Struct RpcModule

pub struct RpcModule<Context> { /* private fields */ }

Available on crate feature server only.

Sets of JSON-RPC methods can be organized into “module“s that are in turn registered on the server or, alternatively, merged with other modules to construct a cohesive API. RpcModule wraps an additional context argument that can be used to access data during call execution.

Implementations

impl<Context> RpcModule<Context>

pub fn new(ctx: Context) -> Self

Create a new module with a given shared Context.

pub fn from_arc(ctx: Arc<Context>) -> Self

Create a new module from an already shared Context.

This is useful if Context needs to be shared outside of an RpcModule.

pub fn remove_context(self) -> RpcModule<()>

Transform a module into an RpcModule<()> (unit context).

impl<Context: Send + Sync + 'static> RpcModule<Context>

pub fn register_method<R, F>( &mut self, method_name: &'static str, callback: F, ) -> Result<&mut MethodCallback, RegisterMethodError>

where Context: Send + Sync + 'static, R: IntoResponse + 'static, F: Fn(Params<'_>, &Context, &Extensions) -> R + Send + Sync + 'static,

Register a new synchronous RPC method, which computes the response with the given callback.

Examples

use jsonrpsee_core::server::RpcModule;

let mut module = RpcModule::new(());
module.register_method("say_hello", |_params, _ctx, _| "lo").unwrap();

pub fn remove_method( &mut self, method_name: &'static str, ) -> Option<MethodCallback>

Removes the method if it exists.

Be aware that a subscription consist of two methods, subscribe and unsubscribe and it’s the caller responsibility to remove both subscribe and unsubscribe methods for subscriptions.

pub fn register_async_method<R, Fun, Fut>( &mut self, method_name: &'static str, callback: Fun, ) -> Result<&mut MethodCallback, RegisterMethodError>

where R: IntoResponse + 'static, Fut: Future<Output = R> + Send, Fun: Fn(Params<'static>, Arc<Context>, Extensions) -> Fut + Clone + Send + Sync + 'static,

Register a new asynchronous RPC method, which computes the response with the given callback.

Examples

use jsonrpsee_core::server::RpcModule;

let mut module = RpcModule::new(());
module.register_async_method("say_hello", |_params, _ctx, _| async { "lo" }).unwrap();

pub fn register_blocking_method<R, F>( &mut self, method_name: &'static str, callback: F, ) -> Result<&mut MethodCallback, RegisterMethodError>

where Context: Send + Sync + 'static, R: IntoResponse + 'static, F: Fn(Params<'_>, Arc<Context>, Extensions) -> R + Clone + Send + Sync + 'static,

Register a new blocking synchronous RPC method, which computes the response with the given callback. Unlike the regular register_method, this method can block its thread and perform expensive computations.

pub fn register_subscription<R, F, Fut>( &mut self, subscribe_method_name: &'static str, notif_method_name: &'static str, unsubscribe_method_name: &'static str, callback: F, ) -> Result<&mut MethodCallback, RegisterMethodError>

where Context: Send + Sync + 'static, F: Fn(Params<'static>, PendingSubscriptionSink, Arc<Context>, Extensions) -> Fut + Send + Sync + Clone + 'static, Fut: Future<Output = R> + Send + 'static, R: IntoSubscriptionCloseResponse + Send,

Register a new publish/subscribe interface using JSON-RPC notifications.

It implements the ethereum pubsub specification with an option to choose custom subscription ID generation.

Furthermore, it generates the unsubscribe implementation where a bool is used as the result to indicate whether the subscription was successfully unsubscribed to or not. For instance an unsubscribe call may fail if a non-existent subscription ID is used in the call.

This method ensures that the subscription_method_name and unsubscription_method_name are unique. The notif_method_name argument sets the content of the method field in the JSON document that the server sends back to the client. The uniqueness of this value is not machine checked and it’s up to the user to ensure it is not used in any other RpcModule used in the server.

Arguments

• subscription_method_name - name of the method to call to initiate a subscription
• notif_method_name - name of method to be used in the subscription payload (technically a JSON-RPC notification)
• unsubscription_method - name of the method to call to terminate a subscription
• callback - A callback to invoke on each subscription; it takes three parameters:
  • Params: JSON-RPC parameters in the subscription call.
  • PendingSubscriptionSink: A pending subscription waiting to be accepted, in order to send out messages on the subscription
  • Context: Any type that can be embedded into the RpcModule.

Returns

An async block which returns something that implements crate::server::IntoSubscriptionCloseResponse which decides what action to take when the subscription ends whether such as to sent out another message on the subscription stream before closing down it.

NOTE: The return value is ignored if PendingSubscriptionSink hasn’t been called or is unsuccessful, as the subscription is not allowed to send out subscription notifications before the actual subscription has been established.

This is implemented for Result<T, E> and ().

It’s recommended to use Result if you want to propagate the error as special error notification Another option is to implement crate::server::IntoSubscriptionCloseResponse if you want customized behaviour.

