com.pushtechnology.diffusion.client.features

Interface UpdateConstraint

All Known Subinterfaces:

UpdateConstraint.PartialJSON

public interface UpdateConstraint

A constraint to be applied to an update operation or the creation of an update stream.

Constraints describe a condition that must be satisfied for an operation to succeed. Constraints can be applied to the setting of a value or creation of an update stream. Constraints are only evaluated on the server.

The constraints are evaluated using the:

• active session locks
• existence of the topic
• current value of the topic

The value of a topic can be described in several ways. The value can be described as an exact value, a partial value or an unset value.

Constraints can be composed with one another using logical ANDs or ORs. It is possible to compose a constraint that can never be satisfied although certain combinations, such as ANDing two incompatible constraints are prevented. Multiple session locks can be held but a topic can only have a single value.

Constraints can be created using a UpdateConstraint.Factory, an instance of which can be obtained using update constraints. For example:

 
 UpdateConstraint.Factory factory = Diffusion.updateConstraints();
 UpdateConstraint constraint = factory.locked(lock).and(factory.value(EQ, expectedValue));
 
 

Since:

6.2

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	UpdateConstraint.Factory Factory for the constraint types.
static class	UpdateConstraint.Operator An operator used in a constraint comparison.
static interface	UpdateConstraint.PartialJSON A constraint requiring the current value of a JSON topic to match the partially described value.

Method Summary

Modifier and Type	Method and Description
UpdateConstraint	and(UpdateConstraint other) Returns a composed constraint that represents a logical AND of this constraint and another.
UpdateConstraint	or(UpdateConstraint other) Returns a composed constraint that represents a logical OR of this constraint and another.

Method Detail

and

UpdateConstraint and(UpdateConstraint other)

Returns a composed constraint that represents a logical AND of this constraint and another.

Parameters:

other - a constraint that will be logically-ANDed with this constraint

Returns:

a composed constraint that represents a logical AND of this constraint and the other constraint

Throws:

IllegalArgumentException - if the composed constraint would be unsatisfiable

or

UpdateConstraint or(UpdateConstraint other)

Returns a composed constraint that represents a logical OR of this constraint and another.

Parameters:

other - a constraint that will be logically-ORed with this constraint

Returns:

a composed constraint that represents a logical OR of this constraint and the other constraint

Since:

6.10