Documentation

Overview

Package node sets up multi-protocol Ethereum nodes.

In the model exposed by this package, a node is a collection of services which use shared resources to provide RPC APIs. Services can also offer devp2p protocols, which are wired up to the devp2p network when the node instance is started.

Resources Managed By Node

All file-system resources used by a node instance are located in a directory called the data directory. The location of each resource can be overridden through additional node configuration. The data directory is optional. If it is not set and the location of a resource is otherwise unspecified, package node will create the resource in memory.

To access to the devp2p network, Node configures and starts p2p.Server. Each host on the devp2p network has a unique identifier, the node key. The Node instance persists this key across restarts. Node also loads static and trusted node lists and ensures that knowledge about other hosts is persisted.

JSON-RPC servers which run HTTP, WebSocket or IPC can be started on a Node. RPC modules offered by registered services will be offered on those endpoints. Users can restrict any endpoint to a subset of RPC modules. Node itself offers the "debug", "admin" and "web3" modules.

Service implementations can open LevelDB databases through the service context. Package node chooses the file system location of each database. If the node is configured to run without a data directory, databases are opened in memory instead.

Node also creates the shared store of encrypted Ethereum account keys. Services can access the account manager through the service context.

Sharing Data Directory Among Instances

Multiple node instances can share a single data directory if they have distinct instance names (set through the Name config option). Sharing behaviour depends on the type of resource.

devp2p-related resources (node key, static/trusted node lists, known hosts database) are stored in a directory with the same name as the instance. Thus, multiple node instances using the same data directory will store this information in different subdirectories of the data directory.

LevelDB databases are also stored within the instance subdirectory. If multiple node instances use the same data directory, opening the databases with identical names will create one database for each instance.

The account key store is shared among all node instances using the same data directory unless its location is changed through the KeyStoreDir configuration option.

Data Directory Sharing Example

In this example, two node instances named A and B are started with the same data directory. Node instance A opens the database "db", node instance B opens the databases "db" and "db-2". The following files will be created in the data directory:

data-directory/
     A/
         nodekey            -- devp2p node key of instance A
         nodes/             -- devp2p discovery knowledge database of instance A
         db/                -- LevelDB content for "db"
     A.ipc                  -- JSON-RPC UNIX domain socket endpoint of instance A
     B/
         nodekey            -- devp2p node key of node B
         nodes/             -- devp2p discovery knowledge database of instance B
         static-nodes.json  -- devp2p static node list of instance B
         db/                -- LevelDB content for "db"
         db-2/              -- LevelDB content for "db-2"
     B.ipc                  -- JSON-RPC UNIX domain socket endpoint of instance B
     keystore/              -- account key store, used by both instances

Index

Examples

Constants

View Source
const (
	DefaultHTTPHost    = "localhost" // Default host interface for the HTTP RPC server
	DefaultHTTPPort    = 8545        // Default TCP port for the HTTP RPC server
	DefaultWSHost      = "localhost" // Default host interface for the websocket RPC server
	DefaultWSPort      = 8546        // Default TCP port for the websocket RPC server
	DefaultGraphQLHost = "localhost" // Default host interface for the GraphQL server
	DefaultGraphQLPort = 8547        // Default TCP port for the GraphQL server
)

Variables

View Source
var (
	ErrDatadirUsed    = errors.New("datadir already used by another process")
	ErrNodeStopped    = errors.New("node not started")
	ErrNodeRunning    = errors.New("node already running")
	ErrServiceUnknown = errors.New("unknown service")
)
View Source
var DefaultConfig = Config{
	DataDir:             DefaultDataDir(),
	HTTPPort:            DefaultHTTPPort,
	HTTPModules:         []string{"net", "web3"},
	HTTPVirtualHosts:    []string{"localhost"},
	HTTPTimeouts:        rpc.DefaultHTTPTimeouts,
	WSPort:              DefaultWSPort,
	WSModules:           []string{"net", "web3"},
	GraphQLPort:         DefaultGraphQLPort,
	GraphQLVirtualHosts: []string{"localhost"},
	P2P: p2p.Config{
		ListenAddr: ":30303",
		MaxPeers:   50,
		NAT:        nat.Any(),
	},
}

    DefaultConfig contains reasonable default settings.

