Software development - the java perspective

Software Development
= the Java perspective =

Three-Tier Architecture
Database
4 TOTAL SALES
Storage
>GET SALES
TOTAL
>GET SALES
TOTAL
GET LIST OF ALL
SALES MADE
LAST YEAR
ADD ALL SALES
TOGETHER
QUERY
SALE 1
SALE 2
SALE 3
Presentation tier
The top-most level of the application
is the user interface. The main function
of the interface is to translate tasks
and results to something the user can
understand.
Logic tier
This layer coordinates the
application, processes commands,
makes logical decisions and
evaluations, and performs
calculations. It also moves and
processes data between the two
surrounding layers.
Data tier SALE 4
Here information is stored and retrieved
from a database or file system. The
information is then passed back to the
logic tier for processing, and then
eventually back to the user.

<html>
<head>
...
</head>
<body>
...
</body>
</html>
Hyper-Text Markup Language
start tag
data related to the page
CSS, JS, page title, etc.
actual page content
end tag

HTML - Demo
http://www.w3schools.com/html/tryit.asp
?filename=tryhtml_layout_divs

Cascading Style Sheets
#header {
background-color:black;
color:white;
text-align:center;
padding:5px;
}

CSS - Demo
http://www.w3schools.com/html/tryit.asp
?filename=tryhtml_layout_divs
http://www.mezzoblue.com/zengarden/all
designs/
http://www.csszengarden.com/217/
http://www.csszengarden.com/215/

var sum = function() {
var i, result = 0;
for (i = 0; i < arguments.length; ++i) {
x += arguments[i];
}
return result;
}
sum(1, 2, 3); // returns 6
JavaScript

JavaScript is NOT Java
public int sumAll(int... numbers) {
int result = 0;
for(int i = 0 ; i<numbers.length;i++){
result+=numbers[i];
}
return result;
}
sum(1, 2, 3); // returns 6

JavaScript is NOT Java
JavaScript Java
Can Run in a Browser? Yes Yes, with applets
(old technology)
Can Run on a Server? Yes (e.g. Node.js) Yes
Compiled? No, interpreted Yes, to bytecode
Threads Single-threaded Multi-threaded
Types Loose typing Strong typing
Characteristics Prototype-based
Higher-order functions
Classes

JavaScript - Demo
http://jsfiddle.net/w24pysbx/

Presentation --> Logic
Database
4 TOTAL SALES
Storage
>GET SALES
TOTAL
>GET SALES
TOTAL
GET LIST OF ALL
SALES MADE
LAST YEAR
ADD ALL SALES
TOGETHER
QUERY
SALE 1
SALE 2
SALE 3
Presentation tier
The top-most level of the application
is the user interface. The main function
of the interface is to translate tasks
and results to something the user can
understand.
Logic tier
This layer coordinates the
application, processes commands,
makes logical decisions and
evaluations, and performs
calculations. It also moves and
processes data between the two
surrounding layers.
Data tier SALE 4
Here information is stored and retrieved
from a database or file system. The
information is then passed back to the
logic tier for processing, and then
eventually back to the user.

Web Services (WS)
A method of communication between two
devices over a network.

Web Services (WS)
A method of communication between two
devices over a network.
REST
● Exposes RESOURCES which
represent DATA
● Uses HTTP verbs (GET /
POST / DELETE)
● Simple point-to-point
communication
● Multiple data formats
(XML/JSON)
● Stateless communication
SOAP
● Exposes OPERATIONS which
represent LOGIC
● Uses HTTP verb: POST
● Loosly coupled distributed
messaging
● Only XML
● Supports stateless and stateful
● Async messaging
● Strong typing (WSDL)

