Home > Articles > Programming > PHP

  • Print
  • + Share This
This chapter is from the book

IRC Network Basics

Having chosen a communication standard for the chat, we should take a look at how exactly IRC networks are built.

Ideally, you should have evaluated the IRC network basics discussed in this section prior to choosing IRC—since it's a bad thing to find out that IRC introduces a complicated structure after already having made the decision to use it. To this point, however, we've been working with "common knowledge" about using IRC networks, just for the sake of application planning. Now that we've led you to the "right" method to use for the application (IRC), this section provides the details you need to execute that plan.

IRC networks distinguish between clients and servers. Users can participate on the network only by using a special client software that establishes a client link to a server. All servers on the network are interconnected using special server links. Current implementations of IRC servers only support hierarchical structures, meaning that there must not be redundant ways to reach a server. This forms the net into a tree-like structure prone to network splits, but also greatly simplifies routing: All servers simply have to send all incoming data to all other links, without fearing to send redundant information to a server.

Each server can have a number of clients; the maximum number depends on the number of connections the server is willing to accept (of course, limits also exist in terms of network capacity and server load). As shown in Figure 3.2, each server can reach every other server across more or fewer server hops, so each server simply sends all incoming data to all outgoing links. For example, Server C and Server F might carry clients participating in the same channel (channels are IRC's chat rooms—places where people can "meet" and "talk"). In this example, Server C would send the data via the only link it has: Server B. Server B then distributes the data to its other links, namely Server A and Server D. Server A doesn't have any other links, so it won't do anything, but Server D would pass on the data to Server E, and Server E in turn to Server F. Pretty easy to implement, but with one drawback: If Server A doesn't have any clients connected to it participating in the channels to which Server C sends data, all data for Server A targeted at this channel would simply waste bandwidth.

RFC for IRC

Similar to all open standards on the Internet, the basics of the IRC protocol have been specified in an RFC (Request For Comments). The RFC for IRC is RFC 1459, which can be retrieved, for example, at http://www.irchelp.org, a site that carries a lot of information on IRC.

03fig02.gifFigure 3.2. A sample IRC network structure.

This is one of the main problems of this "limited by design" network: All public traffic has to go to all servers. But will this problem really arise under the conditions in which we intend to implement our IRC network? Surely not, as the number of clients we intend to handle will never be so large as to be harmful, given a standard server-hosting situation. In internal networks, this problem shouldn't arise at all.

To reduce the total number of critical links, the network can be laid out to follow its physical topology. If one server is connected with higher capacity than the rest, for example, it can take more leaf nodes than others (connecting lots of leaf nodes to a server with a small backbone wouldn't even make sense). Another option is to set up the routing to fit the network. For example, U.S. servers are homed in the States, German servers are homed in Germany, and so on. Frankfurt has an overseas link to New York; thus, the IRC server in Frankfurt should link to New York's server (following the network's physical layout). It could also be done in another way: Frankfurt could link to, say, Poland. But if Poland doesn't have its own overseas link, the traffic routed from Frankfurt to Poland would need to find some other way to cross the ocean—it would be routed to some other country (or even two or three countries) until it finds a free overseas link. This additional routing wastes a lot of bandwidth; thus, attempts are being made to adapt the IRC network structure to best fit the underlying physical network structure.

These design problems are present only in the biggest networks, carrying tens of thousands of users. These networks really need to find reliable links for their backbones. Typical Web-based chat rooms or networks are unlikely to carry more than 1,000 clients at once, so you shouldn't run into serious problems at first. To avoid complications, however, it's a good idea to plan around these sorts of problems that may arise eventually.

From a server's point of view, the network looks like Figure 3.3.

03fig03.gifFigure 3.3. Network structure from a server's point of view.

The structure implemented here is similar to a mixture of a multiplexor, demultiplexor, and a hub. In the direction client to network, the server compresses all data from the clients and sends it to the network links. In the other direction, it determines which information from the network is important for which client and sends it to the appropriate link. All incoming data from the network that has to be passed on to the other network links is sent on directly.

Basically, this is the setup we'd need for our own chat system. Now take a minute and try to imagine how we can achieve our goal. We need a working server environment that fits the following description:

  • Accepts IRC network links

  • Accepts IRC client links

  • Provides a Web-based user interface

  • Is as easy to implement as possible

  • + Share This
  • 🔖 Save To Your Account

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020