Web Architecture Flashcards
1
Q
How can resources be represented?
A
text (plain, html, csv), image, audio, video, application
2
Q
How can resources be identified?
A
With URIs (Uniform Resource Identifiers)
3
Q
How can resources be interacted with?
A
Using network protocols like HTTP
4
Q
What does the bow-tie model represent?
A
The shape of the web
Sections such as LSCC core, IN, OUT, and disconnected components
5
Q
What is the web?
A
A distibuted information system that provides acess to resources
6
Q
What is hypertext?
A
A way to link information in a non-linear interactive way - cannot be represented conveniently on paper
7
Q
What are 2 disadvantages of hypertext?
A
Disorienting - easy to lose sense of direction
Cognitive overhead - additional effort to maintain several trails at once
8
Q
What is hypermedia?
A
Non-textual media
9
Q
What are nodes, links, anchors, and endpoints?
A
Node - a point in the network e.g. a webpage
Link - a connection between nodes
Anchor - the clickable element that links pages
Endpoint - the destination of a link
<a href="http://www.endpoint.com/">anchor</a>
10
Q
What are embedded links?
A
Links that are encapsulated in a node, and form part of the document content
11
Q
What are first class links?
A
Where links are separated from nodes allowing multiple link overlays/linkbases (links over same node), creating different connections without changing the node
Link bases can be tailored to reader
Has 2 endpoints
12
Q
What are bidirectional links?
A
Links that can be traversed backwards as well as forwards
13
Q
What are N-ary links?
A
Links involving more than 2 nodes, allowing relationships between multiple entities
14
Q
What are generic links?
A
Links where, by using locspecs, all occurences of a word can be linked to the same endpoint
15
Q
What are functional links?
A
Links that represent predefined relationships
16
Q
What are typed links?
A
Links that define the nature or relationship of the link, such as “friend,” “parent,” or “employee”
17
Q
What is REST?
A
Representational State Transfer
A web architecture style that uses stateless communication to manipulate resource representation
18
Q
What does REST aim to do (2)?
A
Minimise latency and network communication
Maximise independence and scalability of components
19
Q
What are the 4 components of REST?
A
Origin servers - the ultimate place you get a resource from
Gateways - for integrating legacy servers
Proxies - to filter & cache
User agents
User agent & origin server are end points that communicate using HTTP
If using gateway, origin server & gateway don’t communicate in HTTP
20
Q
What are the 5 constraints of REST?
A
Client-server - separation of concerns (client: user interface, server: data storage)
Stateless - no context stored on server, session state kept on client
Caching - response data labelled as cacheable or non-cacheable
Uniform interface between components - identify what next possible actions could be
Layered - system components have no knowledge of components they don’t directly interact with
21
Q
What are the 3 advantages of client-server constraint?
A
- Improves portability
- Improves scalability (as server simplified)
- Allows components to evolve separately
22
Q
What are the 3 advantages and 1 disadvantage of stateless constraint?
A
Advantages:
* Improves reliability
* Improves scalability
* Improves visibililty (of requests)
Disadvantage:
* Increases per-action overhead
23
Q
What are the 2 advantages and 1 disadvantage of caching constraint?
A
Advantages:
* Eliminates some actions
* Reduces latency
Disadvantage:
* Reduces reliability
24
Q
What are the 2 advantages and 1 disadvantage of uniform interface constraint?
A
Advantages:
* Improves visibility (of interactions)
* Implementations decoupled from services they provide
Disadvantage:
* Reduces efficiency
25
What are the 2 advantages and 1 disadvantage of layered constraint?
Advantages:
* Limits system complexity
* Improves scalability
Disadvantage:
* Adds latency & overhead
26
What are the 3 principles of address identifiers?
**Global** - addresses should be unambiguous & human readable
**Distinct identifiers** - using same URI for different resources creates a URI collision
**Avoid aliases** - don't use different URIs for same resource
27
How should documents be named?
Use **logical names** rather than physical addresses to avoid issues when documents are moved
28
URL vs URN
**URL** specifies location of resource on internet
**URN** uniquely identifies resource by name - not that good approach as can just use HTTP
29
What are IRIs (Internationalised Resource Identifiers)?
An extension to URIs, allowing Unicode characters
30
Why shouldn't you change URIs?
Breaks pages linked to old URI -> 404
31
What are the 5 principles of representation?
