We couldn´t go to this class because it was at the same time that an important course presentation. If we hadn´t gone to the other course it wouldn´t be possible to make it. So we are going to speak about the ninth class.
See you soon!

2.1.4.2. E-MAIL

Electronic mail is another Internetdiensst dar. e-mail is so popular because it has a lot of advantages compared to conventional mail offers.
Email is shothand term meaning Electronic Mail. Email much the same as a letter, only that it is exchanged in a different way. Computers use the TCP/IP protocol suite to send email messages in the form of packets. The first thing you need to send and recieve emails is an email address. When you create an account with a Internet Service Provider you are usually given an email address to send from and recieve emails. If this isn't the case you can create an email address / account at web sites such as yahoo, hotmail and lycos.


The header of an email includes the From:, To:, Cc: and Subject: fields. So you enter the name and address of the recipient in the Fom: field, the name and address of anyone who is being copied to in the Cc: field, and the subject of the message obviously in the Subject: field.
The part below the header of the email is called the body, and contains the message itself.
Spelling the correct address is critical with an email. Like with a normal postal letter, if you get the address wrong it won't go the correct receiver. If you send an email to an address which doesnt exist the message will come back to you as a Address Unknown erro routine.
Email Protocols: IMAP, POP3, SMTP and HTTP
Basicaly, a protocol is about a standard method used at each end of a communication channel, in order to properly transmit information. In order to deal with your email you must use a mail client to access a mail server. The mail client and mail server can exchange information with each other using a variety of protocols.
IMAP Protocol:
IMAP (Internet Message Access Protocol) – Is a standard protocol for accessing e-mail from your local server. IMAP is a client/server protocol in which e-mail is received and held for you by your Internet server. As this requires only a small data transfer this works well even over a slow connection such as a modem. Only if you request to read a specific email message will it be downloaded from the server. You can also create and manipulate folders or mailboxes on the server, delete messages etc.
POP3 Protocol:
The POP (Post Office Protocol 3) protocol provides a simple, standardized way for users to access mailboxes and download messages to their computers.

When using the POP protocol all your eMail messages will be downloaded from the mail server to your local computer. You can choose to leave copies of your eMails on the server as well. The advantage is that once your messages are downloaded you can cut the internet connection and read your eMail at your leisure without incuring further communication costs. On the other hand you might have transferred a lot of message (including spam or viruses) in which you are not at all interested at this point.
SMTP Protocol:
The SMTP (Simple Mail Transfer Protocol) protocol is used by the Mail Transfer Agent (MTA) to deliver your eMail to the recipient's mail server. The SMTP protocol can only be used to send emails, not to receive them. Depending on your network / ISP settings, you may only be able to use the SMTP protocol under certain conditions.
HTTP Protocol:
The HTTP protocol is not a protocol dedicated for email communications, but it can be used for accessing your mailbox. Also called web based email, this protocol can be used to compose or retrieve emails from an your account. Hotmail is a good example of using HTTP as an email protocol.
The First E-mail on the Internet
In 1971, the first e-mail was typed into the Teletype terminal connected to the Digital Equipment PDP-10 in the rear of the picture below. The message was transmitted via ARPAnet, the progenitor of the Internet, to the PDP-10 in front. Dan Murphy, a Digital engineer, took this photo in the Bolt, Beranek and Newman datacenter.

2.1.4.4 FTP

The Internet is a veritable treasure trove of files and programs.
To these files on their own computers to download the File Transfer Protocol.
Practical significance is also in FTP upload their own home page on the server of the Internet provider. Students, the course IV1 visit can beispieleweise their homework exercise comfortably at home via FTP.

With the help of FTP-Protokolls it will be possible to the user files, programs, music files and the like to download. Publicly available FTP_Server can most conveniently on the browser to display. Nevertheless, the use of a separate FTP program usually practicable. If the server is open to the public talk by anonymous FTP. The user logs in as "Anonymous" on the server and used as a password in normal circumstances their own email address. In an identified FTP is entering a user name and a Passworters required. For the task of building exercises on the IDV for the login user name as the matriculation and personal password of the students.

By using its own FTP software, as shown in the above figure can be seen, the user's hard disk simultaneously directory and the directories on the server at a glance. The handling is similar to the Windows Explorer ajar, and the files can be easily using drag-and-drop up-oder Downgeloadet.

