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. It is only possible to construct logical ANDs of constraints. Constraints can only be composed if the resulting constraint is satisfiable. Multiple session locks can be held but a topic can only have a single value. Constraints specifying multiple topic values cannot be constructed.

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(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 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.

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