Java-Part 9 Index Java – Part 11
*The I/P is a low level routing protocol that breaks data into small packets & sends them to a address across a network.
*The TCP is a higher level protocol that manages to robustly string together these packets, sorting & re transmitting them as necessary to reliably transmit your data.
*The UDP sits next to TCP & can be used directly to support fast, connection less unreliable transport of packets.
*A port is a numbered socket on a particular machine.
*A server is allowed to accept multiple client connected to same port number. Although each session is unique.
*A proxy server speaks the client side of a protocol to another server.
*The internet address is a number that uniquely identifies each computer on the net.
*IPV4[ 32 bit values], IPV6[48 bit values].
*InetAddress[C] => It is used to encapsulate with the numerical I/P address & domain name for that address. You can interact with this class by using the name of I/P host. InetAddress has no visible constructors. To create this object we have to use the factory methods.
*A factory methods merely a convention where by static methods in a class return an instance of that class.
*On the internet it is common to use the same name for different machine
*TCP/IP socket are used to implement reliable, bidirectional persistent point to point stream based connections between hosts on the internet.
*A Socket can be used to connect java I/O system to other programs that may reside either on the local machine or an any other machine on the internet.
*There are 2 types of TCP sockets.
- ServerSocket
- Socket
*The ServerSocket class designed to be a listener which waits for client to connect before doing anything.
*The Socket class is designed to connect to ServerSocket & initiates protocol exchanges. The creation of Socket object implicitly establishes a connection between the client and server.
*There are no methods or constructors that explicitly exposes the details of establishing a connection.
*URL[C] => The web is a loose connection of higher level protocols & file formats all unified in a web browser.
*UrlConnection[C] => It is used to get the information on the internet. We create this object using open connection() method.
*TCP/IP Server Socket =>When you create a ServerSocket, it will register itself with the system as having an interest in client connections.
*ServerSocket has a method called accept() which is a blocking call that will wait for a client to initiate communications & then return with normal socket that is used for communication with the client.
*Java implements datagrams on top of the UDP protocols by using 2 classes.
- DataGramPacket
- DataGramSocket
*TCP/IP reservers lower 1024 ports for specific protocols
- 21 – FTP
- 23 – Telnet
- 25 – Email
- 79 – Finger
- 80 – Http
- 119 – NetNews
phanees tech notes 
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