\( % groupings of objects. \newcommand{\set}[1]{\left\{ #1 \right\}} \newcommand{\seq}[1]{\left(#1\right)} \newcommand{\ang}[1]{\langle#1\rangle} \newcommand{\tuple}[1]{\left(#1\right)} \newcommand{\size}[1]{\left| #1\right|} \newcommand{\comp}{\circ} % numerical shortcuts. \newcommand{\abs}[1]{\left| #1\right|} \newcommand{\floor}[1]{\left\lfloor #1 \right\rfloor} \newcommand{\ceil}[1]{\left\lceil #1 \right\rceil} % linear algebra shortcuts. \newcommand{\change}{\Delta} \newcommand{\norm}[1]{\left\| #1\right\|} \newcommand{\dprod}[1]{\langle#1\rangle} \newcommand{\linspan}[1]{\langle#1\rangle} \newcommand{\conj}[1]{\overline{#1}} \newcommand{\der}[1]{\frac{d#1}{dx}} \newcommand{\lap}{\Delta} \newcommand{\kron}{\otimes} \newcommand{\nperp}{\nvdash} \newcommand{\mat}[1]{\left[ \begin{smallmatrix}#1 \end{smallmatrix} \right]} % derivatives and limits \newcommand{\partder}[2]{\frac{\partial #1}{\partial #2}} \newcommand{\partdern}[3]{\frac{\partial^{#3 #1}}{\partial #2^{#3}}} \newcommand{\gradient}{\nabla} \newcommand{\subdifferential}{\partial} % Arrows \newcommand{\diverge}{\nearrow} \newcommand{\notto}{\nrightarrow} \newcommand{\up}{\uparrow} \newcommand{\down}{\downarrow} % gets and gives are defined! % ordering operators \newcommand{\oleq}{\preceq} \newcommand{\ogeq}{\succeq} % programming and logic operators \newcommand{\dfn}{:=} \newcommand{\assign}{:=} \newcommand{\co}{\ co\ } \newcommand{\en}{\ en\ } % logic operators \newcommand{\xor}{\oplus} \newcommand{\Land}{\bigwedge} \newcommand{\Lor}{\bigvee} \newcommand{\finish}{\Box} \newcommand{\contra}{\Rightarrow \Leftarrow} \newcommand{\iseq}{\stackrel{_?{=}}} % Set theory \newcommand{\symdiff}{\Delta} \newcommand{\setdiff}{\backslash} \newcommand{\union}{\cup} \newcommand{\inters}{\cap} \newcommand{\Union}{\bigcup} \newcommand{\Inters}{\bigcap} \newcommand{\nullSet}{\phi} % graph theory \newcommand{\nbd}{\Gamma} % Script alphabets % For reals, use \Re % greek letters \newcommand{\eps}{\epsilon} \newcommand{\del}{\delta} \newcommand{\ga}{\alpha} \newcommand{\gb}{\beta} \newcommand{\gd}{\del} \newcommand{\gp}{\pi} \newcommand{\gf}{\phi} \newcommand{\gh}{\eta} \newcommand{\gF}{\Phi} \newcommand{\gl}{\lambda} \newcommand{\gm}{\mu} \newcommand{\gn}{\nu} \newcommand{\gr}{\rho} \newcommand{\gs}{\sigma} \newcommand{\gth}{\theta} \newcommand{\gx}{\xi} \newcommand{\gw}{\omega} \newcommand{\sw}{\sigma} \newcommand{\SW}{\Sigma} \newcommand{\ew}{\lambda} \newcommand{\EW}{\Lambda} \newcommand{\Del}{\Delta} \newcommand{\gD}{\Delta} \newcommand{\gG}{\Gamma} \newcommand{\gW}{\Omega} \newcommand{\gS}{\Sigma} \newcommand{\gTh}{\Theta} % Bold english letters. \newcommand{\bA}{\mathbf{A}} \newcommand{\bB}{\mathbf{B}} \newcommand{\bC}{\mathbf{C}} \newcommand{\bD}{\mathbf{D}} \newcommand{\bE}{\mathbf{E}} \newcommand{\bF}{\mathbf{F}} \newcommand{\bG}{\mathbf{G}} \newcommand{\bH}{\mathbf{H}} \newcommand{\bI}{\mathbf{I}} \newcommand{\bJ}{\mathbf{J}} \newcommand{\bK}{\mathbf{K}} \newcommand{\bL}{\mathbf{L}} \newcommand{\bM}{\mathbf{M}} \newcommand{\bN}{\mathbf{N}} \newcommand{\bO}{\mathbf{O}} \newcommand{\bP}{\mathbf{P}} \newcommand{\bQ}{\mathbf{Q}} \newcommand{\bR}{\mathbf{R}} \newcommand{\bS}{\mathbf{S}} \newcommand{\bT}{\mathbf{T}} \newcommand{\bU}{\mathbf{U}} \newcommand{\bV}{\mathbf{V}} \newcommand{\bW}{\mathbf{W}} \newcommand{\bX}{\mathbf{X}} \newcommand{\bY}{\mathbf{Y}} \newcommand{\bZ}{\mathbf{Z}} \newcommand{\bba}{\mathbf{a}} \newcommand{\bbb}{\mathbf{b}} \newcommand{\bbc}{\mathbf{c}} \newcommand{\bbd}{\mathbf{d}} \newcommand{\bbe}{\mathbf{e}} \newcommand{\bbf}{\mathbf{f}} \newcommand{\bbg