Java Client Server

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Java Client Server

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Example

• Iterative function - Newton Raphson
• Used to calculate a square root
• estnew is a native float
• estnew (estold Value/estold)/2
• Sqr root (Value is 100) 10
• Final answer 10
• Initial estimate - estold 1000

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Example bgnd cont.

• estnew (estold Value/estold)/2
• estnew (1000100/1000)/2500
• estnew (500100/500)/2250 etc
• Calc needs estold and Value
• During run client sends strings
• Text command - run Value est
• nrserv sends back - ansnew

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Example client.java

• Network client.java
• Works with nsrerv.java
• Uses sockets
• Input stream inpstr
• Output stream outstr
• sock new Socket
• (157.228.x.x, 4444)

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Example continued.

• Server makes all calculations
• Outval 100
• Outstr.println(outval)
• Iterate - ansoldansnew
• Edit IP address connect to server
• Command ipconfig/all or use wincfg
• Answer is printed on screen

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Example nrserv.java

• Server accepts sock when
• Client connects
• Worker thread created
• class Worker extends Thread
• new Worker( sock ).start()
• Method run() is invoked
• Remember inputs to server - strings

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Example continued

• To read string convert to integer
• valstrg inpstr.readline()
• Value Integer.parseInt(valstrg)
• Wrapper classes
• Lower case float normal native float
• Upper case Float denotes
• Special class/object with methods wrapped around

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Example continued

• To read and convert string to float
• Float temp Float.valueOf(eststrg)
• float estold temp.floatValue()
• This is special feature of Java
• Input - Ctrlstrg valstrg eststrg
• Uses ctrlstrg - Value(int) - estold(float)
• Output value for client estout