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</style><link href="http://www.w3.org/StyleSheets/TR/W3C-ED" rel="stylesheet" type="text/css"><!-- ZZZ ED vs WD --><div class="head">	</style><link href="http://www.w3.org/StyleSheets/TR/W3C-WD" rel="stylesheet" type="text/css"><div class="head">
<p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>	<p><a href="http://www.w3.org/"><img alt="W3C" height="48" src="http://www.w3.org/Icons/w3c_home" width="72"></a></p>
<h1>Web Database</h1>	<h1>Web Database</h1>
<!--ZZZ:-->	<h2 class="no-num no-toc" id="w3c-working-draft-10-september-2009">W3C Working Draft 10 September 2009</h2> <!-- ZZZ -->
<!--<h2 class="no-num no-toc">W3C Working Draft 23 April 2009</h2>-->
<h2 class="no-num no-toc" id="editor-s-draft-date-1-january-1970">Editor's Draft 16 August 2009</h2>	<dl><dt>This Version:</dt>
<!--:ZZZ-->	<dd><a href="http://www.w3.org/TR/2009/WD-webdatabase-20090910/">http://www.w3.org/TR/2009/WD-webdatabase-20090910/</a></dd> <!-- ZZZ date x2 -->
<dl><!-- ZZZ: update the month/day (twice), (un)comment out
<dt>This Version:</dt>
<dd><a href="http://www.w3.org/TR/2009/WD-webdatabase-20090423/">http://www.w3.org/TR/2009/WD-webdatabase-20090423/</a></dd>
<dt>Latest Published Version:</dt>	<dt>Latest Published Version:</dt>
<dd><a href="http://www.w3.org/TR/webdatabase/">http://www.w3.org/TR/webdatabase/</a></dd>	<dd><a href="http://www.w3.org/TR/webdatabase/">http://www.w3.org/TR/webdatabase/</a></dd>
:ZZZ --><dt>Latest Editor's Draft:</dt>	<dt>Latest Editor's Draft:</dt>
<dd><a href="http://dev.w3.org/html5/webdatabase/">http://dev.w3.org/html5/webdatabase/</a></dd>	<dd><a href="http://dev.w3.org/html5/webdatabase/">http://dev.w3.org/html5/webdatabase/</a></dd>
<!-- ZZZ: add the new version after it has shipped	<!-- ZZZ: add the new version after it has shipped
<dt>Previous Versions:</dt>	<dt>Previous Versions:</dt>
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</ul><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- status of document, group responsible (required) --><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Apps	</ul><!-- UNDER NO CIRCUMSTANCES IS THE PRECEDING LIST TO BE REMOVED OR EDITED WITHOUT TALKING TO IAN FIRST --><!-- status of document, group responsible (required) --><p>The W3C <a href="http://www.w3.org/2008/webapps/">Web Apps
Working Group</a> is the W3C working group responsible for this	Working Group</a> is the W3C working group responsible for this
specification's progress along the W3C Recommendation track.	specification's progress along the W3C Recommendation track.
<!--ZZZ:-->	This specification is the 10 September 2009 First Public Working Draft. <!--ZZZ (date and remove 'first public'-->
<!--This specification is the 23 April 2009 Working Draft.-->
This specification is the 16 August 2009 Editor's Draft.
<!--:ZZZ-->
</p><!-- required patent boilerplate --><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5	</p><!-- required patent boilerplate --><p>This document was produced by a group operating under the <a href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5
February 2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/42538/status" rel="disclosure">public list of	February 2004 W3C Patent Policy</a>. W3C maintains a <a href="http://www.w3.org/2004/01/pp-impl/42538/status" rel="disclosure">public list of
any patent disclosures</a> made in connection with the deliverables	any patent disclosures</a> made in connection with the deliverables
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<li><a href="#executing-sql-statements-0"><span class="secno">4.4.1 </span>Executing SQL statements</a></ol></li>	<li><a href="#executing-sql-statements-0"><span class="secno">4.4.1 </span>Executing SQL statements</a></ol></li>
<li><a href="#database-query-results"><span class="secno">4.5 </span>Database query results</a></li>	<li><a href="#database-query-results"><span class="secno">4.5 </span>Database query results</a></li>
<li><a href="#errors-and-exceptions"><span class="secno">4.6 </span>Errors and exceptions</a></ol></li>	<li><a href="#errors-and-exceptions"><span class="secno">4.6 </span>Errors and exceptions</a></ol></li>
<li><a href="#disk-space"><span class="secno">5 </span>Disk space</a></li>	<li><a href="#web-sql"><span class="secno">5 </span>Web SQL</a></li>
<li><a href="#privacy"><span class="secno">6 </span>Privacy</a>	<li><a href="#disk-space"><span class="secno">6 </span>Disk space</a></li>
	<li><a href="#privacy"><span class="secno">7 </span>Privacy</a>
<ol>	<ol>
<li><a href="#user-tracking"><span class="secno">6.1 </span>User tracking</a></li>	<li><a href="#user-tracking"><span class="secno">7.1 </span>User tracking</a></li>
<li><a href="#cookie-resurrection"><span class="secno">6.2 </span>Cookie resurrection</a></ol></li>	<li><a href="#sensitivity-of-data"><span class="secno">7.2 </span>Sensitivity of data</a></ol></li>
<li><a href="#security"><span class="secno">7 </span>Security</a>	<li><a href="#security"><span class="secno">8 </span>Security</a>
<ol>	<ol>
<li><a href="#dns-spoofing-attacks"><span class="secno">7.1 </span>DNS spoofing attacks</a></li>	<li><a href="#dns-spoofing-attacks"><span class="secno">8.1 </span>DNS spoofing attacks</a></li>
<li><a href="#cross-directory-attacks"><span class="secno">7.2 </span>Cross-directory attacks</a></li>	<li><a href="#cross-directory-attacks"><span class="secno">8.2 </span>Cross-directory attacks</a></li>
<li><a href="#implementation-risks"><span class="secno">7.3 </span>Implementation risks</a></li>	<li><a href="#implementation-risks"><span class="secno">8.3 </span>Implementation risks</a></li>
<li><a href="#sql-and-user-agents"><span class="secno">7.4 </span>SQL and user agents</a></li>	<li><a href="#sql-and-user-agents"><span class="secno">8.4 </span>SQL and user agents</a></li>
<li><a href="#sql-injection"><span class="secno">7.5 </span>SQL injection</a></ol></li>	<li><a href="#sql-injection"><span class="secno">8.5 </span>SQL injection</a></ol></li>
<li><a class="no-num" href="#references">References</a></ol>	<li><a class="no-num" href="#references">References</a></ol>
<!--end-toc--><hr><!-- Feature requests for future versions (v2):	<!--end-toc--><hr><!-- Feature requests for future versions (v2):
* deleting databases	* deleting databases
* determining how much storage room is left	* determining how much storage room is left
* handling the database getting corrupted	* handling the database getting corrupted
	--><h2 id="introduction"><span class="secno">1 </span>Introduction</h2><p><i>This section is non-normative.</i><p>This specification introduces a set of APIs to manipulate
XXX should make it clear that UAs should treat data as sensitive and	client-side databases using SQL.<p>The API is asynchronous, so authors are likely to find anonymous
should delete it properly when it is deleted	functions (lambdas) very useful in using this API.<p>Here is an example of a script using this API. First, a function
--><h2 id="introduction"><span class="secno">1 </span>Introduction</h2><p><i>This section is non-normative.</i><p class="XXX">...</p><!-- include an example that does something like the following to show	<code title="">prepareDatabase()</code> is defined. This function
you should never embed strings straight into the statement, even when you	tries to create the database if necessary, giving it one table
have a variable and unknowable number of literals coming:	called "docids" with two columns ("id" and "name"). If it is
var q = "";	successful, or if the table doesn't need creating, it calls a
for each (var i in array)	section function, <code title="">getDatabase()</code>, which obtains
q += (q == "" ? "" : ", ") + "?";	a handle to the database, and then calls the function to do the
executeSql('SELECT rowid FROM t WHERE c IN (' + q + ')', array, ...);	actual work, in this case <code title="">showDocCount()</code>.<pre>function prepareDatabase(ready, error) {
--><h2 id="conformance-requirements"><span class="secno">2 </span>Conformance requirements</h2><p>All diagrams, examples, and notes in this specification are	return openDatabase('documents', '1.0', 'Offline document storage', 510241024, function (db) {
	db.changeVersion('', '1.0', function (t) {
	t.executeSql('CREATE TABLE docids (id, name)');
	}, error);
	});
	}

