How is Subspace RPC implemented in JsonRpc?

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1

Hi Nazar, I want to develop subspace SDKs for other languages like C#, but I’m encountering a bit of an issue with RPC, such as with something like SubscribeSlotInfo subscription. In conventional JsonRpc, I do this by adding a local method and then waiting for the server to call me back. However, in your Rust code, I noticed that after you call subspace_subscribeSlotInfo, it returns a Value, but you are able to directly convert this Value into a Stream and wait for subsequent returns. So, I want to know the details of this RPC implementation. I’m not familiar with Rust, and I’d like to understand firstly, how you convert the return Value of subspace_subscribeSlotInfo into a Stream, and secondly, how the Stream is handled or called back when you await it?

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2

It depends on the library you’re using. Since this is just JSON-RPC 2.0, you can use any library that supports it. If you don’t know Rust it is not that big of a deal, you basically only need this to see available methods:

And then check what fields corresponding data structures have.

3

"Hi Nazar, after I called subspace_subscribeSlotInfo, the node successfully returned a string similar to ‘3PWEWad1yBr88vcl’, but subsequently, it did not continue to call my subspace_slot_info. It seems like some problems have occurred. Can you provide some help?

4

The definition of SlotInfo is as follows:

        public class SlotInfoModel { 
            public UInt64 slot_number { get; set; }
            // size of 32
            public byte[] global_challenge { get; set; }
            public UInt64 solution_range { get; set; }
            public UInt64 voting_solution_range { get; set; }
        }

i use the StreamJsonRpc lib,
The definition of subspace_slot_info is as follows:

rpcClient.AddLocalRpcMethod("subspace_slot_info", new Action<SlotInfo.SlotInfoModel>((result) =>
{



}));

After I called subspace_subscribeSlotInfo , this method did not receive any callbacks.

5

I recommend you read JSON-RPC 2.0 specification if you are not using off-the-shelf JSON-RPC libraries. What you’ve got is an identifier of the subscription. If your node was started with --validator you’ll see subsequent messages with that subscription ID.

6

I have successfully completed the subscription to the RPC event. I will refine the library a bit more before making it open source. Thank you for your help.

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