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Health Care and Information and Communications Technologies ...

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June 2006 Health Care and Information and Communications Technologies: Challenges and Opportunities INTRODUCTION Most countries are at some stage of health sector reform to try to provide expanded and equitable access to quality services while reducing or at least controlling the rising cost of healthcare. Health reform processes have many facets and there is no single model being adopted by all countries. However, ICTs have the potential to make a major contribution to improving access and quality of services while containing costs.
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  • quality of services
  • quality services
  • health-care industry
  • health care industry
  • patient records
  • companies
  • standards
  • computer

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C Socket Programming Tutorial SHARE Session 5958
Writing Client/Server Programs in C
Using Sockets (A Tutorial)
Part I
Session 5958
Greg Granger
grgran@sas.com
grgran@om
SAS/C & C++ Support
SAS Institute
Cary, NC
Slide 1
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
Part I: Socket Programming Overview
Sockets (to me)

Networking (or what’s natural about natural logs)

TCP/IP (and what it means to your life)

More Sockets (we didn’t get enough the first time)

Slide 2
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
What is “Sockets”
An Application Programming Interface (API) used
) us
for InterProcess Communications (IPC). [A well
defined method of connecting two processes,
locally or across a network]
Protocol and Language Independent
ua
Often referred to as Berkeley Sockets or BSD
Sockets
Slide 3
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
Connections and Associations
Connections
In Socket terms a connections between two

processes in called an association.
An association can be abstractly defined as a 5-

tuple which specifies the two processes and a
method of communication. For example:
• {protocol, local-addr, local-process, foreign-addr, foreign-process}
A half-association is a single “side” of an

association (a 3-tuple)
• {protocol, addr, process}
Slide 4
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
Networking Terms
packet - the smallest unit that can be transferred

“through” the network by itselfu
protocol - a set of rules and conventions between

the communicating participants
A collection of protocol layers is referred to as a

“protocol suite”, “protocol family” or “protocol
stack”. TCP/IP is one such protocol suite.
Slide 5
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
Introduction to TCP/IP
What (the heck) is TCP/IP?
sIP?
Internet Protocol (IP)

User Datagram Protocol (UDP)

Transmission Control Protocol (TCP)

TCP/IP Applications

Name Resolution Processing

TCP/IP Network Diagram

Slide 6
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
What is TCP/IP?
Transmission Control Protocol/Internet Protocol

A network protocol suite for interprocess

communication
The protocol of the Internet

Open, nonproprietary

Integrated into UNIX operating systems

Many popular networking applications
• telnet • NFS (network file system)
•net
• X11 GUI • SMTP (mail)
• www • ftp (file transfer protocol)ol)
Slide 7
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
TCP/IP Architectural Model
REXEC / SMTP / TELNET / FTPEC T / FTP
Process (message)
/ DNS / RPC / Local Apps.C / L
Transport (message)
Trarge)
UDP
TCP
TC
Network (packets)ts
ICMP IP (R)ARP
ICMP IP
Ethernet Token-Ring FDDI X.25
Data Linnk (frames)
SNA Hyperchannel Proprietary
Slide 8
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
Internet Protocol (IP)
Establishes a “virtual” network between hosts,

independent of the underlying network topologyr
Provides “routing” throughout the network, using

IP addressing. For example: 149.173.70.9
Features

• Best-effort packet deliveryt
UDP
TCP UDP
• Connectionless (stateless)nnlea
• Unreliable
IP
Physical Network
Slide 9
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NCC Socket Programming Tutorial SHARE Session 5958
User Datagram Protocol (UDP)
User Dag
Application Interface to IP - Packet Oriented

Establishes a “port”, which allows IP to distinguish
b
among processes running on the same host
Features resemble IP semantics

• Connectionless
• Unreliable
UDP
UDP
TCP
• Checksums (optional)
IP
Physical Network
Phy
Slide 10
SAS Institute Inc.c.
SAS/C & C++ Compiler R&D
Feb. 1998
CaCary, NCry, NC