1. Draw a UML sequence diagram that models the following events in a three-tier database client-server architecture: The client applet sends a connection request to the database servlet, which sends back a password request. The user supplies a username and password, which are sent back to the database servlet. The username and password are correct, so the servlet responds with an "OK" message. The user enters search parameters in the applet interface, and the client applet translates these into an SQL query, which is sent to the database servlet. The database servlet sends the SQL query to the remote database, which sends back the results of the query. The servlet passes the results back to the client applet.
时间: 2024-03-14 07:47:48 浏览: 79
UML diagram
Sure, here is a UML sequence diagram that models the events you described:
```
Client Applet Database Servlet Remote Database
| | |
|----> Connection Request ---->| |
| |<---- Password Request ------|
| Username & Password | |
|<---- Password Challenge -----| |
| |----> Validation Request ---->|
| | Username & Password |
| |<----- Validation Result ----|
| Search Parameters & SQL | |
|----> SQL Query Request ---->| |
| |----> SQL Query Request ---->|
| | SQL Query |
| |<----- Query Results --------|
|<---- Query Results ---------| |
```
In this diagram, each horizontal line represents an object or component in the system, and the vertical arrows represent messages being passed between them. The arrows are labeled with the message name and any parameters being passed. The diagram shows the flow of events from the client applet's initial connection request through to the retrieval of query results.
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