I have explained the overall concept of standard meta data and word dictionary in the last posting. (Please refer to the article “Managing standard word dictionary”) There is one more dictionary to be managed by DA(Data Architect), and it is the standard domain dictionary.
As the number of attribute increases, we need a category to represent the character of the attribute apparently and also need specific data type to define the range of data for the attribute. We call it as ‘domain’ and it is consist of ‘domain group’ and ‘domain type’.
We can distinguish the character of the attribute more easily when we check the domain group which is located at the end of the attribute. For example, when we find a attribute ‘APPROVAL STATUS CODE ‘ or column ‘APRO_STS_CD’, we can expect easily that the attribute is for code value. You can create domain group for your needs such as code, flag, name, address, ID, date, year month, amount, height, rate, remark and so on. Of course the word for the domain group should be registered in word dictionary in advance, and it is very important to establish a set of well defined domain group for better communication and higher quality. DA has to define the purpose of the domain group carefully not to be confused by project members.
Once you have finished setting the domain group, the next step is to define the data type of each domain group. You can define a certain data type for a domain group, for example,varchar2(1) data type for flag domain group, date data type for date domain group and varchar2(20), varchar2(50) for name domain group. The purpose of managing the data type of each domain group is to make developers to use same data type for same attribute, and it will reduce system error which can be caused by different data type for same attribute and increase DB performance. You can see the sample domain groups and its data types at the ‘Dictionary’ UI of BluePrint solution.
When new domain type is requested, DA has to consider the optimized number of domain type according to its frequency of use. The smaller number of domain type for each domain group is the better because it is simple and easy to get accustomed to it, and it will be recognized as standard quickly. But even though there are many demands for several data types in one domain group, if DA is too strict to approve new domain type for standard, it can cause inefficiency in DBMS and programming. Therefore, DA has to consider the both sides and approve the request reasonably to get the best result. When a designer wants to request a new domain group and data type, user click ‘New’ button in Dictionary UI, and can see the below application pop-up. The next process is just same as that of standard word registration.
After domain is approved by DA, designers can use the domain to create a new attribute. And after the new attribute is approved as a standard attribute, user can see the related standard attribute with the domain when he click the domain on the grid.
When select Name domain, system shows the all attribute using the Name domain.