	function showDocCount(db, span) {
	db.readTransaction(function (t) {
	t.executeSql('SELECT COUNT(*) AS c FROM docids', [], function (t, r) {
	span.textContent = r.rows[0].c;
	}, function (t, e) {
	// couldn't read database
	span.textContent = '(unknown: ' + e.message + ')';
	});
	});
	}

	prepareDatabase(function(db) {
	// got database
	var span = document.getElementById('doc-count');
	showDocCount(db, span);
	}, function (e) {
	// error getting database
	alert(e.message);
	});</pre><hr><p>The <code title="dom-sqltransaction-executeSql"><a href="#dom-sqltransaction-executesql">executeSql()</a></code> method has
	an argument intended to allow variables to be substituted into
	statements without risking SQL injection vulnerabilities:<pre>db.readTransaction(function (t) {
	t.executeSql('SELECT title, author FROM docs WHERE id=?', [id], function (t, data) {
	report(data.rows[0].title, data.rows[0].author);
	});
	});</pre><hr><p>Sometimes, there might be an arbitrary number of variables to
	substitute in. Even in these case, the right solution is to
	construct the query using only "?" characters, and then to pass the
	variables in as the second argument:<pre>function findDocs(db, resultCallback) {
	var q = "";
	for each (var i in labels)
	q += (q == "" ? "" : ", ") + "?";
	db.readTransaction(function (t) {
	t.executeSql('SELECT id FROM docs WHERE label IN (' + q + ')', labels, function (t, data) {
	resultCallback(data);
	});
	});
	}</pre><h2 id="conformance-requirements"><span class="secno">2 </span>Conformance requirements</h2><p>All diagrams, examples, and notes in this specification are
non-normative, as are all sections explicitly marked non-normative.	non-normative, as are all sections explicitly marked non-normative.
Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL	Everything else in this specification is normative.<p>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and	NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
Line 344 have a variable and unknowable number of	Line 378 have a variable and unknowable number of
scripts in Web applications, and does not necessarily imply the	scripts in Web applications, and does not necessarily imply the
existence of an actual <code>Document</code> object or of any other	existence of an actual <code>Document</code> object or of any other
<code>Node</code> objects as defined in the DOM Core	<code>Node</code> objects as defined in the DOM Core
specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>A DOM attribute is said to be <em>getting</em> when its value is	specifications. <a href="#refsDOMCORE">[DOMCORE]</a><p>An IDL attribute is said to be <em>getting</em> when its value is
being retrieved (e.g. by author script), and is said to be	being retrieved (e.g. by author script), and is said to be
<em>setting</em> when a new value is assigned to it.<p>The term "JavaScript" is used to refer to ECMA262, rather than	<em>setting</em> when a new value is assigned to it.<p>The term "JavaScript" is used to refer to ECMA262, rather than
the official term ECMAScript, since the term JavaScript is more	the official term ECMAScript, since the term JavaScript is more
Line 358 have a variable and unknowable number of	Line 392 have a variable and unknowable number of
another browser window) trying to write to a database with incorrect	another browser window) trying to write to a database with incorrect
assumptions.<pre class="idl">[Supplemental, NoInterfaceObject]	assumptions.<pre class="idl">[Supplemental, NoInterfaceObject]
interface <span>WindowDatabase</span> {	interface <span>WindowDatabase</span> {
<a href="#database">Database</a> <a href="#dom-opendatabase" title="dom-opendatabase">openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize);	<a href="#database">Database</a> <a href="#dom-opendatabase" title="dom-opendatabase">openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize, in optional <a href="#databasecallback">DatabaseCallback</a> creationCallback);
};	};
<span>Window</span> implements <span>WindowDatabase</span>;	<span>Window</span> implements <span>WindowDatabase</span>;

