// Generating request JSON
let batchFactory = BatchFactory(version: "2.0", idGenerator: NumberIdGenerator())
let request = Subtract(minuend: 42, subtrahend: 23)
let batch = batchFactory.create(request)
batch.requestObject // ["jsonrpc": "2.0", "method": "subtract", "params": [42, 23], "id": 1]

// Parsing response JSON
let responseObject: Any = ["jsonrpc": "2.0", "result": 19, "id": 1]
let response = try! batch.responses(from: responseObject)
response // 19 (type of response is inferred from SubtractRequest.Response)

struct Subtract: JSONRPCKit.Request {
    typealias Response = Int

    let minuend: Int
    let subtrahend: Int

    var method: String {
        return "subtract"
    }

    var parameters: Any? {
        return [minuend, subtrahend]
    }

    func response(from resultObject: Any) throws -> Response {
        if let response = resultObject as? Response {
            return response
        } else {
            throw CastError(actualValue: resultObject, expectedType: Response.self)
        }
    }
}

let batchFactory = BatchFactory(version: "2.0", idGenerator: NumberIdGenerator())
let request1 = Subtract(minuend: 42, subtrahend: 23)
let request2 = Subtract(minuend: 23, subtrahend: 42)
let batch = batchFactory.create(request1, request2)

let responseObject = ...
let (response1, response2) = try! batch.responses(from: responseObject)
print(response1) // 19
print(response2) // -19

import APIKit

struct MyServiceRequest<Batch: JSONRPCKit.Batch>: APIKit.Request {
    let batch: Batch

    typealias Response = Batch.Responses

    var baseURL: URL {
        return URL(string: "https://api.example.com/")!
    }

    var method: HTTPMethod {
        return .post
    }

    var path: String {
        return "/"
    }

    var parameters: Any? {
        return batch.requestObject
    }

    func response(from object: Any, urlResponse: HTTPURLResponse) throws -> Response {
        return try batch.responses(from: object)
    }
}

let batchFactory = BatchFactory(version: "2.0", idGenerator: NumberIdGenerator())
let request1 = Subtract(minuend: 42, subtrahend: 23)
let request2 = Subtract(minuend: 23, subtrahend: 42)
let batch = batchFactory.create(request1, request2)
let httpRequest = MyServiceRequest(batch: batch)

Session.sendRequest(httpRequest) { result in
    switch result {
    case .Success(let response1, let response2):
        print(response1.count) // CountCharactersResponse
        print(response2.count) // CountCharactersResponse

    case .Failure(let error):
        print(error)
    }
}