* **W3C representation principles** - follow a format to future proof
* **Separate content, presentation & interaction**
* **Identify links** to other resources
* **Links should be navigable**
* **Links should be web-wide**
32
Data vs metadata
**Data** is the actual information/content
**Metadata** is data that describes other data e.g. file size, creation date
33
What are the 5 principles of interaction?
* **Provide representations**
* **Safe retrieval**
* **References doesn't imply dereference** - just because you can retrieve a representation, doesn't mean you must
* **Reuse representation formats**
* **Representations should be consistent**
34
What is a safe method?
One that doesn't change the state of the resource
35
What is an impotency method?
One that doesn't change the result even when applied multiple times
Only POST isn't impotent
36
What do the HTTP responses (1xx - 5xx) represent?
**1xx** - informational message
**2xx** - success
**3xx** - redirection
**4xx** - client error
**5xx** - server error
37
What are the 2 styles of content negotiation?
**Sever-driven** - server makes final choice of representation
**Client-driven** - clinet makes final choice of representation
38
What are the 3 stages of server-driven content negotiation?
1) Client tells server what it is able to accept in request header
2) Server chooses appropriate representation to return to client based on "quality" (provided by client)
3) Server tells clients its choice in response header
39
Name three properties that can be negotiated
Media type
Language
Encoding
40
What are the 3 stages of client-side content negotiation?
1) Client requests resource representation
2) Server returns HTTP redirect status ("300 multiple choices") with list of URIs
3) Client requests a representation of one of the URIs
41
What is "Client Hints"?
A HTTP extension that allows browsers to state their capabilities & preferences
42
How can you avoid the lost update problem?
When carrying out unsafe methods, check if the state of the resource has change since the GET method
43
What 2 ways are there for validating if resources are the same?
**Strong validation** - checks if representations are byte-for-byte identical
**Weak validation** - checks if representations contain "the same content"
44
What are ETags? What headers can be applied to them?
Entity tags are identifiers for resource versions
Headers:
* `If-Match: , , ...`
* `If-None-Match: , , ...`
45
What are cookies?
A way for web servers to persist state across HTTP requests (even though HTTP is supposed to be stateless)
46
What are "Secure" and "HttpOnly" cookies?
**Secure** - indicates that cookies should only ever be sent over HTTPS
**HttpOnly** - cookies should not be visible from within the Document.cookie interface
47
Discuss the physical limits on data transmission (3)
Sending a message at c (3e8) still takes 0.067s to go halfway round the world
Optical fibres are ~70% of c, coxial cables are >80% of c
Routers, switches, etc introducers delays
48
How does TCP delay HTTP?
HTTP runs of top of TCP
TCP establishes connections with a three-way handshake (>=0.2s)
49
What 2 methods reduce TCP delay for HTTP?
**Keep-Alive** - TCP connections reused for multiple HTTP requests
**Pipelining** - multiple requests made without waiting for responses
50
What 4 improvements were made to adhere to data transfer capacity limits?
**Compressed headers** to reduce amount of data sent
**Prioritised requests** - sends important content first
**Multiplex requests** - when client requests HTML document with multiple images, stylesheets & scripts, send a single connection for all resources
**Server push** - when a client requests HTML doc with image, instead of waiting for them to request image, pre-emptively push resource
51
What are tunnels in the context of proxies?
**CONNECT method establishes** tunnel between client & server
With tunnel established, proxy server no longer inspects/modifies data; **just forwards**
52
How is data secured in HTTPS?
Using the TLS (Transport Layer Security) protocol
53
What are the 4 cryptography principles?
**Confidentiality** - no unathorised reading
**Integrity** - no unauthorised modificaiton
**Authenticaiton** - proof of authorisation
**Non-repudiation** - data author can't deny authorship
54
How are digital signatures created (3 steps)?
Combines asymmetric encryption & cryptographic hash
1) Generate cryptographic hash of image
2) Encrypt hash with private key
3) Attach encrypted hash to message
55
How are digital signatures verified (3 steps)?
1) Generate cryptographic hash of image
2) Decrypt hash with public key
3) Compare hashes
If hashes match, message has not been altered and signature is valid
56
What is the Certificate Authority?
A trusted organisation that issues digital certificates
57
How does the Diffie-Hellman Key Exchange work?
