github.com/agwab/go-ethereum@v1.9.7/node/node_example_test.go (about)

     1  // Copyright 2015 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package node_test
    18  
    19  import (
    20  	"fmt"
    21  	"log"
    22  
    23  	"github.com/ethereum/go-ethereum/node"
    24  	"github.com/ethereum/go-ethereum/p2p"
    25  	"github.com/ethereum/go-ethereum/rpc"
    26  )
    27  
    28  // SampleService is a trivial network service that can be attached to a node for
    29  // life cycle management.
    30  //
    31  // The following methods are needed to implement a node.Service:
    32  //  - Protocols() []p2p.Protocol - devp2p protocols the service can communicate on
    33  //  - APIs() []rpc.API           - api methods the service wants to expose on rpc channels
    34  //  - Start() error              - method invoked when the node is ready to start the service
    35  //  - Stop() error               - method invoked when the node terminates the service
    36  type SampleService struct{}
    37  
    38  func (s *SampleService) Protocols() []p2p.Protocol { return nil }
    39  func (s *SampleService) APIs() []rpc.API           { return nil }
    40  func (s *SampleService) Start(*p2p.Server) error   { fmt.Println("Service starting..."); return nil }
    41  func (s *SampleService) Stop() error               { fmt.Println("Service stopping..."); return nil }
    42  
    43  func ExampleService() {
    44  	// Create a network node to run protocols with the default values.
    45  	stack, err := node.New(&node.Config{})
    46  	if err != nil {
    47  		log.Fatalf("Failed to create network node: %v", err)
    48  	}
    49  	defer stack.Close()
    50  
    51  	// Create and register a simple network service. This is done through the definition
    52  	// of a node.ServiceConstructor that will instantiate a node.Service. The reason for
    53  	// the factory method approach is to support service restarts without relying on the
    54  	// individual implementations' support for such operations.
    55  	constructor := func(context *node.ServiceContext) (node.Service, error) {
    56  		return new(SampleService), nil
    57  	}
    58  	if err := stack.Register(constructor); err != nil {
    59  		log.Fatalf("Failed to register service: %v", err)
    60  	}
    61  	// Boot up the entire protocol stack, do a restart and terminate
    62  	if err := stack.Start(); err != nil {
    63  		log.Fatalf("Failed to start the protocol stack: %v", err)
    64  	}
    65  	if err := stack.Restart(); err != nil {
    66  		log.Fatalf("Failed to restart the protocol stack: %v", err)
    67  	}
    68  	if err := stack.Stop(); err != nil {
    69  		log.Fatalf("Failed to stop the protocol stack: %v", err)
    70  	}
    71  	// Output:
    72  	// Service starting...
    73  	// Service stopping...
    74  	// Service starting...
    75  	// Service stopping...
    76  }