MCA17102: Introduction to Internet Technologies
UNIT – I:
Introduction to Internet, Internet Services, WWW, Working of Internet, Internet Connection Concepts, Introduction to Intranet, DNS working, Configuring Internet Connection, Connecting LAN to Internet. Single User, Multi User, Server, Workstation, Client-Server environment, Computer Network, Types of Computer Network: LAN, WAN, MAN; Network Topologies. Protocols used in internet FTP, HTTP etc. Windows and GUI. Latest Developments and usage of Internet for IOT, Cloud Computing, Web Services.
UNIT – II:
E-Mail Concepts – Configuring E-Mail Program, Sending and Receiving Files through E-Mail, Fighting Spam, Sorting Mail, and avoiding E-Mail viruses. Web-Based chat rooms and discussion boards, Voice and Video conferencing. Streamlining Browsing, Keeping track of Favorite Web Sites, Web Security, Privacy, and Site-Blocking. Searching the Web – Audio and Video on the Web. Two tier-Three Architectures, Internet Architecture
UNIT-III:
Web Browsers, Search Engines, Categories of Search Engines, Searching Criterion, Surfing the Net, Hypertext Transfer Protocol (HTTP), URL. Other Internet Tools. Online Chatting, Messaging, and Conferencing Concepts, E-Mail mailing lists, Usenet newsgroup concepts – Reading usenet newsgroups, Internet Relay Chat, Instant messaging.
UNIT-IV:
HTML-5: Internet Language, Understanding HTML, Create a Web Page, Linking to other Web Pages, Publishing HTML Pages, Text Alignment and Lists, Fonts Text Formatting Control, E-mail Links and link within a Page, Creating HTML Forms with HTML5 controls.
Creating Web Page Graphics, Putting Graphics on a Web Page, Custom Backgrounds and Colors, Creating Animated Graphics. Web Page Design and layout, Advanced Layout with Tables, Using Style Sheets.
Text Books:
1. Dick Oliver: Teach Yourself HTML 4 in 24 Hours, Techmedia. 2. Satish Jain: "O" – Level Information Technology,
3. Craig Zacker: 10 minutes Guide to HTML Style Sheets, PHI. 4. V.K. Jain: "O" – Level Information Technology, BPB Publications.
5. Gill, Nasib Singh: Essentials of Computer and Network Technology, Khanna Books 6. Publishing Co., New Delhi.
7. Margaret Levine Young: Internet – The Complete Reference 8. Harley Hahn: The Internet – Complete Reference, TMH.
Unit-I
Introduction to Internet
Internet refers to network of networks. In this network each computer is recognized by a globally unique address known as IP address. A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name.
For example, a DNS server will resolve a name http://www.vsuniversity.edu to a particular IP address to uniquely identify the computer on which this website is hosted.
Internet is defined as an Information super Highway, to access information over the web. However, It can be defined in many ways as follows:
o Internet is a world-wide global system of interconnected computer networks. o Internet uses the standard Internet Protocol (TCP/IP).
o Every computer in internet is identified by a unique IP address.
o IP Address is a unique set of numbers (such as 110.22.33.114) which identifies a computer location.
o A special computer DNS (Domain Name Server) is used to give name to the IP Address so that user can locate a computer by a name.
o Internet is accessible to every user all over the world.
History of internet:
Some of the mile stones in the history of Internet are:
In 1969, ARPANET (Advanced Research Projects Agency Network) was designed by United States Department of Defense for their military purpose. ARPANE comprises four nodes located at: University of California, Losangels university of California, Santa Barbara and University of Utah and the standard research Institute.
In 1972, the ARPANET was international by connecting 23 nodes at different
colleges in the Europe. In the same period of time Ray Tomlinson convened e-mail In 1976 AT & T Bell labs developed UNIX to UNIX CoPy (UUCP) network.
In 1979, using UUCP, user network (USENET) was developed to connect duke university and university of North Cardina.
In 1980, transmission control protocol/Internet Protocol (TCP/IP) were
established. As the internet became larger, the domain name system (DNS) was developed.
In 1980, the computer science network (CSNET) developed to connect all university computer science departments in U.S. In 1981 CNSET joined with ARPANET.
In 1981, BITNET (Because Its Time Network)is formed by connecting city university of New York. To Yale University. Mailing lists are developed. In 1983, TCP/IP used for all ARPANET hosts.
In 1985, NSFNET (National Science Foundation Network) was formed to connect 5 NSF centers.
1989, NSF took over control of ARPANET. The number of hosts on the Internet exceeded 100,000.
During 1990s, commercial organization started getting on-line URLS appeared, browsing tools, HTML programming language were developed.
In 1991, ‘Gopher’ was developed at university of Minnesota to fetch files on Internet.
In 1991, WWW (World Wide Web) was created by “Team Bernere-Lee”. In 1992, WWW became available to the public.
In 1993, “Mosaic”, a graphical web brow ser was released.
In 1994, another WEB browser “Netscape Navigator” was released by Netscape communications. Internet search engine and directory called “Yahoo” was
developed by graduates’ students ‘David File’ and ‘Jerry Yang’.
In 1995, the Internet programming environment ‘JAVA’ w as released by ‘Sun Micro System ’. Microsoft develops its web browsers, Microsoft Internet Explorer.
Internet Services
Internet Services allows us to access huge amount of information such as text, graphics, sound and software over the internet. Following diagram shows the four different categories of Internet Services.
Communication Services
There are various Communication Services available that offer exchange of information with individuals or groups. The following table gives a brief introduction to these services:
S.No Service Description
1 Electronic Mail: Used to send electronic message over the internet.
2 Telnet: Used to log on to a remote computer that is attached to internet. 3 Newsgroup: Offers a forum for people to discuss topics of common interests. 4 Internet Relay Chat (IRC)
Allows the people from all over the world to communicate in real time. 5 Mailing Lists: Used to organize group of internet users to share common
information through e-mail.
6 Internet Telephony (VoIP): Allows the internet users to talk across internet to any PC equipped to receive the call.
Information Retrieval Services
There exist several Information retrieval services offering easy access to information present on the internet. The following table gives a brief introduction to these services:
S.N. Service Description
1 File Transfer Protocol (FTP): Enable the users to transfer files.
2 Archie: It’s updated database of public FTP sites and their content. It helps to search a file by its name.
3 Gopher: Used to search, retrieve, and display documents on remote sites. 4 Very Easy Rodent Oriented Netwide Index to Computer Achieved
(VERONICA). VERONICA is gopher based resource. It allows access to the information resource stored on gopher’s servers.
