Interface IDeltaType
- Namespace
- PushTechnology.ClientInterface.Data
- Assembly
- Diffusion.Client.dll
The optional extension provided by IDataType implementations that support incremental changes to values.
public interface IDeltaTypeRemarks
Each implementation specifies a value type and a delta type. Two values, oldValue and newValue, can be compared to produce a delta using Diff(object, object). The delta can be separately applied to oldValue to create newValue using Apply(object, object).
Delta types should provide a string representation. Equality is optional for delta types.
Deferred parsing
Implementations can choose not to fully validate values when they are read,
but instead defer parsing until it is required. Consequently, all methods
that accept values can throw System.IO.InvalidDataException.
Since 5.8
Properties
Name
Returns the external identifier for this delta type.
string Name { get; }Property Value
- string
The external identifier for this delta type.
NoChange
Returns a constant that indicates no changes between values.
object NoChange { get; }Property Value
- object
A constant that indicates no changes between values.
Remarks
This constant is returned by Diff(object, object) to indicate oldValue and newValue are equivalent. The result is guaranteed to be equal only to itself.
Methods
Apply(object, object)
Applies a delta to a value.
object Apply(object oldValue, object delta)Parameters
oldValueobjectThe old value object.
deltaobjectThe delta object to apply to the old value object.
Returns
- object
The new value object. The old value object will be returned if the delta had no effect.
Diff(object, object)
Creates a delta from two values.
object Diff(object oldValue, object newValue)Parameters
Returns
- object
The delta representing the difference between oldValue and newValue.
Remarks
If there are many differences between oldValue and newValue, the result might require more bytes to transmit than the new value, or be computationally expensive to apply. In this case, it is better to discard oldValue and publish newValue in its place. This can be checked using IsValueCheaper(object, object).
The implementation can return the special constant NoChange to indicate the oldValue and newValue are equivalent and there is no change to publish.
IsValueCheaper(object, object)
Calculates if value is cheaper than delta.
The result is typically determined by the length of the serialized form but
can also consider the complexity of the delta.
bool IsValueCheaper(object value, object delta)Parameters
Returns
- bool
True if
valueis considered cheaper thandelta. Otherwise false.
ReadDelta(IBytes)
Creates a delta from IBytes.
object ReadDelta(IBytes input)Parameters
inputIBytesThe binary data.
Returns
- object
The delta object.
Remarks
This is equivalent to calling ReadDelta(byte[]) with the result of ToByteArray() as argument.
Since 6.0.
ReadDelta(byte[])
Creates a delta from a binary segment.
object ReadDelta(byte[] input)Parameters
inputbyte[]The binary data. The implementation may re-use the array to avoid copying. The caller must ensure the array is not modified.
Returns
- object
The delta object.
Remarks
This is equivalent to ReadDelta(input,0,input.Length).
ReadDelta(byte[], int, int)
Creates a delta from a binary segment.
object ReadDelta(byte[] input, int offset, int length)Parameters
inputbyte[]The binary data. The implementation may re-use the array to avoid copying. The caller must ensure the array is not modified.
offsetintThe starting index of the segment.
lengthintThe length of the segment.
Returns
- object
The delta object.
ToBytes(object)
Returns the serialized form of the given
delta as IBytes.
IBytes ToBytes(object delta)Parameters
deltaobjectThe delta object.
Returns
Remarks
Since 6.0.
WriteDelta(object, Stream)
Serializes a delta to binary.
void WriteDelta(object delta, Stream outputStream)