forked from cerc-io/plugeth
103 lines
3.7 KiB
Go
103 lines
3.7 KiB
Go
// Copyright 2015 The go-ethereum Authors
|
|
// This file is part of the go-ethereum library.
|
|
//
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public License
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
/*
|
|
Package rpc provides access to the exported methods of an object across a network
|
|
or other I/O connection. After creating a server instance objects can be registered,
|
|
making it visible from the outside. Exported methods that follow specific
|
|
conventions can be called remotely. It also has support for the publish/subscribe
|
|
pattern.
|
|
|
|
Methods that satisfy the following criteria are made available for remote access:
|
|
- object must be exported
|
|
- method must be exported
|
|
- method returns 0, 1 (response or error) or 2 (response and error) values
|
|
- method argument(s) must be exported or builtin types
|
|
- method returned value(s) must be exported or builtin types
|
|
|
|
An example method:
|
|
func (s *CalcService) Div(a, b int) (int, error)
|
|
|
|
When the returned error isn't nil the returned integer is ignored and the error is
|
|
send back to the client. Otherwise the returned integer is send back to the client.
|
|
|
|
The server offers the ServeCodec method which accepts a ServerCodec instance. It will
|
|
read requests from the codec, process the request and sends the response back to the
|
|
client using the codec. The server can execute requests concurrently. Responses
|
|
can be send back to the client out of order.
|
|
|
|
An example server which uses the JSON codec:
|
|
type CalculatorService struct {}
|
|
|
|
func (s *CalculatorService) Add(a, b int) int {
|
|
return a + b
|
|
}
|
|
|
|
func (s *CalculatorService Div(a, b int) (int, error) {
|
|
if b == 0 {
|
|
return 0, errors.New("divide by zero")
|
|
}
|
|
return a/b, nil
|
|
}
|
|
|
|
calculator := new(CalculatorService)
|
|
server := NewServer()
|
|
server.RegisterName("calculator", calculator")
|
|
|
|
l, _ := net.ListenUnix("unix", &net.UnixAddr{Net: "unix", Name: "/tmp/calculator.sock"})
|
|
for {
|
|
c, _ := l.AcceptUnix()
|
|
codec := v2.NewJSONCodec(c)
|
|
go server.ServeCodec(codec)
|
|
}
|
|
|
|
The package also supports the publish subscribe pattern through the use of subscriptions.
|
|
A method that is considered eligible for notifications must satisfy the following criteria:
|
|
- object must be exported
|
|
- method must be exported
|
|
- method argument(s) must be exported or builtin types
|
|
- method must return the tuple Subscription, error
|
|
|
|
|
|
An example method:
|
|
func (s *BlockChainService) Head() (Subscription, error) {
|
|
sub := s.bc.eventMux.Subscribe(ChainHeadEvent{})
|
|
return v2.NewSubscription(sub), nil
|
|
}
|
|
|
|
This method will push all raised ChainHeadEvents to subscribed clients. If the client is only
|
|
interested in every N'th block it is possible to add a criteria.
|
|
|
|
func (s *BlockChainService) HeadFiltered(nth uint64) (Subscription, error) {
|
|
sub := s.bc.eventMux.Subscribe(ChainHeadEvent{})
|
|
|
|
criteria := func(event interface{}) bool {
|
|
chainHeadEvent := event.(ChainHeadEvent)
|
|
if chainHeadEvent.Block.NumberU64() % nth == 0 {
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
return v2.NewSubscriptionFiltered(sub, criteria), nil
|
|
}
|
|
|
|
Subscriptions are deleted when:
|
|
- the user sends an unsubscribe request
|
|
- the connection which was used to create the subscription is closed
|
|
*/
|
|
package v2
|