Application Layer Vocabulary

This set of vocabulary flashcards covers concepts from Chapter 2: Application Layer, including network architectures, cloud computing models, and interaction protocols like HTTP and SMTP.

Application Layer

Layer $5$ in the Internet model; the software that enables users to interact with the network and accomplish tasks.

Presentation Logic

The component of an application program that defines the way the user interacts with the application, such as a GUI or CMD.

Application Logic

The component of an application program that defines the nature of the application tasks.

Data Access Logic

The processing required to access the data, such as SQL.

Data Storage

The function of an application program that provides the ability to keep data either temporarily or permanently.

Host-Based Architecture

An architecture where the server contains all components and performs all tasks; common in the $1960$s with mainframes and terminals.

Client-Based Architecture

An architecture where the client contains presentation, application, and data access logic while the server handles only data storage; common in the $1980$s.

Client-Server Architecture

The most common modern architecture that balances processing between the client (usually responsible for presentation logic) and the server (responsible for data access and storage).

Thin-Client Architecture

A client-server architecture where the client is responsible primarily for presentation logic, while the server handles application logic, data access logic, and data storage.

Thick-Client Architecture

A client-server architecture where the application logic resides primarily on the client side.

Middleware

Software that sits between client and server applications to provide a standard way of communicating and to manage message transfers between them.

Distributed Computing Environment (DCE)

A specific standard for middleware that allows applications to communicate together.

Common Object Request Broker Architecture (CORBA)

A standard for middleware designed to enable communication between applications from different vendors.

Open Database Connectivity (ODBC)

A standard middleware for database access logic.

Scalability

The ability to increase or decrease computing capacity as network demand changes.

Peer-to-Peer Architecture

An architecture where all devices can act as both clients and servers, often used for file-sharing like BitTorrent.

Cloud Computing

A general term for enabling access to computing services over the network by outsourcing infrastructure to specialized firms.

Software as a Service (SaaS)

A cloud model where all application components and associated hardware/software are outsourced and shared via multitenancy, e.g., Gmail or Salesforce.com.

Platform as a Service (PaaS)

A cloud model where application logic and data are managed internally while the provider manages the underlying infrastructure, e.g., Microsoft Azure.

Infrastructure as a Service (IaaS)

A cloud model where all hardware resources are outsourced to a provider, e.g., Amazon Web Services (AWS).

Virtualization Software

Software used to create multiple virtual servers (storage, processing, and memory) on a single physical server.

Server Farm

A cluster of computers linked together so that they act as one computer to process distributed requests.

Mosaic

The first graphical Web browser, released in $1993$.

Hypertext Transfer Protocol (HTTP)

The protocol used for communication between a client Web browser and a Web server.

Mail Transfer Agent (MTA)

The formal name for mail server software, such as Sendmail or Postfix.

Mail User Agent (MUA)

The formal name for mail client software, such as Outlook or Apple Mail.

Simple Mail Transfer Protocol (SMTP)

The protocol used to send a message to a Mail Transfer Agent (MTA); originally handled only text files.

Internet Message Access Protocol (IMAP)

A protocol used by a Mail User Agent (MUA) to retrieve or manage email messages from a server.

Post Office Protocol (POP)

A protocol used by a Mail User Agent (MUA) to retrieve messages from a mail server.

American Standard Code for Information Interchange (ASCII)

A standard for encoding text characters including letters, numbers, and symbols.

Multipurpose Internet Mail Extension (MIME)

A standard used to extend email support for non-ASCII characters and attachments by encoding them into ASCII format.

RFC 822

The standard protocol for the text message format in SMTP email, consisting of header lines and a body section.

File Transfer Protocol (FTP)

An application-layer protocol used for moving files between clients and servers.

Domain Name System (DNS)

The protocol used for mapping domain names to IP addresses.

Telnet / Secure Shell (SSH)

Protocols used for executing commands on a remote system.