🔥 Juno Serverless Blockchain Functions

Developers
1

:wave: Hey everybody,

I’m absolutely thrilled to unveil today’s new addition to the set of features offered by Juno: the introduction of serverless Functions enabling developers to extend the native capabilities of Satellites.

Functions are a set of Rust-based features enabling developers the creation and management of serverless behaviors, called hooks, within canisters which are triggered by specific events like document and asset operations.

A picture is worth a thousand words, so here is basically a representation of a hook that is triggered when a document is set:

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In terms of coding, functions are declared using macros.

#[on_set_doc(collections = ["demo"])]
async fn on_set_doc(context: OnSetDocContext) -> Result<(), String> {
   ic_cdk::print(format!({}, context.caller.to_text()));
   Ok(())
}

Each hook receives a context which includes caller, collection, document, or asset information.

In addition to those functions, I have also improved our custom local development environment, which now supports HTTP outcalls as well. More importantly, it has been simplified to only a few command lines:

  • juno dev eject: scaffolds a Satellite in your project.
  • juno dev start: starts and sets up the configuration for the environment if needed.
  • juno dev build: compiles your custom Satellite.

And that’s it. The local environment takes care of the rest; it supports hot reload :fire:.

Got a tweet out that summarizes all the links. https://twitter.com/daviddalbusco/status/1755961160614965497

Give it a try and let me know what you think.

Happy weekend :sunny:

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2

The next version of Juno will enhance the serverless functions’ features by introducing additional macros. This will allow developers to register synchronous hooks to expand the assertions as well. Thus, they can not only execute jobs after documents and assets have been modified but also implement additional rules to prevent their modification.

#[assert_set_doc]
fn assert_set_doc(_context: AssertSetDocContext) -> Result<(), String> {
    Err("You Shall Not Pass".to_string())
}
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