1) Prime number p and root module g are shared publically
2) A and B pick random large integers: a and b
3) A and B calculate g^amodp=PUa and g^bmodp=PUb respectively and send results publically
4) A calculates PUb^amodp and B calculates PUa^b*modp
58
Authentication vs authorisation
**Authentication** - verifying identity of user/system
**Authorisation** - granting access/permissions to resources
59
What are the 6 steps in granting authorisation in OAuth *(the diagram)*?
1) **Client requests authorisation** from the authorisation server via the resource owner
2) **Resource owner authenticates** the request
3) **Authorisation server sends an authorisation code** to client via the resource owner
4) **Client sends the authorisation code** to the authorisation server
5) **Authorisation server sends access token** to client
6) **Client accesses resource** on resource server
60
What is cross-site request forgery?
When a user (unintentionally) allows one origin to talk to a different origin
User clicks on a link/form while authenticated on a site allowing attacker to perform actions on site with user's authentication
61
How is cross-site request forgery prevented?
Same origin policy
Restricts web pages from making requests to different domains than the one that hosted it
62
How is "same origin" determined?
* URIs use same protocol
* URIs have same host
* URIs have same port
63
What is the default port for HTTP?
80
64
What blocking exceptions are there to same origin policy?
Embedded resources (media, stylesheets, scripts, etc)
65
What is CORS (cross-origin resource sharing)?
Security feature that relaxes SOP, allowing certain origins to make requests to a domain different to the one that served the web page
Servers indicate which origin may make requests and restrict headers send & received
66
What criteria must simple requests satisfy for CORS?
* Only methods: GET, HEAD, POST
* Only headers: Accept:, Accept-Language:, Content-Type:, Content-Language
* Content-Type: text/plain, (application/...), (multipart/...)
67
What is a CORS preflight?
Used for more complex requests (other methods, custom headers)
A preliminary HTTP request to check if actual request is allowed by the server before sending actual request
68
What is SGML (Standard Generalised Markup Language)?
An old markup language (old version of HTML)
A language for defining markup languages
69
What is XML (eXtensible Markup Language)?
A general purpose markup language
A W3C-defined subset of SGML
A language for defining domain-specific markup languages
70
What is DTD (Document Type Definition)?
A formal definition of the grammar for an XML document
Tells document processor how to parse the document
71
What 2 schema language competitors does DTD have?
XML Schema
RELAX NG
72
Document well-formedness vs validity
**Well-formedness** - obeys syntax rules in XML spec
**Validity** - well-formed *and* structure is based on a defined schema (e.g. DTD)
73
What is SVG (Scalable Vector Graphics)?
XML-based language for describing 2D graphics
Uses CSS for styling & animation
Integrates with HTML5
74
What is MathML?
XML-based language for expressing mathematical expressions
Integrates with HTML5
2 sub-languages:
* **Presentational** MathML
* **Semantic** MathML
75
What is EPub (Electronic Publication) (4)?
* A portable & flexible e-book format
* Organises content in a standardised structure using XML/HTML, CSS, & images
* XHTML use makes content adaptable
* Manifest & spine ensure correct order of book's components
76
What is Open Office XML?
File format standard for Microsoft Office documents
Organises document into separate XML files for content, styles, & media in a ZIP
77
What is PDF (Portable Document Format)?
A file format for rendering documents with a fixed layout
Includes interactive features (forms, annotations, links)
78
What is HTML?
A markup language for structured documents
The data format for web pages
79
What does HTML5 introduce?
Audio, video, & canvas
80
What are the 4 benefits of HTML5?
Better support for modern web applications
Replacing Adobe Flash
Handling invalid markup
Improved semantics
81
What does W3C (World Wide Web Consortium) do (3)?
* Standardises technologies (like HTML) used on the web
* Ensures websites/web apps work across different browsers/devices
* Web accessible to all users
82
What does WHATWG (Web Hypertext Application Technology Working Group) do?
Web standards get evolved continuously rather than having fixed versions
83
Name 2 early JavaScript-based web applications
XHR (XML HTTP Request)
AJAX (Asynchronous JavaScript and XML)
84
What 3 modes are used by layout engines in web browsers?
**Quirk mode** - doesn't conform to official standards to maintain backward compatability
**Almost standards mode** - small no. quirks implemented
**Full standards mode** - behaviour describes by HTML & CSS specs
85
What are the 4 design principles of web technologies?
