LambdaFunction

Inherits: Container

Description

The LambdaFunction class allows you to create an abstract AWS Lambda function that acts as a container to instantiate and run components, and expose them via an external entry point.

Important points

• When handling calls the “cmd” parameter determines what action shall be called, while the other parameters are passed to the action itself.

• Container configuration for this Lambda function is stored in "./config/config.yml" file. But this path can be overriden by CONFIG_PATH environment variable.

References

• *:logger:*:*:1.0: (optional) ILogger components to pass log messages.
• *:counters:*:*:1.0: (optional) ICounters components to pass collected measurements.
• *:service:lambda:*:1.0: (optional) ILambdaService services to handle action requests
• *:service:commandable-lambda:*:1.0: (optional) ILambdaService services to handle action requests

Constructors

Creates a new instance of this lambda function.

public LambdaFunction(string name, string description)

• name: string - (optional) a container name (accessible via ContextInfo).
• description: string - (optional) container description (accessible via ContextInfo).

Fields

Instance methods

ActAsync

Calls registered action in this lambda function. The “cmd” parameter in the action parameters determines what 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> - result

ExecuteAsync

Executes this AWS Lambda function and returns the result. This method can be overloaded in child classes if it is necessary to change the default behavior

protected Task<string> ExecuteAsync(string input)

• input: string - event parameters (or function arguments)
• returns: Task<string> - result of the function execution.

GetHandlerAsync

Gets an entry point into this lambda function.

public Func<string, Task<string>> GetHandlerAsync()

• returns: Func<string, Task<string>> - incoming event object with invocation parameters.

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.

Register

Registers all actions in this lambda function.

• Note: Overloading of this method has been deprecated. Use LambdaService instead.

protected void Register()

RegisterAction

Registers an action in this lambda function.

• Note: This method has been deprecated. Use LambdaService instead.

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

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

RegisterServices

Registers all lambda services in the container.

protected void RegisterServices()

RunAsync

Runs this lambda function, loads container configuration, instantiates components and manages their lifecycle. Makes this function ready to access action calls.

public async Task RunAsync()

SetReferences

Sets references to dependent components.

public void SetReferences(IReferences references)

• references: IReferences - references to locate the component’s dependencies.

Examples

class MyLambdaFunction extends LambdaFunction {
    public MyLambdaFunction(): base("mygroup", "MyGroup lambda function") { }
}
var lambda = new MyLambdaFunction();
await service.RunAsync();
Console.WriteLine("MyLambdaFunction is started");

See also

• LambdaClient