de.smartics.exceptions.sample.lib.resource

Class ResourceMessage

java.lang.Object

de.smartics.exceptions.i18n.AbstractMessageBean

de.smartics.exceptions.sample.lib.exceptions.ServiceMessage

de.smartics.exceptions.sample.lib.resource.ResourceMessage

All Implemented Interfaces:

de.smartics.exceptions.i18n.MessageBean, Serializable

public final class ResourceMessage
extends ServiceMessage

Information for a resource that has not been found.

Implementation Notes:

Note that we do not provide getters for the information of this message instance. This is because we know that this information is only required for logging. The exception handler will access the message parameters directly via reflection. We would add getters if we would use this message instance in a context where we want to display this information in another context. This might be that we want to serialize the instance to XML as part of a REST resource or to display the information in a HTML page.

Note that this instance provides a factory to create messages. This is an experiment to make creating messages for log events easier.

Also note the factory methods that help to create message instances for different scenarios, e.g notFound(String, String).

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ResourceMessage.Factory Factory to create log messages for a given service.

Field Summary

Fields

Modifier and Type	Field and Description
private Object	resourceData The optional resource data.
private String	resourceId The identifier of the missing resource.
private static long	serialVersionUID The class version identifier.

Fields inherited from class de.smartics.exceptions.i18n.AbstractMessageBean

code, localizedInfo

Constructor Summary

Constructors

Constructor and Description
ResourceMessage(AnyServiceCode code, String serviceName, String resourceId) Convenience constructor without a cause and no resource data.
ResourceMessage(AnyServiceCode code, String serviceName, String resourceId, Object resourceData) Convenience constructor without a cause.
ResourceMessage(Throwable cause, AnyServiceCode code, String serviceName, String resourceId) Convenience constructor without specifying the resource data.
ResourceMessage(Throwable cause, AnyServiceCode code, String serviceName, String resourceId, Object resourceData) Default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
static ResourceMessage	log(AnyServiceCode code, String serviceName, String resourceId) Factory method to create a log message instance.
static ResourceMessage	log(AnyServiceCode code, String serviceName, String resourceId, Object resourceData) Factory method to create a log message instance.
static ResourceMessage	notFound(String serviceName, String resourceId) Factory method to create a message instance.

Methods inherited from class de.smartics.exceptions.sample.lib.exceptions.ServiceMessage

service, service

Methods inherited from class de.smartics.exceptions.i18n.AbstractMessageBean

getCause, getCauseTrail, getCauseTrail, getCode, getLocalizedInfo, getLocalizedMessage, getLocalizedMessage, getLocalizedMessage, getLocalizedMessage, getLocalizedTextMessage, getLocalizedTextMessage, getLocalizedTextMessage, getMessage, getMessage, getMessage, getMessages, getMessages, toString

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

The class version identifier.

The value of this constant is 1L.

Constant Field Value:

1L

See Also:

Constant Field Values

resourceId

@MessageParam(value="2")
private final String resourceId

The identifier of the missing resource.

Implementation Notes:

As stated above, the fields are not visible as properties. Because of this PMD complaints about unused fields. We mark them with the NOPMD marker to appease the static analyzer.

The message parameter annotation starts with index 2 since the parent message defines the indices 0 and 1. This may be a problem during early development where additional information is added to the parent class. This makes it necessary to renumber the fields and the message texts later. See Bug 712.

resourceData

@MessageParam(value="3")
private final Object resourceData

The optional resource data.

Constructor Detail

ResourceMessage

public ResourceMessage(AnyServiceCode code,
               String serviceName,
               String resourceId)

Convenience constructor without a cause and no resource data.

Parameters:

code - the error or exception code of the exception.

serviceName - the name of the service that encountered a fault situation.

resourceId - the identifier of the missing resource.

ResourceMessage

public ResourceMessage(Throwable cause,
               AnyServiceCode code,
               String serviceName,
               String resourceId)

Convenience constructor without specifying the resource data.

Parameters:

cause - the cause to the problem.

code - the error or exception code of the exception.

serviceName - the name of the service that encountered a fault situation.

resourceId - the identifier of the missing resource.

ResourceMessage

public ResourceMessage(AnyServiceCode code,
               String serviceName,
               String resourceId,
               Object resourceData)

Convenience constructor without a cause.

Parameters:

code - the error or exception code of the exception.

serviceName - the name of the service that encountered a fault situation.

resourceId - the identifier of the missing resource.

resourceData - the optional resource data.

ResourceMessage

public ResourceMessage(Throwable cause,
               AnyServiceCode code,
               String serviceName,
               String resourceId,
               Object resourceData)

Default constructor.

Implementation Notes:

As you can see, the number of parameters can grow quite big. Usually this calls for the builder pattern, especially if there are parameters of the same type. In a real world example the serviceName, resourceId, and resourceData parameters may have their own types. Nonetheless a builder would be handy, albeit the use of the builder will require a couple of lines to construct the message instance. This is unfortunate since the logging or event raising issue comes into the focus of the business logic where it should meld with the background. The factory pattern only helps little, since most of the arguments are different in the context the factory instance is used. In a real world example resource ID and data usually would form an entity, reducing the count to four, which is an admissible number in the context of a message constructor. Six is certainly too much. Five ... usually, too. We let it live, since most of the time we should create new instances with the factory methods. There we can see that the number of parameters is four and less.

Parameters:

cause - the cause to the problem.

code - the error or exception code of the exception.

serviceName - the name of the service that encountered a fault situation.

resourceId - the identifier of the missing resource.

resourceData - the optional resource data.

Method Detail

notFound

public static ResourceMessage notFound(String serviceName,
                       String resourceId)

Factory method to create a message instance.

Parameters:

serviceName - the name of the service that encountered a fault situation.

resourceId - the identifier of the missing resource.

Returns:

the created message instance.

log

public static ResourceMessage log(AnyServiceCode code,
                  String serviceName,
                  String resourceId)

Factory method to create a log message instance.

Parameters:

code - the error or exception code of the exception.

serviceName - the name of the service that logs.

resourceId - the identifier of the resource.

Returns:

the created message instance.

log

public static ResourceMessage log(AnyServiceCode code,
                  String serviceName,
                  String resourceId,
                  Object resourceData)

Factory method to create a log message instance.

Parameters:

code - the error or exception code of the exception.

serviceName - the name of the service that logs.

resourceId - the identifier of the resource.

resourceData - the optional resource data.

Returns:

the created message instance.