    Functions

    func DefaultDataDir

    func DefaultDataDir() string

      DefaultDataDir is the default data directory to use for the databases and other persistence requirements.

      func DefaultHTTPEndpoint

      func DefaultHTTPEndpoint() string

        DefaultHTTPEndpoint returns the HTTP endpoint used by default.

        func DefaultIPCEndpoint

        func DefaultIPCEndpoint(clientIdentifier string) string

          DefaultIPCEndpoint returns the IPC path used by default.

          func DefaultWSEndpoint

          func DefaultWSEndpoint() string

            DefaultWSEndpoint returns the websocket endpoint used by default.

            Types

            type Config

            type Config struct {
            	// Name sets the instance name of the node. It must not contain the / character and is
            	// used in the devp2p node identifier. The instance name of geth is "geth". If no
            	// value is specified, the basename of the current executable is used.
            	Name string `toml:"-"`
            
            	// UserIdent, if set, is used as an additional component in the devp2p node identifier.
            	UserIdent string `toml:",omitempty"`
            
            	// Version should be set to the version number of the program. It is used
            	// in the devp2p node identifier.
            	Version string `toml:"-"`
            
            	// DataDir is the file system folder the node should use for any data storage
            	// requirements. The configured data directory will not be directly shared with
            	// registered services, instead those can use utility methods to create/access
            	// databases or flat files. This enables ephemeral nodes which can fully reside
            	// in memory.
            	DataDir string
            
            	// Configuration of peer-to-peer networking.
            	P2P p2p.Config
            
            	// KeyStoreDir is the file system folder that contains private keys. The directory can
            	// be specified as a relative path, in which case it is resolved relative to the
            	// current directory.
            	//
            	// If KeyStoreDir is empty, the default location is the "keystore" subdirectory of
            	// DataDir. If DataDir is unspecified and KeyStoreDir is empty, an ephemeral directory
            	// is created by New and destroyed when the node is stopped.
            	KeyStoreDir string `toml:",omitempty"`
            
            	// ExternalSigner specifies an external URI for a clef-type signer
            	ExternalSigner string `toml:"omitempty"`
            
            	// UseLightweightKDF lowers the memory and CPU requirements of the key store
            	// scrypt KDF at the expense of security.
            	UseLightweightKDF bool `toml:",omitempty"`
            
            	// InsecureUnlockAllowed allows user to unlock accounts in unsafe http environment.
            	InsecureUnlockAllowed bool `toml:",omitempty"`
            
            	// NoUSB disables hardware wallet monitoring and connectivity.
            	NoUSB bool `toml:",omitempty"`
            
            	// SmartCardDaemonPath is the path to the smartcard daemon's socket
            	SmartCardDaemonPath string `toml:",omitempty"`
            
            	// IPCPath is the requested location to place the IPC endpoint. If the path is
            	// a simple file name, it is placed inside the data directory (or on the root
            	// pipe path on Windows), whereas if it's a resolvable path name (absolute or
            	// relative), then that specific path is enforced. An empty path disables IPC.
            	IPCPath string `toml:",omitempty"`
            
            	// HTTPHost is the host interface on which to start the HTTP RPC server. If this
            	// field is empty, no HTTP API endpoint will be started.
            	HTTPHost string `toml:",omitempty"`
            
            	// HTTPPort is the TCP port number on which to start the HTTP RPC server. The
            	// default zero value is/ valid and will pick a port number randomly (useful
            	// for ephemeral nodes).
            	HTTPPort int `toml:",omitempty"`
            
            	// HTTPCors is the Cross-Origin Resource Sharing header to send to requesting
            	// clients. Please be aware that CORS is a browser enforced security, it's fully
            	// useless for custom HTTP clients.
            	HTTPCors []string `toml:",omitempty"`
            
            	// HTTPVirtualHosts is the list of virtual hostnames which are allowed on incoming requests.
            	// This is by default {'localhost'}. Using this prevents attacks like
            	// DNS rebinding, which bypasses SOP by simply masquerading as being within the same
            	// origin. These attacks do not utilize CORS, since they are not cross-domain.
            	// By explicitly checking the Host-header, the server will not allow requests
            	// made against the server with a malicious host domain.
            	// Requests using ip address directly are not affected
            	HTTPVirtualHosts []string `toml:",omitempty"`
            
            	// HTTPModules is a list of API modules to expose via the HTTP RPC interface.
            	// If the module list is empty, all RPC API endpoints designated public will be
            	// exposed.
            	HTTPModules []string `toml:",omitempty"`
            
