Difference between revisions of "EFS"

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The Eclipse File System (EFS) is an abstract file system API.  It is used in the Eclipse platform to abstract away implementation details about what file system is used to store data in the workspace.  This page is a repository of information for plug-in developers who are writing their own EFS implementations.
 
The Eclipse File System (EFS) is an abstract file system API.  It is used in the Eclipse platform to abstract away implementation details about what file system is used to store data in the workspace.  This page is a repository of information for plug-in developers who are writing their own EFS implementations.
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== A word or two about URI ==
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EFS makes heavy use of Uniform Resource Identifiers, as defined by [http://www.ietf.org/rfc/rfc2396.txt RFC 2396].  URI is used to uniquely identify some file or directory in a backing file system. If you are implementing EFS for your own protocol or file system, an important decision you need to make is how to define a URI encoding for your file system.  If you are not familiar with it, start by perusing the URI spec - you should know the difference between absolute and relative, opaque and hierarchical URIs before proceeding.
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While some file systems and protocols already have well-known mappings onto URI, others do not.  Since the URI specification is quite flexible, the temptation is to simply convert your file system's path strings directly into URI.  For example, a CVS path like extssh:johna@dev.eclipse.org:/cvsroot/eclipse is technically a legal URI.  However, this is not the best representation.  What you need is an absolute, hierarchical URI.  The most important piece of the URI from the viewpoint of EFS is the ''path'' component.  One should be able to navigate to a file's parent, siblings, and children by manipulating only the path portion of the URI and leaving the rest intact. In other words, the rest of the URI should define how to find the root of your file system, and the path segment defines how to navigate down a strict tree hierarchy from that root.
  
 
== Known Implementations ==
 
== Known Implementations ==
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Contact: The [http://dev.eclipse.org/mailman/listinfo/platform-core-dev platform-core-dev mailing list]]<br>
 
Contact: The [http://dev.eclipse.org/mailman/listinfo/platform-core-dev platform-core-dev mailing list]]<br>
 
Description: This plug-in contains two sample EFS implementations. The first is an EFS implementation that treats a single zip file as the backing file system.  The second is an entirely in-memory file system that is useful in automated tests.
 
Description: This plug-in contains two sample EFS implementations. The first is an EFS implementation that treats a single zip file as the backing file system.  The second is an entirely in-memory file system that is useful in automated tests.
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=== CVS ===
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Plug-in id: org.eclipse.team.cvs.core<br>
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CVS: dev.eclipse.org:/cvsroot/eclipse/org.eclipse.team.cvs.core<br>
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Bugs: [https://bugs.eclipse.org/bugs/enter_bug.cgi?product=Platform Eclipse Platform] CVS<br>
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Contact: The [http://dev.eclipse.org/mailman/listinfo/platform-team-dev platform-team-dev mailing list]]<br>
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Description: This plug-in contains an implementation of EFS that interacts with a file system in a CVS repository. This EFS implementation is used internally by the CVS plug-in, and should not be relied upon by other plug-ins. However, it makes a useful example for your own implementation.

Revision as of 10:23, 25 July 2006

Contents

Overview

The Eclipse File System (EFS) is an abstract file system API. It is used in the Eclipse platform to abstract away implementation details about what file system is used to store data in the workspace. This page is a repository of information for plug-in developers who are writing their own EFS implementations.

A word or two about URI

EFS makes heavy use of Uniform Resource Identifiers, as defined by RFC 2396. URI is used to uniquely identify some file or directory in a backing file system. If you are implementing EFS for your own protocol or file system, an important decision you need to make is how to define a URI encoding for your file system. If you are not familiar with it, start by perusing the URI spec - you should know the difference between absolute and relative, opaque and hierarchical URIs before proceeding.

While some file systems and protocols already have well-known mappings onto URI, others do not. Since the URI specification is quite flexible, the temptation is to simply convert your file system's path strings directly into URI. For example, a CVS path like extssh:johna@dev.eclipse.org:/cvsroot/eclipse is technically a legal URI. However, this is not the best representation. What you need is an absolute, hierarchical URI. The most important piece of the URI from the viewpoint of EFS is the path component. One should be able to navigate to a file's parent, siblings, and children by manipulating only the path portion of the URI and leaving the rest intact. In other words, the rest of the URI should define how to find the root of your file system, and the path segment defines how to navigate down a strict tree hierarchy from that root.

Known Implementations

Are you working on an EFS implementation that you would like the community to know about? If so, add it to the list below. If possible, include CVS connection and contact information. You may find others in the community who are working on an implementation for the same kind of file system and may be able to pool resources.

Local file system

Plug-in id: org.eclipse.core.filesystem
CVS: dev.eclipse.org:/cvsroot/eclipse/org.eclipse.core.filesystem
Bugs: Eclipse Platform Resources
Contact: The platform-core-dev mailing list]
Description: This EFS implementation is backed by the local fileystem through a combination of java.io API, and some optional native fragments. The implementation is product quality, and is available in Eclipse Platform 3.2 release or greater.

FTP

Plug-in id: org.eclipse.core.filesystem.ftp
CVS: dev.eclipse.org:/cvsroot/eclipse/platform-core-home/plugins/org.eclipse.core.filesystem.ftp
Bugs: Eclipse Platform Resources
Contact: The platform-core-dev mailing list]
Description: This is a partial EFS implementation backed by the File Transfer Protocol (FTP). This implementation is not currently functional. You will need to create a KeyRing class with your FTP connection information. This plugin depends on the "team extras" FTP plug-in, found in the same repository at the path /platform-vcm-home/plugins/target/org.eclipse.ftp.

UI Examples: Zip and Memory file systems

Plug-in id: org.eclipse.ui.examples.filesystem
CVS: dev.eclipse.org:/cvsroot/org.eclipse/www/eclipse/platform-ui/plugins/org.eclipse.ui.examples.filesystem
Bugs: Eclipse Platform Resources
Contact: The platform-core-dev mailing list]
Description: This plug-in contains two sample EFS implementations. The first is an EFS implementation that treats a single zip file as the backing file system. The second is an entirely in-memory file system that is useful in automated tests.

CVS

Plug-in id: org.eclipse.team.cvs.core
CVS: dev.eclipse.org:/cvsroot/eclipse/org.eclipse.team.cvs.core
Bugs: Eclipse Platform CVS
Contact: The platform-team-dev mailing list]
Description: This plug-in contains an implementation of EFS that interacts with a file system in a CVS repository. This EFS implementation is used internally by the CVS plug-in, and should not be relied upon by other plug-ins. However, it makes a useful example for your own implementation.