3.4 Communication Middleware Components Flashcards
What are the advantages of using middleware in client-server environments?
-> 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.
What are the levels on which communication middleware operates?
-> 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.
Using the layers of the OSI model explain how an SQL command is sent from the client to the server. On the client Side.
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
Using the layers of the OSI model explain how an SQL command is sent from the client to the server. On the server Side.
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