Web Services
Web services allow exchange of information between applications on the web. Using web services, applications can easily interact with each other.
The web services are offered using concept of Utility Computing.
World Wide Web (WWW)
WWW is also known as W3. It offers a way to access documents spread over the several servers over the internet. These documents may contain texts, graphics, audio, video, hyperlinks. The hyperlinks allow the users to navigate between the documents.
Video Conferencing
Video conferencing or Video teleconferencing is a method of communicating by two-way video and audio transmission with help of telecommunication technologies.
Modes of Video Conferencing POINT-TO-POINT: This mode of conferencing connects two
locations only.
Define world wide web Evolution:
World Wide Web was created by Timothy Berners Lee in 1989 at CERN in Geneva. World Wide Web came into existence as a proposal by him, to allow researchers to work together effectively and efficiently at CERN. Eventually it became World Wide Web. The World Wide Web is a software application that makes it easy and possible for anyone to publish and browse hypertext documents on the internet.
It is a collection of on-line documents stored on the servers around the world that are connected to the internet
WWW has the ability to incorporate FTP, WAIS, Gopher, E-mail and FTP applications through one user interface
A web server provides access to all of these services to enable, among other things, web based commerce.
WWW documents are expressed in hypertext markup language (HTML)
HTML allows programmers to insert links that transfer the user to another web page on the same or on a different server
Web server transfer HTML documents to each other through the hypertext transfer protocol (HTTP)
Graphical web browsers such as Netscape Navigator and Microsoft Explorer will read HTML syntax and produce a point-and-click windowing interface for the user. HTML documents give business to opportunities to communicate through graphics,
text and sound to link to other sites and E-mails.
Home pages can also support input forms which can help companies collect user information, such as comments on a product or service which can be used to design new marketing and advertisements strategies or improve existing once. Uniform Resource Locator (URL):
URL denotes the address of the web page being displayed. This general format of URL consists of three parts as follows:
how://where/what
How the web page can be accessed? Where: where the web page can be found?
What: what is the file name corresponding to the page? Ex: http://www.svarts.edu/index.html
http: Defines the Hyper Text Transfer Protocol by which the page can be accessed. This protocol is a set of rules by which an HTML document can be transferred over the web. www.svarts.edu: Identifies the domain name of the computer where the page resides. In this case the computer located at ‘svarts’.
Index.html: The file name which identifies the specific web page.
Like this a URL consists of a protocol,a web server domain name and a file name. The following are different types of protocols that occur in URLs:
Protocol name Use Example
file File transfer ftp://fto.bio.umaine.edu
Gopher Gopher Gopher://gopher.tc.umn.edu/libraries
mailto Sending e-mail to [email protected]
Working of Internet
The Internet has become such a large part of our lives, a good understanding is needed to use this new tool most effectively.
Internet Addresses:
Because the Internet is a global network of computers each computer connected to the Internet must have a unique address.
Internet addresses are in the form nnn.nnn.nnn.nnn where nnn must be a number from 0 - 255. This address is known as an IP address (Internet Protocol)
The diagrammatically below illustrates two computers connected to the Internet. Computer with IP address 1.2.3.4 and another computer with IP address 5.6.7.8.
The Internet is represented as an abstract object in-between.
If we connect to the Internet through an Internet Service Provider (ISP), we are usually assigned a temporary IP address for the duration.
If we connect to the Internet from a local area network (LAN). The computer might have a permanent IP address or it might obtain a temporary one from a DHCP (Dynamic Host Configuration Protocol) server.
In any case, if we are connected to the Internet, this computer has a unique IP address.
The message must be translated from alphabetic text into electronic signals, transmitted over the Internet, and then translated back into alphabetic text. Through the use of a protocol stack. Every computer needs one to communicate
on the Internet and it is usually built into the computer's operating system (i.e. Windows, Unix, etc.).
The protocol stack used on the Internet is referred to as the TCP/IP protocol stack because of the two major communication protocols used.
The TCP/IP stack looks like this: Protocol Layer Comments
Application Protocols Layer Protocols specific to applications such as WWW, e-mail, FTP, etc.
TCP Layer TCP directs packets to a specific application on a computer using a port number. Internet Protocol Layer IP directs packets to a specific computer using an IP address.
Hardware Layer Converts binary packet data to network signals and back.(E.g. ethernet network card, modem for phone lines, etc.)
1. The message would start at the top of the protocol stack on your computer and work it's way downward.
3. The packets would go through the Application Layer and continue to the TCP layer. Each packet is assigned a port number. Ports will be explained later, but suffice to say that many programs may be using the TCP/IP stack and sending messages. We need to know which program on the destination computer needs to receive the message because it will be listening on a specific port.
4. After going through the TCP layer, the packets proceed to the IP layer. This is where each packet receives it's destination address, 5.6.7.8.
5. Now that our message packets have a port number and an IP address, they are ready to be sent over the Internet. The hardware layer takes care of turning our packets containing the alphabetic text of our message into electronic signals and transmitting them over the phone line.
6. On the other end of the phone line your ISP has a direct connection to the Internet. The ISPs router examines the destination address in each packet and determines where to send it. Often, the packet's next stop is another router. More on routers and Internet infrastructure later.
7. Eventually, the packets reach computer 5.6.7.8. Here, the packets start at the bottom of the destination computer's TCP/IP stack and work upwards.
8. As the packets go upwards through the stack, all routing data that the sending computer's stack added (such as IP & port number) is stripped from the packets. 9. When the data reaches the top of the stack, the packets have been re-assembled
into their original form, "Hello computer 5.6.7.8!"
Internet Infrastructure
The Internet backbone is made up of many large networks which interconnect with each other. These large networks are known as Network Service Providers or NSPs.
Some of the large NSPs are UUNet, CerfNet, IBM, BBN Planet, SprintNet, PSINet, as well as others. These networks peer with each other to exchange packet traffic.
Each NSP is required to connect to three Network Access Points or NAPs. At the NAPs, packet traffic may jump from one NSP's backbone to another NSP's backbone. NSPs also interconnect at Metropolitan Area Exchanges or MAEs. MAEs serve the same purpose as the NAPs but are privately owned. NAPs were
the original Internet inter-connect points. Both NAPs and MAEs are referred to as Internet Exchange Points or IXs. NSPs also sell bandwidth to smaller networks, such as ISPs and smaller bandwidth providers.