[Supplemental, NoInterfaceObject]	[Supplemental, NoInterfaceObject]
interface <span>WorkerUtilsDatabase</span> {	interface <span>WorkerUtilsDatabase</span> {
<a href="#database">Database</a> <a href="#dom-opendatabase" title="dom-opendatabase">openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize);	<a href="#database">Database</a> <a href="#dom-opendatabase" title="dom-opendatabase">openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize, in optional <a href="#databasecallback">DatabaseCallback</a> creationCallback);
<a href="#databasesync">DatabaseSync</a> <a href="#dom-opendatabase-sync" title="dom-opendatabase-sync">openDatabaseSync</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize);	<a href="#databasesync">DatabaseSync</a> <a href="#dom-opendatabase-sync" title="dom-opendatabase-sync">openDatabaseSync</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize, in optional <a href="#databasecallback">DatabaseCallback</a> creationCallback);
};	};
<span>WorkerUtils</span> implements <span>WorkerUtilsDatabase</span>;</pre><p>The <dfn id="dom-opendatabase" title="dom-opendatabase"><code>openDatabase()</code></dfn> method on	<span>WorkerUtils</span> implements <span>WorkerUtilsDatabase</span>;
the <code>Window</code> and <code>WorkerUtils</code> interfaces must
return a newly constructed <code><a href="#database">Database</a></code> object that	[Callback=FunctionOnly, NoInterfaceObject]
represents the database requested.<p>The <dfn id="dom-opendatabase-sync" title="dom-opendatabase-sync"><code>openDatabaseSync()</code></dfn>	interface <dfn id="databasecallback">DatabaseCallback</dfn> {
method on the <code>WorkerUtils</code> interfaces must return a	void <span title="dom-databasecallback-handleEvent">handleEvent</span>(in <a href="#database">Database</a> database);
newly constructed <code><a href="#databasesync">DatabaseSync</a></code> object that represents	};</pre><p>The <dfn id="dom-opendatabase" title="dom-opendatabase"><code>openDatabase()</code></dfn> method on
the database requested.<p>These methods take four arguments: a database name, a database	the <code>Window</code> and <code>WorkerUtils</code> interfaces and
version, a display name, and an estimated size, in bytes, of the	the <dfn id="dom-opendatabase-sync" title="dom-opendatabase-sync"><code>openDatabaseSync()</code></dfn>
data that will be stored in the database.<p>The database requested is the one with the given database	method on the <code>WorkerUtils</code> interface take the following
name from the appropriate <span>origin</span>.<p>The <code title="dom-opendatabase"><a href="#dom-opendatabase">openDatabase()</a></code> method	arguments: a database name, a database version, a display name, an
on the <code>Window</code> object must use and create databases from	estimated size — in bytes — of the data that will be
the <span>origin</span> of the <span>active document</span> of the	stored in the database, and optionally a callback to be invoked if
<span>browsing context</span> of the <code>Window</code> object on	the database has not yet been created. The callback, if provided, is
which the method was invoked.<p>The <code title="dom-opendatabase"><a href="#dom-opendatabase">openDatabase()</a></code> and	intended to be used to call <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>; the
<code title="dom-opendatabase-sync"><a href="#dom-opendatabase-sync">openDatabaseSync()</a></code>	callback is invoked with the database having the empty string as its
methods on the <code>WorkerUtils</code> object must use and create	version regardless of the given database version. If the callback is
databases from the <span>origin</span> of the scripts in the	not provided, the database is created with the given database
worker.<p>All strings including the empty string are valid database	version as its version.<p>When invoked, these methods must run the following steps, with all
	but the last two steps being run atomically:<ol><li>

	<p>The user agent may raise a <code>SECURITY_ERR</code> exception
	instead of returning a <code><a href="#database">Database</a></code> object if the request
	violates a policy decision (e.g. if the user agent is configured
	to not allow the page to open databases).</p>

	</li>

	<li>

	<p>For the method on the <code>Window</code> object: let <var title="">origin</var> be the <span>origin</span> of the
	<span>active document</span> of the <span>browsing context</span>
	of the <code>Window</code> object on which the method was
	invoked.</p>

	<p>For the methods on the <code>WorkerUtils</code> object: let
	<var title="">origin</var> be the <span>origin</span> of the
	scripts in the worker.</p>

	</li>

	<li><p>If the database version provided is not the empty string,
	and there is already a database with the given name from the origin
	<var title="">origin</var>, but the database has a different
	version than the version provided, then throw an
	<code>INVALID_STATE_ERR</code> exception and abort these
	steps.</li>

	<li>

	<p>If no database with the given name from the origin <var title="">origin</var> exists, then create the database and let
	<var title="">created</var> be true. If a callback was passed to
	the method, then set the new database's version to the empty
	string. Otherwise, set the new database's version to the given
	database version.</p>

	<p>Otherwise, if a database with the given name already exists,
	let <var title="">created</var> be false.</p>

	</li>

	<li>

	<p>For the <code title="dom-opendatabase"><a href="#dom-opendatabase">openDatabase()</a></code>
	methods: let <var title="">result</var> be a newly constructed
	<code><a href="#database">Database</a></code> object representing the database with the
	given database name from the origin <var title="">origin</var>.</p>

	<p>For the <code title="dom-opendatabase-sync"><a href="#dom-opendatabase-sync">openDatabaseSync()</a></code> method:
	let <var title="">result</var> be a newly constructed
	<code><a href="#databasesync">DatabaseSync</a></code> object representing the database with
	the given database name from the origin <var title="">origin</var>.</p>

	</li>

	<li>

	<p>If <var title="">created</var> is false or if no callback was
	passed to the method, skip this step. Otherwise:</p>

	<p>For the <code title="dom-opendatabase"><a href="#dom-opendatabase">openDatabase()</a></code>
	methods: <span>queue a task</span> to to invoke the callback with
	<var title="">result</var> as its only argument.</p>

	<p>For the <code title="dom-opendatabase-sync"><a href="#dom-opendatabase-sync">openDatabaseSync()</a></code> method:
	invoke the callback with <var title="">result</var> as its only
	argument. If the callback throws an exception, rethrow that
	exception and abort these steps.</p>

	</li>

	<li>

	<p>Return <var title="">result</var>.</p>

	</li>

	</ol><p>All strings including the empty string are valid database
names. Database names must be compared in a	names. Database names must be compared in a
<span>case-sensitive</span> manner.<p class="note">Implementations can support this even in	<span>case-sensitive</span> manner.<p class="note">Implementations can support this even in
environments that only support a subset of all strings as database	environments that only support a subset of all strings as database
names by mapping database names (e.g. using a hashing algorithm) to	names by mapping database names (e.g. using a hashing algorithm) to
the supported set of names.<p>If the database version provided is not the empty string, and the	the supported set of names.<p>The version that the database was opened with is the <dfn id="concept-database-expected-version" title="concept-database-expected-version">expected version</dfn> of
database already exists but has a different version, or no version,
then the method must raise an <code>INVALID_STATE_ERR</code>
exception.<p>The version that the database was opened with is the <dfn id="concept-database-expected-version" title="concept-database-expected-version">expected version</dfn> of
this <code><a href="#database">Database</a></code> or <code><a href="#databasesync">DatabaseSync</a></code> object. It	this <code><a href="#database">Database</a></code> or <code><a href="#databasesync">DatabaseSync</a></code> object. It
can be the empty string, in which case there is no expected version	can be the empty string, in which case there is no expected version
— any version is fine.<p>Otherwise, if the database version provided is the empty string,	— any version is fine.<p>User agents are expected to use the display name and the
or if the database doesn't yet exist, or if the database exists and
the version requested is the same as the current version associated
with the database, then the method must return an object
representing the database that has the name that was given. If no
such database exists, it must be created first.<p>The user agent may raise a <code>SECURITY_ERR</code> exception
instead of returning a <code><a href="#database">Database</a></code> object if the request
violates a policy decision (e.g. if the user agent is configured to
not allow the page to open databases).<p>User agents are expected to use the display name and the
estimated database size to optimize the user experience. For	estimated database size to optimize the user experience. For
example, a user agent could use the estimated size to suggest an	example, a user agent could use the estimated size to suggest an
initial quota to the user. This allows a site that is aware that it	initial quota to the user. This allows a site that is aware that it
Line 430 interface <span>WorkerUtilsDatabase</spa	Line 532 interface <span>WorkerUtilsDatabase</spa

