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// Copyright 2015-2019 Capital One Services, LLC // // 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. //! # Message Broker //! //! This module contains the message broker struct through which guest modules access //! the currently bound `wascap:messaging` capability provider use crate::protobytes; use wapc_guest::host_call; use crate::Result; use codec::messaging::{ BrokerMessage, PublishMessage, RequestMessage, OP_PERFORM_REQUEST, OP_PUBLISH_MESSAGE, }; use waxosuit_codec as codec; /// Exposes message broker functionality to guest modules pub struct MessageBroker {} impl MessageBroker { pub(crate) fn new() -> MessageBroker { MessageBroker {} } /// Publishes a new message on the given subject with an optional reply-to pub fn publish(&self, subject: &str, reply_to: Option<&str>, payload: &[u8]) -> Result<()> { let cmd = PublishMessage { message: Some(BrokerMessage { subject: subject.to_string(), reply_to: reply_to.map_or("".to_string(), |r| r.to_string()), body: payload.to_vec(), }), }; host_call(OP_PUBLISH_MESSAGE, &protobytes(cmd)?).map(|_vec| ()) } /// Publishes a message on the given subject and awaits a reply on an inbox subject pub fn request(&self, subject: &str, payload: &[u8], timeout_ms: u64) -> Result<Vec<u8>> { let cmd = RequestMessage { subject: subject.to_string(), timeout_ms: timeout_ms as _, body: payload.to_vec(), }; // The broker plugin applies no wrapper around the response from the broker, the // raw payload is delivered. host_call(OP_PERFORM_REQUEST, &protobytes(cmd)?) } }