Below is a picture showing this hierarchical infrastructure.
Routers are packet switches.
A router is usually connected between networks to route packets between them. Each router knows about it's sub-networks and which IP addresses they use. The router usually doesn't know what IP addresses are 'above' it.
The basic concept of internet connection
Connection Types:
There exist several ways to connect to the internet. Following are these connection types available:
1. Dial-up Connection
2. ISDN - Integrated Services Digital Network 3. DSL- Digital Subscriber Line
4. Cable TV Internet connections 5. Satellite Internet connections 6. Wireless Internet Connections
The basic concepts of internet connection are as follows.
1. Identify Internet Service Provider: Any home, business or organization that wants to connect to the Internet must use an Internet Service Provider. An ISP is a company that provides the connections and support to access the Internet. It can also provide additional services such as ISPs are essential to gaining access to the Internet. No one gets on the Internet without a host computer, and no one gets on the Internet without going through an ISP.
2. THE RELATIONSHIP BETWEEN ISP AND INTERNET: Individual computers and
local networks connect to the ISP at a Point of Presence (POP). A POP is the connection point between the ISPs network and the particular geographical region that the POP is servicing. ISPs connect to other ISPs in order to send information beyond the boundaries of their own network. The Internets made up of very high-speed data links that interconnect ISP POPs and ISPs to each other. These interconnections are part of the very large, high capacity network known as the Internet Backbone.
3. THE OPTIONS OF CONNECTIONS TO THE ISP : ISPs provide a variety of ways to connect to the Internet, depending on location and desired connection speed. Each Internet access technology uses a network access device, such as a modem, in order to connect to the ISP. It may be built in to your computer or may be provided by the ISP. The simplest arrangement is a modem that provides a direct connection between a computer and the ISP. The choice of Internet access technologies depends on availability, cost, access device used, media used and the speed of the connection.
4. APPROPRIATE ISP LEVELS OF SERVICE TO MEET THE USER
5. THE IMPORTANCE OF THE INTERNET PROTOCOL (IP) : For hosts to communicate on the Internet, they must be running Internet Protocol (IP) software. The IP protocol is one of a group of protocols that are collectively referred to as TCP/IP Transmission Control Protocol / Internet Protocol). The Internet Protocol (IP) uses packets to carry data. Each IP packet must contain a valid source and destination IP address. Without valid address information, packets sent will not reach the destination host.
6. THE IP PACKET : An IP packet has a header at the beginning which contains the source and destination IP addresses. It also contains control information that describes the packet to network devices, it passes through and also helps to control its behavior on the network. The IP packet is sometimes referred to as a datagram.
7. HOW ISPS HANDLE PACKETS: Before being sent on the Internet, messages are divided into packets and each individual packet must have a source and destination IP address. When a packet is sent across the Internet, the ISP determines whether the packet is destined for a local service located on the ISP network, or a remote service located on a different network. Every ISP has a control facility for their network, known as the Network Operations Center (NOC). The NOC usually controls traffic flow and houses services such as email and web hosting. Packets looking for local services are usually forwarded to the NOC and never leave the ISP network.
8. PACKETS FORWARDED ACROSS THE INTERNET: There are network utilities that test connectivity to the destination device. The ping utility tests end-to-end connectivity between source and destination. It measures the time that it takes test packets to make a round trip from the source to the destination and whether the transmission is successful. The trace route utility traces the route from source to destination. Each router through which the packets travel is referred to as a hop. Traceroute displays each hop along the way and the time it takes for each one.
Intranet
Intranet is defined as private network of computers within an organization with its own server and firewall. Moreover we can define Intranet as:
Intranet is system in which multiple PCs are networked to be connected to each other. PCs in intranet are not available to
the world outside of the intranet.
Usually each company or organization has their own Intranet network and members/employees of that company can access the computers in their intranet. Every computer in internet is identified by
Benefits
Communication: Intranet offers easy and cheap communication within an organization. Employees can communicate using chat, e-mail or blogs.
Time Saving: Information on Intranet is shared in real time. Collaboration: Information is distributed among the employees as according to requirement and it can be accessed by the authorized users, resulting in enhanced teamwork.
Platform Independency: Intranet can connect computers and other devices with different architecture.
Cost Effective: Employees can see the data and other documents using browser rather than printing them and distributing duplicate copies among the employees, which certainly decreases the cost.
Workforce Productivity: Data is available at every time and can be accessed using company workstation. This helps the employees work faster.
Business Management: It is also possible to deploy applications that support business operations.
Security: Since information shared on intranet can only be accessed within an organization, therefore there is almost no chance of being theft.
Specific Users: Intranet targets only specific users within an organization therefore, once can exactly know whom he is interacting.
Immediate Updates: Any changes made to information are reflected immediately to all the users.
Applications
Intranet applications are same as that of Internet applications. Intranet applications are also accessed through a web browser. The only difference is that, Intranet applications reside on local server while Internet applications reside on remote server.
Document publication applications: Document publication applications allow publishing documents such as manuals, software guide, employee profits etc without use of paper.
Electronic resources applications: It offers electronic resources such as software applications, templates and tools, to be shared across the network.
Interactive Communication applications: Like on internet, we have e-mail and chat like applications for Intranet, hence offering an interactive communication among employees.
Support for Internet Applications: Intranet offers an environment to deploy and test applications before placing them on Internet.
Internet vs. Intranet
Apart from similarities there are some differences between the two.
Intranet Internet
Localized Network. Worldwide Network Doesn't have access to Intranet Have access to Internet.
More Expensive Less Expensive
More Safe Less Safe
Configuring Internet Connection
The following steps are used to configure the internet connection in our system.
Step 1: Please Click the Start button, go to Control Panel. And then go to Network and Internet->View network status and tasks page.
Step 2: Click on Set up a new connection or network.
Step 3: Select Connect to the Internet and click Next button.
Step 4: Click on Broadband (PPPoE).
Step 5: Type in the information from you ISP. Please make sure all these information is correct. And then, click Connect button.
Step 6: At this time, you have created the PPPoE dial up connection successfully. At the right side corner of your screen, click the same icon which looks like a computer, you can a Broadband Connection. You can
disconnect or connect through the broadband connection.
Connecting LAN to Internet:
We can connect internet access to a LAN using Routers.