The Internet is a great treasure trove of shareware and freeware programs dar. Many manufacturers are usually for about 30 days a shareware version of their software into the network, which for this period is free testable. Freeware programs, however, are unrestricted free usage. The author maintains, however, the full copyright to the program. In addition, there is usually a number of adware programs, which are also free and unbeschränckt usable. The user must, however, with advertising displays live, he will not, he can usually an ad-free version for a fee.

Frequently there are also software, under the GPL (General Public License). GPL called Open Source Software, the user is free to use.
Additionally, the source code of the software. Interested parties may develop this software and then distribute under GPL. The mines found in software demo versions available always have a limited function scope "Commercial" always Software, which is also a demo version of the website, but their use is limited in time.

In the last few years have also exchanges like Kazaa established. The participants enter on one side files from its collection to the public free and may return the data of other users for download for their use.

The use of these exchanges is, however, great caution. Not only that many participants contaminated files to the web, in most cases users try newest MP3_Files, software and films for free to grab. This kind of exchange is, however, illegal, as it infringes the copyrights it. Program, music and video may be used only for its own budget for the purpose of backup copy burned. With the transfer to a third party makes you a criminal offense. Recent CDs and videos contain additional copy protection. This should not be cracked, a recording of an analog copy is allowed. A legal way to come to music, for example, the inclusion of a music webradio dar.

2.1.4.5. Instant Messaging/Chat

Enjoy chats on the Internet as a form of real-time communication great popularity. It can be used with people from all over the world to chat without its own identity announce it. It has been established that people in the chat room under a nickname in appearance occurs. The best known is probably the Instant Messenger ICQ. Anyone know his personal contact list, and you can see at a glance whether friends are online. In addition, of course, new contacts around the world to tap.

Apart from the traditional chat, it is with Instant Messaging Conference talks to lead or online to play. Even in the division Instant messaging is gaining in importance.

2.1.5.1. Safety in internet

2.1.5.1. VIRUSES

Computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation.
A virus might corrupt or delete data on your computer, use your e-mail program to spread itself to other computers, or even erase everything on your hard disk.
Viruses are most easily spread by attachments in e-mail messages or instant messaging messages. That is why it is essential that you never open e-mail attachments unless you know who it's from and you are expecting it.
Viruses can be disguised as attachments of funny images, greeting cards, or audio and video files.
Viruses also spread through downloads on the Internet. They can be hidden in illicit software or other files or programs you might download.
To help avoid viruses, it's essential that you keep your computer current with the latest updates and antivirus tools, stay informed about recent threats, and that you follow a few basic rules when you surf the Internet, download files, and open attachments.
Once a virus is on your computer, its type or the method it used to get there is not as important as removing it and preventing further infection.
TROJANS
In computers, a Trojan horse is a program in which malicious or harmful code is contained inside apparently harmless programming or data in such a way that it can get control and do its chosen form of damage, such as ruining the file allocation table on your hard disk. In one celebrated case, a Trojan horse was a program that was supposed to find and destroy computer viruses. A Trojan horse may be widely redistributed as part of a computer virus.
HOAXES
The Hoaxs (joke or deceit), they are messages with false alarms of virus, or of any other type of alert or chain (even shared in common, or that involves our own health), or of some type of denunciation, distributed by electronic mail, its common denominator, it is to request to him distributes them "to the greater possible amount of well-known".
These alarms, usually they are TOTALLY FALSE, or based on erroneous facts, but what is worse they activate a type of "contamination" very different, propagate hundreds and up to thousands of warning messages on such. And still in the case of denunciations based on fact real, this form to do weakens it totally its true objective.
This is a description of hoaxes more common that they circulate around the network. It never returns to send no of these messages. If somebody of good faith sends one to him of these alarms, avi him to it of pages like this so that it leaves its deceit and it obtains more.

2.1.5.2. FIREWALL

A firewall is a set of related programs, located at a network gateway server, that protects the resources of a private network from users from other networks. (The term also implies the security policy that is used with the programs.) An enterprise with an intranet that allows its workers access to the wider Internet installs a firewall to prevent outsiders from accessing its own private data resources and for controlling what outside resources its own users have access to.
Basically, a firewall, working closely with a router program, examines each network packet to determine whether to forward it toward its destination. A firewall also includes or works with a proxy server that makes network requests on behalf of workstation users. A firewall is often installed in a specially designated computer separate from the rest of the network so that no incoming request can get directly at private network resources.
There are a number of firewall screening methods. A simple one is to screen requests to make sure they come from acceptable (previously identified) domain name and Internet Protocol addresses. For mobile users, firewalls allow remote access in to the private network by the use of secure logon procedures and authentication certificates.
A number of companies make firewall products. Features include logging and reporting, automatic alarms at given thresholds of attack, and a graphical user interface for controlling the firewall.
Computer security borrows this term from firefighting, where it originated. In firefighting, a firewall is a barrier established to prevent the spread of fire

2.2 Search and Find on the Internet

Often, the term is inaccurate search engines for all types of search tools. In this issue very soon, many well-known throughout the Google search engine and all too easy to forget that there are a lot of good search tools and search strategies, especially for the efficient search on the Internet note.


