github.com/cgcardona/r-subnet-evm@v0.1.5/rpc/doc.go (about)

     1  // (c) 2019-2020, Ava Labs, Inc.
     2  //
     3  // This file is a derived work, based on the go-ethereum library whose original
     4  // notices appear below.
     5  //
     6  // It is distributed under a license compatible with the licensing terms of the
     7  // original code from which it is derived.
     8  //
     9  // Much love to the original authors for their work.
    10  // **********
    11  // Copyright 2015 The go-ethereum Authors
    12  // This file is part of the go-ethereum library.
    13  //
    14  // The go-ethereum library is free software: you can redistribute it and/or modify
    15  // it under the terms of the GNU Lesser General Public License as published by
    16  // the Free Software Foundation, either version 3 of the License, or
    17  // (at your option) any later version.
    18  //
    19  // The go-ethereum library is distributed in the hope that it will be useful,
    20  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    21  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    22  // GNU Lesser General Public License for more details.
    23  //
    24  // You should have received a copy of the GNU Lesser General Public License
    25  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    26  
    27  /*
    28  Package rpc implements bi-directional JSON-RPC 2.0 on multiple transports.
    29  
    30  It provides access to the exported methods of an object across a network or other I/O
    31  connection. After creating a server or client instance, objects can be registered to make
    32  them visible as 'services'. Exported methods that follow specific conventions can be
    33  called remotely. It also has support for the publish/subscribe pattern.
    34  
    35  # RPC Methods
    36  
    37  Methods that satisfy the following criteria are made available for remote access:
    38  
    39    - method must be exported
    40    - method returns 0, 1 (response or error) or 2 (response and error) values
    41  
    42  An example method:
    43  
    44  	func (s *CalcService) Add(a, b int) (int, error)
    45  
    46  When the returned error isn't nil the returned integer is ignored and the error is sent
    47  back to the client. Otherwise the returned integer is sent back to the client.
    48  
    49  Optional arguments are supported by accepting pointer values as arguments. E.g. if we want
    50  to do the addition in an optional finite field we can accept a mod argument as pointer
    51  value.
    52  
    53  	func (s *CalcService) Add(a, b int, mod *int) (int, error)
    54  
    55  This RPC method can be called with 2 integers and a null value as third argument. In that
    56  case the mod argument will be nil. Or it can be called with 3 integers, in that case mod
    57  will be pointing to the given third argument. Since the optional argument is the last
    58  argument the RPC package will also accept 2 integers as arguments. It will pass the mod
    59  argument as nil to the RPC method.
    60  
    61  The server offers the ServeCodec method which accepts a ServerCodec instance. It will read
    62  requests from the codec, process the request and sends the response back to the client
    63  using the codec. The server can execute requests concurrently. Responses can be sent back
    64  to the client out of order.
    65  
    66  An example server which uses the JSON codec:
    67  
    68  	 type CalculatorService struct {}
    69  
    70  	 func (s *CalculatorService) Add(a, b int) int {
    71  		return a + b
    72  	 }
    73  
    74  	 func (s *CalculatorService) Div(a, b int) (int, error) {
    75  		if b == 0 {
    76  			return 0, errors.New("divide by zero")
    77  		}
    78  		return a/b, nil
    79  	 }
    80  
    81  	 calculator := new(CalculatorService)
    82  	 server := NewServer()
    83  	 server.RegisterName("calculator", calculator)
    84  	 l, _ := net.ListenUnix("unix", &net.UnixAddr{Net: "unix", Name: "/tmp/calculator.sock"})
    85  	 server.ServeListener(l)
    86  
    87  # Subscriptions
    88  
    89  The package also supports the publish subscribe pattern through the use of subscriptions.
    90  A method that is considered eligible for notifications must satisfy the following
    91  criteria:
    92  
    93    - method must be exported
    94    - first method argument type must be context.Context
    95    - method must have return types (rpc.Subscription, error)
    96  
    97  An example method:
    98  
    99  	func (s *BlockChainService) NewBlocks(ctx context.Context) (rpc.Subscription, error) {
   100  		...
   101  	}
   102  
   103  When the service containing the subscription method is registered to the server, for
   104  example under the "blockchain" namespace, a subscription is created by calling the
   105  "blockchain_subscribe" method.
   106  
   107  Subscriptions are deleted when the user sends an unsubscribe request or when the
   108  connection which was used to create the subscription is closed. This can be initiated by
   109  the client and server. The server will close the connection for any write error.
   110  
   111  For more information about subscriptions, see https://github.com/ethereum/go-ethereum/wiki/RPC-PUB-SUB.
   112  
   113  # Reverse Calls
   114  
   115  In any method handler, an instance of rpc.Client can be accessed through the
   116  ClientFromContext method. Using this client instance, server-to-client method calls can be
   117  performed on the RPC connection.
   118  */
   119  package rpc