feat(rpc): enable custom http agent and https agent

README.md

@@ -152,8 +152,28 @@ After that you can use the `core` object to generate addresses, send requests, e
 
 # RPC
 
+## Default RPC
+
 Please see [Default RPC](https://github.com/nervosnetwork/ckb-sdk-js/blob/develop/packages/ckb-sdk-rpc/src/defaultRPC.ts#L165)
 
+## Persistent Connection
+
+Please add `httpAgent` or `httpsAgent` to enable the persistent connection.
+
+If the SDK is running in Node.js, the following steps make the persistent connection available.
+
+```javascript
+// HTTP Agent
+const http = require('http')
+const httpAgent = new http.Agent({ keepAlive: true })
+core.rpc.setNode({ httpAgent })
+
+// HTTPS Agent
+const https = require('https')
+const httpsAgent = new https.Agent({ keepAlive: true })
+core.rpc.setNode({ httpsAgent })
+```
+
 # Errors
 
 1. RPC Errors

packages/ckb-sdk-rpc/__tests__/ckb-rpc-helpers.js

@@ -1,4 +1,6 @@
 const path = require('path')
+const http = require('http')
+const https = require('https')
 
 const env = path.join(__dirname, '../.env')
 
@@ -32,14 +34,32 @@ describe('ckb-rpc settings and helpers', () => {
     rpc.setDebugLevel(DebugLevel.Off)
   })
 
-  it('set node', () => {
+  it('set node url', () => {
     const node = {
       url: 'http://localhost:8114',
     }
     rpc.setNode(node)
     expect(rpc.node).toEqual(node)
   })
 
+  it('set http agent', () => {
+    const httpAgent = new http.Agent()
+    const node = {
+      httpAgent,
+    }
+    rpc.setNode(node)
+    expect(rpc.node.httpAgent).toBeDefined()
+  })
+
+  it('set https agent', () => {
+    const httpsAgent = new https.Agent()
+    const node = {
+      httpsAgent,
+    }
+    rpc.setNode(node)
+    expect(rpc.node.httpsAgent).toBeDefined()
+  })
+
   it('has 27 default rpc', () => {
     expect(rpc.methods.length).toBe(27)
   })

packages/ckb-sdk-rpc/src/method.ts

@@ -34,6 +34,8 @@ class Method {
       },
       data: payload,
       url: this.node.url,
+      httpAgent: this.node.httpAgent,
+      httpsAgent: this.node.httpsAgent,
     }).then(res => {
       if (res.data.id !== id) {
         throw new Error('JSONRPC id not match')

packages/ckb-types/index.d.ts

@@ -38,6 +38,8 @@ declare namespace CKBComponents {
   export type Since = string
   export interface Node {
     url: string
+    httpAgent?: any
+    httpsAgent?: any
   }
   export interface Method {
     name: string