HTTP API client utility functions (get, post, etc.)

api/Cargo.toml

@@ -7,6 +7,7 @@ workspace = ".."
 [dependencies]
 grin_chain = { path = "../chain" }
 
+hyper = "~0.10.6"
 iron = "~0.5.1"
 log = "~0.3"
 router = "~0.5.1"

api/src/client.rs

@@ -0,0 +1,65 @@
+// Copyright 2016 The Grin Developers
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! High level JSON/HTTP client API
+
+use hyper;
+use hyper::client::Response;
+use hyper::status::StatusClass;
+use serde::{Serialize, Deserialize};
+use serde_json;
+
+use rest::Error;
+
+/// Helper function to easily issue a HTTP GET request against a given URL that
+/// returns a JSON object. Handles request building, JSON deserialization and
+/// response code checking.
+pub fn get<'a, T>(url: &'a str) -> Result<T, Error>
+	where T: Deserialize
+{
+	let client = hyper::Client::new();
+	let res = check_error(client.get(url).send())?;
+	serde_json::from_reader(res)
+		.map_err(|e| Error::Internal(format!("Server returned invalid JSON: {}", e)))
+}
+
+/// Helper function to easily issue a HTTP POST request with the provided JSON
+/// object as body on a given URL that returns a JSON object. Handles request
+/// building, JSON serialization and deserialization, and response code
+/// checking.
+pub fn post<'a, IN, OUT>(url: &'a str, input: &IN) -> Result<OUT, Error>
+	where IN: Serialize,
+	      OUT: Deserialize
+{
+	let in_json = serde_json::to_string(input)
+		.map_err(|e| Error::Internal(format!("Could not serialize data to JSON: {}", e)))?;
+	let client = hyper::Client::new();
+	let res = check_error(client.post(url).body(&mut in_json.as_bytes()).send())?;
+	serde_json::from_reader(res)
+		.map_err(|e| Error::Internal(format!("Server returned invalid JSON: {}", e)))
+}
+
+// convert hyper error and check for non success response codes
+fn check_error(res: hyper::Result<Response>) -> Result<Response, Error> {
+	if let Err(e) = res {
+		return Err(Error::Internal(format!("Error during request: {}", e)));
+	}
+	let response = res.unwrap();
+	match response.status.class() {
+		StatusClass::Success => Ok(response),
+		StatusClass::ServerError => Err(Error::Internal(format!("Server error."))),
+		StatusClass::ClientError => Err(Error::Argument(format!("Argument error"))),
+		_ => Err(Error::Internal(format!("Unrecognized error."))),
+	}
+}

api/src/endpoints.rs

@@ -38,15 +38,15 @@ pub struct ChainApi {
 impl ApiEndpoint for ChainApi {
 	type ID = String;
 	type T = Tip;
-  type OP_IN = ();
-  type OP_OUT = ();
+	type OP_IN = ();
+	type OP_OUT = ();
 
 	fn operations(&self) -> Vec<Operation> {
 		vec![Operation::Get]
 	}
 
 	fn get(&self, id: String) -> ApiResult<Tip> {
-		self.chain_store.head().map_err(|e| ApiError::Internal(e.to_string()))
+		self.chain_store.head().map_err(|e| Error::Internal(e.to_string()))
 	}
 }
 

api/src/lib.rs

@@ -14,6 +14,7 @@
 
 extern crate grin_chain as chain;
 
+extern crate hyper;
 #[macro_use]
 extern crate log;
 extern crate iron;
@@ -21,6 +22,7 @@ extern crate router;
 extern crate serde;
 extern crate serde_json;
 
+pub mod client;
 mod endpoints;
 mod rest;
 

api/src/rest.rs

@@ -18,7 +18,7 @@
 //! To use it, just have your service(s) implement the ApiEndpoint trait and
 //! register them on a ApiServer.
 