<p>The result is <var title="">the statement</var>.</p>	<p>The result is <var title="">the statement</var>.</p>

<p class="XXX">Implementation feedback is requested on what
to do with arguments that are of types that are not supported by
the underlying SQL backend. For example, SQLite doesn't support
booleans, so what should the UA do if passed a boolean? The Gears
team suggests failing, not silently converting types.</p>

</li>	</li>

<li><p>If the <code><a href="#database">Database</a></code> object that the	<li><p>If the <code><a href="#database">Database</a></code> object that the
Line 488 interface <span>WorkerUtilsDatabase</spa	Line 584 interface <span>WorkerUtilsDatabase</spa
example, attempts to read from or write to the file system will	example, attempts to read from or write to the file system will
fail.<p class="note">A future version of this specification will probably	fail.<p class="note">A future version of this specification will probably
define the exact SQL subset required in more detail.<h3 id="asynchronous-database-api"><span class="secno">4.3 </span>Asynchronous database API</h3><pre class="idl">interface <dfn id="database">Database</dfn> {	define the exact SQL subset required in more detail.<h3 id="asynchronous-database-api"><span class="secno">4.3 </span>Asynchronous database API</h3><pre class="idl">interface <dfn id="database">Database</dfn> {
void <a href="#dom-database-transaction" title="dom-database-transaction">transaction</a>(in <a href="#sqltransactioncallback">SQLTransactionCallback</a> callback, optional in <a href="#sqltransactionerrorcallback">SQLTransactionErrorCallback</a> errorCallback, optional in <a href="#sqlvoidcallback">SQLVoidCallback</a> successCallback);	void <a href="#dom-database-transaction" title="dom-database-transaction">transaction</a>(in <a href="#sqltransactioncallback">SQLTransactionCallback</a> callback, in optional <a href="#sqltransactionerrorcallback">SQLTransactionErrorCallback</a> errorCallback, in optional <a href="#sqlvoidcallback">SQLVoidCallback</a> successCallback);
void <a href="#dom-database-readtransaction" title="dom-database-readTransaction">readTransaction</a>(in <a href="#sqltransactioncallback">SQLTransactionCallback</a> callback, optional in <a href="#sqltransactionerrorcallback">SQLTransactionErrorCallback</a> errorCallback, optional in <a href="#sqlvoidcallback">SQLVoidCallback</a> successCallback);	void <a href="#dom-database-readtransaction" title="dom-database-readTransaction">readTransaction</a>(in <a href="#sqltransactioncallback">SQLTransactionCallback</a> callback, in optional <a href="#sqltransactionerrorcallback">SQLTransactionErrorCallback</a> errorCallback, in optional <a href="#sqlvoidcallback">SQLVoidCallback</a> successCallback);

readonly attribute DOMString <a href="#dom-database-version" title="dom-database-version">version</a>;	readonly attribute DOMString <a href="#dom-database-version" title="dom-database-version">version</a>;
void <a href="#dom-database-changeversion" title="dom-database-changeVersion">changeVersion</a>(in DOMString oldVersion, in DOMString newVersion, in <a href="#sqltransactioncallback">SQLTransactionCallback</a> callback, in <a href="#sqltransactionerrorcallback">SQLTransactionErrorCallback</a> errorCallback, in <a href="#sqlvoidcallback">SQLVoidCallback</a> successCallback);	void <a href="#dom-database-changeversion" title="dom-database-changeVersion">changeVersion</a>(in DOMString oldVersion, in DOMString newVersion, in optional <a href="#sqltransactioncallback">SQLTransactionCallback</a> callback, in optional <a href="#sqltransactionerrorcallback">SQLTransactionErrorCallback</a> errorCallback, in optional <a href="#sqlvoidcallback">SQLVoidCallback</a> successCallback);
};	};

[Callback=FunctionOnly, NoInterfaceObject]	[Callback=FunctionOnly, NoInterfaceObject]
Line 541 interface <dfn id="sqltransactionerrorca	Line 637 interface <dfn id="sqltransactionerrorca
the value of the second argument to the <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>	the value of the second argument to the <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>
method.</li>	method.</li>

</ol><p>...and the <i>mode</i> being read/write.<h4 id="executing-sql-statements"><span class="secno">4.3.1 </span>Executing SQL statements</h4><p>The <code title="dom-database-transaction"><a href="#dom-database-transaction">transaction()</a></code>,	</ol><p>...and the <i>mode</i> being read/write.<p>If any of the optional arguments are omitted, then they must be
	treated as if they were null.<h4 id="executing-sql-statements"><span class="secno">4.3.1 </span>Executing SQL statements</h4><p>The <code title="dom-database-transaction"><a href="#dom-database-transaction">transaction()</a></code>,
<code title="dom-database-readTransaction"><a href="#dom-database-readtransaction">readTransaction()</a></code>,	<code title="dom-database-readTransaction"><a href="#dom-database-readtransaction">readTransaction()</a></code>,
and <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>	and <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>
methods invoke callbacks with <code><a href="#sqltransaction">SQLTransaction</a></code>	methods invoke callbacks with <code><a href="#sqltransaction">SQLTransaction</a></code>
objects.<pre class="idl">typedef sequence<any> <dfn id="objectarray">ObjectArray</dfn>;	objects.<pre class="idl">typedef sequence<any> <dfn id="objectarray">ObjectArray</dfn>;

interface <dfn id="sqltransaction">SQLTransaction</dfn> {	interface <dfn id="sqltransaction">SQLTransaction</dfn> {
void <a href="#dom-sqltransaction-executesql" title="dom-sqltransaction-executeSql">executeSql</a>(in DOMString sqlStatement, optional in <a href="#objectarray">ObjectArray</a> arguments, optional in <a href="#sqlstatementcallback">SQLStatementCallback</a> callback, optional in <a href="#sqlstatementerrorcallback">SQLStatementErrorCallback</a> errorCallback);	void <a href="#dom-sqltransaction-executesql" title="dom-sqltransaction-executeSql">executeSql</a>(in DOMString sqlStatement, in optional <a href="#objectarray">ObjectArray</a> arguments, in optional <a href="#sqlstatementcallback">SQLStatementCallback</a> callback, in optional <a href="#sqlstatementerrorcallback">SQLStatementErrorCallback</a> errorCallback);
};	};

[Callback=FunctionOnly, NoInterfaceObject]	[Callback=FunctionOnly, NoInterfaceObject]
Line 611 interface <dfn id="sqlstatementerrorcall	Line 708 interface <dfn id="sqlstatementerrorcall
to the last step. (This is basically a hook for the <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>	to the last step. (This is basically a hook for the <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>
method.)</li>	method.)</li>