            	// HTTPTimeouts allows for customization of the timeout values used by the HTTP RPC
            	// interface.
            	HTTPTimeouts rpc.HTTPTimeouts
            
            	// WSHost is the host interface on which to start the websocket RPC server. If
            	// this field is empty, no websocket API endpoint will be started.
            	WSHost string `toml:",omitempty"`
            
            	// WSPort is the TCP port number on which to start the websocket RPC server. The
            	// default zero value is/ valid and will pick a port number randomly (useful for
            	// ephemeral nodes).
            	WSPort int `toml:",omitempty"`
            
            	// WSOrigins is the list of domain to accept websocket requests from. Please be
            	// aware that the server can only act upon the HTTP request the client sends and
            	// cannot verify the validity of the request header.
            	WSOrigins []string `toml:",omitempty"`
            
            	// WSModules is a list of API modules to expose via the websocket RPC interface.
            	// If the module list is empty, all RPC API endpoints designated public will be
            	// exposed.
            	WSModules []string `toml:",omitempty"`
            
            	// WSExposeAll exposes all API modules via the WebSocket RPC interface rather
            	// than just the public ones.
            	//
            	// *WARNING* Only set this if the node is running in a trusted network, exposing
            	// private APIs to untrusted users is a major security risk.
            	WSExposeAll bool `toml:",omitempty"`
            
            	// GraphQLHost is the host interface on which to start the GraphQL server. If this
            	// field is empty, no GraphQL API endpoint will be started.
            	GraphQLHost string `toml:",omitempty"`
            
            	// GraphQLPort is the TCP port number on which to start the GraphQL server. The
            	// default zero value is/ valid and will pick a port number randomly (useful
            	// for ephemeral nodes).
            	GraphQLPort int `toml:",omitempty"`
            
            	// GraphQLCors is the Cross-Origin Resource Sharing header to send to requesting
            	// clients. Please be aware that CORS is a browser enforced security, it's fully
            	// useless for custom HTTP clients.
            	GraphQLCors []string `toml:",omitempty"`
            
            	// GraphQLVirtualHosts is the list of virtual hostnames which are allowed on incoming requests.
            	// This is by default {'localhost'}. Using this prevents attacks like
            	// DNS rebinding, which bypasses SOP by simply masquerading as being within the same
            	// origin. These attacks do not utilize CORS, since they are not cross-domain.
            	// By explicitly checking the Host-header, the server will not allow requests
            	// made against the server with a malicious host domain.
            	// Requests using ip address directly are not affected
            	GraphQLVirtualHosts []string `toml:",omitempty"`
            
            	// Logger is a custom logger to use with the p2p.Server.
            	Logger log.Logger `toml:",omitempty"`
            
            	Plugins *plugin.Settings `toml:",omitempty"`
            	// Quorum: EnableNodePermission comes from EnableNodePermissionFlag --permissioned.
            	EnableNodePermission bool `toml:",omitempty"`
            	// contains filtered or unexported fields
            }

              Config represents a small collection of configuration values to fine tune the P2P network layer of a protocol stack. These values can be further extended by all registered services.

              func (*Config) AccountConfig

              func (c *Config) AccountConfig() (int, int, string, error)

                AccountConfig determines the settings for scrypt and keydirectory

                func (*Config) ExtRPCEnabled

                func (c *Config) ExtRPCEnabled() bool

                  ExtRPCEnabled returns the indicator whether node enables the external RPC(http, ws or graphql).

                  func (*Config) GraphQLEndpoint

                  func (c *Config) GraphQLEndpoint() string

                    GraphQLEndpoint resolves a GraphQL endpoint based on the configured host interface and port parameters.

                    func (*Config) HTTPEndpoint

                    func (c *Config) HTTPEndpoint() string

                      HTTPEndpoint resolves an HTTP endpoint based on the configured host interface and port parameters.

                      func (*Config) IPCEndpoint

                      func (c *Config) IPCEndpoint() string

                        IPCEndpoint resolves an IPC endpoint based on a configured value, taking into account the set data folders as well as the designated platform we're currently running on.

                        func (*Config) IsPermissionEnabled

                        func (c *Config) IsPermissionEnabled() bool

                          check if smart-contract-based permissioning is enabled by reading `--permissioned` flag and checking permission config file

                          func (*Config) NodeDB

                          func (c *Config) NodeDB() string

                            NodeDB returns the path to the discovery node database.

