Interface IDeltaType
The optional extension provided by IDataType implementations that support incremental changes to values.
Namespace: PushTechnology.ClientInterface.Data
Assembly: Diffusion.Client.dll
Syntax
public interface IDeltaType
Remarks
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
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.
Declaration
string Name { get; }
Property Value
Type | Description |
---|---|
String | The external identifier for this delta type. |
NoChange
Returns a constant that indicates no changes between values.
Declaration
object NoChange { get; }
Property Value
Type | Description |
---|---|
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.
Declaration
object Apply(object oldValue, object delta)
Parameters
Type | Name | Description |
---|---|---|
Object | oldValue | The old value object. |
Object | delta | The delta object to apply to the old value object. |
Returns
Type | Description |
---|---|
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.
Declaration
object Diff(object oldValue, object newValue)
Parameters
Type | Name | Description |
---|---|---|
Object | oldValue | The old value object. |
Object | newValue | The new value object. |
Returns
Type | Description |
---|---|
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.
Declaration
bool IsValueCheaper(object value, object delta)
Parameters
Type | Name | Description |
---|---|---|
Object | value | The value object. |
Object | delta | The delta object. |
Returns
Type | Description |
---|---|
Boolean | True if |
ReadDelta(IBytes)
Creates a delta from IBytes.
Declaration
object ReadDelta(IBytes input)
Parameters
Type | Name | Description |
---|---|---|
IBytes | input | The binary data. |
Returns
Type | Description |
---|---|
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.
Declaration
object ReadDelta(byte[] input)
Parameters
Type | Name | Description |
---|---|---|
Byte[] | input | The binary data. The implementation may re-use the array to avoid copying. The caller must ensure the array is not modified. |
Returns
Type | Description |
---|---|
Object | The delta object. |
Remarks
This is equivalent to ReadDelta(Byte[], Int32, Int32).
ReadDelta(Byte[], Int32, Int32)
Creates a delta from a binary segment.
Declaration
object ReadDelta(byte[] input, int offset, int length)
Parameters
Type | Name | Description |
---|---|---|
Byte[] | input | The binary data. The implementation may re-use the array to avoid copying. The caller must ensure the array is not modified. |
Int32 | offset | The starting index of the segment. |
Int32 | length | The length of the segment. |
Returns
Type | Description |
---|---|
Object | The delta object. |
ToBytes(Object)
Returns the serialized form of the given
delta
as IBytes.
Declaration
IBytes ToBytes(object delta)
Parameters
Type | Name | Description |
---|---|---|
Object | delta | The delta object. |
Returns
Type | Description |
---|---|
IBytes | The delta as IBytes. |
Remarks
Since 6.0.
WriteDelta(Object, Stream)
Serializes a delta to binary.
Declaration
void WriteDelta(object delta, Stream outputStream)
Parameters
Type | Name | Description |
---|---|---|
Object | delta | The delta object. |
Stream | outputStream | The output stream. |