2.2.1. Search


A search engine is a service on the Internet, with the parts you can browse the Internet. A search engine can be equipped with a Indez or a keyword index in a book compared.

For the user is presented a search engine on the Web site, like any other web page. In one form of search criteria can be entered.
In addition, the search to specific objects, bestimmnte addresses or to a specific date range may be restricted.

The search engine provides the user a list of Web Addresses, the criteria at its best.

On the Internet, there are numerous search engines.
Some try to cover the whole WWW, others seek only in a certain part of the WWW pages only in the German language.
But not all websites can be searched via search engines.

How does a search engine?

A search engine searches the Internet when the user submits a search query. Among the billions of documents on the Internet would be much too long. A search engine consists of three parts robots, Indez and Benutzer-Schnitstelle: Very simply, it will be declared websearch.about.com


The technical development of a search engine is demostrate on a schematic representation in the book, but I couldnt copy it here, and with it you can understand the technical development of a search.

I want to speak about some investigations that I have made respect to some things and informatic objects we have been spoken in class. The ones which I pay more attention are:

- ROUTER

Definition:

A network device that forwards packets from one network to another. Based on internal routing tables, routers read each incoming packet and decide how to forward it. The destination address in the packets determines which interface on the router outgoing packets are directed to. In large-scale enterprise routers, the current traffic load, congestion, line costs and other factors determine which outgoing line to forward to.

At the Edge and In Between
Most routers in the world sit in homes and small offices and do nothing more than direct traffic from the network to the Internet. Sitting at the edge of the network, they may also contain a built-in firewall for security, and the firewall serves all users in the network without requiring a personal firewall in each computer.

However, in the larger company, routers are also used to separate local area networks (LANs) into subnetworks (subnets) in order to balance traffic within workgroups and to filter traffic for security purposes and policy management.

Routers in the Core
Within a large enterprise, routers serve as an internet (lower case "i") backbone that connects all internal networks, in which case they are typically connected via Ethernet. Within the global Internet (upper case "I"), routers do all the packet switching between the backbones and are typically connected via T3, ATM or SONET links.

Routable Protocols
Routers route messages transmitted only by a routable protocol such as IP "or" IPX. Multiprotocol routers support more than one; for example, IP "and" IPX. Messages in non-routable protocols, such as NetBIOS and LAT, cannot be routed, but they can be transferred from LAN to LAN via a bridge.

Because routers have to inspect the network address in the packet, they do more processing and add more overhead than a bridge or switch. Routers work at the network layer (layer 3) of the protocol, whereas bridges and switches work at the data link layer (layer 2), also known as the "MAC layer."

Specialized Machines or Regular PCs
Most routers are specialized computer-based devices optimized for communications; however, router functions can also be implemented by adding software to a server. For example, the NetWare operating system includes software to route packets from one subnetwork to another if each is connected to a separate network adapter (NIC). The major router vendors are Cisco Systems and Nortel Networks.

- COOKIES:

A small data file created by a Web server that is stored on your computer either temporarily for that session only or permanently on the hard disk (persistent cookie). Cookies provide a way for the Web site to recognize you and keep track of your preferences
Cookies Are Beneficial
Cookies are commonly used to "maintain the state" of the session as a user browses around the site. The shopping cart is an example. You can place an item in the cart, switch to another page or even another site, and when you come back, the site knows who you are, and you can continue with the order. Without cookies, the site would not be able to identify you automatically because the Internet is "stateless.
Cookies contain a range of URLs (addresses) for which they are valid. When the Web browser or other HTTP application sends a request to a Web server with those URLs again, it also sends along the related cookies. For example, if your user ID and password are stored in a cookie, it saves you from typing in the same information all over again when accessing that service the next time. By retaining user history, cookies allow the Web site to tailor the pages and create a custom experience for that individual.
Your Cookies Know You
Quite a bit of personal data may reside in the cookie files in your computer. As a result, this storehouse of private information is sometimes the object of attack

5 CLASS (7/11/2007)
1.4.2. Drawing from said

The award of texts is not a new invention in the form of sentence and correction instructions, she was an indispensable tool for writers and editors to instructions for the implementation of a manuscript doing.

