CompressionOptions

class CompressionOptions

Options controlling compression in a WebSocket.

A CompressionOptions instance can be passed to WebSocket.connect, or used in other similar places where WebSocket compression is configured.

In most cases the default compressionDefault is sufficient, but in some situations, it might be desirable to use different compression parameters, for example to preserve memory on small devices.

Constructors

CompressionOptions() const

const CompressionOptions({
  bool clientNoContextTakeover = false,
  bool serverNoContextTakeover = false,
  int? clientMaxWindowBits,
  int? serverMaxWindowBits,
  bool enabled = true,
})

Implementation

const CompressionOptions({
  this.clientNoContextTakeover = false,
  this.serverNoContextTakeover = false,
  this.clientMaxWindowBits,
  this.serverMaxWindowBits,
  this.enabled = true,
});

Properties

clientMaxWindowBits final

final int? clientMaxWindowBits

The maximal window size bit count requested by the client.

The windows size for the compression is always a power of two, so the number of bits precisely determines the window size.

If set to null, the client has no preference, and the compression can use up to its default maximum window size of 15 bits depending on the server's preference.

Implementation

final int? clientMaxWindowBits;

clientNoContextTakeover final

final bool clientNoContextTakeover

Whether the client will reuse its compression instances.

Implementation

final bool clientNoContextTakeover;

enabled final

final bool enabled

Whether WebSocket compression is enabled.

If not enabled, the remaining fields have no effect, and the compressionOff instance can, and should, be reused instead of creating a new instance with compression disabled.

Implementation

final bool enabled;

hashCode no setter inherited

int get hashCode

The hash code for this object.

A hash code is a single integer which represents the state of the object that affects operator == comparisons.

All objects have hash codes. The default hash code implemented by Object represents only the identity of the object, the same way as the default operator == implementation only considers objects equal if they are identical (see identityHashCode).

If operator == is overridden to use the object state instead, the hash code must also be changed to represent that state, otherwise the object cannot be used in hash based data structures like the default Set and Map implementations.

Hash codes must be the same for objects that are equal to each other according to operator ==. The hash code of an object should only change if the object changes in a way that affects equality. There are no further requirements for the hash codes. They need not be consistent between executions of the same program and there are no distribution guarantees.

Objects that are not equal are allowed to have the same hash code. It is even technically allowed that all instances have the same hash code, but if clashes happen too often, it may reduce the efficiency of hash-based data structures like HashSet or HashMap.

If a subclass overrides hashCode, it should override the operator == operator as well to maintain consistency.

Inherited from Object.

Implementation

external int get hashCode;

runtimeType no setter inherited

Type get runtimeType

A representation of the runtime type of the object.

Inherited from Object.

Implementation

external Type get runtimeType;

serverMaxWindowBits final

final int? serverMaxWindowBits

The maximal window size bit count requested by the server.

The windows size for the compression is always a power of two, so the number of bits precisely determines the window size.

If set to null, the server has no preference, and the compression can use up to its default maximum window size of 15 bits depending on the client's preference.

Implementation

final int? serverMaxWindowBits;

serverNoContextTakeover final

final bool serverNoContextTakeover

Whether the server will reuse its compression instances.

Implementation

final bool serverNoContextTakeover;

Methods

noSuchMethod() inherited

dynamic noSuchMethod(Invocation invocation)

Invoked when a nonexistent method or property is accessed.

A dynamic member invocation can attempt to call a member which doesn't exist on the receiving object. Example:

dynamic object = 1;
object.add(42); // Statically allowed, run-time error

This invalid code will invoke the noSuchMethod method of the integer 1 with an Invocation representing the .add(42) call and arguments (which then throws).

Classes can override noSuchMethod to provide custom behavior for such invalid dynamic invocations.

A class with a non-default noSuchMethod invocation can also omit implementations for members of its interface. Example:

class MockList<T> implements List<T> {
  noSuchMethod(Invocation invocation) {
    log(invocation);
    super.noSuchMethod(invocation); // Will throw.
  }
}
void main() {
  MockList().add(42);
}

This code has no compile-time warnings or errors even though the MockList class has no concrete implementation of any of the List interface methods. Calls to List methods are forwarded to noSuchMethod, so this code will log an invocation similar to Invocation.method(#add, [42]) and then throw.

If a value is returned from noSuchMethod, it becomes the result of the original invocation. If the value is not of a type that can be returned by the original invocation, a type error occurs at the invocation.

The default behavior is to throw a NoSuchMethodError.

Inherited from Object.

Implementation

@pragma("vm:entry-point")
@pragma("wasm:entry-point")
external dynamic noSuchMethod(Invocation invocation);

toString() inherited

String toString()

A string representation of this object.

Some classes have a default textual representation, often paired with a static parse function (like int.parse). These classes will provide the textual representation as their string representation.

Other classes have no meaningful textual representation that a program will care about. Such classes will typically override toString to provide useful information when inspecting the object, mainly for debugging or logging.

Inherited from Object.

Implementation

external String toString();

Operators

operator ==() inherited

bool operator ==(Object other)

The equality operator.

The default behavior for all Objects is to return true if and only if this object and other are the same object.

Override this method to specify a different equality relation on a class. The overriding method must still be an equivalence relation. That is, it must be:

• Total: It must return a boolean for all arguments. It should never throw.

• Reflexive: For all objects o, o == o must be true.

• Symmetric: For all objects o1 and o2, o1 == o2 and o2 == o1 must either both be true, or both be false.

• Transitive: For all objects o1, o2, and o3, if o1 == o2 and o2 == o3 are true, then o1 == o3 must be true.

The method should also be consistent over time, so whether two objects are equal should only change if at least one of the objects was modified.

If a subclass overrides the equality operator, it should override the hashCode method as well to maintain consistency.

Inherited from Object.

Implementation

external bool operator ==(Object other);

Constants

compressionDefault

const CompressionOptions compressionDefault

Default WebSocket compression configuration.

Enables compression with default window sizes and no reuse. This is the default options used by WebSocket.connect if no CompressionOptions is supplied.

• clientNoContextTakeover: false
• serverNoContextTakeover: false
• clientMaxWindowBits: null (default maximal window size of 15 bits)
• serverMaxWindowBits: null (default maximal window size of 15 bits)

Implementation

static const CompressionOptions compressionDefault = CompressionOptions();

compressionOff

const CompressionOptions compressionOff

No-compression configuration.

Disables compression when used as compression configuration for a WebSocket.

Implementation

static const CompressionOptions compressionOff = CompressionOptions(
  enabled: false,
);