NetB was originally initiated as my class project for Computer Networks in the spring of 2010, when I was a student of the George Washington University. It was designed as a C++ library that implements object-oritented interface for network programming. During the past years, NetB was changed from time to time, as a result of my practice-based learning of network programming. The coding involves socket API, object-oriented design and programming, error handling, asynchronous I/O based on event-driven notification, I/O buffer and protocol message serialization, and implementation of popular Internet protocols. Basically, NetB is a good example if you are interested in the knowledge or expected a deep understanding of the topics below:
1. A loose coupling object-oriented socket API
NetB was not designed into a complicated object hierarchy for socket programming, as usual in most similar libraries. It however implemented a series of loose coupling objects, which may work independently or coorperatively. This feature let NetB working in various weights: from a very thin wrappper of original socket API to a complete object-oritented socket interface with various I/O modes and detailed error handling. It also made it easy to program mixing NetB with any other third-party network libraries. Using NetB never means binding to NetB.
2. Error handling in C++ is not only exceptions
Error handling is necessary in any serious programming, while C++ standard exception is an angel for some programmers and an evil for others. It is always a hard decision for C++ library to throw exceptions or not. NetB supports exceptions, if you like it; NetB does not throw any exceptions, if you don't like it. But those are not the most great when you may determine a single NetB calling throwing exceptions or not. Without exceptions, the only return value is however too weak, so NetB introduced a error object in the calling that may raise errors to provide the same power of error handling as exceptions. Error handling styles are not determined on library level, but on per-calling of functions, which means you may switch at any points.
3. Asynchronous I/O with event-driven notifications
Asynchronous I/O is a basis for high performance network services. Event-driven notification and socket demultiplexing are basic mechanisms of asynchronous socket I/O. Some great implementations can be found in open-source libraries, such as libevent, libev, and libuv. NetB did not mind to re-invent the wheels. It is always easy for NetB to work together with those libraries. However, for convenience, NetB also included a simple event-driven notification interface in object-oriented style. Actually, the performance is not the most concern of NetB, so the I/O event demultiplexing is always done by "select" on all platforms, rather than the native alternatives with better performance. NetB only focused on the events of network I/O (i.e., socket ready events). NetB supports an event loop per thread, but gurantees the safe of multi-threading.
4. I/O buffer and protocol message serialization
A necessary function of network programming is to transfer protocol message over networks, and the workflows of messaging in different applications almost keep unchanged: assembling a protocol message, packing the message into an I/O buffer, sending the data in buffer over a socket, receiving data from socket into an I/O buffer, unpacking a protocol message from the data in buffer, and processing the protocol message. It is obviously that, to get better performance, data should be copied as less as possible in the workflow. An application protocol I/O may be across multiple network I/Os, so a better buffer in such cases should supports writing and reading continously (or streamingly) to avoid copying data per netowrk I/O. In addition, the application protocols are various and packing and unpacking of a prototocol message may be not always a sequential process, so the buffer should also support random access. NetB provided an implementation of such I/O buffer and a set of tools to simplify the packing and unpacking of application protocol messages.
5. Essential support of important Internet protocols
NetB did not implement application frameworks for Internet protcols as usual. It only implemented some wrappers of protocol messages and messaging flows. The fact is the application frameworks using Internet protocols are always various dramatically, with the only unchanged protocol message formats and messaging flows. NetB provides essential support of impotant application protcols, such as HTTP, DNS, and STUN, to make it easy enough to assemble any kind of network applications.
Again NetB is not a software framework, it only consists of the components useful for assembling network applictions. For more details, please refer to the README files, both in "netb" folder and "examples" folder.
NetB is still in development and the supporting platforms will include Linux, Mac OSX, Windows, and the major OS on Raspberry PI. To date, the major work of development is on Mac OSX EI Capitan and OpenMediaVault. The pre-release version will be ready soon. Please follow our updates.
- Build NetB Library
The target of "all" in make file will build a static library, which by default produces an output file libnetb.a in "lib" folder, based on all source code in "netb" folder.
Build NetB static library with:
make
or
make all - Build NetB Examples
A set of examples have been included to illustrate the using and important features of NetB. Target of "examples" in make file will build all examples in "examples" folder. Other targets with the same names of subfolders will build examples in each subfolder.
Build all NetB examples with:
make examplesBuild examples in "examples/http" folder with:
make http - Clean
As usual, target "clean" will remove all midlle files produced in building, and "cleanall" will remove all output files.
make cleanmake cleanall