A router is the device which communicates between two different networks.
To receive internet broadband connectivity, either by cable or Wi-Fi, either an ADSL 2+ router, or Wi-Fi the compatible Access Points is required in order to receive signals. ADSL modems increase the flow of data whereas 802-11n Series provide a speed of 1GB/second.
In the case of a single Personal Computer connected to the internet, the cheapest solution is to use an Ethernet Cable for a stable, flawless connectivity.
In the case of multiple computers, Wi-Fi the Access Points is to be created for accelerated speed, greater security and to manage a Local Area Network Easily.
Router:
A router comes in the shape of a box connected to your computer. We can connect to internet broadband (cable or Wi-Fi) or you can set up a local network. Several computers can share, for example, access to multiple devices (printer, scanner ...) and internet connection.
Wi-Fi router:
It is Very flexible use, it have the ability to link one or more computers at home and thus to move, for example, with a laptop. No need to use cables.
Modem-routers from our ISP:
In most cases, the router from our ISP offers a wide range of services: telephony, free access to television, simultaneous sharing of the connection through Wi-Fi. It is a modem-router connected to a main PC (Live Box, Freebox) that delivers Internet access to other computers. This router is provided when setting up your connection (or not included in the subscription).
Types of Networks
There are several different types of computer networks. Computer networks can be characterized by their size as well as their purpose.
The size of a network can be expressed by the geographic area they occupy and the number of computers that are part of the network.
Networks can cover anything from a handful of devices within a single room to millions of devices spread across the entire globe.
The networks are categorized based on their scale and scope. Those are
Local area network(LAN) Wide area network(WAN)
Metropolitan area network(MAN) Personal area network(PAN)
Local Area Network (LAN)
It is also called LAN and designed for small physical areas such as an office, group of buildings or a factory.
LANs are used widely as it is easy to design and to troubleshoot. Personal computers and workstations are connected to each other through LANs. We can use different types of topologies through LAN; these are Star, Ring, Bus, Tree etc. LAN can be a simple network like connecting two computers, to share files and
network among each other while it can also be as complex as interconnecting an entire building. LAN networks are also widely used to
Metropolitan Area Network (MAN)
It is basically a bigger version of LAN. It is also called MAN and uses the similar technology as LAN. It is designed to extend over the entire city. It can be means to connecting a number of LANs into a larger network or it can be a single cable.
It is mainly hold and operated by single private company or a public company.
Wide Area Network (WAN)
It is also called WAN. WAN can be private or it can be public leased network. It is used for the network that covers large distance such as cover states of a country.
It is not easy to design and maintain.
Communication medium used by WAN are PSTN (Public Switched Telephone Network) or Satellite links.WAN operates on low data rates.
Personal Area Network:
Personal area network or PAN is a computer network designed for communication between computer devices such as mobile computers, cell phones, and personal digital assistants (PDAs) that are close to one person. The scope or the reach of a PAN is a few meters (less than 10 meters).
PANs are basically used to communicate with the personal devices themselves or for connecting to a higher level network and the internet.
PANs can be used to transfer files including e-mail, calendar, appointments, digital photos, and music. These days, PANs are also used to enable wearable computer devices to communicate with other nearby computers and exchange digital information using the electrical conductivity of the human body as a data network.
This type of network provides great flexibility. For example, it allows you to:
Send a document to the printer in the office upstairs while you are sitting on the couch with your laptop.
Network Topologies
A Network Topology is the arrangement with which computer systems or network devices are connected to each other.
Topologies may define both physical and logical aspect of the network. Both logical and physical topologies could be same or different in a same network. Point-to-Point
A point-to-point network contains exactly two hosts such as computer, switches or routers, servers connected back to
back using a single piece of cable. Often, the receiving end of one host is connected to sending end of the other and vice-versa.
If the hosts are connected point-to-point logically, then may have multiple
intermediate devices. But the end hosts are unaware of underlying network and see each other as if they are connected directly.
Bus Topology
In case of Bus topology, all devices share single communication line or cable. Bus topology may have problem while multiple hosts sending data at the same time. Therefore, Bus topology either uses CSMA/CD technology or recognizes one host
as Bus Master to solve the issue. It is one of the simple forms of networking where a failure of a device does not
affect the other devices. But failure of the shared communication line can make all other devices stop functioning.
Both ends of the shared channel have line terminator. The data is sent in only one direction and as soon as it reaches the extreme end, the terminator removes the data from the line.
Star Topology
All hosts in Star topology are connected to a central device, known as hub device, using a point-to-point connection. That is, there exists a point to point connection between hosts and hub.
The hub device can be any of the following: Layer-1 device such as hub or repeater Layer-2 device such as switch or bridge Layer-3 device such as router or gateway
As in Bus topology, hub acts as single point of failure. If hub fails, connectivity of all hosts to all other hosts fails. Every communication between hosts, takes place through only the hub.
Ring Topology
In ring topology, each host machine connects to exactly two other machines, creating a circular network structure.
When one host tries to communicate or send message to a host which is not adjacent to it, the data travels through all intermediate hosts. To connect one more host in the existing structure, the administrator may need only one more extra cable.
Failure of any host results in failure of whole ring. Thus, every connection in the ring is a point of failure. There are methods which employ one more backup ring. Mesh Topology
In this type of topology, a host is connected to one or multiple hosts. This topology has hosts in point-to-point connection with every other host or may also have hosts which are in point-to-point connection to few hosts only.
Hosts in Mesh topology also work as relay for other hosts which do not have direct point-to-point links. Mesh technology comes into two types:
Full Mesh: All hosts have a point-to-point connection to every other host in the network. Thus for every new host n(n-1)/2 connections are required. It provides the most reliable network structure among all network topologies.
Partially Mesh: Not all hosts have point-to-point connection to every other host. Hosts connect to each other in some arbitrarily fashion. This topology exists
where we need to provide reliability to some hosts out of all. Tree Topology
It is also known as Hierarchical Topology, this is the most common form of network topology in use presently. This topology imitates as extended Star topology and inherits properties of bus topology.
This topology divides the network in to multiple levels/layers of network. Mainly in LANs, a network is bifurcated into three types of network devices. The lowermost is access-layer where computers are attached. The middle layer is known as distribution layer, which works as mediator between upper layer and lower layer. The highest layer is known as core layer, and is central point of the network, i.e. root of the tree from which all nodes fork.
