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Structured Naming

Structured Naming. Given Credit Where It Is Due. The following slides are borrowed from Dr. Katerina Goseva-Popstojanova at West Virginia University. Name Spaces. Absolute path name: the first node in the path name is the root of the naming graph. Example: n o <home, steen, mbox>

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Structured Naming

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  1. Structured Naming

  2. Given Credit Where It Is Due • The following slides are borrowed from Dr. Katerina Goseva-Popstojanova at West Virginia University

  3. Name Spaces • Absolute path name: the first node in the path name is the root of the naming graph. Example: no<home, steen, mbox> • Otherwise relative path name

  4. Name Spaces • Global name – denotes the same entry, no matter where that name is used in a system • Local name – interpretation depends on where the name is being used (e.g., environmental variable such as HOME in UNIX) • There are many different ways to organize a name space • Tree (strictly hierarchical) • Directed acyclic graph as in the previous slide

  5. Name Spaces The general organization of the UNIX file system implementation on a logical disk of contiguous disk blocks

  6. Name resolution • Name resolution - the process of looking up a name • Closure mechanism – deals with selecting the initial node in a name space from which to start the name resolution • In UNIX file system,the inode of the root directory is the first inode in the logical disk representing the file system • Resolving a name requires that some mechanism has already been implemented by which the resolution process can start • Example: 130429304052523

  7. Linking and Mounting • Alias – another name for the same entry • Example: environmental variable such as HOME • Two different ways to implement an alias: • Hard links – allow multiple absolute path names to refer to the same node (e.g., /keys and /home/steen/keys) • Symbolic links – represent an entry by a leaf node that stores an absolute path name

  8. Linking and Mounting The concept of a symbolic link explained in a naming graph

  9. Linking and Mounting • Name resolution can be used to merge different name spaces in a transient way • Mounted file system corresponds to letting a directory node store the identifier of a directory node from different (foreign) name space • Mount point – directory node storing the node identifier • Mounting point – directory node in the foreign name space

  10. Linking and Mounting • To mount a foreign name space in a distributed system requires at least • Name of an access protocol • Name of the server • Name of the mounting point in the foreign name space • Each of this needs to be resolved • None of these may be needed in non-distributed systems (e.g., UNIX)

  11. Linking and Mounting Mounting remote name spaces using Sun’s Network File System (NFS)

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