* **Compatability**
* **Interoperability** - well-defined behaviour & graceful error handling
* **Utility** - seperate content & presentation
* **Universal Access**
86
What is sectioning, flow, and phrasing content?
**Sectioning content** defines the structure (headings & sections)
**Flow content** fills sections with main elements (paragraphs, images, lists)
**Phrasing content** adds inline details (links, bold text, ...)
87
In what 3 ways can you style the web?
**HTML style attribute** -
Hello
Provide an **inline stylesheet** in a style element - Link to an **external stylesheet**
88
Describe a CSS rule set
Consists of a selector e.g. h1 (to format h1)
And a declaration block (containing a series of declarations) e.g. font-size: 2em
89
Explain the basic selectors:
E F,
E>F,
E+F,
E~F
**E F** - an F element that is a descendant of an E element
**E > F** - an F element that is a direct child of an E element
**E + F** - an F element that is immediately preceded by an E
**E ~ F** - an F element that is preceded by an E
90
Explain the attribute selectors:
E[foo],
E[foo="bar"],
E[foo^="bar"],
E[foo$="bar"],
E[foo*="bar"]
E[foo] - an E element with a foo attribute
E[foo="bar"] - an E element with a foo attribute whose value is bar
E[foo^="bar"] - an E element with a foo attribute whose value starts with bar
E[foo$="bar"] - an E element with a foo attribute whose value ends with bar
E[foo*="bar"] - an E element with a foo attribute whose value contains bar
91
Give an example of generated content declaration
```
h1:before {
content: "Chapter " counter(chap) ": ";
counter-increment: chap;
}
```
92
What is the hierarchy of the CSS box model?
Margin
Border
Padding
Content
93
What are collapsing margins?
Where adjoining vertical margins combine to form a single margin in a content box
94
Explain the positioning of: static, relative, absolute, fixed
**Static** - default position
**Relative** - positions relative to default position, without affecting other elements
**Absolute** - positions relative to nearest positioned ancestor
**Fixed** - posiitons relative to browser window
95
What problem does XSL (eXtensible Stylesheet Language) address?
The problem of maintaining different versions of a document for presentation on systems with varying screen sizes and document formats
96
XSL-FO vs XSLT vs XPath
**XSL-FO** - specifies **layout** & **formatting** of XML documents
**XSLT** - **transforms** XML documents into different formats
**XPath** - query language for **navigating** & **selecting** **nodes** from XML document
97
XSL vs CSS (pros & cons)
**XSL**
Pros: can modify & transform document structure
Cons: complex, cumbersome, no consideration for differing needs of users vs authors
**CSS**
Pros: simple, cascading
Cons: unable to modify document structure
98
What are the 3 Web API classes?
Document content
Browser services
Hardware access
99
What is DOM (Document Object Model)?
An API for **accessing & manipulating XML & HTML** in web browsers & elsewhere
100
How does DOM work?
DOM is a node interface (node types can be documents, elements, text, etc)
Each node has parents, children, and previous & next siblings
Methods allow the manipulation of children
101
What is Canvas?
API for drawing graphics via JavaScript
102
What are XMLHttpRequest, Fetch, and Web Sockets?
* APIs for fetching representations of resources
* Fetch and Web Sockets are modern replacements for XMLHttpRequest (Fetch is one-time; Web Sockets are persistent)
103
Cookies vs Web Storage vs IndexedDB
**Web storage** API is a more structured, modern alternative to **Cookies**
**IndexedDB** is a more powerful, asynchronous API for larger structured data
104
What are Web Workers & Service Workers
**Web Workers** are JavaScript threads that allow long-running tasks to be executed without blocking the main UI thread
**Service Workers** are a type of Web Worker that act as a proxy between web application & network, allowing offline capabilities
105
What are asm.js and WebAssembly?
**asm.js** - a subset of JavaScript that allows C code to be compiled & run in any browser
**WebAssembly** - a more efficient alternative that is a bytecode format for virtual machines
106
What is SOA (Service-Oriented Architecture)?
A design approach where software components provide services to other components over a network -> flexible, modular, interoperable
107
What is a monolithic design?
Where a program is "composed all in one piece" and is unable to be changed
108
What are SOAP, WSDL, and UDDI?
