CVSup

Computer Networking is a process to connect two or more computers over shared network for exchanging data. These Networks are made by using Hardware and Software’s. Such as, Computers, Network Interfacing cards, operating software’s Microsoft, UNIX or Linux, cables and wires.

Network Types

On the Basis of Geographical Divisions
- LAN (Local Area Network) – It is limited to an area such as a college campus or an office building, and can communicate just three computers up to hundreds of computers.
- WAN (Wide Area Network) – It is a Network made by combining a number of LAN Network. It can be made simple and easy or it can be very complicated.
- Internet – It is a system of computers interconnecting to each other using IP and is spread across the whole world.
- Intranet – This Network is similar to that of the Internet but it is used only as a private network. So the companies take this network for communication and sharing of information within the organization.
- MAN (Metropolitan Area Network) – It is the network designed for the specific city.
On Basis of Architecture
- Peer to Peer – There is no dedicated server in this, so all computers act as client/server to each other. No one responsible to entire network. It is mainly used by small organizations where all users are located in the same area and there is no future expansion.
- Client/Server – In this the most powerful computer is the server and others are client. It is the most competent method to manage the network, storing the data centrally and manage the entire database.
On basis of Geometric Arrangement of computers
- Ring System – All computers are connected to form a ring.
- Star System – All computers are connected to a centrally located computer to form a star formation.
- Bus System – All computers are connected to a single bus connected between them.

Protocols
These are the standards which enable computers to communicate with each other.
Some protocols are:

TCP/IP – Point to Point protocol – Transmission control protocol/ Internet protocol – Backbone of Internet
FTP – File Transfer Protocol – Used to send or receive files from remote hosts
SMTP – Simple Mail Transfer Protocol – Used to send mails
IPX/SPX – Internet Packet Exchange/Sequenced Packet Exchange – For Novell Network operating system

CVSup is a software package for distributing and updating collections of files across a network. It can efficiently and accurately mirror all types of files, including sources, binaries, hard links, symbolic links, and even device nodes. CVSup’s streaming communication protocol and multithreaded architecture make it most likely the fastest mirroring tool in existence today.

CVSup was conceived and developed by John Polstra, a consultant whose specialties include high-performance network communications.

In addition to being a great general-purpose mirroring tool, CVSup includes special features and optimizations specifically tailored to CVS repositories. By taking advantage of the special properties of the files contained in CVS repositories, CVSup is able to perform updates much faster than traditional systems. CVSup parses and understands the RCS files making up a CVS repository. When updates occur, CVSup extracts new deltas directly from the RCS files on the server and edits them into the client’s RCS files. Likewise, CVSup notes the addition of new symbolic tags to the files on the server and sends only the new tags to the client.

CVSup is able to merge new deltas and tags from the server with deltas and tags added locally on the client machine. This makes it possible for the client to check local modifications into his repository without their being obliterated by subsequent updates from the server.

In addition to distributing the RCS files themselves, CVSup is able to distribute specific checked-out versions. The client can specify a symbolic tag, a date, or both and CVSup will extract the appropriate versions from the server’s CVS repository. Checked-out versions do not need to be stored on the server, since CVSup can extract any version directly from the CVS repository. If the client has an existing checked-out tree, CVSup will apply the appropriate edits to update the tree or transform it into the requested version. Only the differences between the existing version and the desired version are sent across the network.

To update non-RCS files, CVSup uses the highly efficient rsync algorithm, developed by Andrew Tridgell and Paul Mackerras.

CVSup uses lightweight processes (threads) to implement a streaming protocol across the network. This completely eliminates the delays associated with the lock-step, request-reply form of communication used by many existing protocols, such as sup and NNTP. Information is transferred at the full available speed of the network in both directions at once. Network latency and server response delays are rendered practically irrelevant.

CVSup uses the “zlib” compression package to optionally compress all communications. This provides an additional 65-75% compression, on top of the diff-based compression already built into CVSup.