1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74

// 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 client interface through which actor modules access
//! the currently bound `wascc:messaging` capability provider

use crate::protobytes;
use crate::MessageBroker;
use wapc_guest::host_call;

/// The reserved capability ID for a message broker. Used for call routing in the host runtime.
pub const CAPID_MESSAGING: &str = "wascc:messaging";

use crate::Result;
use codec::messaging::{
    BrokerMessage, PublishMessage, RequestMessage, OP_PERFORM_REQUEST, OP_PUBLISH_MESSAGE,
};
use wascc_codec as codec;

/// Exposes message broker functionality to actor modules
pub struct DefaultMessageBroker {}

impl DefaultMessageBroker {
    pub fn new() -> Self {
        DefaultMessageBroker::default()
    }
}

impl Default for DefaultMessageBroker {
    fn default() -> Self {
        DefaultMessageBroker {}
    }
}

impl MessageBroker for DefaultMessageBroker {
    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(CAPID_MESSAGING, OP_PUBLISH_MESSAGE, &protobytes(cmd)?)
            .map_err(|e| e.into())
            .map(|_vec| ())
    }

    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(CAPID_MESSAGING, OP_PERFORM_REQUEST, &protobytes(cmd)?).map_err(|e| e.into())
    }
}