**W3C Web Services**
* **SOAP** for invoking services
* **WSDL** for describing services
* **UDDI** for publishing & locating services
109
Explain the 4 levels of the Richardson Maturity Model
**Level 0:**
* Single endpoint to handle all requests
* Minimal use of HTTP standards - relies on single HTTP method
**Level 1:**
* Introduces resources with unique URIs (so multiple endpoints)
* Templates and tunneling used to represent resources
* Still lacks proper use of HTTP methods - relies on single HTTP method
**Level 2:**
* Embraces HTTP standards
* CRUD operations mapped to HTTP verbs
**Level 3:**
* Add hypermedia links with HATEOS
110
What are the 2 pseudostates in UML statecharts?
Initial state
Final state
111
How are choice pseudostates represented?
[In brackets]
112
What is OpenAPI?
A specification for defining RESTful APIs
Formerly known as Swagger
113
How does OpenAPI represent API descriptions?
In JSON or YAML
114
What is Project Xanadu?
The first hypertext project aiming to connect documents bidirectionally
Founded in 1960 by Ted Nelson
115
What are tumblers (Project Xanadu)?
The addressing system used in Xanadu
Tumblers are numeric, write-once identifiers used for addressing of document fragments
116
In what 2 ways can links be stored in Project Xanadu?
**First-class** - separately from documents
Within document - in its **link-train**
117
What are transclusions (Project Xanadu)?
Special links where documents can contain parts of other documents
Address of fragment is inserted and referenced content is retrieved
118
How was the Project Xanadu system distributed? What protocols were introduced?
**Separated front-end clients from back-end servers**
Protocols:
* **Front End to Back End** - facilitated user interaction
* **Back End to Back End** - manage consistency between back end servers
119
What are these: **HES/FRESS** (1967), **ZOG** (1972), **KMS** (1983), **Hyperties** (1983), **NoteCards** (1984), **Intermedia** (1985), **HyperCard** (1987)
Hypertext systems
120
What are the 4 types of hypertext systems?
* **Macro Literary Systems**
* **Problem Exploration** Tools
* Structured **Browsing** Systems
* **General** Hypertext Technology
121
What were Halasz's 7 issues?
1) **Search and query** - link navigation not always best to find things
2) **Composites** - augmenting the basic model
3) **Virtual structures** - documents defined by queries
4) **Computation** in hypermedia networks
5) **Versioning**
6) Support for **collaborative work**
7) **Extensibility**
122
What were Halasz's 4 ammendments to his 7 issues?
* **Ending** the Tyranny of the **Link**
* Very **Large Hypertexts**
* **Open Systems**
* **User Interfaces** for Large Information Spaces
123
What do the following mean in graph theory:
* Diameter
* Average-case diameter
* Degree of a vertex
* Density
**Diameter** - longest distance between any 2 vertices
**Average-case diameter** - average distance between any pair of nodes
**Degree of a vertex** - number of edges connected to it
**Density** - ratio of edges to vertices
124
What does centrality represent in graph theory?
The importance of a node, not "near the centre"
Centrality can be measured in a variety of ways (4)
125
How is degree centrality found?
Simply the number of edges connected to a node
126
How is betweenness centrality found?
The number of shortest paths going through a node
127
How is closeness centrality found?
The average of the shortest distances from a node to all other nodes
i.e. find the shortest path to every other node and average the distances
128
What is a small world network?
A graph where most nodes are not neighbours but most nodes can be reached by a small number of connections
129
What is the average degree of a node?
log(n) where n is the no. nodes
130
What is Barabasi-Albert model?
A tool for understanding the growth and structure of networks
Nodes have preferential treatment - the probability of a new node linking to an existing node is proportional to the degree of that node
131
What 3 things does Google's PageRank Algorithm account for?
No. links
Link quality
Link content
132
What is a Web Crawler?
An algorithm that systematically crawls to web
Starts at a webpage, follows hyperlinks from that page, and follows links on those pages, etc...
Collects & stores metadata about pages
133
What are the 4 policies of Web Crawlers?
**Selection policy** - states which pages to index (breadth-first, PageRank, ...)
**Re-visit policy** - revist pages since they change (especially frequent changers)
**Parallelisation policy** - run multiple processes in parallel e.g. assign a crawler to do all hashs divisible by 5
**Politeness policy** - don't make parallel calls to same server - spread requests
134
What are 2 ways people boost the search rankings of their pages with Search Engine Optimisation?
