Example Component

Created an example component.  I'm hoping this eases the work required
to create a new component and serves as a starting point for engineers
that are new to cross-platform component development.

Author: bendk

.cargo/config.toml

@@ -10,4 +10,5 @@ suggest-debug-ingestion-sizes = ["run", "-p", "suggest", "--bin", "debug_ingesti
 relevancy = ["run", "-p", "examples-relevancy-cli", "--"]
 suggest = ["run", "-p", "examples-suggest-cli", "--"]
 remote-settings = ["run", "-p", "examples-remote-settings-cli", "--"]
+example = ["run", "-p", "examples-example-cli", "--"]
 start-bindings = ["run", "-p", "start-bindings", "--"]

Cargo.lock

@@ -6,6 +6,8 @@ members = [
     "components/as-ohttp-client",
     "components/autofill",
     "components/crashtest",
+    "components/example",
+    #"components/example/cli",
     "components/fxa-client",
     "components/logins",
     "components/merino",

Cargo.toml

@@ -0,0 +1,34 @@
+# Cargo toml example
+[package]
+name = "example-component"
+version = "0.1.0"
+edition = "2021"
+license = "MPL-2.0"
+
+# Dependency tips:
+#   * Try to match the version number from an existing component
+#   * Be careful when adding new dependencies, since they will require an audit when vendoring the
+#      code into moz-central.
+[dependencies]
+# UniFFI is a dependency for any shared Rust component, make the version match what the other
+# components are using.
+uniffi = { version = "0.28.2" }
+# app-services support crates that you probably want to use.
+error-support = { path = "../support/error" }
+interrupt-support = { path = "../support/interrupt" }
+sql-support = { path = "../support/sql" }
+# parking_lot is for Mutex and other synchronization primitives.
+parking_lot = "0.12"
+# Rust bindings for SQLite
+rusqlite = { version = "0.31.0", features = ["bundled"] }
+# viaduct is our HTTP client, you'll probably also want serde + serde_json to handle
+# serialization/deserialization and url to generate request URLs.
+viaduct = { path = "../viaduct" }
+serde = { version = "1", features=["derive"] }
+serde_json = "1"
+url = "2"
+# Useful Rust crates
+log = "0.4"
+thiserror = "1.0"
+
+[dev-dependencies]

components/example/Cargo.toml

@@ -0,0 +1,21 @@
+This crate is an example Rust component.  It aims to show how components are generally structured
+and the best practices to use when creating one.
+
+For this example, we're going to build the classic TODO app example.  Our app will feature:
+
+* UniFFI-generated Kotlin/Swift bindings
+* SQLite persistence
+* Error reporting, that would report to Sentry if we used this in firefox-android
+* An HTTP REST client.
+
+Each file focuses on a particular part of the component:
+
+* `lib.rs`: Defining a public API and using UniFFI to expose it
+* `error.rs`: Error hierarchies and error reporting
+* `schema.rs`: SQLite schema migrations
+* `db.rs`: SQLite DB operations
+* `http.rs`: HTTP requests
+* `../Cargo.toml`: Dependency management
+* `../../../examples/example-cli`: Creating a CLI for your component
+
+Feel free to ignore files that don't relate to your component and to copy+paste the ones that do.