github.com/theQRL/go-zond@v0.1.1/node/doc.go (about)

     1  // Copyright 2016 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  /*
    18  Package node sets up multi-protocol Ethereum nodes.
    19  
    20  In the model exposed by this package, a node is a collection of services which use shared
    21  resources to provide RPC APIs. Services can also offer devp2p protocols, which are wired
    22  up to the devp2p network when the node instance is started.
    23  
    24  # Node Lifecycle
    25  
    26  The Node object has a lifecycle consisting of three basic states, INITIALIZING, RUNNING
    27  and CLOSED.
    28  
    29  	●───────┐
    30  	     New()
    31  	        │
    32  	        ▼
    33  	  INITIALIZING ────Start()─┐
    34  	        │                  │
    35  	        │                  ▼
    36  	    Close()             RUNNING
    37  	        │                  │
    38  	        ▼                  │
    39  	     CLOSED ◀──────Close()─┘
    40  
    41  Creating a Node allocates basic resources such as the data directory and returns the node
    42  in its INITIALIZING state. Lifecycle objects, RPC APIs and peer-to-peer networking
    43  protocols can be registered in this state. Basic operations such as opening a key-value
    44  database are permitted while initializing.
    45  
    46  Once everything is registered, the node can be started, which moves it into the RUNNING
    47  state. Starting the node starts all registered Lifecycle objects and enables RPC and
    48  peer-to-peer networking. Note that no additional Lifecycles, APIs or p2p protocols can be
    49  registered while the node is running.
    50  
    51  Closing the node releases all held resources. The actions performed by Close depend on the
    52  state it was in. When closing a node in INITIALIZING state, resources related to the data
    53  directory are released. If the node was RUNNING, closing it also stops all Lifecycle
    54  objects and shuts down RPC and peer-to-peer networking.
    55  
    56  You must always call Close on Node, even if the node was not started.
    57  
    58  # Resources Managed By Node
    59  
    60  All file-system resources used by a node instance are located in a directory called the
    61  data directory. The location of each resource can be overridden through additional node
    62  configuration. The data directory is optional. If it is not set and the location of a
    63  resource is otherwise unspecified, package node will create the resource in memory.
    64  
    65  To access to the devp2p network, Node configures and starts p2p.Server. Each host on the
    66  devp2p network has a unique identifier, the node key. The Node instance persists this key
    67  across restarts. Node also loads static and trusted node lists and ensures that knowledge
    68  about other hosts is persisted.
    69  
    70  JSON-RPC servers which run HTTP, WebSocket or IPC can be started on a Node. RPC modules
    71  offered by registered services will be offered on those endpoints. Users can restrict any
    72  endpoint to a subset of RPC modules. Node itself offers the "debug", "admin" and "web3"
    73  modules.
    74  
    75  Service implementations can open LevelDB databases through the service context. Package
    76  node chooses the file system location of each database. If the node is configured to run
    77  without a data directory, databases are opened in memory instead.
    78  
    79  Node also creates the shared store of encrypted Ethereum account keys. Services can access
    80  the account manager through the service context.
    81  
    82  # Sharing Data Directory Among Instances
    83  
    84  Multiple node instances can share a single data directory if they have distinct instance
    85  names (set through the Name config option). Sharing behaviour depends on the type of
    86  resource.
    87  
    88  devp2p-related resources (node key, static/trusted node lists, known hosts database) are
    89  stored in a directory with the same name as the instance. Thus, multiple node instances
    90  using the same data directory will store this information in different subdirectories of
    91  the data directory.
    92  
    93  LevelDB databases are also stored within the instance subdirectory. If multiple node
    94  instances use the same data directory, opening the databases with identical names will
    95  create one database for each instance.
    96  
    97  The account key store is shared among all node instances using the same data directory
    98  unless its location is changed through the KeyStoreDir configuration option.
    99  
   100  # Data Directory Sharing Example
   101  
   102  In this example, two node instances named A and B are started with the same data
   103  directory. Node instance A opens the database "db", node instance B opens the databases
   104  "db" and "db-2". The following files will be created in the data directory:
   105  
   106  	data-directory/
   107  		A/
   108  			nodekey            -- devp2p node key of instance A
   109  			nodes/             -- devp2p discovery knowledge database of instance A
   110  			db/                -- LevelDB content for "db"
   111  		A.ipc                  -- JSON-RPC UNIX domain socket endpoint of instance A
   112  		B/
   113  			nodekey            -- devp2p node key of node B
   114  			nodes/             -- devp2p discovery knowledge database of instance B
   115  			static-nodes.json  -- devp2p static node list of instance B
   116  			db/                -- LevelDB content for "db"
   117  			db-2/              -- LevelDB content for "db-2"
   118  		B.ipc                  -- JSON-RPC UNIX domain socket endpoint of instance B
   119  		keystore/              -- account key store, used by both instances
   120  */
   121  package node