Daisy Chain
This topology connects all the hosts in a linear fashion. Similar to Ring topology, all hosts are connected to two hosts only, except the end hosts. Means, if the end hosts in daisy chain are connected then it
represents Ring topology. Each link in daisy chain topology represents single point of failure. Every link failure splits the network into two segments. Every intermediate host works as relay for its immediate hosts.
Hybrid Topology
A network structure whose design contains more than one topology is said to be hybrid topology. Hybrid topology
inherits merits and demerits of all the incorporating topologies.
The combining topologies may contain attributes of Star, Ring, Bus, and Daisy-chain topologies. Most WANs are connected by means
of Dual-Ring topology and networks connected to them are mostly Star topology networks. Internet is the best example of largest Hybrid topology
Domain Names and Address Resolution
Many computers connected to the Internet host part of the DNS database and the software that allows others to access it. These computers are known as DNS servers.
No DNS server contains the entire database; they only contain a subset of it. If a DNS server does not contain the domain name requested by another computer, the DNS server re-directs the requesting computer to another DNS server.
The Domain Name Service is structured as a hierarchy similar to the IP routing hierarchy. The computer requesting a name resolution will be re-directed 'up' the hierarchy until a DNS server is found that can resolve the domain name in the request. In the Figure the top of the tree are the domain roots. Some of the older, more common domains are seen near the top.
When an Internet connection is setup (e.g. for a LAN or Dial-Up Networking in Windows), one primary and one or more secondary DNS servers are usually specified as part of the installation. This way, any Internet applications that need domain name resolution will be able to function correctly. For example, when you enter a web address into your web browser, the browser first connects to our primary DNS server. After obtaining the IP address for the domain name we entered, the browser then connects to the target computer and requests the web page we want.
Internet Protocols
Transmission Control Protocol (TCP)
TCP is a connection oriented protocol and offers end-to-end packet delivery. It acts as back bone for connection. It exhibits the following key features:
Transmission Control Protocol (TCP) corresponds to the Transport Layer of OSI Model.
TCP is a reliable and connection oriented protocol. TCP offers:
o Stream Data Transfer. o Reliability.
o Efficient Flow Control o Full-duplex operation. o Multiplexing.
TCP offers connection oriented end-to-end packet delivery.
TCP ensures reliability by sequencing bytes with a forwarding acknowledgement number that indicates to the destination the next byte the source expect to receive.
It retransmits the bytes not acknowledged with in specified time period. TCP offers following services to the processes at the application layer:
Stream Delivery Service
Sending and Receiving Buffers Bytes and Segments
Full Duplex Service
Internet Protocol (IP)
Internet Protocol is connectionless and unreliable protocol. It ensures no guarantee of successfully transmission of data.
In order to make it reliable, it must be paired with reliable protocol such as TCP at the transport layer.
Internet protocol transmits the data in form of a datagram as shown in the following diagram:
Points to remember:
The length of datagram is variable.
The Datagram is divided into two parts: header and data. The length of header is 20 to 60 bytes.
The header contains information for routing and delivery of the packet.
User Datagram Protocol (UDP)
Like IP, UDP is connectionless and unreliable protocol. It doesn’t require making a connection with the host to exchange data. Since UDP is unreliable protocol, there is no mechanism for ensuring that data sent is received.
UDP transmits the data in form of a datagram. The UDP datagram
consists of five parts as shown in the following diagram:
Points to remember:
UDP is used by the application that typically transmit small amount of data at one time.
Hypertext Transfer protocol (HTTP):
The protocol used to transfer information on the World Wide Web. Web servers and clients communicate with each other via the platform - independent HTTP. It is an application level protocol because it sits on top of the TCP layer in the
protocol stack and is used by specific applications to talk to one another.
HTTP is a connectionless text based protocol. Clients (web browsers) send requests to web servers for web elements such as web pages and images. After the request is serviced by a server, the connection between client and server across the Internet is disconnected. A new connection must be made for each request.
HTTP Sessions Under HTTP there are four steps to communicating across the web: Make the connection
Request a document Respond to a request Close the connection
Connection Setup: The browser opens a standard TCP connection to the server. Port 80 is used by default. When ports other than 80 are used, the port number is added to the URL.
For example http://www.some.erver.com:8080.
Browsers Request: Once the TCP connection is established, the browser requests a given document using its URL. An HTTP request types are get and posts data to a server-side from handler that process the data. The most common HTTP request types are get and post.
Get method:
The Get request typically retrieves information from a server. Common uses of get requests are to retrieve an HTML document or to fetch search results based on a user-submitted search term.
A get requests sends information to the server as part of he URL.
Post Method:
A post request typically sends (or posts) data to a server. Common uses of post requests are to end information to a server, such as authentication information or data from a form that gathers user input.
The post method sends from data as an HTTP message, not as part of the URL.
Server Response: The http (web server) process can automatically insert information into the header of a response. Often this is the MIME type of the document which is based upon the file type. The server response begins with a response begins with a response code. Web servers can send many different codes to the browser.
The codes are grouped together logically with odes in the 200-299 range indicating a successful request, 300-399 indicating that a page may have moved , 400-499 showing client errors and
File Transfer Protocol (FTP)
FTP is used to copy files from one host to another.
The first proposed file transfer mechanisms were developed for implementation on hosts at M.I.T. (RFC 114) in 1971, even before the TCP/IP was existed.
FTP general structure was established in 1973. The base specification RFC959 was published in 1985.
FTP was created with the overall goal of allowing indirect use of computers on a network, by making it easy for users to move files from one place to another. Like most TCP/IP protocols, it is based on a client/server model, with an FTP client on a user machine creating a connection to an FTP server to send and retrieve files to and from the server.
The main objectives of FTP were to make file transfer simple, and to shield the user from implementation details of how the files are actually moved from one place to another. To this end, FTP is designed to automatically deal with many of the issues that can potentially arise due to format differences in files stored on differing systems.
FTP creates two processes such as Control Process and Data Transfer Process at both ends i.e. at client as well as at server.
FTP establishes two different connections: one is for data transfer and other is for control information.
FTP uses port 21 for the control connection and Port 20 for the data connection.
After a TCP connection is established, an FTP control connection is created. Internal FTP commands are passed over this logical connection based on formatting rules established by the Telnet protocol. Each command sent by the client receives a reply from the server to indicate whether it succeeded or failed. A data connection is established for each individual data transfer to be performed.
