The document describes a network time server that provides time information to clients. It has two main use cases: 1) for a client to get the current time from the server for a specified time zone, and 2) for a client to request and receive a list of all available time zones from the server including each zone's name, offset from UTC, and major cities. Conceptual classes identified include: network time service, network client, network connection, server, current time, current time zone, and time zone name.

1. Domain Models - Part Deux

2. Vision Network Time Server Major Features: Gets current time for a given time zone. Get all available time zones. Support 600+ clients. Single clock on a large network. Clock isn’t necessarily the same as the wall clock. This is a real business problem!

3. Use Case UC1: GetCurrentTime Use Case: GetCurrentTime Identifier: UC1 Description: The GetCurrentTime use case models obtaining the current time from a central clock. Actors: Client Preconditions: 1. Network time service is available on the network. Flow of events: 1. The use case starts when the Client opens a network connection to the Server. 2. The Client indicates a need for the current time. 3. The Client provides its current time zone, using the time zone name. 4. The Server provides the Client with the current time in the requested time zone. 5. The Server closes the network connection. Postconditions: 1. The Client has the current time, and the network connection is closed.

4. SSD: UC1

5. Use Case UC2: ListTimeZones Use Case: ListTimeZones Identifier: UC2 Description: The ListTimeZones use case models obtaining a description of all recognized time zones. Actors: Client Preconditions: 1. Network time service is available on the network. Flow of events: 1. The use case starts when the Client opens a network connection to the Server. 2. The Client indicates a need for the complete list of all time zones. 3. For each recognized time zone: 1. Server provides the time zone name. 2. Server provides the time zone offset from UTC. 3. Server provides a list of major cities which use the time zone. 4. The Server closes the network connection. Postconditions: 1. The Client has been given all recognized time zones, and the network connection is closed.

6. How To Make A Domain Model Identify Conceptual Classes

7. Use Case UC1: GetCurrentTime Use Case: GetCurrentTime Identifier: UC1 Description: The GetCurrentTime use case models obtaining the current time from a central clock. Actors: Client Preconditions: 1. Network time service is available on the network. Flow of events: 1. The use case starts when the Client opens a network connection to the Server. 2. The Client indicates a need for the current time. 3. The Client provides its current time zone, using the time zone name. 4. The Server provides the Client with the current time in the requested time zone. 5. The Server closes the network connection. Postconditions: 1. The Client has the current time, and the network connection is closed.

8. Use Case UC1: GetCurrentTime Use Case: GetCurrentTime Identifier: UC1 Description: The GetCurrentTime use case models obtaining the current time from a central clock. Actors: Client Preconditions: 1. Network time service is available on the network . Flow of events: 1. The use case starts when the Client opens a network connection to the Server . 2. The Client indicates a need for the current time . 3. The Client provides its current time zone , using the time zone name . 4. The Server provides the Client with the current time in the requested time zone . 5. The Server closes the network connection . Postconditions: 1. The Client has the current time, and the network connection is closed.

9. Identified Conceptual Classes Network Time Service Network Client Network Connection Server Current Time Current Time Zone Time Zone Name

10. How To Make A Domain Model (The system itself) (Probably an attribute) (Out of system boundary)

11. How To Make A Domain Model Identify Conceptual Classes Put them onto a picture. Draw associations between them.

13. How To Make A Domain Model Identify Conceptual Classes Put them onto a picture. Draw associations between them. Add attributes to fill in details.

15. Use Case UC2: ListTimeZones Use Case: ListTimeZones Identifier: UC2 Description: The ListTimeZones use case models obtaining a description of all recognized time zones. Actors: Client Preconditions: 1. Network time service is available on the network. Flow of events: 1. The use case starts when the Client opens a network connection to the Server. 2. The Client indicates a need for the complete list of all time zones. 3. For each recognized time zone: 1. Server provides the time zone name. 2. Server provides the time zone offset from UTC. 3. Server provides a list of major cities which use the time zone. 4. The Server closes the network connection. Postconditions: 1. The Client has been given all recognized time zones, and the network connection is closed.

16. Use Case UC2: ListTimeZones Use Case: ListTimeZones Identifier: UC2 Description: The ListTimeZones use case models obtaining a description of all recognized time zones. Actors: Client Preconditions: 1. Network time service is available on the network . Flow of events: 1. The use case starts when the Client opens a network connection to the Server . 2. The Client indicates a need for the complete list of all time zones . 3. For each recognized time zone : 1. Server provides the time zone name . 2. Server provides the time zone offset from UTC . 3. Server provides a list of major cities which use the time zone . 4. The Server closes the network connection . Postconditions: 1. The Client has been given all recognized time zones , and the network connection is closed.