                            func (*Config) NodeKey

                            func (c *Config) NodeKey() *ecdsa.PrivateKey

                              NodeKey retrieves the currently configured private key of the node, checking first any manually set key, falling back to the one found in the configured data folder. If no key can be found, a new one is generated.

                              func (*Config) NodeName

                              func (c *Config) NodeName() string

                                NodeName returns the devp2p node identifier.

                                func (*Config) ResolvePath

                                func (c *Config) ResolvePath(path string) string

                                  ResolvePath resolves path in the instance directory.

                                  func (*Config) ResolvePluginBaseDir

                                  func (c *Config) ResolvePluginBaseDir() error

                                    Quorum

                                    Make sure plugin base dir exists

                                    func (*Config) StaticNodes

                                    func (c *Config) StaticNodes() []*enode.Node

                                      StaticNodes returns a list of node enode URLs configured as static nodes.

                                      func (*Config) TrustedNodes

                                      func (c *Config) TrustedNodes() []*enode.Node

                                        TrustedNodes returns a list of node enode URLs configured as trusted nodes.

                                        func (*Config) WSEndpoint

                                        func (c *Config) WSEndpoint() string

                                          WSEndpoint resolves a websocket endpoint based on the configured host interface and port parameters.

                                          type DuplicateServiceError

                                          type DuplicateServiceError struct {
                                          	Kind reflect.Type
                                          }

                                            DuplicateServiceError is returned during Node startup if a registered service constructor returns a service of the same type that was already started.

                                            func (*DuplicateServiceError) Error

                                            func (e *DuplicateServiceError) Error() string

                                              Error generates a textual representation of the duplicate service error.

                                              type Node

                                              type Node struct {
                                              	// contains filtered or unexported fields
                                              }

                                                Node is a container on which services can be registered.

                                                func New

                                                func New(conf *Config) (*Node, error)

                                                  New creates a new P2P node, ready for protocol registration.

                                                  func (*Node) AccountManager

                                                  func (n *Node) AccountManager() *accounts.Manager

                                                    AccountManager retrieves the account manager used by the protocol stack.

                                                    func (*Node) Attach

                                                    func (n *Node) Attach() (*rpc.Client, error)

                                                      Attach creates an RPC client attached to an in-process API handler.

                                                      func (*Node) Close

                                                      func (n *Node) Close() error

                                                        Close stops the Node and releases resources acquired in Node constructor New.

                                                        func (*Node) Config

                                                        func (n *Node) Config() *Config

                                                          Config returns the configuration of node.

                                                          func (*Node) DataDir

                                                          func (n *Node) DataDir() string

                                                            DataDir retrieves the current datadir used by the protocol stack. Deprecated: No files should be stored in this directory, use InstanceDir instead.

                                                            func (*Node) EventMux

                                                            func (n *Node) EventMux() *event.TypeMux

                                                              EventMux retrieves the event multiplexer used by all the network services in the current protocol stack.

                                                              func (*Node) GetNodeKey

                                                              func (n *Node) GetNodeKey() *ecdsa.PrivateKey

                                                                Quorum

                                                                delegate call to node.Config

                                                                func (*Node) HTTPEndpoint

                                                                func (n *Node) HTTPEndpoint() string

                                                                  HTTPEndpoint retrieves the current HTTP endpoint used by the protocol stack.

                                                                  func (*Node) IPCEndpoint

                                                                  func (n *Node) IPCEndpoint() string

                                                                    IPCEndpoint retrieves the current IPC endpoint used by the protocol stack.

                                                                    func (*Node) InstanceDir

                                                                    func (n *Node) InstanceDir() string

                                                                      InstanceDir retrieves the instance directory used by the protocol stack.

                                                                      func (*Node) IsPermissionEnabled

                                                                      func (n *Node) IsPermissionEnabled() bool

                                                                        Quorum

                                                                        delegate call to node.Config

                                                                        func (*Node) OpenDatabase

                                                                        func (n *Node) OpenDatabase(name string, cache, handles int, namespace string) (ethdb.Database, error)

                                                                          OpenDatabase opens an existing database with the given name (or creates one if no previous can be found) from within the node's instance directory. If the node is ephemeral, a memory database is returned.

