feat: adding generic types for server/client

client.ts

@@ -1,11 +1,13 @@
 import { parseMessage, sendMessage } from "./messages.ts";
 import { RPCClientOptions, RPCReply, RPCService } from "./types.ts";
 
-export async function initializeClient(
+export async function initializeClient<
+  Contracts extends Record<string, RPCService>,
+>(
   options: RPCClientOptions,
-): Promise<Record<string, RPCService>> {
+): Promise<Contracts> {
   const ws = new WebSocket(options.host);
-  const call = (service: string, ...args: unknown[]) => {
+  const call = (service: string, ...args: never[]) => {
     return new Promise<RPCReply>((resolve) => {
       const controller = new AbortController();
       const messageId = crypto.randomUUID();
@@ -27,7 +29,7 @@ export async function initializeClient(
     });
   };
   const callService = (service: string) => {
-    return (...args: unknown[]) => {
+    return (...args: never[]) => {
       return call(service, ...args);
     };
   };
@@ -51,5 +53,5 @@ export async function initializeClient(
     };
   });
 
-  return proxy;
+  return proxy as Contracts;
 }

examples/contracts/service1.ts

@@ -0,0 +1,7 @@
+import { RPCReply } from "../../mod.ts";
+
+type ServiceContracts = {
+  hello: (clientName: string) => Promise<RPCReply<void>>;
+};
+
+export default ServiceContracts;

examples/contracts/service2.ts

@@ -0,0 +1,7 @@
+import { RPCReply } from "../../mod.ts";
+
+type ServiceContracts = {
+  hello: (clientName: string) => Promise<RPCReply<void>>;
+};
+
+export default ServiceContracts;

examples/contracts/service3.ts

@@ -0,0 +1,7 @@
+import { RPCReply } from "../../mod.ts";
+
+type ServiceContracts = {
+  hello: (clientName: string) => Promise<RPCReply<void>>;
+};
+
+export default ServiceContracts;

examples/service-1/main.ts

@@ -1,4 +1,6 @@
 import { initializeClient, initializeServer } from "../../mod.ts";
+import Service2Contracts from "../contracts/service2.ts";
+import Service3Contracts from "../contracts/service3.ts";
 
 /**
  * Services
@@ -20,11 +22,11 @@ initializeServer({
   services,
 });
 
-const service2 = await initializeClient({
+const service2 = await initializeClient<Service2Contracts>({
   host: "ws://localhost:3002",
 });
 
-const service3 = await initializeClient({
+const service3 = await initializeClient<Service3Contracts>({
   host: "ws://localhost:3003",
 });
 

examples/service-2/main.ts

@@ -1,5 +1,6 @@
 import { initializeClient, initializeServer } from "../../mod.ts";
-
+import Service1Contracts from "../contracts/service1.ts";
+import Service3Contracts from "../contracts/service3.ts";
 /**
  * Services
  */
@@ -20,11 +21,11 @@ initializeServer({
   services,
 });
 
-const service1 = await initializeClient({
+const service1 = await initializeClient<Service1Contracts>({
   host: "ws://localhost:3001",
 });
 
-const service3 = await initializeClient({
+const service3 = await initializeClient<Service3Contracts>({
   host: "ws://localhost:3003",
 });
 

examples/service-3/main.ts

@@ -1,4 +1,6 @@
 import { initializeClient, initializeServer } from "../../mod.ts";
+import Service1Contracts from "../contracts/service1.ts";
+import Service2Contracts from "../contracts/service2.ts";
 
 /**
  * Services
@@ -20,11 +22,11 @@ initializeServer({
   services,
 });
 
-const service1 = await initializeClient({
+const service1 = await initializeClient<Service1Contracts>({
   host: "ws://localhost:3001",
 });
 
-const service2 = await initializeClient({
+const service2 = await initializeClient<Service2Contracts>({
   host: "ws://localhost:3002",
 });
 

messages.ts

@@ -5,7 +5,5 @@ export function sendMessage(socket: WebSocket, message: RPCMessage | RPCReply) {
 }
 
 export function parseMessage(message: string) {
-  return JSON.parse(
-    message,
-  ) as RPCMessage | RPCReply;
+  return JSON.parse(message) as RPCMessage | RPCReply;
 }

server.ts

@@ -16,7 +16,6 @@ export function initializeServer(options: RPCServerOptions) {
     const { socket, response } = Deno.upgradeWebSocket(req);
 
     socket.addEventListener("message", async (event) => {
-      // TODO: handle parse errors
       const message = parseMessage(event.data) as RPCMessage;
       const service = options.services.get(message.service);
 

types.ts

@@ -1,16 +1,16 @@
 export interface RPCMessage {
   id: string;
   service: string;
-  args: unknown[];
+  args: never[];
 }
 
-export interface RPCReply {
+export interface RPCReply<T = unknown> {
   id: string;
   ok: boolean;
-  payload: unknown;
+  payload: T;
 }
 
-export type RPCService = <T extends RPCReply>(...args: unknown[]) => Promise<T>;
+export type RPCService = (...args: never[]) => Promise<RPCReply>;
 
 export interface RPCServerOptions extends Deno.ServeOptions {
   port: number;