Download principles of Bt, eMule, and thunder Software

From: http://www.verycd.com/groups/eMuleBeta/186538.topic

Download principle of BT

BT is a shared software (not "abnormal"). Its full name is BitTorrent.
Generally, downloading is to transfer files from the server to the client, such as FTP, HTTP, and pub. However, there is a problem. As the number of users increases, the demand for bandwidth also increases. Too many users will cause bottlenecks, and the server will be suspended if the problem persists, therefore, many servers have limits on the number of users and the download speed, which causes many problems for users.
Inconvenience.
But Bt is different. The more users use BT to download, the faster the download. Why? Because BT uses a pyramid scheme to achieve sharing. BT first divides a file into Z parts on the uploader. A randomly downloads N parts on the server, and B randomly downloads M parts on the server, in this way, the bt of Party A will go to Party B's computer to obtain the M part that has been downloaded by Party B, the bt of Party B will go to the computer of Party A as needed to obtain the N part that has been downloaded by Party A, which not only reduces the load on the server side, but also speeds up the user side (Party A and Party B) the download speed and efficiency are also improved, and the restrictions between regions are also reduced. For example, if C needs to connect to the server for download, it may only be a few K, but it would be much faster to Get It On A and B's computers. So the more people you use, the more people you download, and the faster you get. Here is the advantage of BT. In addition, while you download the file, you are also uploading (some part of the file that someone else takes from your computer). So while enjoying the download provided by others, you are also contributing.

How eMule downloads

The electricity supplier is a file sharing software built on point-to-point (peer2peer) technology. It differs from traditional file sharing: shared files are not waiting for the client to download on a centralized server, but are scattered on the hard disks of all participants. All participants form a virtual network, and each user can download files from any machine in the virtual network! At the same time, everyone can share their files with anyone. There are some servers in the "China Telecom" system, but these servers do not store files, but the directories or addresses of these shared files. Each client obtains or searches for the address of the shared file from the server and automatically downloads the file from another client. The more clients involved, the faster the download speed.

2. Download Principle
After you select the file you want in the search list and start downloading it, the electric terminal records the file size, file name, and another special value called hash. To be more specific, it is a hash value of md4. This value is calculated based on the content of the file you want to download. It allows you to know if the file you are downloading is what you want. This is especially important when other attributes of the file are changed (such as names. After obtaining this information, the e-mapreduce software sends a request to all added servers to obtain files with the same hash value. The server returns the user information that holds the file. In this way, our client can directly communicate with the user who owns the file to see if it can download the required file from him. The best part of the power register is that you download files from many users at the same time instead of just one user. If another user only needs a small part of the file, he will automatically share it with everyone, and you can download it from the user's machine. Of course, the same is true for you. If you get a file clip, the system will share it with you.

How thunder works

Thunder will collect information about all the computers installed with thunder on the Internet.
1. In fact, many software programs collect servers on the Internet, such as the Internet Express, but the Internet Express will not collect the user name and password. Why? Because of the Internet ExpressProgramThe user name and password are included, that is, they do not want everyone to use them. but Xunlei programmers can ignore you and collect the data for other users. to put it bluntly, it is the "leeching" That webmasters hate most ".

For example, the download location containing the username: ftp: // thund: Issue@202.154.123.218/0718/World War. rmvb

In this example, thund: issue is the user name and password.

2. What I mentioned above is that the benefits of webmasters who provide downloads are damaged. The downloading users seem to say, what is my concern? I can download it quickly.

Hey, the world is not that cheap. if there are just a few download sites on the Internet, the functions are not very great, and webmasters are not stupid, so that you will be able to steal the chain all the time. is there any way to add download points? It's not the one who used the thunder download.

Lightning, but you cannot see it in the toolbar in the lower-right corner of the system. It can only be seen in the online process.

What are the functions of these two threads? It is to share files on your hard disk like BT and let others download them. therefore, the LAN network management can work hard, and you cannot find it. Why is the traffic in your network so large.

As we can see from the above, the programmer of thunder knows that the user does not want to share files on his computer with others, so he quietly starts two threads of thunder behind the system, so that you do not notice.

So even if you are not downloading, you will be slow to access the Internet. Hard Drives won't take long before they can be thrown into the trash.

3. on the client of thunder, you can search for different things to download. if you search for win2003, you will find the download point of win2003. however, these download points are not on the thunder server. However, this method makes thunder users feel that thunder provides fast download points.

This kind of behavior will be supported by many ordinary thunder users. however, this leeching seriously affects the survival of a website. moreover, every thunder user does not necessarily agree to upload data to others when he opens a computer every day.