With an asynchronous system, the requesting system waits for a response in real time.
Answer: B
Correct answer: False
Waiting for a response in real time is synchronous behaviour. An asynchronous request is issued and the requester continues with other work, collecting the response later. The statement has given the definition of one under the name of the other.
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Query-by-Example (QBE) is the most widely available direct-manipulation database query language.
Answer: A
Correct answer: True
QBE lets a user build a query by filling in a grid rather than writing a statement, and it is the direct-manipulation query interface most widely available - present in some form in nearly every desktop database product. It has never been standardised, so the details differ between products.
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A fat client is a PC configured for handling user interfaces and some application processing, usually with no or limited local data storage.
Answer: B
Correct answer: False
A PC handling the user interface and some processing with little or no local data is a thin client. A fat client takes on the presentation, extensive application logic and many database functions besides, which is why it needs a more capable machine and is harder to keep consistent across an organisation.
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Client/server environments use a local area network (LAN) to support a network of personal computers, each with its own storage, that are also able to share common devices and software attached to the LAN.
Answer: A
Correct answer: True
This is the ordinary client/server arrangement: personal computers with their own processing and storage, joined by a local network, sharing servers, printers and applications across it. The network is what makes the shared resources reachable and what distinguishes the arrangement from a set of standalone machines.
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The database server is responsible for database storage, access, and processing.
Answer: A
Correct answer: True
The database server does all three: it stores the data, controls access to it, and performs the processing needed to answer a query - selecting, joining, aggregating - so that only the result crosses the network. That last point is what separates it from a file server, which ships whole files and leaves the work to the client.
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The first client/server architectures developed were file servers.
Answer: A
Correct answer: True
The file server came first, sharing files across a local network with the processing left on the client. Its weaknesses - heavy network traffic and weak concurrency control, since each client worked on its own copy of the file - are what drove the move to database servers and to true client/server architectures.
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Centralized systems are more susceptible to security threats than client/server architectures
Answer: B
Correct answer: False
A centralised system has one place to defend, one set of controls and one point of access. A client/server system spreads the data and the processing over many machines and a network, each of which can be attacked, so it is the distributed arrangement that is more exposed - not less.
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Writing stored procedures takes less time than using Visual Basic or PowerBuilder to create an application.
Answer: B
Correct answer: False
Stored procedures generally take longer to write than the equivalent in a rapid application development tool, and that is the recognised cost of using them. What is bought with the extra effort is better performance, less network traffic and consistent enforcement of rules across every application.
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Data processing logic includes such activities as data validation and identification of processing errors.
Answer: A
Correct answer: True
Processing logic is where the application decides whether what it has been given makes sense: checking that values are within range and consistent with one another, and detecting errors before they reach the database. Placing it in a tier of its own means every client is validated by the same rules.
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ODBC requires the specific driver.
Answer: A
Correct answer: True
ODBC works by defining a common interface and requiring each database vendor to supply a driver implementing it for their product. The application calls the interface, the driver translates, and so the same code reaches any database for which a driver exists - but nothing at all without the specific driver installed.
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