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<!--
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* acontrol.html
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*
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* Authors: Jivka Bojilova
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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* For Details: http://www.nceas.ucsb.edu/
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* Created: 2000 April 5
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* Version: 0.01
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* File Info: '$Id: acontrol.html 881 2001-12-18 19:50:12Z berkley $'
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*
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* October Meeting SDSC, 2000
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-->
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<HTML>
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<HEAD>
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<TITLE>Metacat</TITLE>
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<link rel="stylesheet" type="text/css" href="@docrooturl@default.css">
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</HEAD>
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<BODY>
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<table width="100%">
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<tr>
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<td class="tablehead" colspan="2"><p class="label">Metacat User
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Authentication and Access Control</p></td>
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<td class="tablehead" colspan="2" align="right">
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<a href="./xmlindex.html">Back</a> | <a href="./metacattour.html">Home</a> |
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<a href="./metacatout.html">Next</a>
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</td>
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</tr>
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</table>
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<p><b>Authentication</b></p>
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<p>Metacat has a public interface for porting authentication
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schemes to Metacat. Currently an LDAP scheme is implemented.
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LDAP stands for Lightweight Directory Access Protocol.
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It is an optimized database for fast retrival of stored data:
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It is used by Metacat to store its users and their information.
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The users can be organized in one or more groups.
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</p>
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<P> <img src="auth.gif">
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<P> <b>Access control in Metacat. </b></p>
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<ul>
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<li> Metacat users stored in the LDAP directory database are authenticated
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to use Metacat services and resources.</li>
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<li> A persistant session is assigned to an authenticated user.</li>
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<li> Metacat also allows document level access control via Access Control
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Lists (ACLs).</li>
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</ul>
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<!--<img src="acontrol.gif">-->
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<b>ACLs</b>
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<p>Metacat allows a user to set permissions for users or groups on individual
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documents by using
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a special XML file called an Access file.
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The <a href="./packages.html">Package</a> file
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specifies which documents the Access file refers to.
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A sample Access file looks like the following:</p>
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<pre>
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<?xml version="1.0"?>
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<!DOCTYPE acl PUBLIC "-//NCEAS//eml-access-2.0//EN" "eml-access-2.0.dtd">
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<acl authSystem="knb" order="allowFirst">
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<identifier>nceas.36.1</identifier>
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<allow>
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<principal>jones</principal>
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<principal>higgins</principal>
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<principal>berkley</principal>
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<principal>bojilova</principal>
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<permission>read</permission>
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<duration>
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<startDate>10/9/2000</startDate>
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<stopDate>10/9/2001</stopDate>
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</duration>
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<ticketCount>100</ticketCount>
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</allow>
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<allow>
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<principal>bojilova</principal>
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<permission>write</permission>
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<ticketCount>10</ticketCount>
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</allow>
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<allow>
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<principal>reviewers</principal>
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<permission>read</permission>
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<ticketCount>5</ticketCount>
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</allow>
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<allow>
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<principal>blankman</principal>
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<permission>all</permission>
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</allow>
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<deny>
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<principal>eddins</principal>
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<permission>all</permission>
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</deny>
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</acl>
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</pre>
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<p>This file is read into Metacat like any other XML file. Like
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<a href="./packages.html">Packages</a> the doctype is checked against
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the accessdoctype parameter in the <a href="./properties.html">Metacat
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Properties</a> file. If the doctype matches, special postprocessing
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is performed on the document and the persmissions described in the file
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are applied to the specified document.
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</p>
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<p>The main tag <acl> has attributes 'order' and 'authSystem'.
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Order refers to which permission type to process first, allow or deny.
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The allowed values are "allowFirst" and "denyFirst". The default is "allowFirst".
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</p>
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<p>The <identifier> tag specifies the document identifier for the Access file
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itself as stored in Metacat.
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</p>
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<p>Next are the permissions themselves. An allow tag gives permissions to
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the specified user(s) (<principal>) and a deny tag takes the permissions
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away from the user(s). A principal should be a registered user or group.
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A timed duration can be set on the permission after
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which the user(s) will no longer have the specified permission. A ticket count
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can also be set. This gives the user the number of accesses specified. After
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the user has accessed the document that number of times, the permissions are
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revoked.
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</p>
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<br>
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<a href="./xmlindex.html">Back</a> | <a href="./metacattour.html">Home</a> |
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<a href="./ldap.html">Next</a>
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</BODY>
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</HTML>
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