<li><p><span>Queue a task</span> to invoke the <i>transaction	<li><p>If the <i>transaction callback</i> is not null, <span>queue
callback</i> with the aforementioned <code><a href="#sqltransaction">SQLTransaction</a></code>	a task</span> to invoke the <i>transaction callback</i> with the
object as its only argument, and wait for that task to be	aforementioned <code><a href="#sqltransaction">SQLTransaction</a></code> object as its only
run.</li>	argument, and wait for that task to be run.</li>

<li><p>If the callback couldn't be called (e.g. it was null), or if	<li><p>If the callback raised an exception, jump to the last
the callback was invoked and raised an exception, jump to the last
step.</li>	step.</li>
<!--
<li><p>If the callback could be called and returned false, let
<i>callback-canceled</i> be true. Otherwise, let it be
false.</p></li>
-->
<li><p>While there are any statements queued up in the transaction,	<li><p>While there are any statements queued up in the transaction,
perform the following steps for each queued up statement in the	perform the following steps for each queued up statement in the
transaction, oldest first. Each statement has a statement,	transaction, oldest first. Each statement has a statement,
Line 642 interface <dfn id="sqlstatementerrorcall	Line 734 interface <dfn id="sqlstatementerrorcall
<li><p>Create a <code><a href="#sqlresultset">SQLResultSet</a></code> object that represents	<li><p>Create a <code><a href="#sqlresultset">SQLResultSet</a></code> object that represents
the result of the statement.</li>	the result of the statement.</li>

<li><p>If the statement has a result set callback, <span>queue a	<li><p>If the statement has a result set callback that is not
task</span> to invoke it with the <code><a href="#sqltransaction">SQLTransaction</a></code>	null, <span>queue a task</span> to invoke it with the
object as its first argument and the new	<code><a href="#sqltransaction">SQLTransaction</a></code> object as its first argument and the
<code><a href="#sqlresultset">SQLResultSet</a></code> object as its second argument, and wait	new <code><a href="#sqlresultset">SQLResultSet</a></code> object as its second argument, and
for that task to be run.</li>	wait for that task to be run.</li>

<li><p>If the callback was invoked and raised an exception, jump	<li><p>If the callback was invoked and raised an exception, jump
to the last step in the overall steps.</li>	to the last step in the overall steps.</li>
Line 658 interface <dfn id="sqlstatementerrorcall	Line 750 interface <dfn id="sqlstatementerrorcall
say to jump to the "in case of error" steps), run the following	say to jump to the "in case of error" steps), run the following
substeps:</p>	substeps:</p>

<ol><li><p>If the statement had an associated error callback, then	<ol><li><p>If the statement had an associated error callback that is
<span>queue a task</span> to invoke that error callback with the	not null, then <span>queue a task</span> to invoke that error
<code><a href="#sqltransaction">SQLTransaction</a></code> object and a newly constructed	callback with the <code><a href="#sqltransaction">SQLTransaction</a></code> object and a newly
<code><a href="#sqlerror">SQLError</a></code> object that represents the error that	constructed <code><a href="#sqlerror">SQLError</a></code> object that represents the
caused these substeps to be run as the two arguments,	error that caused these substeps to be run as the two arguments,
respectively, and wait for the task to be run.</li>	respectively, and wait for the task to be run.</li>

<li><p>If the error callback returns false, then move on to the	<li><p>If the error callback returns false, then move on to the
Line 675 interface <dfn id="sqlstatementerrorcall	Line 767 interface <dfn id="sqlstatementerrorcall

</ol></li>	</ol></li>

<li><p>If a <i>postflight operation</i> was defined for this	<li>
instance of the transaction steps, run that. If it fails, then jump
to the last step. <!--The operation, if any, might depend
<i>callback-canceled</i>.--> (This is basically a hook for the
<code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>
method.)</li>

<li><p>Commit the transaction.</li>	<p>If a <i>postflight operation</i> was defined for this instance
	of the transaction steps, then: as one atomic operation, commit
	the transaction and run the <i>postflight operation</i>. If either
	fails, then do neither, and instead jump to the last step. (This
	is basically a hook for the <code title="dom-database-changeVersion"><a href="#dom-database-changeversion">changeVersion()</a></code>
	method.)</p>

	<p>Otherwise: commit the transaction and run the <i>postflight
	operation</i>. If an error occurred in the committing of the
	transaction, jump to the last step.</p>

<li><p>If an error occurred in the committing of the transaction,	</li>
jump to the last step.</li>

<li><p><span>Queue a task</span> to invoke the <i>success	<li><p><span>Queue a task</span> to invoke the <i>success
callback</i>.</li>	callback</i>, if it is not null.</li>

<li><p>End these steps. The next step is only used when something	<li><p>End these steps. The next step is only used when something
goes wrong.</li>	goes wrong.</li>

<li><p><span>Queue a task</span> to invoke the <i>error	<li><p><span>Queue a task</span> to invoke the <i>error
callback</i> with a newly constructed <code><a href="#sqlerror">SQLError</a></code> object	callback</i>, if it is not null, with a newly constructed
that represents the last error to have occurred in this	<code><a href="#sqlerror">SQLError</a></code> object that represents the last error to have
transaction. Rollback the transaction. Any still-pending statements	occurred in this transaction. Rollback the transaction. Any
in the transaction are discarded.</li>	still-pending statements in the transaction are discarded.</li>

</ol><p>The <span>task source</span> for these tasks is the <dfn id="database-access-task-source">database	</ol><p>The <span>task source</span> for these <span title="concept-task">tasks</span> is the <dfn id="database-access-task-source">database access task
access task source</dfn>.<h3 id="synchronous-database-api"><span class="secno">4.4 </span>Synchronous database API</h3><pre class="idl">interface <dfn id="databasesync">DatabaseSync</dfn> {	source</dfn>.<h3 id="synchronous-database-api"><span class="secno">4.4 </span>Synchronous database API</h3><pre class="idl">interface <dfn id="databasesync">DatabaseSync</dfn> {
void <a href="#dom-database-sync-transaction" title="dom-database-sync-transaction">transaction</a>(in <a href="#sqltransactionsynccallback">SQLTransactionSyncCallback</a> callback);	void <a href="#dom-database-sync-transaction" title="dom-database-sync-transaction">transaction</a>(in <a href="#sqltransactionsynccallback">SQLTransactionSyncCallback</a> callback);
void <a href="#dom-database-sync-readtransaction" title="dom-database-sync-readTransaction">readTransaction</a>(in <a href="#sqltransactionsynccallback">SQLTransactionSyncCallback</a> callback);	void <a href="#dom-database-sync-readtransaction" title="dom-database-sync-readTransaction">readTransaction</a>(in <a href="#sqltransactionsynccallback">SQLTransactionSyncCallback</a> callback);

readonly attribute DOMString <a href="#dom-database-sync-version" title="dom-database-sync-version">version</a>;	readonly attribute DOMString <a href="#dom-database-sync-version" title="dom-database-sync-version">version</a>;
void <a href="#dom-database-sync-changeversion" title="dom-database-sync-changeVersion">changeVersion</a>(in DOMString oldVersion, in DOMString newVersion, in <a href="#sqltransactionsynccallback">SQLTransactionSyncCallback</a> callback);	void <a href="#dom-database-sync-changeversion" title="dom-database-sync-changeVersion">changeVersion</a>(in DOMString oldVersion, in DOMString newVersion, in optional <a href="#sqltransactionsynccallback">SQLTransactionSyncCallback</a> callback);
};	};