To ensure that files are sent and received without loss of data that could corrupt them, FTP uses the reliable Transmission Control Protocol (TCP) at the transport layer. An authentication system is used to ensure that only authorized clients are allowed to access a server. At the same time, a feature sometimes called
anonymous FTP allows an organization that wishes it to set up a general information server to provide files to anyone who might want to retrieve them. The interface between an FTP user and the protocol is provided in the form of a
set of interactive user commands. After establishing a connection and completing authentication, two basic commands can be used to send or receive files. Additional support commands are provided to manage the FTP connection, as well as to perform support functions such as listing the contents of a directory or deleting or renaming files.
In recent years, graphical implementations of FTP have been created to allow users to transfer files using mouse clicks instead of memorizing commands. FTP can also be used directly by other applications to move files from one place to another.
Windows and GUI
A window is a (usually) rectangular portion of the display on a computer monitor that presents its contents (e.g., the contents of a directory, a text file or an image) seemingly independently of the rest of the screen. Windows are one of the elements that comprise a graphical user interface (GUI).
A GUI is a type of human-computer interface (i.e., a system for people to interact with a computer) that uses windows, icons, pull-down menus and a pointer and that can be manipulated by a mouse (and usually to some extent by a keyboard as well). An icon is a small picture or symbol that represents a program (or command), file, directory (also called a folder) or device (such as a hard disk or floppy disk).
The GUI represents a major advance over the command line interface (CLI) of the console, which displays only text (i.e., no images) and is accessed solely by a keyboard. It has made computers much easier to learn and work with, and it has also led to the development of major new applications for them, including desktop publishing and CAD (computer-aided de sign).
The words window and windows are generic terms and should not be confused with Microsoft Windows (although they sometimes are). The latter is the trade name that Microsoft selected for its series of operating systems that employ a GUI. (The originally intended name was Interface Manager, but Microsoft's marketing expert Rowland Hanson convinced co-founder Bill Gates that Microsoft Windows was preferable).
Flexibility of Windows
The ways in which they can be manipulated usually include 1. Opening and closing
2. Moving to any area of the screen by dragging
3. Repositioning so that they appear to be behind or in front of other windows or objects on the screen.
Multiple Windows
Another major feature of windows is the ability for multiple windows to be open simultaneously. This is particularly valuable in a multitasking environment, i.e., an operating system in which multiple programs can run seemingly simultaneously and without interfering with each other. Each window can display a different application, or it can display different files that have been opened or created with a single application (e.g., text, image or spreadsheet files).
Multiple open windows can be arranged with respect to each other, they can be arranged so that they are contiguous and do not overlap (tiled windows) or so they do overlap (overlaid windows). Overlaid windows resemble a stack of documents lying on top of one another (part of the desktop metaphor that characterizes most GUIs at present), and only the upper-most window is displayed in full. Any window can be moved to the top of the stack and made the active window (i.e., ready for receiving user input) by positioning the pointer in any portion of it that is visible and clicking a mouse button.
Specialized Windows
There is various type of windows, and their functions and appearances can vary substantially. For example, a browser is a specialized type of window that has additional functionality, including the ability for the user to move forward or backward through a sequence of documents (i.e., web pages). The more advanced browsers (e.g., Mozilla and Opera) have also incorporated the tabbed concept that had earlier been developed for windows for other applications.
Other types of windows have reduced functionality. For example, terminal windows emulate a console and thus contain only text. They offer all of the advantages of the console to users of a CLI together with some of the advantages of conventional windows, including the ability to be used while the GUI is in operation and the ability for multiple terminal windows to be open simultaneously.
Child windows
Child windows are windows that are opened either automatically or as a result of some user activity when using a parent window. They can range in functionality from the very simple to the full complement of controls. Some annoying pop-up windows that appear when visiting some websites purposely lack buttons for closing them.
Message windows
Internet of Things (IoT)
The Internet of things (IoT) is the network of physical devices, vehicles, home
appliances, and other
items embedded with electronics, software, sensors, actuators, and network connectivity which enable these objects to connect and exchange data.
Each thing is uniquely identifiable through its embedded computing system but is able to inter-operate within the existing Internet infrastructure.
The IoT allows objects to be sensed or controlled remotely across existing network infrastructure, creating opportunities for more direct integration of the physical world into computer-based systems, and resulting in improved efficiency, accuracy and economic benefit in addition to reduced human intervention.
Real World Applications of IoT
1. Smart Home:
With IoT creating the buzz, ‘Smart Home’ is the most searched IoT associated feature on Google.
In a Smart Home, we could switch on air conditioning before reaching home or switch off lights even after you have left home, and unlock the doors to friends for temporary access even when you are not at home.
2. Wearables:
Wearable devices are installed with sensors and softwares which collect data and information about the users. This data is later pre-processed to extract essential insights about user.
These devices broadly cover fitness, health and entertainment requirements. The pre-requisite from internet of things technology for wearable applications is to be highly energy efficient or ultra-low power and small sized.
3. Connected Cars
A connected car is a vehicle which is able to optimize it’s own operation, maintenance as well as comfort of passengers using onboard sensors and internet connectivity.
Major brands like Tesla, BMW, Apple, Google are working on bringing the next revolution in automobiles.
4. Industrial Internet
Industrial Internet is the new buzz in the industrial sector, also termed as Industrial Internet of Things ( IIoT ). It is empowering industrial engineering with sensors, software and big data analytics to create brilliant machines.
5. Smart Cities
6. IoT in agriculture
With the continuous increase in world’s population, demand for food supply is extremely raised. Governments are helping farmers to use advanced techniques and research to increase food production. Smart farming is one of the fastest growing fields in IoT.
7.Smart Retail
IoT provides an opportunity to retailers to connect with the customers to enhance the in-store experience.
Smartphones will be the way for retailers to remain connected with their consumers even out of store.
8. Energy Engagement
The basic idea behind the smart grids is to collect data in an automated fashion and analyze the behavior or electricity consumers and suppliers for improving efficiency as well as economics of electricity use.
Smart Grids will also be able to detect sources of power outages more quickly and at individual household levels like near by solar panel, making possible distributed energy system.
9. IOT in Healthcare
Connected healthcare yet remains the sleeping giant of the Internet of Things applications. The concept of connected healthcare system and smart medical devices bears enormous potential not just for companies, but also for the well-being of people in general.
