Allow generalising over RPC implementation (#634)

* WIP generalising RPC client

* WIP: non-object-safe RpcClientT.. aah generics everywhere

* WIP object-safe RpcClientT trait and no more extra generics

* Get core things compiling again with object-safe RpcClientT trait

* Make jsonrpsee optional and get test-runtime working again

* cargo fmt

* add RpcParams object to enforce correct formatting of rps params

* Wee tweaks

* clippy fixes

* cargo fmt

* TWeak a few types

* make sure we get jsonrpsee-types, too

* Add examples for rpc_params/RpcParams

* more doc tweaks

* remove a now unneeded dev note

* Option<Box<RawValue>> instead to avoid allocations in some cases

* update docs

* tweak RpcClientT trait docs

* Tweak docs around RpcClient and RpcClientT. Don't expose RpcClientT directly

* more doc tweaking about RpcParams and undo decision not to expose RpcParamsT

* Doc tweak

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

* more doc tweaks

* Fix doc thing

* Add an example of injecting a custom RPC client

* Fix a typo

* Address clippy things in example

* Fix a silly typo

* another clippy fix

* rpc_params to panic instead of returning a result, like serde_json::json, and deref on Rpc<T>

* fix docs

Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>

testing/test-runtime/Cargo.toml

@@ -13,3 +13,4 @@ subxt = { path = "../../subxt" }
 sp-core = "6.0.0"
 tokio = { version = "1.8", features = ["macros", "rt-multi-thread"] }
 which = "4.2.2"
+jsonrpsee = { version = "0.15.1", features = ["async-client", "client-ws-transport"] }

testing/test-runtime/build.rs

@@ -15,10 +15,6 @@ use std::{
     thread,
     time,
 };
-use subxt::rpc::{
-    self,
-    ClientT,
-};
 
 static SUBSTRATE_BIN_ENV_VAR: &str = "SUBSTRATE_NODE_PATH";
 
@@ -62,7 +58,8 @@ async fn run() {
 
             // It might take a while for substrate node that spin up the RPC server.
             // Thus, the connection might get rejected a few times.
-            let res = match rpc::ws_client(&format!("ws://localhost:{}", port)).await {
+            use client::ClientT;
+            let res = match client::build(&format!("ws://localhost:{}", port)).await {
                 Ok(c) => c.request("state_getMetadata", None).await,
                 Err(e) => Err(e),
             };
@@ -157,3 +154,41 @@ impl Drop for KillOnDrop {
         let _ = self.0.kill();
     }
 }
+
+// Use jsonrpsee to obtain metadata from the node.
+mod client {
+    pub use jsonrpsee::{
+        client_transport::ws::{
+            InvalidUri,
+            Receiver,
+            Sender,
+            Uri,
+            WsTransportClientBuilder,
+        },
+        core::{
+            client::{
+                Client,
+                ClientBuilder,
+            },
+            Error,
+        },
+    };
+
+    pub use jsonrpsee::core::client::ClientT;
+
+    /// Build WS RPC client from URL
+    pub async fn build(url: &str) -> Result<Client, Error> {
+        let (sender, receiver) = ws_transport(url).await?;
+        Ok(ClientBuilder::default().build_with_tokio(sender, receiver))
+    }
+
+    async fn ws_transport(url: &str) -> Result<(Sender, Receiver), Error> {
+        let url: Uri = url
+            .parse()
+            .map_err(|e: InvalidUri| Error::Transport(e.into()))?;
+        WsTransportClientBuilder::default()
+            .build(url)
+            .await
+            .map_err(|e| Error::Transport(e.into()))
+    }
+}