PATTERNS OF DATA MODELING- P2 ppt

Ngày tải lên: 05/07/2014, 06:20

... Modeling Notation 1 1.3 What Is a Pattern? 2 1.4 Why Are Patterns Important? 3 1.5 Drawbacks of Patterns 4 1.6 Pattern vs. Seed Model 4 1.7 Aspects of Pattern Technology 5 1.8 Chapter Summary 6 Bibliographic ... Summary 89 Bibliographic Notes 89 References 90 Chapter 7 Summary of Templates 91 Part II: Antipatterns 95 Chapter 8 Universal Antipatterns 97 8.1 Symmetric Relationship Ant...

Ngày tải lên: 05/07/2014, 06:20

... chapter starts with a discussion of models and then introduces the topic of patterns. 1.1 What Is a Model? A model is an abstraction of some aspect of a problem. Most software models are expressed as ... combinations. Patterns provide a higher level of building blocks than modeling primitives. Patterns are prototypical model fragments that distill the knowledge of experts. •...

Ngày tải lên: 05/07/2014, 06:20

... the sequence of types in the levels of the hierarchy. • Simple tree. Restricts nodes to a single tree. Treats nodes the same. Use when tree de- composition is merely a matter of data structure. • ... context. Figure 2.11 shows an excerpt of this book’s file structure where I have kept old copies of files from reviews. File names are unique within the context of their directory....

Ngày tải lên: 05/07/2014, 06:20

... node name could also be invariant over time (candidate key of nodeName alone). Note that the handling of time reflects a limitation of relational DBMSs. It would be better to use time intervals ... Changing over Time Template 53 in a use of the template. A Node is a position within a directed graph. The distinction be- tween parent and child causes the sense of direction that effect...

Ngày tải lên: 05/07/2014, 06:20

... Nodes were important. A UDG (undirected graph) is a set of nodes and a set of edges that connect nodes. You need not show UDG in a use of the template. A Node is an entity type whose records ... cannot handle edges that connect twice to the same node. A UDG (undirected graph) is a set of nodes and a set of edges that connect nodes. (Note: in an undirected graph all the nodes need no...

Ngày tải lên: 05/07/2014, 06:20

... Universal Antipatterns An antipattern is a characterization of a common software flaw. When you find an antipat- tern, substitute the correction. Universal antipatterns are antipatterns that ... UML diagram Use when Frequency Item description Relates data and metadata in the same model. The same model relates data and metadata. Frequent Homomor- phism Expresses an analogy between...

Ngày tải lên: 05/07/2014, 06:20

... of 2054. •A MajorLanguage of English and long AbbreviationType yields a Phrase of “truck.” •A MajorLanguage of French and long AbbreviationType yields a Phrase of “camion.” •A MajorLanguage of ... AbbreviationType yields a Phrase of “trk.” •A Dialect of British English and long AbbreviationType yields a Phrase of “lorry.” In practice, many persons could populate data and d...

Ngày tải lên: 05/07/2014, 06:20

... enter data 170 Chapter 13 / Softcoded Values A SoftcodedVal ue is a piece of data for an Entity and has parallel fields for different data types. A SoftcodedValue can have one of four data types—integer, ... softcoded values. The model combines data and metadata. The top entity types shaded in gray (EntityType, Attribute, EnumValue) concern metadata . The bottom (Entity, Softcod...

Ngày tải lên: 05/07/2014, 06:20

... data. Of course, writing the software was more dif- ficult than with hardcoding and required skilled developers. You should consider using softcoded values for an application with uncertain data ... volatile applications, softcoding adds stability to the data representation, minimizes changes to application logic, and reduces the likelihood of data conversion. A softcoded model is...

Ngày tải lên: 05/07/2014, 06:20