Rust developers should be sure to check out these essential topics:
- Ditto Edge Sync Platform Basics
- Mesh Networking 101
- Data-Handling Essentials
- Ditto Query Language (DQL)
Playground Quickstart
Ditto offers a "playground" mode that lets you start playing and developing with Ditto without any authentication hassle.
use std::sync::Arc;
use dittolive_ditto::prelude::*;
fn main() -> anyhow::Result<()> {
let app_id = AppId::from_env("DITTO_APP_ID")?;
let playground_token = std::env::var("DITTO_PLAYGROUND_TOKEN")?;
let cloud_sync = true;
let custom_auth_url = None;
// Initialize Ditto
let ditto = Ditto::builder()
.with_root(Arc::new(PersistentRoot::from_current_exe()?))
.with_identity(|ditto_root| {
identity::OnlinePlayground::new(
ditto_root,
app_id,
playground_token,
cloud_sync,
custom_auth_url,
)
})?
.build()?;
// Start syncing with peers
ditto.start_sync()?;
Ok(())
}
Write data using Ditto Query Language (DQL)
The preferred method to write data to Ditto is by using DQL.
To do this, we'll first access the Ditto [Store
][store], then
execute a DQL insert statement.
use dittolive_ditto::prelude::*;
use serde::{Deserialize, Serialize};
#[derive(Serialize, Deserialize)]
struct Car {
color: String,
make: String,
}
async fn dql_insert_car(ditto: &Ditto, car: &Car) -> anyhow::Result<()> {
let store = ditto.store();
let query_result = store.execute(
// `cars` is the collection name
"INSERT INTO cars DOCUMENTS (:newCar)",
Some(serde_json::json!({
"newCar": car
}).into())
).await?;
// Optional: See the count of items inserted
let item_count = query_result.item_count();
// Optional: Inspect each item that was inserted
for query_item in query_result.iter() {
println!("Inserted: {}", query_item.json_string());
}
Ok(())
}
// To call:
async fn call_dql_insert(ditto: Ditto) -> anyhow::Result<()> {
let my_car = Car {
color: "blue".to_string(),
make: "ford".to_string(),
};
dql_insert_car(&ditto, &my_car).await?;
Ok(())
}
- See the DQL INSERT documentation for more info on DQL inserts
- See
QueryResult
andQueryResultItem
to learn about the returned values - See the Ditto Rust template repository for full examples
- Tip: Make sure you have
serde
added to yourCargo.toml
with thederive
feature - Tip: Make sure you have
serde_json
added to yourCargo.toml
# Cargo.toml
[dependencies]
serde = { version = "1.0.204", features = ["derive"] }
serde_json = "1.0.120"
Read data using DQL
use dittolive_ditto::prelude::*;
use serde::{Deserialize, Serialize};
#[derive(Serialize, Deserialize)]
struct Car {
color: String,
make: String,
}
async fn dql_select_cars(ditto: &Ditto, color: &str) -> anyhow::Result<Vec<Car>> {
let store = ditto.store();
let query_result = store.execute(
"SELECT * FROM cars WHERE color = :myColor",
Some(serde_json::json!({
"myColor": color
}).into())
).await?;
let cars = query_result.iter()
.map(|query_item| query_item.deserialize_value::<Car>())
.collect::<Result<Vec<Car>, _>>()?;
Ok(cars)
}
// To call:
async fn call_dql_select(ditto: Ditto) -> anyhow::Result<()> {
let cars: Vec<Car> = dql_select_cars(&ditto, "blue").await?;
Ok(())
}
- See the DQL SELECT documentation for more info on DQL selects
- See the Ditto Rust template repository for full examples
Notes about using a Rust-wrapped C library (advanced)
Please note: this crate uses sane defaults that should "just work". These notes should not be required to get started with Ditto, instead they're meant for people interested in more advanced use-cases such as dynamically linking or pre-downloading the companion C-library artifact.
Ditto's core functionality is released and packaged as a C library, which is
then imported into Rust via the ::dittolive-ditto-sys
crate.
Downloading the companion binary artifact
This crate will, at build time, download the appropriate binary artifact from
https://software.ditto.live/rust/Ditto/<version>/<target>/release/[lib]dittoffi.{a,so,dylib,dll,lib}
- For example: https://software.ditto.live/rust/Ditto/4.5.4/aarch64-apple-darwin/release/libdittoffi.dylib
If you wish to avoid this, you will have to do it yourself:
-
Download the proper binary artifact;
-
Instruct
::dittolive-ditto-sys
'build.rs
script to use it by setting theDITTOFFI_SEARCH_PATH
environment variable appropriately (using an absolute path is recommended).
More precisely, the library search resolution order is as follows:
$DITTOFFI_SEARCH_PATH
(if set)$OUT_DIR
(e.g.${CARGO_TARGET_DIR}/<profile>/build/dittolive-ditto-sys-.../out
)- the current working directory (
$PWD
) $CARGO_TARGET_DIR
- Host built-in defaults (e.g.
/usr/lib
,/lib
,/usr/local/lib
,$HOME/lib
) controlled by (system) linker setup.
If the library artifact is not found at any of these locations, the build script
will attempt its own download into the $OUT_DIR
(and use that path).
Linking
C linkage is typically accompanied with some idiosyncrasies, such as symbol conflicts, or path resolution errors.
The first question you should answer is whether you want your application to use static or dynamic linking to access the Ditto library.
Statically linking libdittoffi
(default, recommended)
This happens whenever the LIBDITTO_STATIC
is explicitly set to 1
, or unset.
If you have a special path to the libdittoffi.a
/dittoffi.lib
file (on Unix
and Windows, respectively), then you can use the DITTOFFI_SEARCH_PATH
env var
to point to its location (using an absolute path), at linkage time (during
cargo build
exclusively).
Dynamically linking (advanced)
You can opt into this behavior by setting the LIBDITTO_STATIC=0
environment variable.
When opting into this, you will have to handle library path resolution to the
libdittoffi.so
/libdittoffi.dylib
/dittoffi.dll
file (on Linux, macOS, and Windows, respectively).
That is, whilst the DITTOFFI_SEARCH_PATH
is still important to help the
cargo build
/ linkage step resolve the dynamic library, the actual usage of
this file happens at runtime, when the (Rust) binary using ::dittolive_ditto
is executed.
It is thus advisable to install the C dynamic library artifact under one of the
system folders, such as /usr/lib
or whatnot on Unix.
Otherwise, you would have to either:
-
meddle with link-time flags to set OS-specific loader metadata in the binary, such as the
R{,UN}PATH
/install_path
, paying special attention to the choice of absolute paths, binary-relative paths (such as$ORIGIN/...
on Linux), or even working-directory-relative paths, or -
use env vars directives for the system dynamic loader, such as
DYLD_FALLBACK_LIBRARY_PATH
on macOS, orLD_LIBRARY_PATH
on Linux.
(For the technically-savy, on macOS, the install_path
of our .dylib
artifact
is set to $rpath/libdittoffi.dylib
).
Dependencies
~10–19MB
~225K SLoC