tailieunhanh - Dictionary of Computer and Internet Terms phần 10

sneakernet (tiếng lóng) việc thực hành chuyển các tập tin từ máy này sang máy khác bằng cách thực hiện một đĩa trong phòng. sniffer một thiết bị phần cứng hoặc chương trình máy tính cho ngăn chặn các gói dữ liệu khi chúng đi qua một mạng lưới hoặc | 499 UML ULV Ultra Low Voltage. UML Unified Modeling Language a language used for the visual representation of software systems and other types of systems . Much of UML was developed at Rational Software and it was adopted as a standard by the Object Management Group OMG in 1997. UML includes standard notation for representing classes and their attributes and associations and it includes state transition interaction component and deployment diagrams. Figure 279 shows an example of a UML class diagram for a program that keeps track of the movement of boats. Each class is enclosed in a rectangle with the name of the class at the top. The middle part of the rectangle lists attributes or variables for the members of that class. FIGURE 279. UML class diagram For example boats have a name represented as a string x and y position coordinates and vx and vy velocity components all of which are double-precision numbers. The bottom part of the class lists the operations or methods of that class. In this example two specific types of boats sailboats and motorboats inherit from the class Boat. Inheritance is indicated by an open arrow. Another class is the wind. The line connecting the wind and sailboat class indicates an interaction between those two classes since the operation that sets the velocity of the sailboat needs to know the wind direction and speed. Figure 280 shows an example of a UML deployment diagram for a three-tier system where customers use a browser to connect over the Internet to the web server. The web server is in turn connected to the corporate mainframe database. UML is designed for the development of complicated systems so a complete design will include many different UML diagrams. UML diagrams can be created by hand or with a specialized software drawing tool. unboxing 500 FIGURE 280. UML deployment diagram unboxing in Microsoft .NET Framework the opposite of BOXING the automatic conversion of simple objects back into value types such as numbers and .