< six > business entity of UML core elements of object-oriented analysis

A: Basic concepts

A version of the----> Business entity classes (Class). This is especially useful for building a domain model during the business modeling phase. A business entity is a very important factor in the business model, which builds a conceptual understanding of key concepts in the problem domain. is an important means for people to know the problem area. If the participants and use cases describe what we achieve in this problem area, then the business entity describes what we use to achieve our business goals and what we record with them.
----> Official definition: Business entities perform business use case processing or use of "things" on behalf of business roles.
----> A business entity often represents something that is valuable to multiple business use cases or instances of use cases, and generally a good business entity does not contain information about the use of principals and methods of use.
----> How to understand the above definition?
(1) The business entity comes from the real world, and in the problem domain of our modeling we will be able to find something corresponding to it, and this thing is used or created by the participants in the process of accomplishing their business goals. does not necessarily correspond to a specific thing, DTOs are used as data tools.
(2) The business entity must be found in the process of analyzing the business process, and the business process is actually the use case scenario of the business. This means that a business entity must be used or created at least by a business use case scenario, something that is not contributing to a business use case scenario, even if it exists objectively and should not be modeled. For example, in the scene of buying clothes, clothes hangers are no contribution.
(3) The business entity as a version of the class, with all the properties of the object, including properties and methods, and the independence of the object, that is, the business entity should only contain its own inherent characteristics, but not to contain information about how it is used by the outside world. For example: A knife, is a knife, has its own intrinsic properties and behavior. This business entity we describe its size, material, appearance, sharpness, etc., can not describe it is used to cut vegetables. Because it is not used to cut vegetables, it depends on the business scenario. The cooking scene in the chef's kitchen is to cut vegetables. The villain is the weapon used to rob.

Two: properties of business entities
----> properties are records used to hold the characteristics of a business entity, and the set of properties of a business entity determines its uniqueness.
----> properties can be easily found in the real thing that it corresponds to. For example, a coin, we can easily find its properties: denomination, material, size, anti-counterfeiting logo. However, in modeling, we do not need to enumerate all of its properties, only useful in the scene.
----> Generally, if only one object can use this property directly, or it can only be accessed through this object, it should exist as a property. Otherwise, it should be modeled as a single business entity.

Three: Methods of business Entities
The----> method is to access a handle to a business entity that specifies how it can be used externally.
----> method is all the information that is externally capable of using this business entity.
----> does not need to enumerate all the possible methods of this business entity, only the applications in the scenario.
The method of----> Business entities is also the embodiment of the abstract perspective in the object-oriented approach.

Four: Get business entities
-----> in the definition of a business entity: the "things" that a business entity processes or uses when executing business cases on behalf of a business role. A business entity often represents something that is valuable to a business use case or use case instance. This definition is actually the way we get business entities.
-----> (1) Establish business use case scenarios. (2) Analyzing the nouns behind the verbs from the business use case scenario, they are the alternative objects of the business entity. (3) Depending on whether the target has contributed to the business objective, this filter selects the matching object from the alternate list. For example, a post office is a place where it is a constraint to send a letter, or a precondition that does not directly contribute to the business goal of the letter, and should be removed from the list. The rest becomes the initial business entity. (4) Analyze the relationships between business entities and determine which ones should be modeled separately and which should be attributes. For example, addresses and stamps are on envelopes, where addresses are only able to be hosted, and only envelopes are used to read addresses, so the address should be an attribute of the envelope. Although stamps are also on the envelope, the sender can handle the stamps separately, for example, when they are not affixed to the envelope on the purchase of stamps, so stamps should be modeled separately.

< six > business entity of UML core elements of object-oriented analysis