ISTM 210: Web Fundamentals, Architecture, Networking, and the SDLC

Comprehensive vocabulary flashcards covering HTML structure, client-server web architecture, cloud computing paradigms, networking basics, requirements engineering, Waterfall vs. Agile methodologies, and the SDLC.

HTML Element

A foundational building block of an HTML document composed of an opening tag, content, and a closing tag (e.g., <p>GeeksforGeeks</p>) that dictates document structure to web browsers.

The declaration placed on the very first line of an HTML document that instructs the web browser about what version of HTML the page is written in.

alt Attribute

A mandatory attribute of the <img> element that holds a textual replacement for the image, providing accessibility for screen readers and serving as fallback text during network errors, content blocking, or linkrot.

Description List (

)

An HTML list type used to display name/value pairs, using <dt> to define terms and <dd> to describe each term.

Client/Server Architecture

A network architecture where the client (frontend, user machine) is untrusted and renders content, while the server (backend, business machine) is trusted and handles authentication, business rules, database access, and access control.

Stateless Protocol

A communications protocol, such as HTTP, that carries no memory between requests; every exchange is a single cycle where the client requests and the server responds, after which both sides forget each other.

HTTP Cookie

A small claim ticket returned by a server after sign-in that stores a session identifier, allowing the browser to remain authenticated on every subsequent request without re-submitting credentials.

Content Delivery Network (CDN)

A distributed system of caching servers that reduces geographic delay by serving static assets (images, scripts, stylesheets) from the city nearest to the user.

Application Programming Interface (API)

A published interface acting as a menu that accepts requests in a documented format (typically a URL, HTTP method, and JSON) and returns documented responses, abstracting away the internal code and databases of both systems.

Hypervisor

A software layer that divides physical server CPU, memory, storage, and networking into isolated shares, allowing multiple virtual machines with their own operating systems to run on a single host.

Shared Responsibility Model

A cloud security framework defining boundaries between provider and customer: IaaS gives the user control down to the OS and middleware; PaaS shifts runtime and OS management to the provider; and SaaS rents the entire application. Customer responsibility for data, user access, and sharing never disappears.

Infrastructure as a Service (IaaS)

A cloud service model where the provider supplies raw virtual machines, storage, and networking, leaving operating system patches, applications, data, and outages to the customer.

Platform as a Service (PaaS)

A cloud service model where the provider manages the hardware, virtualization, operating system, and runtime/scaling, while the customer is responsible only for application code, data, and user access.

Software as a Service (SaaS)

A cloud model where the provider manages the complete software stack and application delivery, trading away customer configuration control for complete vendor maintenance.

Service-Level Agreement (SLA)

A provider's written commitment guaranteeing a measurable level of service availability (such as $99.9\%$ availability, allowing up to about $8\text{ hours, } 46\text{ minutes}$ of annual downtime) along with remedies if that benchmark is missed.

Recovery Time Objective (RTO)

The maximum acceptable duration of downtime to restore a business system following an interruption.

Recovery Point Objective (RPO)

The maximum acceptable amount of data loss measured in time, which dictates the necessary frequency of backups and data replication.

3-2-1 Backup Rule

A baseline data protection standard requiring three total copies of data maintained on two different types of storage media, with one copy stored in an offsite location.

Local Area Network (LAN)

A computer network that interconnects nearby computing devices within a constrained physical area, such as a home, office, or school campus.

Internet

A global physical network of interconnected networks originated in $1969$ by the Department of Defense agency DARPA via ARPANET, communicating using the standard TCP/IP protocol suite.

World Wide Web (WWW)

A content management and linked document system created in the $1980\text{s}$ by Tim Berners-Lee that operates as an application on top of the Internet using HTTP.

TCP/IP

The industry-standard suite of communications protocols enabling packet switching across networks; IP addresses and routes packets, while TCP provides reliable, ordered delivery and automatic retransmission of lost packets.

Uniform Resource Locator (URL)

The unique global address assigned to each web resource, broken down into scheme (protocol), subdomain, registrable domain, path, query string, and fragment.

Registrable Domain

The actual registered domain name directly preceding the public suffix when reading right to left, which establishes true legal ownership (e.g., in paypal.com.secure-billing.net, the domain owner is secure-billing.net).

Virtual Private Network (VPN)

A network security technology that builds an encrypted tunnel across shared or public network infrastructure to securely link a client to a private network.

Physical Transmission Media

Wired communication channels consisting of twisted-pair cabling (e.g., modern gigabit Ethernet), coaxial cabling (copper center conductor shielded by mesh), and fiber-optic cabling (glass fiber core transmitting light pulses over the longest distances and highest speeds).

Bandwidth vs. Latency

Two essential network performance metrics: bandwidth represents data capacity moved per second (the width of the pipe), while latency represents the round-trip travel time (the length of the pipe).

SWOT Analysis

A strategic planning framework used in systems planning that categorizes internal Strengths and Weaknesses alongside external Opportunities and Threats to anchor future requirements to real business conditions.

Requirement (Systems Engineering)

A business need made testable: a clear, specific statement that allows an evaluator to definitively verify with a 'yes' or 'no' whether the finished system performs as expected.

Functional Requirement

A statement specifying what functions or business actions a system must execute, such as calculating state tax, saving a shopping cart, or emailing receipts.

Non-functional Requirement

A statement specifying how well the system must execute its functions, including performance thresholds, concurrent user capacity, uptime percentages, security compliance, and user training time.

Say-Do Gap

The discrepancy observed between what employees report in interviews (the official procedure) and what they actually execute during direct observation (informal workarounds, side spreadsheets, and paper notes).

Commercial Off-The-Shelf (COTS)

A pre-built software package purchased from a commercial vendor that offers fast deployment and lower upfront costs, balanced against vendor dependence and limited customization.

Waterfall Methodology

A sequential systems development methodology where the seven SDLC phases occur in a strict, linear order, requiring heavy upfront design and proving best suited for stable requirements with high costs for late changes.

Agile Methodology

An iterative software development methodology established by the $2001$ Agile Manifesto that reorganizes project phases into short, repeating cycles over small vertical slices of a system to embrace evolving requirements.

Scrum

The most common agile framework, which organizes work into timeboxed sprint cycles (typically $2\text{ to }4\text{ weeks}$) ending in working software, guided by a Product Owner who manages the backlog and a Scrum Master who resolves blockers.

Systems Development Lifecycle (SDLC)

The end-to-end framework used to create information systems, encompassing seven primary phases: planning, analysis, design, development, testing, implementation, and maintenance.

Requirements Definition Document (RDD)

The primary formal deliverable produced at the end of the SDLC Analysis phase, compiling all documented business and user requirements gathered through requirements elicitation.

Scope Creep

The uncontrolled growth or modification of project requirements after the Requirements Definition Document (RDD) has already been finalized and signed off.

System Conversion Approaches

The four main rollout strategies used during SDLC Implementation: direct conversion (immediate cutover), parallel conversion (both systems run simultaneously), phased conversion (incremental modular rollout), and pilot conversion (deployed to a small test group first).

Knight Capital Implementation Failure

A famous SDLC implementation failure where a botched, uncontained big-bang launch without a phased or pilot rollout resulted in a trading loss of approximately $\$460\text{ million}$ in $45\text{ minutes}$.