                                                                          func (*Node) OpenDatabaseWithFreezer

                                                                          func (n *Node) OpenDatabaseWithFreezer(name string, cache, handles int, freezer, namespace string) (ethdb.Database, error)

                                                                            OpenDatabaseWithFreezer opens an existing database with the given name (or creates one if no previous can be found) from within the node's data directory, also attaching a chain freezer to it that moves ancient chain data from the database to immutable append-only files. If the node is an ephemeral one, a memory database is returned.

                                                                            func (*Node) PluginManager

                                                                            func (n *Node) PluginManager() *plugin.PluginManager

                                                                              Quorum

                                                                              This can be used to inspect plugins used in the current node

                                                                              func (*Node) RPCHandler

                                                                              func (n *Node) RPCHandler() (*rpc.Server, error)

                                                                                RPCHandler returns the in-process RPC request handler.

                                                                                func (*Node) Register

                                                                                func (n *Node) Register(constructor ServiceConstructor) error

                                                                                  Register injects a new service into the node's stack. The service created by the passed constructor must be unique in its type with regard to sibling ones.

                                                                                  func (*Node) ResolvePath

                                                                                  func (n *Node) ResolvePath(x string) string

                                                                                    ResolvePath returns the absolute path of a resource in the instance directory.

                                                                                    func (*Node) Restart

                                                                                    func (n *Node) Restart() error

                                                                                      Restart terminates a running node and boots up a new one in its place. If the node isn't running, an error is returned.

                                                                                      func (*Node) Server

                                                                                      func (n *Node) Server() *p2p.Server

                                                                                        Server retrieves the currently running P2P network layer. This method is meant only to inspect fields of the currently running server, life cycle management should be left to this Node entity.

                                                                                        func (*Node) Service

                                                                                        func (n *Node) Service(service interface{}) error

                                                                                          Service retrieves a currently running service registered of a specific type.

                                                                                          func (*Node) Start

                                                                                          func (n *Node) Start() error

                                                                                            Start create a live P2P node and starts running it.

                                                                                            func (*Node) Stop

                                                                                            func (n *Node) Stop() error

                                                                                              Stop terminates a running node along with all it's services. In the node was not started, an error is returned.

                                                                                              func (*Node) WSEndpoint

                                                                                              func (n *Node) WSEndpoint() string

                                                                                                WSEndpoint retrieves the current WS endpoint used by the protocol stack.

                                                                                                func (*Node) Wait

                                                                                                func (n *Node) Wait()

                                                                                                  Wait blocks the thread until the node is stopped. If the node is not running at the time of invocation, the method immediately returns.

                                                                                                  type PrivateAdminAPI

                                                                                                  type PrivateAdminAPI struct {
                                                                                                  	// contains filtered or unexported fields
                                                                                                  }

                                                                                                    PrivateAdminAPI is the collection of administrative API methods exposed only over a secure RPC channel.

                                                                                                    func NewPrivateAdminAPI

                                                                                                    func NewPrivateAdminAPI(node *Node) *PrivateAdminAPI

                                                                                                      NewPrivateAdminAPI creates a new API definition for the private admin methods of the node itself.

                                                                                                      func (*PrivateAdminAPI) AddPeer

                                                                                                      func (api *PrivateAdminAPI) AddPeer(url string) (bool, error)

                                                                                                        AddPeer requests connecting to a remote node, and also maintaining the new connection at all times, even reconnecting if it is lost.

                                                                                                        func (*PrivateAdminAPI) AddTrustedPeer

                                                                                                        func (api *PrivateAdminAPI) AddTrustedPeer(url string) (bool, error)

                                                                                                          AddTrustedPeer allows a remote node to always connect, even if slots are full

                                                                                                          func (*PrivateAdminAPI) PeerEvents

                                                                                                          func (api *PrivateAdminAPI) PeerEvents(ctx context.Context) (*rpc.Subscription, error)

                                                                                                            PeerEvents creates an RPC subscription which receives peer events from the node's p2p.Server

                                                                                                            func (*PrivateAdminAPI) RemovePeer

                                                                                                            func (api *PrivateAdminAPI) RemovePeer(url string) (bool, error)

                                                                                                              RemovePeer disconnects from a remote node if the connection exists

                                                                                                              func (*PrivateAdminAPI) RemoveTrustedPeer

                                                                                                              func (api *PrivateAdminAPI) RemoveTrustedPeer(url string) (bool, error)

                                                                                                                RemoveTrustedPeer removes a remote node from the trusted peer set, but it does not disconnect it automatically.

