DirectClient

Abstract client that calls a controller directly in the same memory space.

Description

The DirectClientclass allows you to create clients that call a controller directly in the same memory space.

Important points

  • It is used when multiple microservices are deployed in a single container (monolyth) and communication between them can be done by direct calls rather than through the network.

Configuration parameters

  • dependencies:
    • controller: override controller descriptor

References

  • *:logger:*:*:1.0 - (optional) ILogger components to pass log messages
  • *:counters:*:*:1.0 - (optional) ICounters components to pass collected measurements
  • *:traces:*:*:1.0 - (optional) ITracer components to record traces
  • *:discovery:*:*:1.0 - (optional) IDiscovery services to resolve a connection

Constructors

NewDirectClient

NewDirectClient is creates a new instance of the client.

NewDirectClient() *DirectClient

Fields

Controller

The controller reference.

Controller: interface{}

Opened

The open flag.

Opened: bool = True

Logger

The logger.

Logger: CompositeLogger

Counters

The performance counters

Counters: CompositeCounters

DependencyResolver

The dependency resolver used to get the controller’s reference.

DependencyResolver: DependencyResolver

Tracer

The tracer.

Tracer *ctrace.CompositeTracer

Methods

Close

Closes a component and frees used resources.

(c *DirectClient) Close(ctx context.Context, context IContext) error

  • ctx: context.Context - operation context.
  • context: IContext - (optional) a context to trace execution through a call chain.
  • returns: error - returns error if not closed

Configure

Configures component by passing configuration parameters.

(c *DirectClient) Configure(ctx context.Context, config *cconf.ConfigParams)

  • ctx: context.Context - operation context.
  • config: *cconf.ConfigParams - configuration parameters to be set.

Instrument

Adds instrumentation to log calls and measures call time. It returns a Timing object that is used to end the time measurement.

(c *DirectClient) Instrument(ctx context.Context, context IContext, name string) *service.InstrumentTiming

  • ctx: context.Context - operation context.
  • context: IContext - (optional) a context to trace execution through a call chain.
  • name: string - method name.
  • returns: *service.InstrumentTiming - InstrumentTiming object used to end the time measurement.

IsOpen

Checks if the component is open.

(c *DirectClient) IsOpen() bool

  • returns: bool - True if the component has been opened and False otherwise.

Open

Opens the component.

(c *DirectClient) Open(ctx context.Context, context IContext) error

  • ctx: context.Context - operation context.
  • context: IContext - (optional) a context to trace execution through a call chain.

SetReferences

Sets references to dependent components.

(c *DirectClient) SetReferences(ctx context.Context, references crefer.IReferences)

  • ctx: context.Context - operation context.
  • references: crefer.IReferences - references to locate the component dependencies.

Examples

type MyDirectClient struct {
	*DirectClient
}
func NewMyDirectClient()* MyDirectClient {
	c:= MyDirectClient{}
	c.DirectClient = NewDirectClient()
	c.DependencyResolver.Put(context.Background(), "controller", cref.NewDescriptor(
        "mygroup", "controller", "*", "*", "*"))
	return &c
}

func (c *MyDirectClient) SetReferences(ctx context.Context, references cref.IReferences) {
	c.DirectClient.SetReferences(ctx, references)
	specificController, ok := c.Controller.(tdata.IMyDataController)
	if !ok {
		panic("MyDirectClient: Cant't resolv dependency 'controller' to IMyDataController")
	}
	c.specificController = specificController
}
...
func (c * MyDirectClient) GetData(ctx context.Context, context IContext, id string)(result MyData, err error) {
	timing := c.Instrument(ctx, context, "myclient.get_data")
	defer timing.EndTiming(ctx);

	return c.specificController.GetData(ctx, context, id)
}
...

client = NewMyDirectClient();
client.SetReferences(context.Background(), cref.NewReferencesFromTuples(
	cref.NewDescriptor("mygroup","controller","default","default","1.0"), controller,
));
res, err := client.GetData(context.Background(), "123", "1")