10. IoT in Poultry and Farming
Cloud
Computing
Cloud Computing provides us means of accessing the applications as utilities over the Internet. It allows us to create, configure, and customize the applications online.
The term Cloud refers to a Network or Internet. In other words, we can say that Cloud is something, which is present at remote location. Cloud can provide services over public and private networks, i.e., WAN, LAN or VPN. Applications such as e-mail, web conferencing, customer relationship management (CRM) execute on cloud.
Cloud Computing refers to manipulating, configuring, and accessing the hardware and software resources remotely. It offers online data storage, infrastructure, and application.
Cloud computing offers platform independency, as the software is not required to be installed locally on the PC. Hence, the Cloud Computing is making our business applications mobile and collaborative.
There are two types of working models for cloud computing: 1. Deployment Models
2. Service Models Deployment Models
Deployment models define the type of access to the cloud, i.e., how the cloud is located? Cloud can have any of the four types of access: Public, Private, Hybrid, and Community.
Service Models
Cloud computing is based on service models. These are categorized into three basic service models which are -
Infrastructure-as–a-Service (IaaS) Platform-as-a-Service (PaaS)
Benefits of Cloud Computing:
Cloud Computing has numerous advantages. Some of them are listed below - One can access applications as utilities, over the Internet.
One can manipulate and configure the applications online at any time.
It does not require installing software to access or manipulating cloud application. Cloud Computing offers online development and deployment tools, programming
runtime environment through PaaS model.
Cloud resources are available over the network in a manner that provides platform independent access to any type of clients.
Cloud Computing offers on-demand self-service. The resources can be used without interaction with cloud service provider.
Cloud Computing is highly cost effective because it operates at high efficiency with optimum utilization. It just requires an Internet connection.
Cloud Computing offers load balancing that makes it more reliable.
Characteristics of Cloud Computing
There are four key characteristics of cloud computing. 1. On Demand Self Service
Cloud Computing allows the users to use web services and resources on demand. One can logon to a website at any time and use them.
2. Broad Network Access
Since cloud computing is completely web based, it can be accessed from anywhere and at any time.
3. Resource Pooling
Cloud computing allows multiple tenants to share a pool of resources. One can share single physical instance of hardware, database and basic infrastructure. 4. Rapid Elasticity
It is very easy to scale the resources vertically or horizontally at any time. Scaling of resources means the ability of resources to deal with increasing or decreasing demand.
The resources being used by customers at any given point of time are automatically monitored.
Measured Service
In this service cloud provider controls and monitors all the aspects of cloud service. Resource optimization, billing, and capacity planning etc. depend on it.
Cloud Computing Applications
Business Applications:
SN Application Description
1 MailChimp
It offers an e-mail publishing platform. It is widely employed by the businesses to design and send their e-mail campaigns.
2 Chatter
Chatter app helps the employee to share important information about organization in real time. One can get the instant feed regarding any issue.
3 Google Apps for Business
Google offers creating text documents, spreadsheets, presentations, etc., on Google Docs which allows the business users to share them in collaborating manner.
4 Quickbooks
It offers online accounting solutions for a business. It helps in monitoring cash flow, creating VAT returns and creating business reports.
Data Storage and Backup:
Box.com, Mozy, Joukuu are the applications offering data storage and backup services in cloud.
SN Application Description
1 Box.com
Box.com offers drag and drop service for files. The users need to drop the files into Box and access from anywhere.
2 Mozy
Mozy offers online backup service for files to prevent data loss.
3 Joukuu
Joukuu is a web-based interface. It allows to display a single list of contents for files stored in Google Docs, Box.net and Dropbox.
Management Applications:
There are apps available for management task such as time tracking, organizing notes. Applications performing such tasks are discussed below:
SN Application Description
1 Toggl
It helps in tracking time period assigned to a particular project.
2 Evernote
It organizes the sticky notes and even can read the text from images which helps the user to locate the notes easily.
3 Outright
Social Applications:
There are several social networking services providing websites such as Facebook, Twitter, etc.
SN Application Description
1 Facebook
It offers social networking service. One can share photos, videos, files, status and much more.
2 Twitter
It helps to interact with the public directly. One can follow any celebrity, organization and any person, who is on twitter and can have latest updates regarding the same.
Entertainment Applications:
SN Application Description
1 Audio box.fm: It offers streaming service. The music files are stored online and can be played from cloud using the own media player of the service.
Art Applications:
SN Application Description
1 Moo: It offers art services such as designing and printing business cards, postcards and mini cards.
Web services
Web services are open standard (XML, SOAP, HTTP, etc.) based web applications that interact with other web applications for the purpose of exchanging data. Web services can convert your existing applications into web applications.
Web services are XML-based information exchange systems that use the Internet for direct application-to-application interaction. These systems can include
programs, objects, messages, or documents.
A web service is a collection of open protocols and standards used for exchanging data between applications or systems. Software applications written in various programming languages and running on various platforms can use web services to exchange data over computer networks like the Internet in a manner similar to inter-process communication on a single computer.
Components of Web Services
The basic web services platform is XML + HTTP. All the standard web services work using the following components −
SOAP (Simple Object Access Protocol)
UDDI (Universal Description, Discovery and Integration) WSDL (Web Services Description Language)
How Does a Web Service Work?
A web service enables communication among various applications by using open standards such as HTML, XML, WSDL, and SOAP.
A web service takes the help of −
XML to tag the data
SOAP to transfer a message
UNIT – II E-Mail Concepts
E-mail: E-mail means electronic mail. E-mail system was developed to allow two individuals to communicate each other using computers. In early days e-mail technology allows one person to send plain text message via internet to another person. It was likely posting a letter, except that the communication was electronic instead of paper.
E-mail features:
These days e-mail facility allows many features: 1. Composing and sending or Receiving messages.
2. Storing/Forwarding/replying/deleting to a message with normal facilities such as carbon copies, blind carbon copy etc.
3. Communicating with one of millions of computers. 4. Communicating with many users at a time.
5. Sending text, voice, graphics and video messages.
6. Sending a message that interacts with other computer programs. Advantages:
1. Convenient:
No need to go to post office.
No need to search for stamps and stationary. Very easy to send a short notice or memo.
2. Speed: Based on communication network, e-mail is very fast.
3. Inexpensive: Once you are online, the cost of sending a message is very less. 4. Printable:
It is very easy to obtain the hard copy.