The error notification has the following format:

{
 "jsonrpc": "2.0",
 "method": "<method>",
 "params": {
   "subscription": "<subscriptionID>",
   "error": <your msg>
   }
 }
}

Examples

use jsonrpsee_core::server::{RpcModule, SubscriptionSink, SubscriptionMessage};
use jsonrpsee_types::ErrorObjectOwned;

let mut ctx = RpcModule::new(99_usize);
ctx.register_subscription("sub", "notif_name", "unsub", |params, pending, ctx, _| async move {

    let x = match params.one::<usize>() {
        Ok(x) => x,
        Err(e) => {
           pending.reject(ErrorObjectOwned::from(e)).await;
           // If the subscription has not been "accepted" then
           // the return value will be "ignored" as it's not
           // allowed to send out any further notifications on
           // on the subscription.
           return Ok(());
        }
    };

    // Mark the subscription is accepted after the params has been parsed successful.
    // This is actually responds the underlying RPC method call and may fail if the
    // connection is closed.
    let sink = pending.accept().await?;
    let sum = x + (*ctx);

    // This will send out an error notification if it fails.
    //
    // If you need some other behavior implement or custom format of the error field
    // you need to manually handle that.
    let msg = SubscriptionMessage::from_json(&sum)?;

    // This fails only if the connection is closed
    sink.send(msg).await?;

    Ok(())
});

pub fn register_subscription_raw<R, F>( &mut self, subscribe_method_name: &'static str, notif_method_name: &'static str, unsubscribe_method_name: &'static str, callback: F, ) -> Result<&mut MethodCallback, RegisterMethodError>

where Context: Send + Sync + 'static, F: Fn(Params<'_>, PendingSubscriptionSink, Arc<Context>, &Extensions) -> R + Send + Sync + Clone + 'static, R: IntoSubscriptionCloseResponse,

Similar to RpcModule::register_subscription but a little lower-level API where handling the subscription is managed the user i.e, polling the subscription such as spawning a separate task to do so.

This is more efficient as this doesn’t require cloning the params in the subscription and it won’t send out a close message. Such things are delegated to the user of this API

Examples

use jsonrpsee_core::server::{RpcModule, SubscriptionSink, SubscriptionMessage};
use jsonrpsee_types::ErrorObjectOwned;

let mut ctx = RpcModule::new(99_usize);
ctx.register_subscription_raw("sub", "notif_name", "unsub", |params, pending, ctx, _| {

    // The params are parsed outside the async block below to avoid cloning the bytes.
    let val = match params.one::<usize>() {
        Ok(val) => val,
        Err(e) => {
            // If the subscription has not been "accepted" then
            // the return value will be "ignored" as it's not
            // allowed to send out any further notifications on
            // on the subscription.
            tokio::spawn(pending.reject(ErrorObjectOwned::from(e)));
            return;
        }
    };

    tokio::spawn(async move {
        // Mark the subscription is accepted after the params has been parsed successful.
        // This is actually responds the underlying RPC method call and may fail if the
        // connection is closed.
        let sink = pending.accept().await.unwrap();
        let sum = val + (*ctx);

        let msg = SubscriptionMessage::from_json(&sum).unwrap();

        // This fails only if the connection is closed
        sink.send(msg).await.unwrap();
    });
});

pub fn register_alias( &mut self, alias: &'static str, existing_method: &'static str, ) -> Result<(), RegisterMethodError>

Register an alias for an existing_method. Alias uniqueness is enforced.

Methods from Deref<Target = Methods>

pub fn verify_method_name( &mut self, name: &'static str, ) -> Result<(), RegisterMethodError>

Verifies that the method name is not already taken, and returns an error if it is.

pub fn verify_and_insert( &mut self, name: &'static str, callback: MethodCallback, ) -> Result<&mut MethodCallback, RegisterMethodError>

Inserts the method callback for a given name, or returns an error if the name was already taken. On success it returns a mut reference to the MethodCallback just inserted.

pub fn merge( &mut self, other: impl Into<Methods>, ) -> Result<(), RegisterMethodError>

Merge two Methods’s by adding all MethodCallbacks from other into self. Fails if any of the methods in other is present already.

pub fn method(&self, method_name: &str) -> Option<&MethodCallback>

Returns the method callback.

pub fn method_with_name( &self, method_name: &str, ) -> Option<(&'static str, &MethodCallback)>

Returns the method callback along with its name. The returned name is same as the method_name, but its lifetime bound is 'static.

pub async fn call<Params: ToRpcParams, T: DeserializeOwned + Clone>( &self, method: &str, params: Params, ) -> Result<T, MethodsError>

Helper to call a method on the RPC module without having to spin up a server.

The params must be serializable as JSON array, see ToRpcParams for further documentation.

Returns the decoded value of the result field in JSON-RPC response if successful.