Data Formats
JSON
{
"books": [
{
"category": "reference",
"author": "Nigel Rees",
"title": "Sayings of the Century",
"price": 8.95,
"copies": 3
},
{
"category": "fiction",
"author": "Evelyn Waugh",
"title": "Sword of Honour",
"price": 12.99,
"copies": 5
}
]
}
XML
<books>
<book>
<category>reference</category>
<author>Nigel Rees</author>
<title>Sayings of the Century</title>
<price>8.95</price>
<copies>3</copies>
</book>
<book>
<category>fiction</category>
<author>Evelyn Waugh</author>
<title>Sword of Honour</title>
<price>12.99</price>
<copies>5</copies>
</book>
</books>

SOAP
Request
<soap12:Envelope
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">
<soap12:Body>
<GetWeather xmlns="http://www.webserviceX.NET">
<CityName>New York</CityName>
<CountryName>United States</CountryName>
</GetWeather>
</soap12:Body>
</soap12:Envelope>

SOAP
Response
<soap12:Envelope
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:soap12="http://www.w3.org/2003/05/soap-envelope">
<soap12:Body>
<GetWeatherResponse xmlns="http://www.webserviceX.NET">
<GetWeatherResult>
Wind from the NW (320 degrees) at 13 MPH
Visibility 3 mile(s)
SkyConditions overcast
Temperature 39.9 F (4.4 C)
</GetWeatherResult>
</GetWeatherResponse>
</soap12:Body>
</soap12:Envelope>

REST
Request
GET /globalweather.asmx/GetWeather?
CityName=NewYork&CountryName=United%20States HTTP/1.1
Host: www.webservicex.net
Response
HTTP/1.1 200 OK
Content-Type: text/xml; charset=utf-8
Content-Length: length
<string xmlns="http://www.webserviceX.NET">
Wind from the NW (320 degrees) at 13 MPH
Visibility 3 mile(s)
SkyConditions overcast
Temperature 39.9 F (4.4 C)
</string>

App Servers
A web server serves up static resources
(HTML, CSS, JS, text, images, etc.)
and nothing else.
A servlet container is using Java to
dynamically generate the web page on
the server side.
An application server supports the entire
Java Enterprise Edition stack
(JEE, formerly known as J2EE)

App Servers
A web server serves up static resources
(HTML, CSS, JS, text, images, etc.)
and nothing else.

App Servers
A servlet container is using Java to
dynamically generate the web page on
the server side.

App Servers
An application server supports the entire
Java Enterprise Edition stack
(JEE, formerly known as J2EE)

Databases
Database Management Systems is an umbrella
term that refers to the systems that handle, or
heavily assist in handling, dealing with collections
of information that need to be persisted.
DBMS are based on database models, structures
defined for handling the data:
● The Relational Model
● The Model-less, Schema-less (NoSQL)
Approach
Popular DBMS:
●Relational (RDBMS)
●NoSQL (NewSQL)

NoSQL databases
Schema-less databases do not come
with a model as used (or needed) with
structured relational solutions.
●Key-values Stores
●Column Family Stores
●Document Databases
●Graph Databases

NoSQL databases
Key-values Stores: Using a hash table where there is
a unique key and a pointer to a particular item of data.

NoSQL databases
Column Family Stores: There are still keys but they
point to multiple columns. The columns are arranged
by column family.

NoSQL databases
Document Databases: The model is basically
versioned documents that are collections of other key-value
collections. The semi-structured documents are
stored in formats like JSON.

NoSQL databases
Graph Databases: Instead of tables of rows and
columns and the rigid structure of SQL, a flexible
graph model is used.

NoSQL databases
Term Matching Databases
Key-value
Memcache, Redis, Riak,
Dynamo, FoundationDB,
Aerospike, FairCom c-treeACE
Document
MongoDB, CouchDB,
Couchbase, MarkLogic
Clusterpoint,
Column Cassandra, Accumulo,
Hbase, Druid, Vertica
Graph
Neo4J, InfiniteGraph,
OrientDB, Allegro,
Virtuoso, Stardog

Demo
HTML + CSS + JS
REST API
Java application server
MySQL database server

Software development - the java perspective

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