**Legitimate SEO (white hat)** - prioritises user experience, good design, valid metadata
**Illegitimate SEO (black hat)** - manipulates search engine
135
How is SEO combatted?
Regularly update algorithms
Favour legitimate SEOs and penalise illegitimate SEOs
136
What is IETF (Internet Engineering Task Force)?
Makes web standards / is a web standard organisation (like W3C)
Consesus-driven decision-making
137
What is ergodic literature?
Where, not only does the reader read the literature, they also make decisions (Minecraft type beat)
138
What is ludic narrative?
Storytelling approach where plot unfolds through interactive mechanics, allowing players to influence story through choices & actions
139
How is hyperdrama different to traditional drama?
Interactive, non-linear narratives
Can be experienced across different platforms
140
What is a journal's impact factor?
An indicator of its importance within its field
Decided through a rigorous review process
141
When did scholarly publishing begin?
1665
142
What are the 2 problems with journals having subscription costs?
Impedes new discoveries by limiting key information
Low-income countries & independent scholars can't access them
143
What are the 4 ideals of Open Access?
Entirely online
Available 24/7
All papers citation-linked
Full searchable, navigable, and retreivable
144
Green OA vs Gold OA
**Gold OA** - articles made freely available, with costs covered by author
**Green OA** - as Gold OA isn't always possible, offers access to an earlier version of research in public repository
145
What are the 4 problems with OA?
50% of new papers still behind a paywall
Green OA relies on publishers policies
Gold OA relies on publishers changing their model
Scientific publications are lucrative
146
What 3 things differentiate open hypermedia from traditional hypermedia?
* Dynamic structure
* Decentralised
* More interactive
147
What is DHRM (Dexter Hypertext Reference Model) and Hyper-G?
**DHRM (1988-90)**
A model of an open hypertext system
Compares the functionalities of existing systems
**Hyper-G (1989-90)**
An implementation of an open hypertext system
Aligns with the Dexter model
148
What are Hyper-G's 2 link categories?
**Core links** - relate documents stored on same server; changes processed by single server
**Surface links** - relate documents stored on different servers; changes involve multiple servers
149
What are the 2 types of link integrity failure?
**Dangling link problem** - when an endpoint refers to an invalid node
**Content reference problem** - when an endpoint refers to a valid node, but to an invalid location within that node
150
What is microcosm?
A distributed system of interconnected servers
Organises data into self-contained units called *microcosms*
Microcosms communicate with each other to share data & updates
151
What are the 2 advantages and 2 disadvantages of microcosm?
Advantages:
* Flexible, varied linking
* Integrates with 3rd party applications
Disadvantages:
* Poor scalability
* No support for link integrity
152
What does shim do in OHP (Open Hypermedia Protocol)?
Translates between OHP and the linkserver's native protocol
153
What is a LocSpec in OHP?
Identifies the position of an anchor (by byte offset / specific string occurence / named location)
154
What is the advantage and disadvantage of OHP?
Advantage:
* Commonly used & accepted model
Disadvantage:
* High message overhead
155
How are linkbases automatically created (OH)?
1) Extract key phrases from documents based on location & frequency
2) Create generic links to those documents based on phrases
3) Use linkbase editor to delete unwanted links
156
What 4 places can we inject links?
During **batch processing**
On demand in **origin server**
Using **proxy server**
In the **user agent**
157
What are the 3 limitations of HTML linking?
* URIs can identify **entire resources** but **not parts** of them
* **Unflexible tags**
* **Links** are **fixed** & **one-directional**
158
What is XPointer in relation to XPath?
XPath can't identify ranges in a document, only elements
XPointer allows XPath path expressions to be used as fragment identifiers in URIs
159
What is XLink?
A W3C standard for creating hyperlinks
160
What is the state of XLink now?
Declined use due to shift from XML to JSON
HTML & JavaScript have largely replaced its functionality
161
How is JSON superior to XML (4)?
Simpler, more concise, easier to read & write
Better parsing
Smaller file size
No strict schema
162
Contextual vs behavioural advertising
**Contextual** - based on content in the page
**Behavioural** - based on profiling of a specific user
163
AdWords Auctions for contextual ads (4 steps)
1) Find all ads whose **keywords match** search terms
2) **Ignore** ads in **ineligible countries**
3) **Calculate AdRank**
4) Show ads with **sufficient AdRank**
164
What is AdSense?