}{\mathbf{g}} \newcommand{\bbh}{\mathbf{h}} \newcommand{\bbk}{\mathbf{k}} \newcommand{\bbl}{\mathbf{l}} \newcommand{\bbm}{\mathbf{m}} \newcommand{\bbn}{\mathbf{n}} \newcommand{\bbp}{\mathbf{p}} \newcommand{\bbq}{\mathbf{q}} \newcommand{\bbr}{\mathbf{r}} \newcommand{\bbs}{\mathbf{s}} \newcommand{\bbt}{\mathbf{t}} \newcommand{\bbu}{\mathbf{u}} \newcommand{\bbv}{\mathbf{v}} \newcommand{\bbw}{\mathbf{w}} \newcommand{\bbx}{\mathbf{x}} \newcommand{\bby}{\mathbf{y}} \newcommand{\bbz}{\mathbf{z}} \newcommand{\0}{\mathbf{0}} \newcommand{\1}{\mathbf{1}} % Caligraphic english alphabet \newcommand{\cA}{\mathcal{A}} \newcommand{\cB}{\mathcal{B}} \newcommand{\cC}{\mathcal{C}} \newcommand{\cD}{\mathcal{D}} \newcommand{\cE}{\mathcal{E}} \newcommand{\cF}{\mathcal{F}} \newcommand{\cG}{\mathcal{G}} \newcommand{\cH}{\mathcal{H}} \newcommand{\cI}{\mathcal{I}} \newcommand{\cJ}{\mathcal{J}} \newcommand{\cK}{\mathcal{K}} \newcommand{\cL}{\mathcal{L}} \newcommand{\cM}{\mathcal{M}} \newcommand{\cN}{\mathcal{N}} \newcommand{\cO}{\mathcal{O}} \newcommand{\cP}{\mathcal{P}} \newcommand{\cQ}{\mathcal{Q}} \newcommand{\cR}{\mathcal{R}} \newcommand{\cS}{\mathcal{S}} \newcommand{\cT}{\mathcal{T}} \newcommand{\cU}{\mathcal{U}} \newcommand{\cV}{\mathcal{V}} \newcommand{\cW}{\mathcal{W}} \newcommand{\cX}{\mathcal{X}} \newcommand{\cY}{\mathcal{Y}} \newcommand{\cZ}{\mathcal{Z}} % Formatting shortcuts \newcommand{\red}[1]{\textcolor{red}{#1}} \newcommand{\blue}[1]{\textcolor{blue}{#1}} \newcommand{\htext}[2]{\texorpdfstring{#1}{#2}} % Statistics \newcommand{\distr}{\sim} \newcommand{\stddev}{\sigma} \newcommand{\covmatrix}{\Sigma} \newcommand{\mean}{\mu} \newcommand{\param}{\theta} \newcommand{\gthEst}{\hat{\theta}} \newcommand{\ftr}{\phi} \newcommand{\est}[1]{\hat{#1}} % General utility \newcommand{\todo}[1]{\textbf{[TODO]}] \footnote{TODO: #1}} \newcommand{\tbc}{[\textbf{Incomplete}]} \newcommand{\chk}{[\textbf{Check}]} \newcommand{\why}{[\textbf{Find proof}]} \newcommand{\opt}[1]{\textit{#1}} \newcommand{\experience}[1]{[\textbf{Personal Experience}]: #1 \blacktriangle} \newcommand{\pf}[1]{[\textbf{Proof}]: #1 \Box} \newcommand{\core}[1]{\textbf{Core Idea}: #1 \Arrowvert} \newcommand{\example}[1]{\textbf{Example}: #1 \blacktriangle} \newcommand{\error}[1]{\textbf{Error alert}: #1 \triangle} \newcommand{\oprob}{[\textbf{OP}]: } \renewcommand{\~}{\htext{$\sim$}{~}} \DeclareMathOperator*{\argmin}{arg\,min} \DeclareMathOperator*{\argmax}{arg\,max} \)

+Application layer

Content delivery network

Transferring large files to the consumer is faster when it is cached at a location close to the consumer (in terms of time). Large companies may use their own special content delivery network, or provide such a service to others, in order to get more patronage from consumers whose ISp’s have slow links to distant servers.

Eg: Akamai.

HTTP

This is a primitive protocol meant to transfer files from servers to clients, with annotation about meta-information.

Web services architecture

Broker, provider, consumer

There is a services broker/ directory, with which various service machines register details about their services, and which can be used by other machines to locate services fitting their needs. Having done that, the service consumer and provider interact directly.

Various protocols define format for transmitting objects (SOAP XML), service descriptions (Web Service Description Language) etc..

Service oriented architecture (SOA)

The basic unit of communication is a message, rather than an operation. This is often implemented using web services.

+Application layer