LambdaService

Implements: ILambdaService, IOpenable, IConfigurable, IReferenceable

Description

The LambdaService class allows you to create abstract services that receive remove calls via the AWS Lambda protocol.

Important points

This service is intended to work inside LambdaFunction container that exploses registered actions externally.

Configuration parameters

• dependencies:
  • controller: override for Controller dependency

References

• *:logger:*:*:1.0: (optional) ILogger components to pass log messages.
• *:counters:*:*:1.0: (optional) ICounters components to pass collected measurements.

Constructors

Creates an instance of this service.

public LambdaService(string name)

• name: string - service name to generate action cmd.

Creates an instance of this service.

public LambdaService()

Fields

Instance methods

ActAsync

Calls registered action in this lambda function. The “cmd” parameter in the action parameters determines the action shall be called.

• This method shall only be used in testing.

public Task<string> ActAsync(string input)

• input: string - action parameters.
• returns: Task<string> - results

ApplyInterceptors

Applies given action to the interseptors

protected Func<string, Task<string>> ApplyInterceptors(Func<string, Task<string>> action)

• action: Func<string, Task<string>> - applied action.
• returns: Func<string, Task<string>> - wrapped interceptors action.

ApplyValidation

Applies a validation according to a given schema.

protected Func<string, Task<string>> ApplyValidation(Schema schema, Func<string, Task<string>> action)

• schema: Schema - validation schema
• action: Func<string, Task<string>> - action
• returns: Func<string, Task<string>> - results

CloseAsync

Closes a component and frees used resources.

public Task CloseAsync(string correlationId)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.

Configure

Configures a component by passing configuration parameters.

public void Configure(ConfigParams config)

• config: ConfigParams - configuration parameters to be set.

GenerateActionCmd

Adds .cmd to the name of the command.

public string GenerateActionCmd(string name)

• name: string - name of the command
• returns: string - T - generated command

GetActions

Gets all the actions supported by the service.

public IList<LambdaAction> GetActions()

• returns: IList<LambdaAction> - array with supported actions.

Instrument

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

protected CounterTiming Instrument(string correlationId, string name)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• name: string - method name.
• returns: CounterTiming - CounterTiming object to end the time measurement.

InstrumentError

Adds instrumentation to error handling.

protected void InstrumentError(string correlationId, string methodName, Exception ex, bool rethrow = false)

• correlationId: string - (optional) transaction id to trace execution through call chain.
• methodName: string - a method name.
• ex: Exception - Error that occured during the method call.
• rethrow: bool - True to throw the exception.

IsOpen

Checks if the component is open.

public bool IsOpen()

• returns: bool - true if the component is open and false otherwise.

OpenAsync

Opens the component.

public Task OpenAsync(string correlationId)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.

RegisterAction

Registers an action in AWS Lambda function.

protected void RegisterAction(string name, Schema schema, Func<string, Task<string>> action)

• name: string - action name
• schema: Schema - validation schema used to validate received parameters.
• action: Func<string, Task<string>> - action function that is called when an operation is invoked.

RegisterActionWithAuth

Registers an action with authorization.

protected void RegisterActionWithAuth(string name, Schema schema, Func<string, Func<string, Task<string>>, Task<string>> authorize, Func<string, Task<string>> action)

• name: string - action’s name
• schema: Schema - validation schema used to validate received parameters.
• authorize: Func<string, Func<string, Task<string>>, Task<string>> - authorization interceptor
• action: Func<string, Task<string>> - action function that is called when an operation is invoked.

RegisterInterceptor

Registers a middleware for actions in AWS Lambda service.

protected void RegisterInterceptor(string cmd, Func<string, Func<string, Task<string>>, Task<string>> action)

• cmd: string - command name.
• action: Func<string, Func<string, Task<string>>, Task<string>> - action function that is called when middleware is invoked.

SetReferences

Sets references to dependent components.

public virtual void SetReferences(IReferences references)

• references: IReferences - references used to locate the component dependencies.

Abstract methods

Register

Registers all service routes in an HTTP endpoint.

This method is called by the service and must be overriden in child classes.

protected abstract void Register()

Examples

public class MyLambdaService : LambdaService
{
    private IMyController _controller;
    public MyLambdaService() : base("v1.myservice")
    {
        _dependencyResolver.Put(
            "controller",
            new Descriptor("mygroup", "controller", "*", "*", "1.0")
        );
    }
    public override void SetReferences(IReferences references)
    {
        base.SetReferences(references);
        this._controller = _dependencyResolver.GetRequired<IMyController>("controller");
    }
    protected override void Register()
    {
        RegisterAction("get_mydata", null, async (input) =>
        {
            var body = AwsLambdaHelper.GetParameters(input);
            var data = await this._controller.GetMyDataAsync(
            GetCorrelationId(input),
                body.GetAsNullableString("id")
            );
            return JsonConverter.ToJson(data);
        });
    }
}

/// ...

var service = new MyLambdaService();
service.Configure(ConfigParams.FromTuples(
    "connection.protocol", "http",
    "connection.host", "localhost",
    "connection.port", 8080
));
service.SetReferences(References.FromTuples(
   new Descriptor("mygroup", "controller", "default", "default", "1.0"), controller
));
await service.OpenAsync("123");
Console.WriteLine("The GRPC service is running on port 8080");

See also

• LambdaClient