[Callback=FunctionOnly, NoInterfaceObject]	[Callback=FunctionOnly, NoInterfaceObject]
Line 759 interface <dfn id="sqltransactionsynccal	Line 854 interface <dfn id="sqltransactionsynccal
these steps. (<a href="#dom-sqlerror-code-2" title="dom-sqlerror-code-2">Error code	these steps. (<a href="#dom-sqlerror-code-2" title="dom-sqlerror-code-2">Error code
2</a>.)</li>	2</a>.)</li>

<li><p>If the third argument is null, rollback the transaction,	<li><p>If the third argument is not null, invoke the callback given
throw a <code><a href="#sqlexception">SQLException</a></code> exception, and abort these steps.	by the third argument, passing it the <var title="">transaction</var> object as its only argument.</li>
(<a href="#dom-sqlerror-code-0" title="dom-sqlerror-code-0">Error code
0</a>.)</li>

<li><p>Invoke the callback given by the third argument, passing it
the <var title="">transaction</var> object as its only
argument.</li>

<li><p>Mark the <code><a href="#sqltransactionsync">SQLTransactionSync</a></code> object as <i title="">stale</i>.</p>	<li><p>Mark the <code><a href="#sqltransactionsync">SQLTransactionSync</a></code> object as <i title="">stale</i>.</p>

Line 809 interface <dfn id="sqltransactionsynccal	Line 898 interface <dfn id="sqltransactionsynccal

</ol><h4 id="executing-sql-statements-0"><span class="secno">4.4.1 </span>Executing SQL statements</h4><p>The <code title="dom-database-sync-transaction"><a href="#dom-database-sync-transaction">transaction()</a></code>, <code title="dom-database-sync-readTransaction"><a href="#dom-database-sync-readtransaction">readTransaction()</a></code>,	</ol><h4 id="executing-sql-statements-0"><span class="secno">4.4.1 </span>Executing SQL statements</h4><p>The <code title="dom-database-sync-transaction"><a href="#dom-database-sync-transaction">transaction()</a></code>, <code title="dom-database-sync-readTransaction"><a href="#dom-database-sync-readtransaction">readTransaction()</a></code>,
and <code title="dom-database-sync-changeVersion"><a href="#dom-database-sync-changeversion">changeVersion()</a></code>	and <code title="dom-database-sync-changeVersion"><a href="#dom-database-sync-changeversion">changeVersion()</a></code>
methods return <code><a href="#sqltransactionsync">SQLTransactionSync</a></code> objects.<pre class="idl">// typedef sequence<any> <a href="#objectarray">ObjectArray</a>;	methods invoke callbacks that are passed
	<code><a href="#sqltransactionsync">SQLTransactionSync</a></code> objects.<pre class="idl">// typedef sequence<any> <a href="#objectarray">ObjectArray</a>;

interface <dfn id="sqltransactionsync">SQLTransactionSync</dfn> {	interface <dfn id="sqltransactionsync">SQLTransactionSync</dfn> {
<a href="#sqlresultset">SQLResultSet</a> <a href="#dom-sqltransaction-sync-executesql" title="dom-sqltransaction-sync-executeSql">executeSql</a>(in DOMString sqlStatement, optional in <a href="#objectarray">ObjectArray</a> arguments);	<a href="#sqlresultset">SQLResultSet</a> <a href="#dom-sqltransaction-sync-executesql" title="dom-sqltransaction-sync-executeSql">executeSql</a>(in DOMString sqlStatement, in optional <a href="#objectarray">ObjectArray</a> arguments);
};</pre><p>A <code><a href="#sqltransactionsync">SQLTransactionSync</a></code> object is initially <i title="">fresh</i>, but it will be marked as <i title="">stale</i>	};</pre><p>A <code><a href="#sqltransactionsync">SQLTransactionSync</a></code> object is initially <i title="">fresh</i>, but it will be marked as <i title="">stale</i>
once it has been committed or rolled back.<p>When the <dfn id="dom-sqltransaction-sync-executesql" title="dom-sqltransaction-sync-executeSql"><code>executeSql(<var title="">sqlStatement</var>, <var title="">arguments</var>)</code></dfn> method is invoked, the user	once it has been committed or rolled back.<p>When the <dfn id="dom-sqltransaction-sync-executesql" title="dom-sqltransaction-sync-executeSql"><code>executeSql(<var title="">sqlStatement</var>, <var title="">arguments</var>)</code></dfn> method is invoked, the user
agent must run the following algorithm:<ol><li><p>If the <code><a href="#sqltransactionsync">SQLTransactionSync</a></code> object is <i title="">stale</i>, then throw an <code>INVALID_STATE_ERR</code>	agent must run the following algorithm:<ol><li><p>If the <code><a href="#sqltransactionsync">SQLTransactionSync</a></code> object is <i title="">stale</i>, then throw an <code>INVALID_STATE_ERR</code>
Line 900 interface <dfn id="sqltransactionsync">S	Line 990 interface <dfn id="sqltransactionsync">S
const unsigned short <a href="#dom-sqlexception-code-timeout" title="dom-SQLException-code-TIMEOUT">TIMEOUT_ERR</a> = 7;	const unsigned short <a href="#dom-sqlexception-code-timeout" title="dom-SQLException-code-TIMEOUT">TIMEOUT_ERR</a> = 7;
readonly attribute unsigned short <a href="#dom-sqlerror-code" title="dom-SQLError-code">code</a>;	readonly attribute unsigned short <a href="#dom-sqlerror-code" title="dom-SQLError-code">code</a>;
readonly attribute DOMString <a href="#dom-sqlerror-message" title="dom-SQLError-message">message</a>;	readonly attribute DOMString <a href="#dom-sqlerror-message" title="dom-SQLError-message">message</a>;
};</pre><p>The <dfn id="dom-sqlerror-code" title="dom-SQLError-code"><code>code</code></dfn> DOM	};</pre><p>The <dfn id="dom-sqlerror-code" title="dom-SQLError-code"><code>code</code></dfn> IDL
attribute must return the most appropriate code from the table	attribute must return the most appropriate code from the table
below.<p>The <dfn id="dom-sqlerror-message" title="dom-SQLError-message"><code>message</code></dfn>	below.<p>The <dfn id="dom-sqlerror-message" title="dom-SQLError-message"><code>message</code></dfn>
DOM attribute must return an error message describing the error	IDL attribute must return an error message describing the error
encountered. The message should be localized to the user's	encountered. The message should be localized to the user's
language.<hr><p>Errors in the synchronous database API are reported using	language.<hr><p>Errors in the synchronous database API are reported using
<code><a href="#sqlexception">SQLException</a></code> exceptions:<pre class="idl">exception <dfn id="sqlexception">SQLException</dfn> {	<code><a href="#sqlexception">SQLException</a></code> exceptions:<pre class="idl">exception <dfn id="sqlexception">SQLException</dfn> {
Line 918 interface <dfn id="sqltransactionsync">S	Line 1008 interface <dfn id="sqltransactionsync">S
unsigned short <a href="#dom-sqlexception-code" title="dom-SQLException-code">code</a>;	unsigned short <a href="#dom-sqlexception-code" title="dom-SQLException-code">code</a>;
DOMString <a href="#dom-sqlexception-message" title="dom-SQLException-message">message</a>;	DOMString <a href="#dom-sqlexception-message" title="dom-SQLException-message">message</a>;
};</pre><p>The <dfn id="dom-sqlexception-code" title="dom-SQLException-code"><code>code</code></dfn>	};</pre><p>The <dfn id="dom-sqlexception-code" title="dom-SQLException-code"><code>code</code></dfn>
DOM attribute must return the most appropriate code from the table	IDL attribute must return the most appropriate code from the table
below.<p>The <dfn id="dom-sqlexception-message" title="dom-SQLException-message"><code>message</code></dfn> DOM	below.<p>The <dfn id="dom-sqlexception-message" title="dom-SQLException-message"><code>message</code></dfn> IDL
attribute must return an error message describing the error	attribute must return an error message describing the error
encountered. The message should be localized to the user's	encountered. The message should be localized to the user's
language.<hr><p>The error codes are as follows:<table><thead><tr><th>Constant	language.<hr><p>The error codes are as follows:<table><thead><tr><th>Constant
Line 978 interface <dfn id="sqltransactionsync">S	Line 1068 interface <dfn id="sqltransactionsync">S
<td>A lock for the transaction could not be obtained in a	<td>A lock for the transaction could not be obtained in a
reasonable time.	reasonable time.