Contextual advertising based on keyword matching
Publishers partake in auctions for different ad positions
165
What are the 3 advertising cost models?
**Cost per Mille** - pay per 1000 impressions (displays of ad)
**Cost per Click** - pay when someone clicks on ad
**Cost per Action** - pay when someone does a specific action linked to the ad (e.g. sign up to mailing list, purchase something, ...)
166
What is RTB (Real Time Bidding)?
Utilises computer algorithms to automatically buy & sell ads in real-time
Uses per impression content
167
What ecosystems is RTB (Real-Time Bidding) built on (4)?
**Ad exchange** - marketplace for advertising space
**Supply-Side Platform** - for selling advertising
**Demand-Side Platform** - for buying advertising
**Data Management Platform** - manage cookie IDs to target ads
168
In what order is data built on through the advertising ecosystem (4)?
1. **Browser**
1. **Website** adds
1. **Add server** adds
1. **Advertiser** adds
169
What is fingerprinting?
A stateless tracking technique (like cookies)
Identifier derived from information taken from device (like a hash)
170
Semantic Web vs Annotated Web
**Semantic Web** - extension of current web; enables data to be interconnected & understood by machines
**Annotated Web** - a web where extra data (metadata/annotations) is added to content to make it easier to understand for humans & machines
171
What are the 2 components of resource description framework?
**Literals** (object) - have value but no identity
**Resources** (subject) - represent objects with identity
Linked with a predicate (arrow)
172
What are the 4 semantic web publishing practices?
1) Using **URIs to identify** things
2) Making **URIs accessible via HTTP**
3) **Providing useful information** when URIs are accessed
4) **Linking to other URIs** for better connectivity
173
What are the 5 quality levels of linked data?
Lowest to highest:
* 1: available on the web
* 2: machine-readable
* 3: non-proprietary format
* 4: uses W3C standards
* 5: linked to other people's data
174
Do hypertext links have to be explicit, static and textual?
No:
* May be derived from underlying relationships
* Can be computed on the fly
* May change depending on who's viewing them
175
What is sculptural hypertext?
Instead of adding links between nodes, assumes all nodes are linked and remove links until desired structure achieved
176
What are the following hypermedias:
* Temporal
* Computational
* Conceptual
* Pervasive
* Adaptive
**Temporal** - content changes over time
**Computational** - content dynamically generated/altered using algorithms/user input
**Conceptual** - links based on ideas/concepts, not just direct connections
**Pervasive** - content linked with real world e.g. augmented reality
**Adaptive** - content & links personalised based on user preferences
177
What is net neutrality?
The principle that Internet Service Providers must treat all Internet communications equally
178
What are the 6 arguments for net neutrality?
**Accessibility**
**Choice** - promotes competition
**Experimentation** - equal access for all companies
**Free Speech**
**Innovation**
**Unbiased**
179
What are the 3 arguments against net neutrality?
**Anti-competitive**
**Increases quality**
**Regulation** - stop illegal content
180
What 3 intellectual properties are there on websites? How are they protected?
**Text/design/graphics/layout/music/software** - protected by copyright
**Logos/branding** - protected by trademark rights
**Underlying database** - protected by database rights
181
What 4 rights does a copyright owner have?
* Copy the work
* Make an adaptation of a work
* Show the work to the public
* Issue copies to the public
**(For a limited time)**
182
What are the 2 types of copyright infringement?
**Primary infringement** - anyone who does any of the rights of the owner
**Secondary infringement** - if someone facilitates other people infringing on a copyright
183
What is cyber squatting?
Registering a domain name with no legitimate reason other than to benefit from another's reputation
Make money by trafficking users to unrelated material or selling domain at inflated price
184
How can trademark holders police the use of its mark?
Instead of being responsible for policing, can use the **Creative Commons Attribution** license
185
What do the following CCAs allow for:
* CCA
* CCA-ShareAlike
* CCA-NonCommercial
* CCA-NoDerivs
* CCA-NonCommercial-ShareAlike
* CCA-NonCommercial-NoDerivs
**CCA**: can distribute/remix/tweak/build on work as long as credited
**CCA-ShareAlike**: licence any new creations under identical terms
**CCA-NonCommercial**
**CCA-NoDerivs**: work must remain unchanged
**CCA-NonCommercial-ShareAlike**
**CCA-NonCommercial-NoDerivs**
