Docs missing for metadata

[jtremback]

I don't see any documentation here or in the jsonrpc spec on "metadata", and what its role is.

[tomusdrw]

Metadata is a custom extension of JSONRPC spec. It allows a method handler to access some additional data from the transport layer, which is not part of the payload itself.

For instance you can check an HTTP header and alter the behaviour (obviously it's against transport-agnostic JSONRPC spec). More real-life example would be to check authorization header presence in jsonrpc-core middleware and reject the request even before reaching the method handler.

It's also used by our PubSub mechanism (also a custom extension), where metadata contains a pipe allowing the method handlers to send notifications to the clients.

jsonrpc_core::IoHandler is a pure implementation of JSONRPC spec. This extension is only available in jsonrpc_core::MetaIoHandler.

Let me know if you need any more detailed info on this.

[greenpdx]

need some help with Metadata, If I could get just a simple template I could do it. This is what I have now

 extern crate jsonrpc_core;
 extern crate jsonrpc_http_server;

use jsonrpc_core::*;
use jsonrpc_http_server::{ServerBuilder, DomainsValidation, AccessControlAllowOrigin, RestApi, MetaExtractor};

#[derive(Clone, Default)]
struct Meta(usize);
impl MetaExtractor<Meta> for Meta {
    fn read_metadata(&self, req: &server::Request) -> Meta {
        (*self)(req)
    }
}

fn main() {
    let mut io = MetaIoHandler::default();
    io.add_method_with_meta("say_hello", |_parm: Params, meta: Meta| {
        println!("Hello {:?}", _parm );
        futures::finished(Value::String(format!("hello: {}", meta.0)))
        //Ok(Value::String("hello".to_string()))
    });

    let _server = ServerBuilder::new(io)
        .threads(3)
        .rest_api(RestApi::Unsecure)
        .meta_extractor(Meta::read_metadata())
        .cors(DomainsValidation::AllowOnly(vec![AccessControlAllowOrigin::Any]))
        .start_http(&"0.0.0.0:3030".parse().unwrap())
        .expect("unable to start");

    _server.wait();
}

[tomusdrw]

@greenpdx Please have a look at the example I added here: #219

[greenpdx]

I am testing it using Vue, send it a json request with params
{ jsonrpc: 2.0, method: say_hello, params: [23, 16], id: 1}

but I get this error
{ "jsonrpc": "2.0", "error": { "code": -32600, "message": "Invalid request" }, "id": 1 }

[tomusdrw]

Can you make sure that the request is a properly formed JSON?
Can you also run your rust server with RUST_LOG="rpc=trace" (and please initialize env_logger)? It wil then display the trace data.

[greenpdx]

Yes, it was me. I was added a header for cors that I did not need. I am changing the Header from Authorization to Host, because I wanted to use an existing request header. it works
thanks

[tomusdrw]

Perfect! Glad it works :)

[greenpdx]

Now I am trying it with remote_addr.
next I want to add a meta and middleware to it