[govpp.git] / api / binapi.go

// Copyright (c) 2017 Cisco and/or its affiliates.
//
// 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.

package api

import (
        "time"
)

// MessageType represents the type of a VPP message.
// Note: this is currently derived from the message header (fields),
// and in many cases it does not represent the actual type of VPP message.
// This means that some replies can be identified as requests, etc.
// TODO: use services to identify type of message
type MessageType int

const (
        // RequestMessage represents a VPP request message
        RequestMessage MessageType = iota
        // ReplyMessage represents a VPP reply message
        ReplyMessage
        // EventMessage represents a VPP event message
        EventMessage
        // OtherMessage represents other VPP message
        OtherMessage
)

// Message is an interface that is implemented by all VPP Binary API messages generated by the binapigenerator.
type Message interface {
        // GetMessageName returns the original VPP name of the message, as defined in the VPP API.
        GetMessageName() string

        // GetCrcString returns the string with CRC checksum of the message definition (the string represents a hexadecimal number).
        GetCrcString() string

        // GetMessageType returns the type of the VPP message.
        GetMessageType() MessageType
}

// DataType is an interface that is implemented by all VPP Binary API data types by the binapi_generator.
type DataType interface {
        // GetTypeName returns the original VPP name of the data type, as defined in the VPP API.
        GetTypeName() string
}

// ChannelProvider provides the communication channel with govpp core.
type ChannelProvider interface {
        // NewAPIChannel returns a new channel for communication with VPP via govpp core.
        // It uses default buffer sizes for the request and reply Go channels.
        NewAPIChannel() (Channel, error)

        // NewAPIChannelBuffered returns a new channel for communication with VPP via govpp core.
        // It allows to specify custom buffer sizes for the request and reply Go channels.
        NewAPIChannelBuffered(reqChanBufSize, replyChanBufSize int) (Channel, error)
}

// Channel provides methods for direct communication with VPP channel.
type Channel interface {
        // SendRequest asynchronously sends a request to VPP. Returns a request context, that can be used to call ReceiveReply.
        // In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
        SendRequest(msg Message) RequestCtx

        // SendMultiRequest asynchronously sends a multipart request (request to which multiple responses are expected) to VPP.
        // Returns a multipart request context, that can be used to call ReceiveReply.
        // In case of any errors by sending, the error will be delivered to ReplyChan (and returned by ReceiveReply).
        SendMultiRequest(msg Message) MultiRequestCtx

        // SubscribeNotification subscribes for receiving of the specified notification messages via provided Go channel.
        // Note that the caller is responsible for creating the Go channel with preferred buffer size. If the channel's
        // buffer is full, the notifications will not be delivered into it.
        SubscribeNotification(notifChan chan Message, event Message) (SubscriptionCtx, error)

        // SetReplyTimeout sets the timeout for replies from VPP. It represents the maximum time the API waits for a reply
        // from VPP before returning an error.
        SetReplyTimeout(timeout time.Duration)

        // CheckCompatibility checks the compatiblity for the given messages.
        // It will return an error if any of the given messages are not compatible.
        CheckCompatiblity(msgs ...Message) error

        // Close closes the API channel and releases all API channel-related resources in the ChannelProvider.
        Close()
}

// RequestCtx is helper interface which allows to receive reply on request.
type RequestCtx interface {
        // ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
        // The reply will be decoded into the msg argument. Error will be returned if the response cannot be received or decoded.
        ReceiveReply(msg Message) error
}

// MultiRequestCtx is helper interface which allows to receive reply on multi-request.
type MultiRequestCtx interface {
        // ReceiveReply receives a reply from VPP (blocks until a reply is delivered from VPP, or until an error occurs).
        // The reply will be decoded into the msg argument. If the last reply has been already consumed, lastReplyReceived is
        // set to true. Do not use the message itself if lastReplyReceived is true - it won't be filled with actual data.
        // Error will be returned if the response cannot be received or decoded.
        ReceiveReply(msg Message) (lastReplyReceived bool, err error)
}

// SubscriptionCtx is helper interface which allows to control subscription for notification events.
type SubscriptionCtx interface {
        // Unsubscribe unsubscribes from receiving the notifications tied to the subscription context.
        Unsubscribe() error
}

var registeredMessages = make(map[string]Message)

// RegisterMessage is called from generated code to register message.
func RegisterMessage(x Message, name string) {
        name = x.GetMessageName() + "_" + x.GetCrcString()
        /*if _, ok := registeredMessages[name]; ok {
                panic(fmt.Errorf("govpp: duplicate message registered: %s (%s)", name, x.GetCrcString()))
        }*/
        registeredMessages[name] = x
}

// GetRegisteredMessages returns list of all registered messages.
func GetRegisteredMessages() map[string]Message {
        return registeredMessages
}

// GoVppAPIPackageIsVersion1 is referenced from generated binapi files
// to assert that that code is compatible with this version of the GoVPP api package.
const GoVppAPIPackageIsVersion1 = true