                                                                                                                func (*PrivateAdminAPI) StartRPC

                                                                                                                func (api *PrivateAdminAPI) StartRPC(host *string, port *int, cors *string, apis *string, vhosts *string) (bool, error)

                                                                                                                  StartRPC starts the HTTP RPC API server.

                                                                                                                  func (*PrivateAdminAPI) StartWS

                                                                                                                  func (api *PrivateAdminAPI) StartWS(host *string, port *int, allowedOrigins *string, apis *string) (bool, error)

                                                                                                                    StartWS starts the websocket RPC API server.

                                                                                                                    func (*PrivateAdminAPI) StopRPC

                                                                                                                    func (api *PrivateAdminAPI) StopRPC() (bool, error)

                                                                                                                      StopRPC terminates an already running HTTP RPC API endpoint.

                                                                                                                      func (*PrivateAdminAPI) StopWS

                                                                                                                      func (api *PrivateAdminAPI) StopWS() (bool, error)

                                                                                                                        StopWS terminates an already running websocket RPC API endpoint.

                                                                                                                        type PublicAdminAPI

                                                                                                                        type PublicAdminAPI struct {
                                                                                                                        	// contains filtered or unexported fields
                                                                                                                        }

                                                                                                                          PublicAdminAPI is the collection of administrative API methods exposed over both secure and unsecure RPC channels.

                                                                                                                          func NewPublicAdminAPI

                                                                                                                          func NewPublicAdminAPI(node *Node) *PublicAdminAPI

                                                                                                                            NewPublicAdminAPI creates a new API definition for the public admin methods of the node itself.

                                                                                                                            func (*PublicAdminAPI) Datadir

                                                                                                                            func (api *PublicAdminAPI) Datadir() string

                                                                                                                              Datadir retrieves the current data directory the node is using.

                                                                                                                              func (*PublicAdminAPI) NodeInfo

                                                                                                                              func (api *PublicAdminAPI) NodeInfo() (*QuorumNodeInfo, error)

                                                                                                                                NodeInfo retrieves all the information we know about the host node at the protocol granularity.

                                                                                                                                func (*PublicAdminAPI) Peers

                                                                                                                                func (api *PublicAdminAPI) Peers() ([]*p2p.PeerInfo, error)

                                                                                                                                  Peers retrieves all the information we know about each individual peer at the protocol granularity.

                                                                                                                                  type PublicWeb3API

                                                                                                                                  type PublicWeb3API struct {
                                                                                                                                  	// contains filtered or unexported fields
                                                                                                                                  }

                                                                                                                                    PublicWeb3API offers helper utils

                                                                                                                                    func NewPublicWeb3API

                                                                                                                                    func NewPublicWeb3API(stack *Node) *PublicWeb3API

                                                                                                                                      NewPublicWeb3API creates a new Web3Service instance

                                                                                                                                      func (*PublicWeb3API) ClientVersion

                                                                                                                                      func (s *PublicWeb3API) ClientVersion() string

                                                                                                                                        ClientVersion returns the node name

                                                                                                                                        func (*PublicWeb3API) Sha3

                                                                                                                                        func (s *PublicWeb3API) Sha3(input hexutil.Bytes) hexutil.Bytes

                                                                                                                                          Sha3 applies the ethereum sha3 implementation on the input. It assumes the input is hex encoded.

                                                                                                                                          type QuorumNodeInfo

                                                                                                                                          type QuorumNodeInfo struct {
                                                                                                                                          	*p2p.NodeInfo
                                                                                                                                          	Plugins interface{} `json:"plugins"`
                                                                                                                                          }

                                                                                                                                            Quorum: an extended nodeInfo to include plugin details for current node

                                                                                                                                            type Service

                                                                                                                                            type Service interface {
                                                                                                                                            	// Protocols retrieves the P2P protocols the service wishes to start.
                                                                                                                                            	Protocols() []p2p.Protocol
                                                                                                                                            
                                                                                                                                            	// APIs retrieves the list of RPC descriptors the service provides
                                                                                                                                            	APIs() []rpc.API
                                                                                                                                            
                                                                                                                                            	// Start is called after all services have been constructed and the networking
                                                                                                                                            	// layer was also initialized to spawn any goroutines required by the service.
                                                                                                                                            	Start(server *p2p.Server) error
                                                                                                                                            
                                                                                                                                            	// Stop terminates all goroutines belonging to the service, blocking until they
                                                                                                                                            	// are all terminated.
                                                                                                                                            	Stop() error
                                                                                                                                            }

                                                                                                                                              Service is an individual protocol that can be registered into a node.

