Add sytstem_health rpc endpoint

packages/types/src/Health.ts

@@ -0,0 +1,34 @@
+// Copyright 2017-2019 @polkadot/types authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import Struct from './codec/Struct';
+import Bool from './Bool';
+import U32 from './U32';
+
+const JSON_MAP = new Map([
+  ['isSyncing', 'is_syncing']
+]);
+
+export default class Health extends Struct {
+  constructor (value?: any) {
+    super({
+      peers: U32,
+      isSyncing: Bool
+    }, value, JSON_MAP);
+  }
+
+  /**
+   * @description The sync status
+   */
+  get isSyncing (): Bool {
+    return this.get('isSyncing') as Bool;
+  }
+
+  /**
+   * @description The numbers of peers as [[U32]]
+   */
+  get peers (): U32 {
+    return this.get('peers') as U32;
+  }
+}

packages/types/src/index.ts

@@ -42,6 +42,7 @@ export { default as H256 } from './H256';
 export { default as H512 } from './H512';
 export { default as Hash } from './Hash';
 export { default as Header } from './Header';
+export { default as Health } from './Health';
 export { default as i8 } from './I8';
 export { default as i16 } from './I16';
 export { default as i32 } from './I32';