-use std::error::Error;
+use std::error;
 use std::fmt::{self, Display, Debug, Formatter};
 use std::io::Read;
 use std::net::ToSocketAddrs;
@@ -35,34 +35,34 @@ use serde_json;
 
 /// Errors that can be returned by an ApiEndpoint implementation.
 #[derive(Debug)]
-pub enum ApiError {
+pub enum Error {
 	Internal(String),
 	Argument(String),
 }
 
-impl Display for ApiError {
+impl Display for Error {
 	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
 		match *self {
-			ApiError::Argument(ref s) => write!(f, "Bad arguments: {}", s),
-			ApiError::Internal(ref s) => write!(f, "Internal error: {}", s),
+			Error::Argument(ref s) => write!(f, "Bad arguments: {}", s),
+			Error::Internal(ref s) => write!(f, "Internal error: {}", s),
 		}
 	}
 }
 
-impl Error for ApiError {
+impl error::Error for Error {
 	fn description(&self) -> &str {
 		match *self {
-			ApiError::Argument(_) => "Bad arguments.",
-			ApiError::Internal(_) => "Internal error.",
+			Error::Argument(_) => "Bad arguments.",
+			Error::Internal(_) => "Internal error.",
 		}
 	}
 }
 
-impl From<ApiError> for IronError {
-	fn from(e: ApiError) -> IronError {
+impl From<Error> for IronError {
+	fn from(e: Error) -> IronError {
 		match e {
-			ApiError::Argument(_) => IronError::new(e, status::Status::BadRequest),
-			ApiError::Internal(_) => IronError::new(e, status::Status::InternalServerError),
+			Error::Argument(_) => IronError::new(e, status::Status::BadRequest),
+			Error::Internal(_) => IronError::new(e, status::Status::InternalServerError),
 		}
 	}
 }
@@ -89,7 +89,7 @@ impl Operation {
 	}
 }
 
-pub type ApiResult<T> = ::std::result::Result<T, ApiError>;
+pub type ApiResult<T> = ::std::result::Result<T, Error>;
 
 /// Trait to implement to expose a service as a RESTful HTTP endpoint. Each
 /// method corresponds to a specific relative URL and HTTP method following
@@ -147,7 +147,7 @@ struct ApiWrapper<E>(E);
 
 impl<E> Handler for ApiWrapper<E>
 	where E: ApiEndpoint,
-	      <<E as ApiEndpoint>::ID as FromStr>::Err: Debug + Send + Error
+	      <<E as ApiEndpoint>::ID as FromStr>::Err: Debug + Send + error::Error
 {
 	fn handle(&self, req: &mut Request) -> IronResult<Response> {
 		match req.method {
@@ -200,7 +200,7 @@ impl<E> Handler for OpWrapper<E>
 
 fn extract_param<ID>(req: &mut Request, param: &'static str) -> IronResult<ID>
 	where ID: ToString + FromStr,
-	      <ID as FromStr>::Err: Debug + Send + Error + 'static
+	      <ID as FromStr>::Err: Debug + Send + error::Error + 'static
 {
 
 	let id = req.extensions.get::<Router>().unwrap().find(param).unwrap_or("");
@@ -232,7 +232,7 @@ impl ApiServer {
 	/// endpoint.
 	pub fn register_endpoint<E>(&mut self, subpath: String, endpoint: E)
 		where E: ApiEndpoint,
-		      <<E as ApiEndpoint>::ID as FromStr>::Err: Debug + Send + Error
+		      <<E as ApiEndpoint>::ID as FromStr>::Err: Debug + Send + error::Error
 	{
 
 		assert_eq!(subpath.chars().nth(0).unwrap(), '/');
@@ -251,7 +251,7 @@ impl ApiServer {
 				};
 				let full_path = format!("{}", root.clone());
 				self.router.route(op.to_method(), full_path.clone(), wrapper, route_name);
-        info!("POST {}", full_path);
+				info!("POST {}", full_path);
 			} else {
 
 				// regular REST operations
@@ -264,7 +264,7 @@ impl ApiServer {
 				};
 				let wrapper = ApiWrapper(endpoint.clone());
 				self.router.route(op.to_method(), full_path.clone(), wrapper, route_name);
-        info!("{} {}", op.to_method(), full_path);
+				info!("{} {}", op.to_method(), full_path);
 			}
 		}