Information Technology Reference
In-Depth Information
<<interface>>
NotificationManager
<<exception>>
OrchestrationManagementException
<<Message Management>>
+ createMessage(Publisher, Topic) : Notification
+ deliverMessage(Subscriber, Expertise, int, AlertPolicyAge) : Alerts[
]
+ publishMessage(Notification)
+ getMessageStatus(Identifier) : MessageStatus
+ markAlertAsRead(Identifier, Identifier) : void
<<Topic Management>>
+ getAllTopics() : Topic[
]
+ getTopic(Identifier) : Topic
+ registerTopic (Topic) : Identifier
+ getChildTopics(Identifier) : Topic[
]
+ getRootTopic() : Topic
<<exception>>
ExpertiseException
<<exception>>
TopicException
<<exception>>
MessageException
<<exception>>
SubscriberException
<<Publisher management>>
+ getPublisher(Identifier) : Publisher
+ registerPublisher(Publisher) : Identifier
+ getPublisherChildrenTopics(Identifier, Identifier) : Topic[
]
+ getAllPublisher() : Publisher[
]
<<exception>>
PublisherException
<<interface>>
RegistrationManager
<<Expertise Management>>
+ getAllExpertises() : Expertise[
]
+ getExpertise(Identifier) : Expertise
+ getChildExpertises(Identifier) : Expertise[
]
+ getRootExpertise() : Expertise
<<Subscriber Management>>
+ getSubscriber(Identifier) : Subscriber
+ registerSubscriber(Subscriber) : Identifier
+ unregisterSubscriber (Identifier) : boolean
+ getSubscriberChildrenExpertises(Identifier, Identifier) : Expertise[
]
+ getAllSubscriber() : Subscriber[
]
UserManager
Preservation
Orchestration
Manager
<<use>>
<<use>>
RepInfoGapManager
Fig. 17.13
CASPAR POM component interface
17.6 Preservation DataStores
17.6.1 Introduction
Long-Term Digital Preservation (LTDP) systems aim to ensure the use of digital
information beyond the lifetime of the technology used to create that information.
While data on paper can easily be stored and dispersed for 100 years or more at
low cost, in the digital world this task is more challenging and requires carefully
planned digital preservation and distribution systems. The preservation challenge is
twofold: bit preservation and logical preservation. Bit preservation is the ability to
restore the bits in the presence of storage media degradation and obsolescence, or
even environmental catastrophes like fire or flooding. Logical preservation includes
preserving the understandability and usability of the data in the future when current
technologies for computer hardware, operating systems, data management products
and applications may no longer exist.
At the heart of any LTDP system, there is a storage component that includes
the ultimate place of the data. This storage component needs to store the ever
growing data produced by diverse devices in different formats using dispersed deliv-
ery vehicles. Traditional archival storage support mostly bit preservation and may
