JSON-RPC client generation (#2778)

* Bump jsonrpc & generate clients.

* Initial version of JSON-RPC client.

* Re-wort

* Remove spurious `#[derive(Encode, Decode)]`

They did not compile, since `Encode` and `Decode` are deliberately not
implemented for `usize`.

Fixes #2742.

* Re-write rpc-client example.

* Update to jsonrpc=12.0.0

* Remove unnecessary import

* Bump version.

* Revert version bump.

* Bump again.

substrate/core/rpc/src/chain/error.rs

@@ -14,6 +14,9 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
+
+//! Error helpers for Chain RPC module.
+
 use client;
 use crate::rpc;
 use crate::errors;

substrate/core/rpc/src/chain/mod.rs

@@ -16,27 +16,28 @@
 
 //! Substrate blockchain API.
 
-use std::sync::Arc;
+pub mod error;
+pub mod number;
 
-use log::warn;
-use client::{self, Client, BlockchainEvents};
-use jsonrpc_derive::rpc;
-use jsonrpc_pubsub::{typed::Subscriber, SubscriptionId};
-use primitives::{H256, Blake2Hasher};
-use crate::rpc::Result as RpcResult;
-use crate::rpc::futures::{stream, Future, Sink, Stream};
-use runtime_primitives::generic::{BlockId, SignedBlock};
-use runtime_primitives::traits::{Block as BlockT, Header, NumberFor};
-
-use crate::subscriptions::Subscriptions;
-
-mod error;
 #[cfg(test)]
 mod tests;
-mod number;
 
+use std::sync::Arc;
+
+use client::{self, Client, BlockchainEvents};
+use crate::rpc::Result as RpcResult;
+use crate::rpc::futures::{stream, Future, Sink, Stream};
+use crate::subscriptions::Subscriptions;
+use jsonrpc_derive::rpc;
+use jsonrpc_pubsub::{typed::Subscriber, SubscriptionId};
+use log::warn;
+use primitives::{H256, Blake2Hasher};
+use runtime_primitives::generic::{BlockId, SignedBlock};
+use runtime_primitives::traits::{Block as BlockT, Header, NumberFor};
 use self::error::Result;
 
+pub use self::gen_client::Client as ChainClient;
+
 /// Substrate blockchain API
 #[rpc]
 pub trait ChainApi<Number, Hash, Header, SignedBlock> {

substrate/core/rpc/src/chain/number.rs

@@ -14,7 +14,9 @@
 // You should have received a copy of the GNU General Public License
 // along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
 
-use serde::Deserialize;
+//! Chain RPC Block number type.
+
+use serde::{Serialize, Deserialize};
 use std::{convert::TryFrom, fmt::Debug};
 use primitives::U256;
 
@@ -25,7 +27,7 @@ use primitives::U256;
 /// or we attempt to parse given hex value.
 /// We do that for consistency with the returned type, default generic header
 /// serializes block number as hex to avoid overflows in JavaScript.
-#[derive(Deserialize)]
+#[derive(Serialize, Deserialize)]
 #[serde(untagged)]
 pub enum NumberOrHex<Number> {
 	/// The original header number type of block.