Even the use of large and small description and bold is a form of the award. Strictly speaking, this is a simple form of physical distinction. Physical award means the document content with certain attributes to the visual representation to describe and has become part of the layout design.


In the data processing called the Mount of tags in a conventional text file also labeling. When tags are instructions, which consist of two parts. In between, there is either plain text or another tag. In the latter case, talk of a so-called nesting of tags. Since Tags also from text drawing, it is necessary that these differ from the rest of the text at once. Usually, in the markup languages, like HTML and the Grösser Kleiner characters. The opposite of a markup language are file formats, a spezific coding. For example, you can expect special HTML tags in a text with a particular font, color and size. The Physical award may also refer the entire document cover. To include tags for the indication of the page width also added. Of the difference between the logical distinction of a text, the structure of a document describes. This includes, for example, headings, lists, paragraphs, Rahemn, lists and references. There is, of course, for a reception by the people sense that this text elements also represent different visually. The term is also awarded in the name HTML: Hyper Text Markup Language.That name is also clear that with this language called Hyper Text, which are non-linear lyrics, excellent. The connections between individual hyper text, called Links, a part of the structure of a hypertext there.

The objective of the award is a logical addition to the structure, above all, a computer-aided processing of hypertext. For various output devices are certain physical representations different. For various output devices are certain physical representations different.
This is in the HTML Cascading Style Sheets are available. This clean segregation of us layout structure is in daily practice in many HTML is not given. Why is that old versions of CSS browser does not support the use of style sheets is still not as widespread.

For the most flexible use is a separation of the structure, content and format requirements.The mixture of structure and format in HTML, despite the obvious disadvantages of not more than initially disturbing. The use of formatting commands within a document was also rather the usual WYSIWYG view and we have not even thought of a treatment for a variety of output devices. In the early days of the Internet was an easy-to-learn and easy-to-use tool also important. Thus wore these design weaknesses of HTML significantly to the spread of the WWW. But the latest labor Creating Web pages, the same treatment content sources for different output devices, the application of existing enterprise Style Guides, version management, and from certain project sizes is a clean separation of the structure, content and layout is essential.

It seems somewhat restrictive, though always of texts such as Hyper text of the speech, it is still at Internet sites throughout today to multimedia presentations. The concept of hypertext, however, to a close only monomediale representation.
The reason for the continued use of the term text is that the description of multimedia web pages also by simple texts.


Besides HTML, there are other ways to multimedia documents to structure and save. Together, these data formats that it is mainly due to a physical description of a document designed:
Word processing programs
Page description languages
Document Formats

In contrast to HTML, it is in these file formats but to no markup languages and the structure, content and the data in a single file.

The possibilities for physical distinction has been in HTML CSS 2.0 a level achieved, even nourished hopes that HTML in the near future as a universal page description language, and as a universal document format will be used. A possible indication of this is in the fact that HTML now all Office-Pakten as of alternative export file format. In contrast to the layout are the tags for structuring content in HTML less advanced . This is not necessarily a disadvantage to be seen as the integration of tags to the physical presentation and the low level language with a reason for the slight learnability of HTML been. In addition, HTML, in contrast to many word processing file formats, Desktop-Publishing file formats to un document formats as a platform file format to be considered.
Due to the limited opportunities for structuring content, the use of HTML for the creation of documents for an information-processing little sense. The commands for structuring a document available on the Internet hypertext designed and authoritatively defined without their own extensions are possible. For the simple publishing documents on the Internet that makes sense. Typical Internet documents are not too large claims in terms of structuring options. Adding custom tags in HTML is not desirable, such as not useful, because yes, the Internet is different clients on a defined standard of the language relate.

Unlike this layout-oriented tasks, but it looks at data-centric tasks.
These are problems, mainly in the storage and transmission of data provided by operating daily incurred. These data have a complex internal structure, and should not be only for a presentation prepared on the Internet, but also the most easily can be processed electronically. A most convenient exchange of documents and an easy-to-use information further processing but also for layout centered desirable. More and more often is for the business daily business, the need for such a layout-oriented software systems within heterogeneous IT infrastructure, but also between the EDV-Lanschaften cooperating organizations.
New technical requirements for such systems also come from the leadership of the organizations themselves: there is a vital interest in data and document centered sources with different formats for the Knowledge-based management systems and to merge and process. But also for a more intelligent "search and find" on the Internet, such as search engines and software agents, HTML is not the ultimate savior.

