The specification: Specification

The base protocol consists of a header and a content part.

The header part consists of header fields. Each header field is comprised of a name and a value, separated by : (a colon and a space). Each header field is terminated by \r\n.

Header Field Name	Value Type	Description
Content-Length	number	The length of the content part in bytes. This header is required.
Content-Type	string	The mime type of the content part. Defaults to application/vscode-jsonrpc; charset=utf-8

The content part of a message uses JSON-RPC to describe requests, responses and notifications.

综上，一个例子：

Content-Length: ...\r\n
\r\n
{
	"jsonrpc": "2.0",
	"id": 1,
	"method": "textDocument/completion",
	"params": {
		...
	}
}

定义了一些基本类型：integer, uinteger, decimal, LSPObject, LSPArray, LSPAny