                                                                                                                                              Notes:

                                                                                                                                              • Service life-cycle management is delegated to the node. The service is allowed to initialize itself upon creation, but no goroutines should be spun up outside of the Start method.

                                                                                                                                              • Restart logic is not required as the node will create a fresh instance every time a service is started.

                                                                                                                                              Example
                                                                                                                                              Output:
                                                                                                                                              
                                                                                                                                              Service starting...
                                                                                                                                              Service stopping...
                                                                                                                                              Service starting...
                                                                                                                                              Service stopping...
                                                                                                                                              

                                                                                                                                              type ServiceConstructor

                                                                                                                                              type ServiceConstructor func(ctx *ServiceContext) (Service, error)

                                                                                                                                                ServiceConstructor is the function signature of the constructors needed to be registered for service instantiation.

                                                                                                                                                type ServiceContext

                                                                                                                                                type ServiceContext struct {
                                                                                                                                                	EventMux       *event.TypeMux    // Event multiplexer used for decoupled notifications
                                                                                                                                                	AccountManager *accounts.Manager // Account manager created by the node.
                                                                                                                                                	// contains filtered or unexported fields
                                                                                                                                                }

                                                                                                                                                  ServiceContext is a collection of service independent options inherited from the protocol stack, that is passed to all constructors to be optionally used; as well as utility methods to operate on the service environment.

                                                                                                                                                  func (*ServiceContext) ExtRPCEnabled

                                                                                                                                                  func (ctx *ServiceContext) ExtRPCEnabled() bool

                                                                                                                                                    ExtRPCEnabled returns the indicator whether node enables the external RPC(http, ws or graphql).

                                                                                                                                                    func (*ServiceContext) NodeKey

                                                                                                                                                    func (ctx *ServiceContext) NodeKey() *ecdsa.PrivateKey

                                                                                                                                                      NodeKey returns node key from config

                                                                                                                                                      func (*ServiceContext) OpenDatabase

                                                                                                                                                      func (ctx *ServiceContext) OpenDatabase(name string, cache int, handles int, namespace string) (ethdb.Database, error)

                                                                                                                                                        OpenDatabase opens an existing database with the given name (or creates one if no previous can be found) from within the node's data directory. If the node is an ephemeral one, a memory database is returned.

                                                                                                                                                        func (*ServiceContext) OpenDatabaseWithFreezer

                                                                                                                                                        func (ctx *ServiceContext) OpenDatabaseWithFreezer(name string, cache int, handles int, freezer string, namespace string) (ethdb.Database, error)

                                                                                                                                                          OpenDatabaseWithFreezer opens an existing database with the given name (or creates one if no previous can be found) from within the node's data directory, also attaching a chain freezer to it that moves ancient chain data from the database to immutable append-only files. If the node is an ephemeral one, a memory database is returned.

                                                                                                                                                          func (*ServiceContext) ResolvePath

                                                                                                                                                          func (ctx *ServiceContext) ResolvePath(path string) string

                                                                                                                                                            ResolvePath resolves a user path into the data directory if that was relative and if the user actually uses persistent storage. It will return an empty string for emphemeral storage and the user's own input for absolute paths.

                                                                                                                                                            func (*ServiceContext) Service

                                                                                                                                                            func (ctx *ServiceContext) Service(service interface{}) error

                                                                                                                                                              Service retrieves a currently running service registered of a specific type.

                                                                                                                                                              type StopError

                                                                                                                                                              type StopError struct {
                                                                                                                                                              	Server   error
                                                                                                                                                              	Services map[reflect.Type]error
                                                                                                                                                              }

                                                                                                                                                                StopError is returned if a Node fails to stop either any of its registered services or itself.

                                                                                                                                                                func (*StopError) Error

                                                                                                                                                                func (e *StopError) Error() string

                                                                                                                                                                  Error generates a textual representation of the stop error.