Delve exposes a JSON-RPC API interface.
Note that this JSON-RPC interface is served over a streaming socket, not over HTTP.
Here is an (incomplete) list of language implementations.
Delve currently supports two versions of its API. By default a headless instance of dlv will serve APIv1, however new clients should use APIv2 as new features will only be made available through version 2. To select APIv2 use --api-version=2 command line argument.
All the methods of the type service/rpc2.RPCServer can be called using JSON-RPC, the documentation for these calls is available on godoc.
Note that all exposed methods take one single input parameter (usually called args) of a struct type and also return a result of a struct type. Also note that the method name should be prefixed with RPCServer. in JSON-RPC.
Your client wants to set a breakpoint on the function main.main.
The first step will be calling the method FindLocation with Scope = api.EvalScope{ GoroutineID: -1, Frame: 0} and Loc = "main.main". The JSON-RPC request packet should look like this:
{"method":"RPCServer.FindLocation","params":[{"Scope":{"GoroutineID":-1,"Frame":0},"Loc":"main.main"}],"id":2}
the response packet will look like this:
{"id":2,"result":{"Locations":[{"pc":4199019,"file":"/home/a/temp/callme/callme.go","line":31,"function":{"name":"main.main","value":4198992,"type":84,"goType":0}}]},"error":null}
Now your client should call the method CreateBreakpoint and specify 4199019 (the pc field in the response object) as the target address:
{"method":"RPCServer.CreateBreakpoint","params":[{"Breakpoint":{"addr":4199019}}],"id":3}
if this request is successful your client will receive the following response:
{"id":3,"result":{"Breakpoint":{"id":1,"name":"","addr":4199019,"file":"/home/a/temp/callme/callme.go","line":31,"functionName":"main.main","Cond":"","continue":false,"goroutine":false,"stacktrace":0,"LoadArgs":null,"LoadLocals":null,"hitCount":{},"totalHitCount":0}},"error":null}