Java System

Architectures

David DavenportBilkent UniversityAnkara – TurkeyEmail: david@bilkent.edu.tr

Basic Forms of Java Programs

• Console Applications( MSDOS-like )– text only!

• GUI Applications( Windows-like )– text & graphics– menus, buttons, mouse,

keyboard

• Applets– GUI programs restricted

for use in web-browsers

Other Forms of Java Programs

• Web Server Applications– html client– data only ~ XML, JSON…

• Mobile Applications– Android only Java– html5, Javascript, CSS

using libraries, e.g. JQuery Mobile, phonegap, …

– Java for everything?

• Cards, TV, …– misc!

Java Applications

JavaProgram

network

Java applications (console & GUI) have full accessto local machine

resources, including local files, databases

& network connections.

JavaApplet

WebBrowser

Java Applets

networkWeb

server

ServerJava

Program

Java Applets are embedded in html web pages, downloaded from web servers and run by web browsers. For security reasons, they

can communicate only with the machine from which they originated and cannot access local files or databases (although these restrictions can be lifted if the user agrees to trust them!)

Networked Java Applications

JavaProgram

network

JavaProgram

JavaProgram

JavaProgram

Java programs can communicate with each other either directly or via a server program, allowing them to freely exchange

information.

Some database systems offer direct

network access.

Networked Java Applets

Webserver

JavaApplet

JavaApplet

JavaApplet

ServerJava

Program

Since Java Applets cannot

normally communicate

with each other directly, they

must do so via a server

application program.

Similarly, if they need to store

information, they can only do so on

a server machine.

Java Servlets

WebBrowser

WebBrowser

WebBrowser

JavaServlets

Webserver

Java Servlets extend web server functionality allowing it to

dynamically generate web pages using information stored in

databases or files.

Communications use HTML…

Java Web Services

WebBrowser

Java Program

JavaWeb

Services

Webserver

Web services extend web server functionality allowing it to

dynamically respond to service requests using information from

databases, files or even other web services!

Clients may be web browsers, but are more likely to be other application

programs.

Communications use

XML/JSON

MobileApp

Data Formats…

Name Telno David 1248 Gunes 1814 Derya 5678

<table><tr>

<td>David</td><td>1248</td>

</tr><tr>

<td>Gunes</td><td>1814</td>

</tr><tr>

<td>Derya</td><td>5678</td>

</tr></table>

<teldir><person>

<name>David

</name><telno>

1248</telno>

</person><person>

<name>Gunes

</name><telno>

1814</telno>

</person><person>

<name>Derya

</name><telno>

5678</telno>

</person></teldir>

{"teldir":[{"name":"David", "telno":"1248"}, {"name":"Gunes", "telno":"1814"}, {"name":"Derya", "telno":"5678" ]}

name,telnoDavid,1248Gunes,1814Derya,5678

Mobile Applications

Hardwarescreen orientation (portrait, lanscape)screen size (phone, tablet)screen resolution (DPI)optional sensors (GPS, accelerometer, …)

Development environments/languagesto each his own?

Java for Android, Objective-C for iOs, …cross platform?

embedded webbrowser~ html5, Javascript, CSS + libraries…

Java for all? ~ Codename One

Operating SystemsAndroid, iOS, Windows, Blackberry, …

Changing

rapidly

Persistent StorageAlternatives

Files ~ sequential/random-access, diy/Serialization, …Database ~ JDBC, SQL, …Cloud? ~ …other? ~ local storage on phones, webbrowser, etc.

Tables, e.g. TelDirName Telno David 1248 Derya 5678 Gunes 1814

SQL w3schools select * from TelDirselect Name from TelDirselect Telno from TelDir where Name = 'Derya‘

insert into TelDir ( Name, Telno) values ( ‘Ayse’, 9999)

update TelDir set TelNo = 0000 where Name = ‘Ayse’

delete from TelDir where TelNo = 5678

+ commands to manipulate tables, etc.

Database

JDBC allows your Java program to connect to any database and talk SQL to it. examples

examples…

see w3schools…

Considerations

• User Interaction– Text only

– Text & graphics • Static (html?)• Interactive (GUI?)

– Mouse/touch/voice/…

• Single/multi-user– Stand-alone

– Network• Web-browser (applet)• Application

• Client software distribution & installation– Floppy disks/CD’s/

usb memory sticks/ download?

– WebStart– Applets– Server-based

• Data storage & retrieval– Files– Database (local/network)– Cloud storage