Package io.mats3.spring
Annotation Interface MatsClassMapping
@Documented
@Retention(RUNTIME)
@Target({TYPE,ANNOTATION_TYPE})
@Repeatable(MatsClassMappings.class)
@Service
public @interface MatsClassMapping
A class annotated with this repeatable annotation will become a Mats Endpoint, where an instance of the class itself
is the State (STO) object for the Endpoint, and each @
Stage
-annotated method on the class is a stage of
the Endpoint. This annotation is meta-annotated with @Service
, and is thus also a Spring bean. This singleton
Spring bean acts as a "template" for the State, and any wired (injected/autowired) fields will be available for the
stage-methods, but will not be regarded as part of the State when serialized and sent on the wire. You should use the
Java-modifier transient
on such Spring-injected fields, so that the serializer understands that it is
not a part of state. In addition, if a field is of type ProcessContext
, it will be injected by
the Mats JavaConfig machinery before a stage-method is invoked.
All methods that are annotated with @Stage
is regarded as a stage of the Mats Endpoint. To know the
order of the stages, and ordinal must be assigned to the Stage - read its JavaDoc. The initial stage is the method
annotated with @Stage(0)
(The constant Stage.INITIAL
is conveniently available),
and the subsequent stages are the ordered list of these stage-methods. The last stage will typically have a return
type - which defines the return type of the endpoint - while no other stage can have a return type. It is, however,
still possible to return early if needed, by using context.reply(..)
. If the
last stage does not have a return type (i.e. it is void
), it will be a Terminator. Any methods that are
not annotated with @Stage
is ignored, thus you may structure and divide your code into sub methods as
you see fit.
Note: If you only need a single stage, i.e. a single-stage Endpoint, or Terminator, you should instead
consider MatsMapping
.
Note: You should mark the injected/autowired fields with the java keyword transient
to ensure
that the serializer understands that it is not part of the state. (The values are null
'ed out before
state serialization takes place, so an injected DataSource will never be attempted serialized as state. However, some
type of serializers, e.g. Gson, will prepare to serialize all fields, even though they will always be null, and thus
possibly fail on newer versions of Java. Such preparation does not take place if a field is marked transient.)
Each stage-method can take zero, one, two or many arguments. The machinery looks for a ProcessContext and an incoming
DTO argument. Neither ProcessContext nor an incoming DTO is required. The rationale for taking more than the required
arguments is that you could potentially want to invoke it differently in a testing scenario (depending on how you
feel towards testing).
- 0: No ProcessContext nor incoming DTO.
- 1: Either it is a ProcessContext, otherwise it must be the incoming DTO.
- 2: If one is a ProcessContext, the other must be the incoming DTO.
- 2+: One may be the ProcessContext, and the others are searched for the @
Dto
annotation, and if one is found, this is the incoming DTO.
List<Car> cars = new ArrayList<>()
. A field of type ProcessContext is not a state field.
It is worth noting that the singleton Spring-constructed bean instance is never actually employed outside of being
inspected at start up: Its class is inspected to set up the MatsEndpoint and its stages, and the singleton instance
is used as a template for which fields of the Endpoint's State object are injected, and which fields are
state.
In a multi-MatsFactory setup, you may qualify which MatsFactory this Endpoint should be constructed on - read JavaDoc
on @MatsMapping
for how this works.- See Also:
-
Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic @interface
static @interface
Each method in the class that shall correspond to a Stage on the Mats endpoint must be annotated with this@Stage
annotation. -
Optional Element Summary
Optional ElementsModifier and TypeOptional ElementDescriptionThe Mats Endpoint Id that this endpoint should listen to.Specified theMatsFactory
to use by means of specifying the bean name of theMatsFactory
.Class<? extends Annotation>
Specifies theMatsFactory
to use by means of a specific qualifier annotation type (which thus must be meta-annotated withQualifier
).Specified theMatsFactory
to use by means of specifying the@Qualifier
value.Alias for "endpointId", so that if you only need to set the endpointId, you can do so directly:@MatsEndpointSetup("endpointId")
-
Element Details
-
endpointId
The Mats Endpoint Id that this endpoint should listen to.- Returns:
- the Mats Endpoint Id which this endpoint listens to.
- Default:
- ""
-
value
Alias for "endpointId", so that if you only need to set the endpointId, you can do so directly:@MatsEndpointSetup("endpointId")
- Returns:
- the endpointId.
- Default:
- ""
-
matsFactoryCustomQualifierType
Class<? extends Annotation> matsFactoryCustomQualifierTypeSpecifies theMatsFactory
to use by means of a specific qualifier annotation type (which thus must be meta-annotated withQualifier
). Notice that this will search for the custom qualifier annotation type, as opposed to if you add the annotation to the @MatsEndpointSetup-annotated method directly, in which case it "equals" the annotation instance (as Spring also does when performing injection with such qualifiers). The difference comes into play if the annotation has values, where e.g. a@SpecialMatsFactory(location="central")
is not equal to@SpecialMatsFactory(location="region_west")
- but they are equal when comparing types, as the qualification here does. Thus, if using this qualifier-approach, you should probably not use values on your custom qualifier annotations (instead make separate custom qualifier annotations, e.g.@MatsFactoryCentral
and@MatsFactoryRegionWest
for the example).- Returns:
- the custom qualifier type which the wanted
MatsFactory
is qualified with.
- Default:
- java.lang.annotation.Annotation.class
-
matsFactoryQualifierValue
String matsFactoryQualifierValueSpecified theMatsFactory
to use by means of specifying the@Qualifier
value. Spring performs such lookup by first looking for actual qualifiers with the specified value, e.g.@Qualifier(value="the_value")
. If this does not produce a result, it will try to find a bean with this value as the bean name.- Returns:
- the qualifier value which the wanted
MatsFactory
is qualified with.
- Default:
- ""
-
matsFactoryBeanName
String matsFactoryBeanNameSpecified theMatsFactory
to use by means of specifying the bean name of theMatsFactory
.- Returns:
- the bean name of the wanted
MatsFactory
.
- Default:
- ""
-