We can keep an electronic copy of a message for our own records. 5. Reliable:
Although messages are occasionally lost this is rear.
Mail system will notify the sender if the mail was undelivered.
6. Global: Even increasingly people and business all over the world is using e-mails. 7. Generality: E-mails are not limited to text; it allows the transfer of graphics, programs and even sounds.
Disadvantages:
1. Misdirection: It is far so likely that you will accidentally send e-mail to an unknown recipient, thus with e-mail you are your own enemy.
2. Interception: E-mail system allows Interception of messages. It is simply for some one to pass on your message called e-mail forwarding to another party.
3. Forgery: E-mail does not preclude forgeries. That is someone impersonating the sender, since the sender is not authenticated in anyway. Forgery is possible.
4. Overload: e-mail is too convenient it results in a flood of mails. 5. Junk:
Junk means unwanted.
The process of sending junk e-mails to lots of websites simultaneously is known as spamming.
6. No response: A mild frustration sometimes associated with using e-mails is dealing with recipients who do not respond to their e-mail on a regular basis.
The important item to access computer systems are: 1. User ID or Login Name 2. Password
User ID:
Synonyms for user- id are ‘user name’ and ‘account name’. User id stands for identification of user.
User id identifies you to the computer. It should be unique.
It should be easy to remember.
User id allows a-z letters 0-9 numbers and one special character. The first character should be a letter.
No significance of upper case and lower case. Password:
It is a secret code that authenticates you to the computer. This simply checks that you are who you say you are.
You are the only person who knows the password to your computer account No one except you can access your account.
A good password should be - 1. At least 6 characters long.
2. Contain non-alphabetical symbols such as &, %,! Etc 3. Can contain a number.
4. Process upper case and lower case letters.
5. Should be case sensitive i.e. ‘Mother’ is differing from’ mother’ and ‘moTher’. 6. Should be easy to remember.
7. It is very important to change password regularly.
8. To change the password type the old password, type the new password and then finally type the new password second time for verification.
9. When you type a password it is not echo on screen.
E-mail addresses
The basic form of an e-mail address is [email protected] The text before the @ sign specifies the user name of the individual, while the
text after the @ sign indicates how the computer system can locate that individuals mail box.
Ex: RameshReddy is working as a Associate Professor in the Department of Computer Science in VS University. Then his mail id would be
E-mail Message Components
E-mail Header
The first five lines of an E-mail message is called E-mail header. The header part comprises of following fields:
From Date
To
Subject
CC
BCC
From: The From field indicates the sender’s address i.e. who sent the e-mail. Date: The Date field indicates the date when the e-mail was sent.
To: The To field indicates the recipient’s address i.e. to whom the e-mail is sent.
Subject: The Subject field indicates the purpose of e-mail. It should be precise and to the point.
CC: CC stands for Carbon copy. It includes those recipient addresses whom we want to keep informed but not exactly the intended recipient.
BCC: BCC stands for Black Carbon Copy. It is used when we do not want one or more of the recipients to know that someone else was copied on the message.
Greeting: Greeting is the opening of the actual message. Eg. Hi Sir or Hi Guys etc. Text: It represents the actual content of the message.
Configuring E-Mail Program:
Consider the following steps to set up E-mail with Microsoft Outlook 2007 for the First Time.
1) Open Microsoft Outlook 2007
2) In the ‘Tools’ menu select ‘Account Settings…’
4) Make sure ‘Microsoft Exchange, POP3, IMAP, or HTTP’ radio button is checked, then click ‘Next >’.
5) Make sure ‘Internet E-mail’ radio button is checked, then click ‘Next >’
6) Enter your email settings. The important points to remember are:
a. User Name: If your email address was [email protected] your User name would be “youremail” (we ignore the ‘@yourdomain.com.au’)
b. Password: Make sure this has your password entered correctly.
c. Incoming mail server (POP3): Make sure this has your correct server settings. Eg: yourdomain.com.au
d. Outgoing mail server (SMTP): This should have the same settings as your incoming mail server (unless you are using your ISP’s outgoing mail server).
8) Then click the ‘Outgoing Servers’ tab
9) Make sure the ‘My outgoing server (SMTP) requires authentication’
checkbox is checked, and the ‘Use same settings as my incoming mail server’ radio button is selected.
Sending and Receiving Files through E-Mail: Attachment:
Ability to attach file(s) along with the message is one of the most useful features of email. The attachment may be a word document, PowerPoint presentation, audio/video files, or images.
In order to attach file(s) to an email, click the attach button. As a result, a dialog box appears asking for specifying the name and location of the file you want to attach. Once you have selected the appropriate file, it is attached to the mail.
Usually a paper clip icon appears in the email which indicates that it has an attachment. When adding an attachment it is better to compress the attached files so as to reduce the
file size and save transmission time as sending and downloading large files consumes a lot of space and time.
MIME Types:
MIME is acronym of Multipurpose Internet Mail Extensions. MIME compliant mailer allows us to send files other than simple text i.e. It allows us to send audio, video, images, document, and pdf files as an attachment to an email.
Suppose if you want to send a word processor document that has a group of tabular columns with complex formatting. If we transfer the file as text, all the formatting may be lost. MIME compliant mailer takes care of messy details and the message arrives as desired.
The following table describes commonly used MIME Types:
1. Type Subtype Description File extension(s)
2. Application
postscript tex
troff
Printable postscript document TEX document
Printable troff document
.eps, .ps .tex
.t, .tr, .roff
3. Audio
aiff au midi real audio
Apple sound
Sun Microsystems sound
Musical Instrument Digital Interface Progressive Network sound
.aif, .aiff,.aifc .au, .snd .midi, .mid .ra, .ram
4. image
gif jpeg png triff
Graphics Interchange Format Joint Photographic Experts Group Portable Network Graphics
Tagged Image Modeling Language
.gif
.jpeg, .jpg, .jpe .png
.tiff, .tif 5. Model vrml Virual reality Modelling Language .wrl
6. Text plain sgml
html
Hyper Text Markup Language Unformatted text
Standard Generalized Markup language
.html, .htm .txt
.sgml
7. Video
avi mpeg quicktime sgi-movie
Microsoft Audio Video Interleaved Moving Pictures Expert Group Apple QuickTime movie
silicon graphic movie
.avi
.mpeg, .mpg .qt, .mov .movie
Sending attachments can be a good way to transfer a copy of a file if the sender and recipient have agreed on a format.