For these application areas is not only a cross-platform format required, but it also needs to develop a scope of independent us the opportunity provide any bedeutungsspezifische information in a document. In HTML, there are approaches, such as meta tags to describe a document, but they are not expandable. Is a markup language that is not confined to a given grammar and vocabulary is not expandable, but with the possibility of their own markup language to create, which can arbitrarily complex document structures can be mapped.
A markup language that satisfies this is called a meta-language. So far, the most comprehensive approach for such a meta language, SGML (Standard Generalized Markup Language), which build on the work of GML in the year 1986 standard.


SGML is used in many industries for the document management.
Quote value are primarily the automotive and defense industries, which are both due to the complex nature of the early SGML documents for their application areas adapt . The disadvantage of SGML that is a very complex and difficult. This promises to remedy the Extensible Markup Language, with the help of SGML has been defined.



1.4.2.1 Basic concepts of Hypertext Markup Language

In comparison to a conventional desktop publishing Programe are the design options in W3 still some limits. The development and standardization of HTML but is a constant He further ungso rizess
subject, but in addition to the current standard HTML 4.01 and x HTML 1.o of each client developers deviating from the standard implements additional features. With an extensive support of the W • C already standardized CCS-2 is thus a real page design for Web pages possible.

Heading
As the quell code apparent Could the HTML document with any text editor or word processing has been applied. Every HTML document begins with the day </ html>. Too formatted text is basically at the beginning of one-and final-Tag marked with the final-tag a slash (1) are presented. Such a comprehensive text tags are also containers. The opposite of this are tags that are not final-tag, such as the first day in these key from Abb.I-2.7.Das day <DOCTYPE> is optional, and refers to the HTML version, and used language



In actual textteil there is a lot more opportunities, single-day u setzn. Can titles in six different sizes are defined, but the definition of font and size for each <Hx> tags to W3- Clientes can be set. The syntax is <Hx> text </ Hz>, where x is a number between 1 and 6, and the headings - defined level.




To sign so-called style formatting tags are used, the most important are as follows:
- Emphasize
- strong emphasis.
- Bold
- italics



Listen than enumerating lists, numbered lists, or lists of descriptive executed. An enumerative list starts with the
day (Unnumbered List), the individual list entries are like all other forms of Lise with the </ UL> day. Should the individual list entries are numbered, it is with the
day (ordered List), and started with the </ OL> tag. A special case is the descriptive list (definition list), whose list of entries with
day labeled.

The full hypertext functionality in HTML, but only by the possibility of generating links cross-references) to apply. Links with the day (Anchor). For external links to realize the HREF attribute (Hypertext Reference).

Embedded graphics and multimedia objects. A picture says more than a thousand words and it is also in W3 using HTML embedded in the graphics a key design element. With the optional ALIGN determines whether the following text above, in the middle or bottom of the image to be published.
Multimedia objects are not all W3-Clients processed, but must be equipped with an external helper application or a Browser-Plug-In executed.
A special type of graphics integration are called Click Images, the graphics are, by clicking on the various links different areas can be created.
Frames are long of the most common browsers, and are now at Version 4.0 component of HTML-Sprachumfanges. Previously, the browser manufacturers developed their own language constructs in the Internet clients. At Frames is a possibility of additional design of hypermedia documents. With the help of frames can be a side window into several smaller ones.
Form into HTML documents is a further possibility of interaction in W3. The processing of the data is entered, we at the Clickable images through a server script.


1.4.2.1.1. Cascading Style Sheets

A key feature of a markup language is the separation of HTML is not consistently implemented: There are many tags to layout design. For the separation of layout and structure serve Cascading Style Sheets, with the HTML documents linked, or in an HTML file can be directly involved. The possibilities of using CSS2 come, as far as the client, in the area of layouts far beyond the optical tags for presentation in HTML, and in combination with HTML CSS also suitable as a full page description language, such as PostScript. The issue is not only to a limited visual presentation, there are also commands for the acoustic output.
Style sheets can be in the head define an HTML file, although this format information only for such a file. If you want to have a consistent layout across multiple files, it is necessary that this format definitions in a separate file. The use of multiple CSS files is also possible. This is erfordelich when different style sheets for multiple output devices wishes.
This is true not only for output devices that use different media, but also for output devices, that the same medium. Thus, for example, has an optical output to a printer, unlike on a monitor.

We couldn´t go to the class, therefore we can summarize the concepts or speak about something concerning this day.