Metadata: Difference between revisions
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*A [[Files|file]] contains something the user wishes to store, such as some text or a photograph; the [[Filing_System|filing system]] will keep some metadata in the form of [[File_Attributes|file attributes]] (such as size, date and [[File_Permissions|permissions]]). | *A [[Files|file]] contains something the user wishes to store, such as some text or a photograph; the [[Filing_System|filing system]] will keep some metadata in the form of [[File_Attributes|file attributes]] (such as size, date and [[File_Permissions|permissions]]). | ||
** Some files, such as a photographic [https://en.wikipedia.org/wiki/JPEG JPEG], contain their own metadata in turn, such as the camera and exposure details the time and date (of the photograph, not the file it is copied into) etc. as well as the picture itself. | ** Some files, such as a photographic [https://en.wikipedia.org/wiki/JPEG JPEG], contain their own metadata in turn, such as the camera and exposure details the time and date (of the photograph, not the file it is copied into) etc. as well as the picture itself. | ||
*A program ‘binary’ file may contain information about the processor it can run on, the compiler used to generate it etc.<br /> (You may be interested enough to peruse a format like [https://en.wikipedia.org/wiki/Executable_and_Linkable_Format ELF], widely used in [https://en.wikipedia.org/wiki/Unix Unix] Systems, other OSes such as RISC OS, and even game consoles such as most PlayStations, the Dreamcast and the Wii. | *A program ‘binary’ file may contain information about the processor it can run on, the compiler used to generate it etc.<br /> (You may be interested enough to peruse a format like [https://en.wikipedia.org/wiki/Executable_and_Linkable_Format ELF], widely used in [https://en.wikipedia.org/wiki/Unix Unix] Systems, other OSes such as RISC OS, and even game consoles such as most PlayStations, the Dreamcast and the Wii.) | ||
*An executing [[Processes|process]] will have some metadata, such as its priority etc. which is used by the O.S. for purposes such as scheduling. | *An executing [[Processes|process]] will have some metadata, such as its priority etc. which is used by the O.S. for purposes such as scheduling. | ||
*You should be able to think of other examples! | *You should be able to think of other examples! | ||
Latest revision as of 09:38, 25 May 2021
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Metadata is data about other data. It is most easily explained by illustration:
- A file contains something the user wishes to store, such as some text or a photograph; the filing system will keep some metadata in the form of file attributes (such as size, date and permissions).
- Some files, such as a photographic JPEG, contain their own metadata in turn, such as the camera and exposure details the time and date (of the photograph, not the file it is copied into) etc. as well as the picture itself.
- A program ‘binary’ file may contain information about the processor it can run on, the compiler used to generate it etc.
(You may be interested enough to peruse a format like ELF, widely used in Unix Systems, other OSes such as RISC OS, and even game consoles such as most PlayStations, the Dreamcast and the Wii.) - An executing process will have some metadata, such as its priority etc. which is used by the O.S. for purposes such as scheduling.
- You should be able to think of other examples!
Articles on Major concepts
Cache • Cacheability • Concepts • Context • Direct Memory Access (DMA) • Exceptions • Hypervisor • Metadata • Process Scheduling • Processor Privilege • Real Time • Reentrancy • Synchronisation • Virtualisation
