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data_modeling_and_database_design_in_gellish_english [2018/10/02 14:53]
andries
data_modeling_and_database_design_in_gellish_english [2018/10/02 15:00]
andries facts replaced by ideas
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 ===== How to write Gellish enabled software ===== ===== How to write Gellish enabled software =====
-==== 1. Limitations of conventional database design ====+==== 1. Limitations of conventional database design ​and data exchange ​====
  
-Conventional data modelling ​for any application domain typically results in a domain specific (conceptual,​ logical and physical) data model, also called a scheme. Such a data model documents the requirements and capabilities for storage of data in a database or data exchange messages. Thus it defines the semantic capabilities for expressions of ideas that can be stored in the database or exchanged between systems. \\ +Conventional data modeling ​for any application domain typically results in a domain specific (conceptual,​ logical and physical) data model, also called a scheme. Such a data model documents the requirements and capabilities for storage of data in a database or data exchange messages. Thus it defines the semantic capabilities for expressions of ideas that can be stored in the database or exchanged between systems. \\ 
-In conventional data modelling methodologies,​ such as ER (entity-relationship), ORM (Object-Role Modelling) and others, each data model consists of a definition of the concepts (classes or entity types and attribute types) that are relevant for the application domain, together with relations between those concepts. The concepts are the kinds (classes) that will classify the instances of objects and their aspects, whereas the relations determine the kinds of ideas or facts (instances) that can be stored or exchanged. Such a data model thus defines the structure of the data (the definitions of the database tables and relations between their columns (attributes)). \\+In conventional data modelling methodologies,​ such as ER (Entity-Relationship), ORM (Object-Role Modelling) and others, each data model consists of a definition of the concepts (classes or entity types and attribute types) that are relevant for the application domain, together with relations between those concepts. The concepts are the kinds (classes) that will classify the instances of objects and their aspects, whereas the relations determine the kinds of ideas or facts (instances) that can be stored or exchanged. Such a data model thus defines the structure of the data (the definitions of the database tables and relations between their columns (attributes)). \\
 Once conventional data models are created, they are fixed and specific for the application domain specific (the Universe of Discourse), whereas software is dedicated to that fixed structure. Thus the storage capabilities of the resulting databases are fixed and limited to the application domain. As a consequence modifications of the storage capabilities are time consuming and costly. \\ Once conventional data models are created, they are fixed and specific for the application domain specific (the Universe of Discourse), whereas software is dedicated to that fixed structure. Thus the storage capabilities of the resulting databases are fixed and limited to the application domain. As a consequence modifications of the storage capabilities are time consuming and costly. \\
  
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 Note that the expressions in Table 1 use concepts from the Gellish taxonomic dictionary in which a large number of subtypes of pumps are defined. Assume, for example, that P-1301 was classified as a line shaft pump. Then that would allocate knowledge about line shaft pumps to P-1301, but the taxonomic dictionary would ensure that the knowledge about pumps and centrifugal pumps remains applicable, because it is defined in the dictionary that a line shaft pump is a subtype of centrifugal pump. Thus the taxonomic dictionary specifies that knowledge about pumps and centrifugal pumps is also applicable for their subtypes, such as for line shaft pumps. Note that the expressions in Table 1 use concepts from the Gellish taxonomic dictionary in which a large number of subtypes of pumps are defined. Assume, for example, that P-1301 was classified as a line shaft pump. Then that would allocate knowledge about line shaft pumps to P-1301, but the taxonomic dictionary would ensure that the knowledge about pumps and centrifugal pumps remains applicable, because it is defined in the dictionary that a line shaft pump is a subtype of centrifugal pump. Thus the taxonomic dictionary specifies that knowledge about pumps and centrifugal pumps is also applicable for their subtypes, such as for line shaft pumps.
  
-Gellish makes a distinction between kinds of relations that are used to express knowledge (ideas about kinds of things) and kinds of relations that are used to express information about individual things. For example, ​fact 101 expresses the knowledge that a +Gellish makes a distinction between kinds of relations that are used to express knowledge (ideas about kinds of things) and kinds of relations that are used to express information about individual things. For example, ​idea 101 expresses the knowledge that a 
-  * pump <can have as aspect a> capacity (fact 101)+  * pump <can have as aspect a> capacity (idea 101)
 This knowledge can be used to create a statement that expresses information about P-1301, stating that P-1301 has a particular capacity, called cap-1301 (say). For the expression of that latter another kind of relation shall be used in Gellish as follows: This knowledge can be used to create a statement that expresses information about P-1301, stating that P-1301 has a particular capacity, called cap-1301 (say). For the expression of that latter another kind of relation shall be used in Gellish as follows:
-  * P-1301 <has as aspect> cap-1301 (fact 302)+  * P-1301 <has as aspect> cap-1301 (idea 302)
  
 In the Gellish Dictionary it is defined which kind of relation shall be used to create information about individual things as a realization of a kind of relation used to express knowledge. Table 2 illustrates which relation types should be used to create realizations of the relation types used in Table 1. In the Gellish Dictionary it is defined which kind of relation shall be used to create information about individual things as a realization of a kind of relation used to express knowledge. Table 2 illustrates which relation types should be used to create realizations of the relation types used in Table 1.
data_modeling_and_database_design_in_gellish_english.txt · Last modified: 2018/10/02 15:00 by andries