3.4 Communication Middleware Components

Question 1

What are the advantages of using middleware in client-server environments?

Answer 1

-> Network Indepence: Front-end applications can access the database server regardless of the network protocol used

-> Database server Independence: Front-end applications can access data from different database servers without writing commands that are specific to any particular database server.

Question 2

What are the levels on which communication middleware operates?

Answer 2

-> Physical Level: It addresses how clients and servers are physically linked to each other.

-> Logical Level: It addresses how the client and server communicate with each other.

Question 3

Using the layers of the OSI model explain how an SQL command is sent from the client to the server. On the client Side.

Answer 3

Application Layer -> SQL request is sent
Presentation Layer -> The SQL request is formatted
Session Layer -> A session is established with the server.
Transport Layer -> Checksum data, and transport layer ID is added to the request
Network Layer -> Formats the data into packets
Data Link Layer -> Converts the data into frames
Physical Layer -> Transmit the data through a physical network

Question 4

Using the layers of the OSI model explain how an SQL command is sent from the client to the server. On the server Side.

Answer 4

Physical Layer -> Receives the data frames
Data Link Layer -> validates the data frames
Network Layer -> assembles the messages
Transport Layer -> validates transport layer id
Session Layer -> validate session information
Presentation layer -> Format the SQL command
Application Layer -> Recieve and execute the SQL command