CapGdlrCommandBus

Inherits: GdlrCapability < RefCounted < Object

Capability that dispatches commands.

Description

A command is a serializable request. The bus wraps it in a CapGdlrCommandBus.CommandEnvelope, runs the envelope through the bus middleware, and then executes it according to CapGdlrCommandBus.CommandRoute.exec_kind: local handlers from CapGdlrCommandHandlers, a remote CapGdlrCommandTransport, or both.

Godular ships a service for this capability at res://addons/godular/built_ins/services/command_bus.svc.gd. It needs a CapGdlrCommandHandlers and a CapGdlrCommandTransport:

const SvcCommandBus = preload("res://addons/godular/built_ins/services/command_bus.svc.gd")
const SvcCommandHandlers = preload("res://addons/godular/built_ins/services/command_handlers.svc.gd")

static var PROVIDERS = {
    CapGdlrCommandHandlers: {"use": SvcCommandHandlers},
    CapGdlrCommandTransport: {"use": MyTransport},
    CapGdlrCommandBus: {
        "use": SvcCommandBus,
        "inject": [CapGdlrCommandHandlers, CapGdlrCommandTransport],
    },
}

Tutorials

• Command bus

Methods

void	use(middleware: Callable) abstract
void	clear_middleware() abstract
CapGdlrCommandBus.CommandResult	dispatch(command_or_envelope: Variant, meta_params: Dictionary = {}) abstract

---

Enumerations

enum CommandStatus: 🔗

CommandStatus NACK = 0

The command was not accepted. CapGdlrCommandBus.CommandResult.reason explains why.

CommandStatus ACK = 1

The command was accepted.

CommandStatus TIMEOUT = 2

The command timed out.

---

enum ExecKind: 🔗

ExecKind NONE = -1

No route. The bus rejects the command.

ExecKind LOCAL = 0

Local handlers only.

ExecKind REMOTE = 1

The remote transport only.

ExecKind DUAL_LOCAL_FIRST = 2

Local handlers first, then the remote transport. The remote result is returned.

ExecKind DUAL_REMOTE_FIRST = 3

The remote transport first, then local handlers. The remote result is returned.

---

Method Descriptions

void use(middleware: Callable) abstract 🔗

Adds bus middleware. middleware receives the next step of the chain and returns a callable that takes an envelope and returns a CapGdlrCommandBus.CommandResult:

bus.use(func(next: Callable) -> Callable:
    return func(envelope: CapGdlrCommandBus.CommandEnvelope):
        print("dispatching ", envelope.command)
        return await next.call(envelope)
)

The first middleware added is the outer layer.

---

void clear_middleware() abstract 🔗

Removes every bus middleware.

---

CapGdlrCommandBus.CommandResult dispatch(command_or_envelope: Variant, meta_params: Dictionary = {}) abstract 🔗

Dispatches a command and returns its result. command_or_envelope is a CapGdlrCommandBus.Command or a CapGdlrCommandBus.CommandEnvelope. For a command, the bus creates a CapGdlrCommandBus.CommandMeta and sets each key of meta_params on it. The envelope must have a CapGdlrCommandBus.CommandMeta.route.