> ## Documentation Index
> Fetch the complete documentation index at: https://gb.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Protocol Usage

### JSON

Standard JSON

> **Query**: `https://mlink-live.nms.saturn.spiderrockconnect.com/rest/json?apikey="your_api_key_token"&cmd=getmsg&msgtype=OptionNbboQuote&pkey=SPX-NMS-EQT-2024-03-15-4550-C`

> **Response**:

```bash theme={null}
[
  {"header":{"mTyp":"OptionNbboQuote"},"message":{"pkey":{"okey":{"at":"EQT","ts":"NMS","tk":"SPX","dt":"2024-03-15","xx":4550,"cp":"Call"}},"updateType":"PrcChange","bidPrice":288.7,"askPrice":292.2,"bidSize":52,"askSize":30,"cumBidSize":52,"cumAskSize":30,"bidExch":"CBOE","askExch":"CBOE","bidMask":4,"askMask":4,"bidTime":31904651,"askTime":31904651,"srcTimestamp":1690379504651660288,"netTimestamp":1690379504651853000}},
  {"header":{"mTyp":"QueryResult"},"message":{"numMessagesSent":1,"queryElapsed":1.4089,"result":"Ok"}}
]
```

in case we want to show any error response

```md theme={null}
Error: listen EADDRINUSE: address already in use :::3000
```

## Framed JSON

SpiderRock JSON with protobuf-like header. The framing header is a fixed length (14 bytes) and in the form: \r\nJMMMMMLLLLLL, where J is the protocol \[J = framed json, P = protobuf], MMMMM is the message number (zero padded), and LLLLLL is the message length (zero padded).

> **Query**: `https://mlink-live.nms.saturn.spiderrockconnect.com/rest/jsonf?apikey="your_api_key"&cmd=getmsg&msgtype=OptionNbboQuote&pkey=SPX-NMS-EQT-2024-03-15-4550-C`

> **Response**:

```bash theme={null}
J02785000423{"header":{"mTyp":"OptionNbboQuote"},"message":{"pkey":{"okey":{"at":"EQT","ts":"NMS","tk":"SPX","dt":"2024-03-15","xx":4550,"cp":"Call"}},"updateType":"PrcChange","bidPrice":289.4,"askPrice":291.9,"bidSize":11,"askSize":62,"cumBidSize":11,"cumAskSize":62,"bidExch":"CBOE","askExch":"CBOE","bidMask":4,"askMask":4,"bidTime":31982946,"askTime":31982592,"srcTimestamp":1690379582946764032,"netTimestamp":1690379582946960400}}
J03445000101{"header":{"mTyp":"QueryResult"},"message":{"numMessagesSent":1,"queryElapsed":1.4177,"result":"Ok"}}
```

## Protobuf

Google's mechanism for serializing structured data, generally more efficient for processing higher bandwidth, lower-latency applications. See compilation notes below for usages. See above Framed JSON for header information.

> **Query**: `https://mlink-live.nms.saturn.spiderrockconnect.com/rest/proto?apikey="your_api_key"&cmd=getmsg&msgtype=OptionNbboQuote&pkey=SPX-NMS-EQT-2024-03-15-4550-C`

> **Response**:

```bash theme={null}
P02745000499<OptionNbboQuote as protoBuf/binary message>
P03320000111<QueryResult as protoBuf/binary message>
```

<Tip>
  Unlimited editors available under the [Startup
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</Tip>

### Compiling SR proto files

`.proto` files exist in [SRMLink/proto\_files](https://github.com/SpiderRock/MLink-Samples/blob/main/proto_files)

* spiderrock\_common.proto
* All Token .proto files for SpiderRock specific messages

Both of these files need to be compiled to use [protobuf](https://protobuf.dev/overview/) with MLink.

* To compile, first install the compiler, [download the package](https://github.com/protocolbuffers/protobuf/releases/tag/v22.2) and follow the instructions in the README.
* Then, run the compiler, specifying your application's source directory (the current directory is used by default), the destination directory (where you want the generated code to go), and the path to your .proto file.

For python, using python\_out:

```python python theme={null}
protoc -I=$SRC_DIR --python_out=$DST_DIR $SRC_DIR/[File].proto
```

In your specified destination, this will generate N .py files:

* spiderrock\_common\_pb2.py
* "Specific message"\_pb2.py