In order to facilitate students' online learning and online discussion and exchange, a university plans to develop a set of online forum system (BBS). The main requirements of the system are as follows:
1. Section management. In order to facilitate discussion and communication, the system administrator (only one system administrator) can set up multiple sections according to actual needs to manage discussion posts by category. Each forum is designated by the system administrator to one or more registered users as moderators. Moderators manage the managed forums on a daily basis, including pinning posts, deleting prohibited posts, disabling and blocking user accounts, etc. System administrators can be free moderators, and can manage all posts in all forums and all registered users on a daily basis.
2. Anonymous user forum access. The BBS system allows anonymous users to access and browse posts, but cannot post and reply.
3. Register for user forum access. The system provides a user registration function. When registering, you need to provide user name, email, nickname, password and other information. Registered users can only post, reply to, modify and delete their own posts after logging in. When posting and replying to posts, you can add one or more attachments. In order to facilitate browsing and learning, this BBS system provides registered users with the function of post retrieval based on subject and content, and can view the posts (including reply posts) made by any registered user.
4. The system has the function of filtering prohibited stickers. The BBS system supports the system administrator to maintain and set prohibited words, and automatically searches the content of each newly published main post, reply post and modified post. If there are prohibited words, publication is prohibited.
【Require】:
1. Draw a use case diagram of the system
2. Draw the system sequence diagram of the posting process and define the main operating contracts
3. Draw the state diagram of the post object
4. Draw the design class diagram of the system, and give the main attributes and methods of at least 3 classes
5. Draw the deployment diagram of the system
