Descriptor

Component locator based on group, type, kind, name and version of the component.

Description

The Descriptor class provides you with a component locator. This locator is often used in the PipServices toolkit. It locates components using the following fields:

  • Group: a package or just named group of components, like “pip-services”.
  • Type: logical component type that defines it’s contract, like “persistence” .
  • Kind: physical implementation type, like “mongodb”.
  • Name: unique component name, like “default”.
  • Version: version of the component contract, like “1.0”.

Important points

  • The locator matching can be done by all or only few selected fields.
  • The fields that shall be excluded from the matching must be set to ""* or *null*.
  • This approach allows to implement many interesting scenarios. For instance:
    • Locate all loggers (match by type and version)
    • Locate persistence components for a microservice (match by group and type)
    • Locate specific component by its name (match by name)

Constructors

Creates a new instance of the descriptor.

public Descriptor(string group, string type, string kind, string name, string version)

  • group: string - a logical component group
  • type: string - a logical component type or contract
  • kind: string - a component implementation type
  • name: string - a unique component name
  • version: string - a component implementation version

Properties

Group

Gets the component’s logical group.

public string Group [ get, private set ]

  • returns: string - the component’s logical group

Type

public string Type [ get, private set ]

Kind

Gets the component’s implementation type.

public string Kind [ get, private set ]

  • returns: string - the component’s implementation type.

Name

Gets the unique component’s name.

public string Name [ get, private set ]

  • returns: string - the unique component’s name.

Version

Gets the component’s implementation version.

public string Version [ get, private set ]

  • returns: string - the component’s implementation version.

Instance methods

Equals

Compares this descriptor to a value. If value is a Descriptor it tries to match them, otherwise the method returns false.

public override bool Equals(object obj)

  • obj: object - the value to match against this descriptor.
  • returns: bool - true if the value is matching descriptor and false otherwise.

ExactMatch

Matches this descriptor to another descriptor by all fields. No exceptions are made.

public bool ExactMatch(Descriptor descriptor)

  • descriptor: Descriptor - the descriptor to match this one against.
  • returns: bool - true if descriptors match and false otherwise.

GetHashCode

TODO add description

public override int GetHashCode()

  • returns: int - TODO: add description

IsComplete

Checks whether all descriptor fields are set. If descriptor has at least one “*” or null field it is considered “incomplete”,

public bool IsComplete()

  • returns: bool - true if all descriptor fields are defined and false otherwise.

Match

Partially matches this descriptor to another descriptor. Fields that contain “*” or null are excluded from the match.

public bool Match(Descriptor descriptor)

  • descriptor: Descriptor the descriptor to match this one against.
  • returns: bool - true if descriptors match and false otherwise

ToString

Gets a string representation of the object. The result is a colon-separated list of descriptor fields as “mygroup:connector:aws:default:1.0”

public override string ToString()

  • returns: string - a string representation of the object.

Static methods

FromString

Parses colon-separated list of descriptor fields and returns them as a Descriptor.
Throws a ConfigException if the descriptor string is of a wrong format.

public static Descriptor FromString(string value)

  • value: string - colon-separated descriptor fields to initialize Descriptor.
  • returns: Descriptor - a newly created Descriptor.

Examples

var locator1 = new Descriptor("mygroup", "connector", "aws", "default", "1.0");
var locator2 = Descriptor.fromString("mygroup:connector:*:*:1.0");

locator1.match(locator2);       // Result: true
locator1.equal(locator2);       // Result: true
locator1.exactMatch(locator2);  // Result: false