de.aristaflow.adept2.base.configuration

Annotation Type Property

@Target(value={})
public @interface Property

The definition of a configuration property in a ConfigurationDescription.

When a property is declared in a configuration description of a component, the configuration (in the form of a Properties-object) that is received by an instance of that component always contains a value for that property. This value was either explicitly set in the configuration or it's the default value assigned to the property.

A property is either required or a default value that matches the type and the restrictions of the property must be specified. The default default value is the empty string, so omitting the default value of an optional property may work where it fits the type and restrictions.

TODO: Where to use the description? Add it to the exception message in case of illegal property values? Might also be used in a graphical configuration tool (if we should ever get one).

Author:

Patrick Schmidt

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
java.lang.String	name The name of the property, e.g.

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
boolean	defaultNull Whether an empty string as default value is to be interpreted as null.
java.lang.String	defaultValue The default value of the property.
java.lang.String	description A short description of the component.
boolean	documentationOnly Whether the configuration description is only for documentation purpose, that is, it should be part of the generated configuration documentation but it should not be considered within the actual configuration.
boolean	isRequired Whether the property is required in configurations.
java.lang.String[]	restrictions Further restrictions on the allowed values of a property.
Property.Type	type See Property.Type for more information on which string values are legal string representations of the respective type.

Element Detail

name

public abstract java.lang.String name

The name of the property, e.g. isCaching.

Returns:

name of the property

description

public abstract java.lang.String description

A short description of the component.

Returns:

short description of the component

Default:

""

isRequired

public abstract boolean isRequired

Whether the property is required in configurations. Otherwise the defaultValue() will be used (i.e. it will be transparently filled into the configuration of the component.

Please note, in case of Property.Type.STRING, a required property also means the value must be non-empty!

Returns:

whether the property is required in configurations

Default:

false

type

public abstract Property.Type type

See Property.Type for more information on which string values are legal string representations of the respective type.

Returns:

the data type of the property

Default:

de.aristaflow.adept2.base.configuration.Property.Type.STRING

defaultValue

public abstract java.lang.String defaultValue

The default value of the property. If isRequired() is set to true the defaultValue is ignored. Otherwise it has to be a legal string representation of the type defined in type(). If the property is not required and no default value is provided, the empty string will be used, that is, the empty string is the default for the default value.

Returns:

The default value of the property.

Default:

""

defaultNull

public abstract boolean defaultNull

Whether an empty string as default value is to be interpreted as null. This attribute is only relevant in case the default value is set to the empty string (or not provided at all).

Returns:

Whether an empty string as default should be interpreted as null instead of the empty string.

Default:

false

documentationOnly

public abstract boolean documentationOnly

Whether the configuration description is only for documentation purpose, that is, it should be part of the generated configuration documentation but it should not be considered within the actual configuration. For instance, the configuration of component/service types and instances should be documented but cannot be retrieved from the static configuration description.

Default:

false

restrictions

public abstract java.lang.String[] restrictions

Further restrictions on the allowed values of a property. Restrictions are expressed through strings of the format: <restrictionType>: <restrictionData> or <restrictionType>/<restrictionOptions>: <restrictionData>. The following restriction types are available:

• oneof: a comma-separated list of allowed values. Whitespace around the commas is discarded. By default the values are treated case-sensitive. Use i as option for case-insensitive comparisons.
  Example:
  oneof: apple, orange, banana
oneof/i: apple, orange, banana (case-insensitive comparison)
• length: a restriction on the length of values, either a fixed length or a range. x can be used as a wildcard.
  Examples:
  length: 5 (a fixed length)
  length: 1 to 6
length: 1 to x (minimum length of 1 and no maximum length)
• pattern: a regular expression the values have to match. Leading and trailing whitespace around the pattern is ignored; use parentheses if it's important. By default the pattern matching is case-sensitive. Use i as option for case-insensitive matching.
  Example:
  pattern: prefix.*
  See Pattern for more information an regular expression patterns in Java.
• range: an interval of allowed values (only available for number types). x can be used as a wildcard. Intervals may be open (( or closed ([) (closed is default if omitted).
  Examples:
  range: 1 to 6 (values between 1 and 6, boundaries included)
  range: [1 to 6] (equal to previous example)
  range: 0 to 1) (values between 0 and 1, right boundary not included)
  range: 5 to x (minimum of 5, no maximum)
  range: x to 8 (maximum of 8, no minimum)

Returns:

further restrictions on the allowed values of a property

Default:

{}