updating readme

esp-idf-examples/simplewifi-rpc/.gitignore

@@ -5,3 +5,4 @@ src/localnim/
 .env
 results.json
 main/nimble/
+rpc_cli

esp-idf-examples/simplewifi-rpc/Makefile

@@ -16,19 +16,19 @@ default: mpack_rpc_queue_server
 
 json_rpc_server: clean
 	nim prepare main/wifi_example_main.nim --nimblePath:$(NIMBLE)/pkgs -d:$(ESP_IDF_VERSION) -d:TcpMpackRpcServer $(NIMFLAGS) && idf.py reconfigure 
-	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpMpackRpcServer rpc_cli_test.nim
+	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpMpackRpcServer -o:rpc_cli rpc_cli_test.nim 
 
 mpack_rpc_server: clean
 	nim prepare main/wifi_example_main.nim --nimblePath:$(NIMBLE)/pkgs -d:$(ESP_IDF_VERSION) -d:TcpMpackRpcServer $(NIMFLAGS) && idf.py reconfigure 
-	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpMpackRpcServer  rpc_cli_test.nim
+	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpMpackRpcServer -o:rpc_cli rpc_cli_test.nim 
 
 mpack_rpc_queue_server: clean
 	nim prepare main/wifi_example_main.nim --nimblePath:$(NIMBLE)/pkgs -d:$(ESP_IDF_VERSION) -d:TcpMpackRpcQueueServer $(NIMFLAGS) && idf.py reconfigure 
-	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpMpackRpcQueueServer  rpc_cli_test.nim
+	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpMpackRpcQueueServer -o:rpc_cli rpc_cli_test.nim 
 
 tcp_echo_server: clean
 	nim prepare main/wifi_example_main.nim --nimblePath:$(NIMBLE)/pkgs -d:$(ESP_IDF_VERSION) -d:TcpEchoServer $(NIMFLAGS) && idf.py reconfigure 
-	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpEchoServer rpc_cli_test.nim
+	nim c --nimblePath:$(NIMBLE)/pkgs -d:TcpEchoServer -o:rpc_clirpc_cli_test.nim 
 
 build: 
 	idf.py build

esp-idf-examples/simplewifi-rpc/README.md

@@ -41,3 +41,21 @@ idf.py -p [port] monitor
 # or together:
 idf.py -p [port] flash monitor
 ```
+
+## Testing Example 
+
+The RPC methods use raw sockets and `selectors` library from Nim's stdlib. This allows the ESP32 code to efficiently check sockets for new messages. The makefile now builds a variant of `rpc_cli` that should work with the chosen method (e.g. mpack or json).
+
+Run it like: 
+
+```sh
+./rpc_cli --ip:$IP --count:1 '{"method": "add", "params": [1,2]}' 
+```
+
+## Notes on the RPC protocol
+
+The `rpc_cli` should give an example of the RPC protocol used. It's roughly based on JSON-RPC, however, using raw socket require a bit more work. Sending RPC messages are sent "raw", e.g. just the message. This limits RPC calls to 1400 bytes and could be fixed in the future. 
+
+For receiving the RPC responses, a very simple protocol is used based on the Erlang "ports" protocol. A 4-byte signed integer with the size of the RPC result is sent first, in network byte order. The RPC client must read these 4 bytes, then read the number of bytes sent. The `rpc_cli` provides an example of how to do this in Nim. This enables returning message that are larger than 1400 bytes. Ideally, this will be done for the incoming RPC message as well. 
+
+The JSON version of the rpc server currently returns a "raw" response.