update readme

examples/client.cpp

@@ -0,0 +1,59 @@
+#include <rest_rpc.hpp>
+using namespace rest_rpc;
+
+// Only need a declaration.
+std::string_view echo(std::string_view str);
+int add(int a, int b);
+
+void basic_usage() {
+  auto rpc_call = []() -> asio::awaitable<void> {
+    rpc_client client;
+    auto ec0 = co_await client.connect("127.0.0.1:9004");
+    if(ec0) {
+      REST_LOG_ERROR << ec0.message();
+      co_return;
+    }
+    
+    auto r = co_await client.call<echo>("test");
+    if(r.ec==rpc_errc::ok) {
+      REST_LOG_INFO << "call result: " << r.value;
+      assert(r.value == "test");
+    }
+    
+    auto r1 = co_await client.call<add>(1, 2);
+    if(r1.ec==rpc_errc::ok) {
+      REST_LOG_INFO << "call result: " << r1.value;
+      assert(r1.value == 3);
+    }
+  };
+  
+  sync_wait(get_global_executor(), rpc_call());
+}
+
+void subscribe() {
+  REST_LOG_INFO << "will subscribe, waiting for publish";
+  auto sub = [&]() -> asio::awaitable<void> {
+    rpc_client client;
+    co_await client.connect("127.0.0.1:9004");
+    while (true) {
+      auto [ec, result] = co_await client.subscribe<std::string>("topic1");
+      if (ec != rpc_errc::ok) {
+        REST_LOG_ERROR << "subscribe failed: " << make_error_code(ec).message();
+        break;
+      }
+      
+      if (result == "close") {
+        co_return;
+      }
+      
+      REST_LOG_INFO << result;
+    }
+  };
+  
+  sync_wait(get_global_executor(), sub());
+}
+
+int main() {
+  basic_usage();
+  subscribe();
+}