Group items tagged

by the container in order to realize common use cases

An interface becomes a vehicle for encapsulation or abstraction,

“Interfaces are used to encode similarities which the classes of various types share, but do not necessarily constitute a class relationship. For instance, a human and a parrot can both whistle; however, it would not make sense to represent Humans and Parrots as subclasses of a Whistler class. Rather they would most likely be subclasses of an Animal class (likely with intermediate classes), but both would implement the Whistler interface.” [http://en.wikipedia.org/wiki/Java_interface]

Extensive use of interfaces derives from a

Premature Extensibility Is the Root of Some Evil

The number of artifacts will double and you will have to introduce a configuration facility

Individuals: instances or objects

Attributes: aspects, properties, features, characteristics, or parameters

Relations: ways in which classes and individuals can be related to one another

Function terms:

Restrictions: formally stated descriptions of what must be true in order for some assertion to be accepted as input

Rules: statements in the form of an if-then (antecedent-consequent) sentence that describe the logical inferences that can be drawn from an assertion in a particular form

Axioms: assertions (including rules) in a logical form

Events: the changing of attributes or relations

Benefit

Violation of the encapsulation

domain model's objects cannot guarantee their correctness

Necessitates a service layer when sharing domain logic across differing consumers of an object model.

Makes a model less expressive and harder to understand.

Facilitates code duplication among transactional scripts and similar use cases, reduces code reuse.

Liabilities

Liabilities

Liabilities

this practice was deprecated due to incompatibility problems when the experimental types were standardized

Limitations

may incorrectly classify a content's media type:

but depending on the system's regional settings, it may expect a semicolon as a separator instead of a comma, since in some languages the comma is used as the decimal separator

Also, many regional versions of Excel will not be able to deal with Unicode in CSV

Most of the important information is really stored in the edges

measures the number of linearly independent paths through a program's source code

count of the number of

through the source code

In an EAV data model, each attribute-value pair is a fact describing an entity, and a row in an EAV table stores a single fact

EAV tables are often described as "long and skinny": "long" refers to the number of rows, "skinny" to the few columns

Data is recorded as three columns: The entity: the item being described. The attribute or parameter: a foreign key into a table of attribute definitions. At the very least, the attribute definitions table would contain the following columns: an attribute ID, attribute name, description, data type, and columns assisting input validation

The value of the attribute

Row modeling, where facts about something (in this case, a sales transaction) are recorded as multiple rows rather than multiple columns

differences between row modeling and EAV (which may be considered a generalization of row-modeling) are:

A row-modeled table is homogeneous in the facts that it describes

The data type of the value column/s in a row-modeled table is pre-determined by the nature of the facts it records. By contrast, in an EAV table, the conceptual data type of a value in a particular row depend on the attribute in that row

In the EAV table itself, this is just an attribute ID, a foreign key into an Attribute Definitions table

The Attribute

The Value

Coercing all values into strings

larger systems use separate EAV tables for each data type (including binary large objects, "BLOBS"), with the metadata for a given attribute identifying the EAV table in which its data will be stored

Where an EAV system is implemented through RDF, the RDF Schema language may conveniently be used to express such metadata

access to metadata must be restricted, and an audit trail of accesses and changes put into place to deal with situations where multiple individuals have metadata access

quality of the annotation and documentation within the metadata (i.e., the narrative/explanatory text in the descriptive columns of the metadata sub-schema) must be much higher, in order to facilitate understanding by various members of the development team.

Attribute metadata

Validation metadata include data type, range of permissible values or membership in a set of values, regular expression match, default value, and whether the value is permitted to be null

Presentation metadata: how the attribute is to be displayed to the user

Grouping metadata: Attributes are typically presented as part of a higher-order group, e.g., a specialty-specific form. Grouping metadata includes information such as the order in which attributes are presented

Advanced validation metadata Dependency metadata: