Container

Inversion of control (IoC) container that creates components and manages their lifecycle.

Description

The Container class allows you to create an inversion of control (IoC) container that creates components and manages their lifecycle.

Important points

  • The container is driven by configuration, which is usually stored in a JSON or YAML file.
  • The configuration contains a list of components identified by their type or locator, followed by their configuration.
  • On start, a container performs the following actions:
    • Creates components using their types or calls registered factories to create them using their locators.
    • Configures components that implement IConfigurable interface and passes them their configuration parameters.
    • Sets references to components that implement IReferenceable interface and passes them references of all components in the container.
    • Opens components that implement IOpenable interface.
  • On stop, a container reverses the orden of its actions:

Configuration parameters

  • name: context (container or process) name
  • description: human-readable description of the context
  • properties: section of additional descriptive properties
    • …

Constructors

NewContainer

Creates a new instance of the container.

NewContainer(name string, description string) *Container

  • name: string - (optional) container’s name (accessible via ContextInfo)
  • description: string - (optional) container’s description (accessible via ContextInfo)

NewEmptyContainer

Creates a new empty instance of the container.

NewEmptyContainer() *Container

InheritContainer

Creates a new instance of the container inherit from reference.

InheritContainer(name string, description string, referenceable IReferenceable) *Container

  • name: string - a container name (accessible via ContextInfo)
  • description: string - a container description (accessible via ContextInfo)
  • referenceable: IReferenceable - referenceble object for inherit

Fields

config

Configuration of the container

config: ContainerConfig

references

Container’s references

references: ContainerReferences

logger

Logger.

logger: ILogger

info

Container’s information.

info: ContextInfo

factories

Default factories.

factories: DefaultContainerFactory

Methods

AddFactory

Adds a factory to the container. The factory is used to create components
added to the container by their locators (descriptors).

(c *Container) AddFactory(factory IFactory)

  • factory: IFactory - component factory to be added.

Close

Closes the component and frees used resources.

(c *Container) Close(ctx context.Context, correlationId string) error

  • ctx: context.Context - operation context.
  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • returns: error - returns error if not closed

Configure

Configures the component by passing its configuration parameters.

(c *Container) Configure(ctx context.Context, conf *ConfigParams)

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

IsOpen

Checks if the component is open.

(c *Container) IsOpen() bool

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

Open

Opens the component.

(c *Container) Open(ctx context.Context, correlationId string) error

  • ctx: context.Context - operation context.
  • correlationId: string - (optional) transaction id to trace execution through call chain.
  • returns: error - returns error if not opened

ReadConfigFromFile

Reads the container’s configuration from a JSON or YAML file and parameterizes it with the given values.

(c *Container) ReadConfigFromFile(ctx context.Context, correlationId string, path string, parameters *ConfigParams) error

  • ctx: context.Context - operation context.
  • correlationId: string - (optional) transaction id used to trace execution through the call chain.
  • path: string - path to the configuration file
  • parameters: ConfigParams - configuration parameters or nil to skip parameterization.
  • returns: error - returns error if not readed

Examples

- descriptor: mygroup:mycomponent1:default:default:1.0
  param1: 123
  param2: ABC
- type: mycomponent2,mypackage
  param1: 321
  param2: XYZ

container := NewEmptyContainer()
container.AddFactory(newMyComponentFactory())

parameters := NewConfigParamsFromValue(os.Environ())
container.ReadConfigFromFile(context.Background(), "123", "./config/config.yml", parameters)

err := container.Open(context.Background(), "123")
fmt.Println("Container is opened")
...
err = container.Close(context.Background(), "123")
fmt.Println("Container is closed")

See also