Monday, February 22, 2010

Embedded Linux - Standards Based

The Linux operating system and accompanying open source projects adhere to industry standards; in most cases, the implementation available in open source is the canonical, or reference, implementation of a standard. A reference implementation embodies the interpretation of the specification and is the basis for conformance testing. In short, the reference implementation is the standard by which others are measured.

If you’re new to the notion of a reference implementation, it may be a little confusing. Take for example the Portable Operating System Interface for Unix (POSIX) for handling threads and interprocess communication, commonly called pthreads. The POSIX group, part of the Institute of Electrical and Electronics Engineers (IEEE) is a committee that designs APIs for accomplishing the tasks of interacting with a thread but leaves the implementation of that standard to another group. In practice, when work begins on a standard, one or more of the participants on the committee volunteer to create the code to bring the standard to life, creating the reference implementation. The reference implementation includes a test suite; other implementations consider the passage of the test suite as evidence that the code works as per the specification.

Using standards-based software is not only about quality but also about independence. Basing a project on software that adheres to standards reduces the chances of lock-in due to vendor-specific features. A vendor may be well meaning, but the benefits of those extra features are frequently outweighed by the lack of interoperability and freedom that silently become part of the transaction and frequently don’t receive the serious consideration they merit.

Standards are increasingly important in a world where many embedded devices are connected, many times to arbitrary systems rather than just to each other. The Ethernet is one such connection method, but others abound, like Zigbee, CANbus, and SCSI, to name a few.

Source of Information : Pro Linux Embedded Systems (December 2009)

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