Components module

Contains standard component definitions that can be used to build applications and services.

Packages

The module contains the following packages:

Auth - authentication credential stores
Build - basic factories for constructing objects
Cache - distributed cache
Config - configuration readers and managers, whose main task is to deliver configuration parameters to the application from wherever they are being stored
Connect - connection discovery and configuration services
Count - performance counters
Info - context info implementations that manage the saving of process information and sending additional parameter sets
Lock - distributed lock components
Log - basic logging components that provide console and composite logging, as well as an interface for developing custom loggers
State - TODO: add description
Trace - TODO: add description
Test - minimal set of test components to make testing easier
Component - the root package

Use

Warning! Config package now not work with condition {{#if var}} something {{/}} in config files. Use Mustache syntax, for example {{#var}} something {{/var}}

Use

Add this to your package’s pubspec.yaml file:

dependencies:
  pip_services3_components: version

Now you can install package from the command line:

pub get

Example how to use Logging and Performance counters. Here we are going to use CompositeLogger and CompositeCounters components. They will pass through calls to loggers and counters that are set in references.

import 'package:pip_services3_commons/src/config/ConfigParams.dart';
import 'package:pip_services3_commons/src/config/IConfigurable.dart';
import 'package:pip_services3_commons/src/refer/IReferences.dart';
import 'package:pip_services3_commons/src/refer/IReferenceable.dart';
import 'package:pip_services3_components/src/log/CompositeLogger.dart';
import 'package:pip_services3_components/src/count/CompositeCounters.dart';
import 'package:pip_services3_components/src/count/Timing.dart';


class MyComponent implements IConfigurable, IReferenceable {
  CompositeLogger _logger = CompositeLogger();
  CompositeCounters _counters = CompositeCounters();
  
  configure(ConfigParams config) {
    this._logger.configure(config);
  }
  
  setReferences(IReferences refs) {
    this._logger.setReferences(refs);
    this._counters.setReferences(refs);
  }
  
  myMethod(String correlationId, dynamic param1) {
    try{
      this._logger.trace(correlationId, "Executed method mycomponent.mymethod");
      this._counters.increment("mycomponent.mymethod.exec_count", 1);
      Timing timing = this._counters.beginTiming("mycomponent.mymethod.exec_time");
      ....
      timing.endTiming();
    } catch(e) {
      this._logger.error(correlationId, e, "Failed to execute mycomponent.mymethod");
      this._counters.increment("mycomponent.mymethod.error_count", 1);
    }
  }
}

Example how to get connection parameters and credentials using resolvers. The resolvers support “discovery_key” and “store_key” configuration parameters to retrieve configuration from discovery services and credential stores respectively.

import 'package:pip_services3_commons/src/config/ConfigParams.dart';
import 'package:pip_services3_commons/src/config/IConfigurable.dart';
import 'package:pip_services3_commons/src/refer/IReferences.dart';
import 'package:pip_services3_commons/src/refer/IReferenceable.dart';
import 'package:pip_services3_commons/src/run/IOpenable.dart';
import 'package:pip_services3_components/src/connect/ConnectionParams.dart';
import 'package:pip_services3_components/src/connect/ConnectionResolver.dart';
import 'package:pip_services3_components/src/auth/CredentialParams.dart';
import 'package:pip_services3_components/src/auth/CredentialResolver.dart';

class MyComponent implements IConfigurable, IReferenceable, IOpenable {
  final _connectionResolver = ConnectionResolver();
  final _credentialResolver = CredentialResolver();
  bool _opened = false;

  @override
  void configure(ConfigParams config) {
    _connectionResolver.configure(config);
    _credentialResolver.configure(config);
  }

  @override
  void setReferences(IReferences refs) {
    _connectionResolver.setReferences(refs);
    _credentialResolver.setReferences(refs);
  }

  // ...
  @override
  Future open(String? correlationId) async {
    ConnectionParams? connection =
        await _connectionResolver.resolve(correlationId);

    CredentialParams? credential =
        await _credentialResolver.lookup(correlationId);

    if (connection != null && credential != null) {
      String? host = connection.getHost();
      int? port = connection.getPort();
      String? user = credential.getUsername();
      String? pass = credential.getPassword();
      // ...
      _opened = true;
    }
  }

  @override
  Future close(String? correlationId) {
    // do closing
    return Future.value();
  }

  @override
  bool isOpen() {
    return _opened;
  }
}

Example how to use caching and locking. Here we assume that references are passed externally.

import 'package:pip_services3_commons/src/refer/Descriptor.dart';
import 'package:pip_services3_commons/src/refer/References.dart';
import 'package:pip_services3_commons/src/refer/IReferences.dart';
import 'package:pip_services3_commons/src/refer/IReferenceable.dart';
import 'package:pip_services3_components/src/lock/ILock.dart';
import 'package:pip_services3_components/src/lock/MemoryLock.dart';
import 'package:pip_services3_components/src/cache/ICache.dart';
import 'package:pip_services3_components/src/cache/MemoryCache.dart';

class MyComponent implements IReferenceable {
  ICache? _cache;
  ILock? _lock;

  @override
  void setReferences(IReferences refs) {
    _cache =
        refs.getOneRequired<ICache>(Descriptor('*', 'cache', '*', '*', '1.0'));
    _lock =
        refs.getOneRequired<ILock>(Descriptor('*', 'lock', '*', '*', '1.0'));
  }

  Future myMethod(String? correlationId, dynamic param1) async {
    // First check cache for result
    dynamic result = await _cache!.retrieve(correlationId, 'mykey');

    // Lock..
    await _lock!.acquireLock(correlationId, 'mykey', 1000, 1000);

    // Do processing
    // ...

    // Store result to cache async
    await _cache!.store(correlationId, 'mykey', result, 3600000);

    // Release lock async
    await _lock!.releaseLock(correlationId, 'mykey');
  }
}

void main() async {
// Use the component
  MyComponent myComponent = MyComponent();

  myComponent.setReferences(References.fromTuples([
    Descriptor('pip-services', 'cache', 'memory', 'default', '1.0'),
    MemoryCache(),
    Descriptor('pip-services', 'lock', 'memory', 'default', '1.0'),
    MemoryLock(),
  ]));

  await myComponent.myMethod(null, 'param1');
}

If you need to create components using their locators (descriptors) implement component factories similar to the example below.

import 'package:pip_services3_components/src/build/Factory.dart';
import 'package:pip_services3_commons/src/refer/Descriptor.dart';

class MyFactory extends Factory {
  static Descriptor myComponentDescriptor =
      Descriptor('myservice', 'mycomponent', 'default', '*', '1.0');

  MyFactory() : super() {
    registerAsType(MyFactory.myComponentDescriptor, MyComponent);
  }
}

// Using the factory

MyFactory myFactory = MyFactory();

MyComponent1 myComponent1 = myFactory.create(
    Descriptor('myservice', 'mycomponent', 'default', 'myComponent1', '1.0'));
MyComponent2 myComponent2 = myFactory.create(
    Descriptor('myservice', 'mycomponent', 'default', 'myComponent2', '1.0'));
...