Examples

#[tokio::main]
async fn main() {
    use jsonrpsee::{RpcModule, IntoResponse};
    use jsonrpsee::core::RpcResult;

    let mut module = RpcModule::new(());
    module.register_method::<RpcResult<u64>, _>("echo_call", |params, _, _| {
        params.one::<u64>().map_err(Into::into)
    }).unwrap();

    let echo: u64 = module.call("echo_call", [1_u64]).await.unwrap();
    assert_eq!(echo, 1);
}

pub async fn raw_json_request( &self, request: &str, buf_size: usize, ) -> Result<(String, Receiver<String>), Error>

Make a request (JSON-RPC method call or subscription) by using raw JSON.

Returns the raw JSON response to the call and a stream to receive notifications if the call was a subscription.

Examples

#[tokio::main]
async fn main() {
    use jsonrpsee::{RpcModule, SubscriptionMessage};
    use jsonrpsee::types::{response::Success, Response};
    use futures_util::StreamExt;

    let mut module = RpcModule::new(());
    module.register_subscription("hi", "hi", "goodbye", |_, pending, _, _| async {
        let sink = pending.accept().await?;

        // see comment above.
        sink.send("one answer".into()).await?;

        Ok(())
    }).unwrap();
    let (resp, mut stream) = module.raw_json_request(r#"{"jsonrpc":"2.0","method":"hi","id":0}"#, 1).await.unwrap();
    // If the response is an error converting it to `Success` will fail.
    let resp: Success<u64> = serde_json::from_str::<Response<u64>>(&resp).unwrap().try_into().unwrap();
    let sub_resp = stream.recv().await.unwrap();
    assert_eq!(
        format!(r#"{{"jsonrpc":"2.0","method":"hi","params":{{"subscription":{},"result":"one answer"}}}}"#, resp.result),
        sub_resp
    );
}

pub async fn subscribe_unbounded( &self, sub_method: &str, params: impl ToRpcParams, ) -> Result<Subscription, MethodsError>

Helper to create a subscription on the RPC module without having to spin up a server.

The params must be serializable as JSON array, see ToRpcParams for further documentation.

Returns Subscription on success which can used to get results from the subscription.

Examples

#[tokio::main]
async fn main() {
    use jsonrpsee::{RpcModule, SubscriptionMessage};
    use jsonrpsee::core::{EmptyServerParams, RpcResult};

    let mut module = RpcModule::new(());
    module.register_subscription("hi", "hi", "goodbye", |_, pending, _, _| async move {
        let sink = pending.accept().await?;
        sink.send("one answer".into()).await?;
        Ok(())
    }).unwrap();

    let mut sub = module.subscribe_unbounded("hi", EmptyServerParams::new()).await.unwrap();
    // In this case we ignore the subscription ID,
    let (sub_resp, _sub_id) = sub.next::<String>().await.unwrap().unwrap();
    assert_eq!(&sub_resp, "one answer");
}

pub async fn subscribe( &self, sub_method: &str, params: impl ToRpcParams, buf_size: usize, ) -> Result<Subscription, MethodsError>

Similar to Methods::subscribe_unbounded but it’s using a bounded channel and the buffer capacity must be provided.

pub fn method_names(&self) -> impl Iterator<Item = &'static str> + '_

Returns an Iterator with all the method names registered on this server.

pub fn extensions(&mut self) -> &Extensions

Similar to Methods::extensions_mut but it’s immutable.

pub fn extensions_mut(&mut self) -> &mut Extensions

Get a mutable reference to the extensions to add or remove data from the extensions.

This only affects direct calls to the methods and subscriptions and can be used for example to unit test the API without a server.

Examples

#[tokio::main]
async fn main() {
    use jsonrpsee::{RpcModule, IntoResponse, Extensions};
    use jsonrpsee::core::RpcResult;

    let mut module = RpcModule::new(());
    module.register_method::<RpcResult<u64>, _>("magic_multiply", |params, _, ext| {
        let magic = ext.get::<u64>().copied().unwrap();
        let val = params.one::<u64>()?;
        Ok(val * magic)
    }).unwrap();

    // inject arbitrary data into the extensions.
    module.extensions_mut().insert(33_u64);

    let magic: u64 = module.call("magic_multiply", [1_u64]).await.unwrap();
    assert_eq!(magic, 33);
}

Trait Implementations

impl<Context: Clone> Clone for RpcModule<Context>

fn clone(&self) -> RpcModule<Context>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Context: Debug> Debug for RpcModule<Context>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<Context> Deref for RpcModule<Context>

type Target = Methods

The resulting type after dereferencing.

fn deref(&self) -> &Methods

Dereferences the value.

impl<Context> DerefMut for RpcModule<Context>

fn deref_mut(&mut self) -> &mut Methods

Mutably dereferences the value.

impl<Context> From<RpcModule<Context>> for Methods

fn from(module: RpcModule<Context>) -> Methods

Converts to this type from the input type.