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 constructor(name?: string)

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

Fields

Instance methods

act

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 act(params: any): Promise<any>

• params: any - action parameters.
• returns: Promise<any> - results

applyInterceptors

Applies given action to the interseptors

protected applyInterceptors(action: (params: any) => Promise<any>): (params: any) => Promise<any>

• action: (params: any) => Promise<any> - applied action.
• returns: (params: any) => Promise<any> - wrapped interceptors action.

applyValidation

Applies a validation according to a given schema.

protected applyValidation(schema: Schema, action: (params: any) => Promise<any>): (params: any) => Promise<any>

• schema: Schema - validation schema
• action: (params: any) => Promise<any> - action
• returns: (params: any) => Promise<any> - results

close

Closes a component and frees used resources.

public close(correlationId: string): Promise<void>

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

configure

Configures a component by passing configuration parameters.

public configure(config: ConfigParams): void

• config: ConfigParams - configuration parameters to be set.

generateActionCmd

Adds .cmd to the name of the command.

protected generateActionCmd(name: string): string

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

getActions

Gets all the actions supported by the service.

public getActions(): LambdaAction[]

• returns: LambdaAction[] - array with supported actions.

instrument

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

protected instrument(correlationId: string, name: string): InstrumentTiming

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

isOpen

Checks if the component is open.

public isOpen(): boolean

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

open

Opens the component.

public open(correlationId: string): Promise<void>

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

registerAction

Registers an action in AWS Lambda function.

protected registerAction(name: string, schema: Schema, action: (params: any) => Promise<any>): void

• name: string - action name
• schema: Schema - validation schema used to validate received parameters.
• action: (params: any) => Promise<any> - action function that is called when an operation is invoked.

registerActionWithAuth

Registers an action with authorization.

protected registerActionWithAuth(name: string, schema: Schema, authorize: (call: any, next: (call: any) => Promise<any>) => Promise<any>, action: (call: any) => Promise<any>): void

• name: string - action’s name
• schema: Schema - validation schema used to validate received parameters.
• authorize: (call: any, next: (call: any) => Promise<any> - authorization interceptor
• action: (call: any) => Promise<any> - action function that is called when an operation is invoked.

registerInterceptor

Registers a middleware for actions in AWS Lambda service.

protected registerInterceptor(action: (params: any, next: (params: any) => Promise<any>) => Promise<any>): void

• action: (params: any, next: (params: any) => Promise<any>) => Promise<any> - action function that is called when middleware is invoked.

setReferences

Sets references to dependent components.

public setReferences(references: IReferences): void

• 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 register(): void

Examples

class MyLambdaService extends LambdaService {
   private _controller: IMyController;
   ...
   public constructor() {
      base('v1.myservice');
      this._dependencyResolver.put(
          "controller",
          new Descriptor("mygroup","controller","*","*","1.0")
      );
   }
   public setReferences(references: IReferences): void {
      base.setReferences(references);
      this._controller = this._dependencyResolver.getRequired<IMyController>("controller");
   }
   public register(): void {
       registerAction("get_mydata", null, async (params) => {
           let correlationId = params.correlation_id;
           let id = params.id;
           return await this._controller.getMyData(correlationId, id);
       });
       ...
   }
}

let 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
));

service.open("123");
console.log("The GRPC service is running on port 8080");

See also

• LambdaClient