Application Layer - CH 2 (EXAM 1) Flashcards
What is the application layer?
software enabling users to interact with the network and accomplish tasks
What are the 4 components (logic) of the layer?
presentation, application, data access, data storage
What is host-based architecture?
server that is server-based
server has all 4 logics
What are the advantages of host-based architecture?
simple, single point of control
What are the disadvantages of host-based architecture?
host (server) can be a bottleneck
upgrades are expensive
What is client-based architecture?
client contains presentation, application, and data access logic
What are the advantages of client-based architecture
hardware and applications are less expensive
simple architecture
What are the disadvantages of client-based architecture?
data must travel back and forth between client and server
What are the 2 types of client-server architecture?
thin and thick client
What is a thick client?
client has presentation and application logic
server has data access and data storage
What is a thin client?
client has presentation logic
server has application, data access, and data storage
What are the advantages of client-server architecture?
more efficient because of distributed processing
allows hardware and software from vendors to speak together
less bandwith
What are the disadvantages of client-server architecture?
challenges in configuring different hardware and software from different vendors
middleware required (sometimes)
What is middleware?
software acts as a middleman by sitting between client and server applications
manages message transfers
What are the advantages of client-server architecture?
load balancing, more scalable
What are the disadvantages of client-server architecture?
each tier increases network load
more complex to develop applications
What is peer-to-peer architecture?
no middleware
all devices act as client and server (4 logics in each)
What are the advantages of peer-to-peer architecture?
resilient to failure
data stored anywhere on network
distributes bandwith requirements
What are the disadvantages of peer-to-peer architecture?
security and finding data
What is cloud computing?
enabling access to computing services over the network
models define who manages each application function and software/hardware
What are the 3 types of cloud computing models?
SaaS
PaaS
IaaS
What is SaaS?
all app components and hardware/software are outsourced
ex: salesforce
What is PaaS?
app and data logic managed internally
ex: Azure
What is IaaS?
all hardware is OUTSOURCED
What criteria should be followed when choosing architecture?
infrastructure (server client and circuit costs), dev costs (software), scalability (growing or decreasing)
What are the email protocols?
mail transfer agent (MTA)
mail server software (postfix)
mail user agent (MUA)
mail client software (outlook, gmail)
SMTP
sending messages to a MTA
IMAP /POP
used by a MUA to retrieve messages from MTA
ASCII
standard to encode characters
What are the steps of sending an email?
message sent through 2 tier thick client
sending client -> senders mail server (SMTP)
seners mail server -> reveivers mail server (SMTP)
message in receivers mail server (mailbox)
receiving client -> receivers mail server (IMAP / POP)
receivers mail server -> receiving client (IMAP / POP)
Email in an SMTP packet
header and body
plain text, NO attachments
What is MIME?
supports attachments and non ASCII characters
Other app layer protocols
FTP SSH IRC XMPP DNS