</table><h2 id="disk-space"><span class="secno">5 </span>Disk space</h2><p>User agents should limit the total amount of space allowed for	</table><h2 id="web-sql"><span class="secno">5 </span>Web SQL</h2><p class="XXX">Need to define the SQL dialect.<h2 id="disk-space"><span class="secno">6 </span>Disk space</h2><p>User agents should limit the total amount of space allowed for
databases.	databases.

<p>User agents should guard against sites storing data under the	<p>User agents should guard against sites storing data under the
Line 991 interface <dfn id="sqltransactionsync">S	Line 1081 interface <dfn id="sqltransactionsync">S
is using.<p>A mostly arbitrary limit of five megabytes per	is using.<p>A mostly arbitrary limit of five megabytes per
<span>origin</span> is recommended. Implementation feedback is	<span>origin</span> is recommended. Implementation feedback is
welcome and will be used to update this suggestion in the	welcome and will be used to update this suggestion in the
future.<h2 id="privacy"><span class="secno">6 </span>Privacy</h2><h3 id="user-tracking"><span class="secno">6.1 </span>User tracking</h3><p>A third-party advertiser (or any entity capable of getting	future.<h2 id="privacy"><span class="secno">7 </span>Privacy</h2><h3 id="user-tracking"><span class="secno">7.1 </span>User tracking</h3><p>A third-party advertiser (or any entity capable of getting
content distributed to multiple sites) could use a unique identifier	content distributed to multiple sites) could use a unique identifier
stored in its	stored in its
client-side database	client-side database
Line 1030 interface <dfn id="sqltransactionsync">S	Line 1120 interface <dfn id="sqltransactionsync">S

<p>However, this also puts the user's data at risk.</p>	<p>However, this also puts the user's data at risk.</p>

<!-- XXX should there be an explicit way for sites to state when	<!--v2 consider adding an explicit way for sites to state when
data should expire? as in	data should expire, as in localStorage.expireData(365); -->
localStorage.expireData(365); ? -->

</dd>	</dd>

<dt>Treating persistent storage as cookies</dt>	<dt>Treating persistent storage as cookies</dt>
<dd>	<dd>

<p>User agents should present the	<p>If users attempt to protect their privacy by clearing cookies
database feature	without also clearing data stored in the

	database

to the user in a way that does not distinguish them from HTTP
session cookies. <a href="#refsRFC2109">[RFC2109]</a> <a href="#refsCOOKIES">[COOKIES]</a></p>

<p>This might encourage users to view such storage with healthy	feature, sites can defeat those attempts by using the two features
suspicion.</p>	as redundant backup for each other. User agents should present the
	interfaces for clearing these in a way that helps users to
	understand this possibility and enables them to delete data in all
	persistent storage features simultaneously. <a href="#refsCOOKIES">[COOKIES]</a></p>

</dd>	</dd>

Line 1103 interface <dfn id="sqltransactionsync">S	Line 1195 interface <dfn id="sqltransactionsync">S
retroactively). This information can then be shared with other	retroactively). This information can then be shared with other
sites, using using visitors' IP addresses and other user-specific	sites, using using visitors' IP addresses and other user-specific
data (e.g. user-agent headers and configuration settings) to combine	data (e.g. user-agent headers and configuration settings) to combine
separate sessions into coherent user profiles.<h3 id="cookie-resurrection"><span class="secno">6.2 </span>Cookie resurrection</h3><p>If the user interface for persistent storage presents data in the	separate sessions into coherent user profiles.<h3 id="sensitivity-of-data"><span class="secno">7.2 </span>Sensitivity of data</h3><p>User agents should treat persistently stored data as potentially
persistent storage features described in this specification	sensitive; it's quite possible for e-mails, calendar appointments,
separately from data in HTTP session cookies, then users are likely	health records, or other confidential documents to be stored in this
to delete data in one and not the other. This would allow sites to	mechanism.<p>To this end, user agents should ensure that when deleting data,
use the two features as redundant backup for each other, defeating a	it is promptly deleted from the underlying storage.<h2 id="security"><span class="secno">8 </span>Security</h2><h3 id="dns-spoofing-attacks"><span class="secno">8.1 </span>DNS spoofing attacks</h3><p>Because of the potential for DNS spoofing attacks, one cannot
user's attempts to protect his privacy.<h2 id="security"><span class="secno">7 </span>Security</h2><h3 id="dns-spoofing-attacks"><span class="secno">7.1 </span>DNS spoofing attacks</h3><p>Because of the potential for DNS spoofing attacks, one cannot
guarantee that a host claiming to be in a certain domain really is	guarantee that a host claiming to be in a certain domain really is
from that domain. To mitigate this, pages can use SSL. Pages using	from that domain. To mitigate this, pages can use SSL. Pages using
SSL can be sure that only pages using SSL that have certificates	SSL can be sure that only pages using SSL that have certificates
identifying them as being from the same domain can access their	identifying them as being from the same domain can access their
databases.	databases.

