API¶

Plugins for Plugeth use Golang’s Native Plugin System. Plugin modules must export variables using specific names and types. These will be processed by the plugin loader, and invoked at certain points during Geth’s operations.

Flags¶

Name: Flags
Type: flag.FlagSet
Behavior: This FlagSet will be parsed and your plugin will be able to access the resulting flags. Flags will be passed to Geth from the command line and are intended to of the plugin. Note that if any flags are provided, certain checks are disabled within Geth to avoid failing due to unexpected flags.

Subcommands¶

Name: Subcommands
Type: map[string]func(ctx *cli.Context, args []string) error
Behavior: If Geth is invoked with ./geth YOUR_COMMAND, the plugin loader will look for YOUR_COMMAND within this map, and invoke the corresponding function. This can be useful for certain behaviors like manipulating Geth’s database without having to build a separate binary.

Initialize¶

Name: Initialize
Type: func(*cli.Context, core.PluginLoader, core.logs )
Behavior: Called as soon as the plugin is loaded, with the cli context and a reference to the plugin loader. This is your plugin’s opportunity to initialize required variables as needed. Note that using the context object you can check arguments, and optionally can manipulate arguments if needed for your plugin.

Todo

explain that plugin could provide node.Node with restricted.backend

InitializeNode¶

Name: InitializeNode
Type: func(core.Node, core.Backend)
Behavior: This is called as soon as the Geth node is initialized. The core.Node object represents the running node with p2p and RPC capabilities, while the Backend gives you access to a wide array of data you may need to access.

GetAPIs¶

Name: GetAPIs
Type: func(core.Node, core.Backend) []rpc.API
Behavior: This allows you to register new RPC methods to run within Geth.

The GetAPIs function itself will generally be fairly brief, and will looks something like this:

  ``func GetAPIs(stack *node.Node, backend core.Backend) []core.API {
  return []rpc.API{
   {
     Namespace: "mynamespace",
     Version:      "1.0",
     Service:      &MyService{backend},
     Public:              true,
   },
  }
}``

The bulk of the implementation will be in the MyService struct. MyService should be a struct with public functions. These functions can have two different types of signatures:

RPC Calls: For straight RPC calls, a function should have a context.Context object as the first argument, followed by an arbitrary number of JSON marshallable arguments, and return either a single JSON marshal object, or a JSON marshallable object and an error. The RPC framework will take care of decoding inputs to this function and encoding outputs, and if the error is non-nil it will serve an error response.
Subscriptions: For subscriptions (supported on IPC and websockets), a function should have a context.Context object as the first argument followed by an arbitrary number of JSON marshallable arguments, and should return an *rpc.Subscription object. The subscription object can be created with rpcSub := notifier.CreateSubscription(), and JSON marshallable data can be sent to the subscriber with notifier.Notify(rpcSub.ID, b).

A very simple MyService might look like:

``type MyService struct{}

  func (h MyService) HelloWorld(ctx context.Context) string {
    return "Hello World"
  }``

And the client could access this with an rpc call to mynamespace_helloworld