<h3 id="cross-directory-attacks"><span class="secno">7.2 </span>Cross-directory attacks</h3><p>Different authors sharing one host name, for example users	<h3 id="cross-directory-attacks"><span class="secno">8.2 </span>Cross-directory attacks</h3><p>Different authors sharing one host name, for example users
hosting content on <code>geocities.com</code>, all share one	hosting content on <code>geocities.com</code>, all share one
set of databases.	set of databases.

Line 1125 interface <dfn id="sqltransactionsync">S	Line 1216 interface <dfn id="sqltransactionsync">S
and overwrite it.<p class="note">Even if a path-restriction feature was made	and overwrite it.<p class="note">Even if a path-restriction feature was made
available, the usual DOM scripting security model would make it	available, the usual DOM scripting security model would make it
trivial to bypass this protection and access the data from any	trivial to bypass this protection and access the data from any
path.<h3 id="implementation-risks"><span class="secno">7.3 </span>Implementation risks</h3><p>The two primary risks when implementing these persistent storage	path.<h3 id="implementation-risks"><span class="secno">8.3 </span>Implementation risks</h3><p>The two primary risks when implementing these persistent storage
features are letting hostile sites read information from other	features are letting hostile sites read information from other
domains, and letting hostile sites write information that is then	domains, and letting hostile sites write information that is then
read from other domains.<p>Letting third-party sites read data that is not supposed to be	read from other domains.<p>Letting third-party sites read data that is not supposed to be
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user's wishlist; or a hostile site could set a user's session	user's wishlist; or a hostile site could set a user's session
identifier to a known ID that the hostile site can then use to track	identifier to a known ID that the hostile site can then use to track
the user's actions on the victim site.<p>Thus, strictly following the <span>origin</span> model described	the user's actions on the victim site.<p>Thus, strictly following the <span>origin</span> model described
in this specification is important for user security.<h3 id="sql-and-user-agents"><span class="secno">7.4 </span>SQL and user agents</h3><p>User agent implementors are strongly encouraged to audit all	in this specification is important for user security.<h3 id="sql-and-user-agents"><span class="secno">8.4 </span>SQL and user agents</h3><p>User agent implementors are strongly encouraged to audit all
their supported SQL statements for security implications. For	their supported SQL statements for security implications. For
example, <code title="">LOAD DATA INFILE</code> is likely to pose	example, <code title="">LOAD DATA INFILE</code> is likely to pose
security risks and there is little reason to support it.<p>In general, it is recommended that user agents not support	security risks and there is little reason to support it.<p>In general, it is recommended that user agents not support
features that control how databases are stored on disk. For example,	features that control how databases are stored on disk. For example,
there is little reason to allow Web authors to control the character	there is little reason to allow Web authors to control the character
encoding used in the disk representation of the data, as all data in	encoding used in the disk representation of the data, as all data in
JavaScript is implicitly UTF-16.<h3 id="sql-injection"><span class="secno">7.5 </span>SQL injection</h3><p>Authors are strongly recommended to make use of the <code title="">?</code> placeholder feature of the <code title="dom-sqltransaction-executeSql"><a href="#dom-sqltransaction-executesql">executeSql()</a></code> method,	JavaScript is implicitly UTF-16.<h3 id="sql-injection"><span class="secno">8.5 </span>SQL injection</h3><p>Authors are strongly recommended to make use of the <code title="">?</code> placeholder feature of the <code title="dom-sqltransaction-executeSql"><a href="#dom-sqltransaction-executesql">executeSql()</a></code> method,
and to never construct SQL statements on the fly.<h2 class="no-num" id="references">References</h2><p>All references are normative unless marked "Non-normative".<dl><dt id="refsCOOKIES">[COOKIES]</dt>	and to never construct SQL statements on the fly.</p><!--START vCard--><!--START vEvent--><h2 class="no-num" id="references">References</h2><!--REFS--><!--END vCard--><!--END vEvent--><p>All references are normative unless marked "Non-normative".</p><!--START vCard--><!--START vEvent--><dl><dt id="refsCOOKIES">[COOKIES]</dt>
<!--	<!--
<dd><cite><a href="http://www.ietf.org/rfc/rfc2965.txt">HTTP State Management	<dd><cite><a href="http://www.ietf.org/rfc/rfc2965.txt">HTTP State Management
Mechanism</a></cite>, D. Kristol, L. Montulli. IETF, October 2000.</dd>	Mechanism</a></cite>, D. Kristol, L. Montulli. IETF, October 2000.</dd>
Line 1171 interface <dfn id="sqltransactionsync">S	Line 1262 interface <dfn id="sqltransactionsync">S

<dt id="refsHTML5">[HTML5]</dt>	<dt id="refsHTML5">[HTML5]</dt>
<!--	<!--
<dd><cite><a href="http://www.w3.org/TR/html5/">HTML 5</a></cite>,	<dd><cite><a href="http://www.w3.org/TR/html5/">HTML5</a></cite>,
I. Hickson, D. Hyatt. W3C, April 2009.</dd>	I. Hickson, D. Hyatt. W3C, April 2009.</dd>
<dd><cite><a href="http://www.w3.org/html/wg/html5/">HTML	<dd><cite><a
5</a></cite>, I. Hickson, D. Hyatt. W3C, August 2009.</dd>	href="http://www.w3.org/html/wg/html5/">HTML5</a></cite>,
	I. Hickson, D. Hyatt. W3C, August 2009.</dd>
-->	-->
<dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML	<dd><cite><a href="http://www.whatwg.org/specs/web-apps/current-work/">HTML5</a></cite>,
5</a></cite>, I. Hickson. WHATWG, August 2009.</dd>	I. Hickson. WHATWG, August 2009.</dd>

<dt id="refsRFC2109">[RFC2109]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2109.txt">HTTP State Management
Mechanism</a></cite>, D. Kristol, L. Montulli. IETF, February 1997.</dd>

<dt id="refsRFC2119">[RFC2119]</dt>	<dt id="refsRFC2119">[RFC2119]</dt>
<dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in	<dd><cite><a href="http://www.ietf.org/rfc/rfc2119.txt">Key words for use in
Line 1199 interface <dfn id="sqltransactionsync">S	Line 1287 interface <dfn id="sqltransactionsync">S
<dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web	<dd><cite><a href="http://dev.w3.org/2006/webapi/WebIDL/">Web
IDL</a></cite>, C. McCormack. W3C, July 2009.</dd>	IDL</a></cite>, C. McCormack. W3C, July 2009.</dd>

</dl>	</dl><!--END vCard--><!--END vEvent-->

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