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Posted to commits@tapestry.apache.org by bu...@apache.org on 2017/09/16 02:22:41 UTC
svn commit: r1018228 [27/41] - in /websites/production/tapestry/content: ./
cache/
Modified: websites/production/tapestry/content/page-navigation.html
==============================================================================
--- websites/production/tapestry/content/page-navigation.html (original)
+++ websites/production/tapestry/content/page-navigation.html Sat Sep 16 02:22:40 2017
@@ -27,16 +27,6 @@
</title>
<link type="text/css" rel="stylesheet" href="/resources/space.css" />
- <link href='/resources/highlighter/styles/shCoreCXF.css' rel='stylesheet' type='text/css' />
- <link href='/resources/highlighter/styles/shThemeCXF.css' rel='stylesheet' type='text/css' />
- <script src='/resources/highlighter/scripts/shCore.js' type='text/javascript'></script>
- <script src='/resources/highlighter/scripts/shBrushJava.js' type='text/javascript'></script>
- <script src='/resources/highlighter/scripts/shBrushXml.js' type='text/javascript'></script>
- <script src='/resources/highlighter/scripts/shBrushPlain.js' type='text/javascript'></script>
- <script>
- SyntaxHighlighter.defaults['toolbar'] = false;
- SyntaxHighlighter.all();
- </script>
<link href="/styles/style.css" rel="stylesheet" type="text/css"/>
@@ -77,109 +67,20 @@
</div>
<div id="content">
- <div id="ConfluenceContent"><div class="aui-label" style="float:right" title="Related Articles">
-
-
-
-
-
-
-
-
-<h3>Related Articles</h3>
-
-<ul class="content-by-label"><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
-
- <div class="details">
- <a href="content-type-and-markup.html">Content Type and Markup</a>
-
-
- </div>
- </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
-
- <div class="details">
- <a href="page-navigation.html">Page Navigation</a>
-
-
- </div>
- </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
-
- <div class="details">
- <a href="page-life-cycle.html">Page Life Cycle</a>
-
-
- </div>
- </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
-
- <div class="details">
- <a href="component-rendering.html">Component Rendering</a>
-
-
- </div>
- </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
-
- <div class="details">
- <a href="component-events.html">Component Events</a>
-
-
- </div>
- </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
-
- <div class="details">
- <a href="component-events-faq.html">Component Events FAQ</a>
-
-
- </div>
- </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span> </div>
-
- <div class="details">
- <a href="request-processing.html">Request Processing</a>
-
-
- </div>
- </li></ul>
-</div>
-
-
-<p>In essence, a Tapestry application is a number of related pages, working together. To some degree, each page is like an application unto itself.</p><p>Any individual request will be targeted at a single page. Requests come in two forms: </p><ul><li><em>component event</em> requests target a specific component on a specific page, triggering an event within that component</li><li><em>render</em> requests target a specific page, and stream the HTML markup for that page back to the client</li></ul><p>This dichotomy between component event requests and render requests alleviates a number of problems in traditional web applications related to the browser back button, or to the user hitting the refresh button in their browser.</p><p><br clear="none"><span style="color: rgb(83,145,38);font-size: 20.0px;line-height: 1.5;">Logical Page Name Shortening</span></p><p>In certain cases, Tapestry will shorten the the logical name of a page. For example, the page class org.example.pages.addr
ess.CreateAddress will be given a logical name of "address/Create" (the redundant "Address" is removed as a suffix). However, this only affects how the page is referenced in URLs; the template file will still be CreateAddress.tml, whether on the classpath, or as address/CreateAddress.tml (in the web context).</p><p><span>Tapestry actually creates multiple names for the name page: "address/Create" and "address/CreateAddress" are both synonymous. You can user either in Java code that refers to a page by name, or as the page parameter of a PageLink.</span></p><h2 id="PageNavigation-ComponentEventRequests&Responses">Component Event Requests & Responses</h2><p>Main Article: <a href="component-events.html">Component Events</a></p><p>Component event requests may take the form of hyperlinks (<a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/EventLink.html">EventLink</a> or <a class="external-link" href="http://tapest
ry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/ActionLink.html">ActionLink</a>) or form submissions (<a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/Form.html">Form</a>).</p><p>The value returned from an <a href="component-events.html">event handler method</a> controls the response sent to the client web browser.</p><p>The URL for a component event request identifies the name of the page, the nested id of the component, and the name of the event to trigger on the component (specified by the "event" parameter of EventLink, or "action" for an ActionLink). Further, a component event request may contain additional context information, which will be provided to the event handler method.</p><p>These URLs expose a bit of the internal structure of the application. Over time, as an application grows and is maintained, the ids of components may change. This means that component event request URLs should
not be bookmarked. Fortunately, users will rarely have the chance to do so (see below).</p><h3 id="PageNavigation-1.Nullresponse">1. Null response</h3><p>If the event handler method returns no value, or returns null, then the current page (the page containing the component) will render the response.</p><p>A page render URL for the current page is created and sent to the client as a client side redirect. The client browser will automatically submit a new request to generate the page.</p><p>The user will see the newly generated content in their browser. In addition, the URL in the browser's address bar will be a render request URL. Render request URLs are shorter and contain less application structure (for instance, they don't include component ids or event types). Render requests URLs are what your users will bookmark. The component event request URLs are transitory, meaningful only while the application is actively engaged, and not meant to be used in later sessions.</p><div class=
"code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">public Object onAction(){
+ <div id="ConfluenceContent"><parameter ac:name="style">float:right</parameter><parameter ac:name="title">Related Articles</parameter><parameter ac:name="class">aui-label</parameter><rich-text-body><parameter ac:name="showLabels">false</parameter><parameter ac:name="showSpace">false</parameter><parameter ac:name="title">Related Articles</parameter><parameter ac:name="cql">label in ("request-processing","rendering") and space = currentSpace()</parameter></rich-text-body><p>In essence, a Tapestry application is a number of related pages, working together. To some degree, each page is like an application unto itself.</p><p>Any individual request will be targeted at a single page. Requests come in two forms: </p><ul><li><em>component event</em> requests target a specific component on a specific page, triggering an event within that component</li><li><em>render</em> requests target a specific page, and stream the HTML markup for that page back to the client</li></ul><
p>This dichotomy between component event requests and render requests alleviates a number of problems in traditional web applications related to the browser back button, or to the user hitting the refresh button in their browser.</p><p><br clear="none"><span style="color: rgb(83,145,38);font-size: 20.0px;line-height: 1.5;">Logical Page Name Shortening</span></p><p>In certain cases, Tapestry will shorten the the logical name of a page. For example, the page class org.example.pages.address.CreateAddress will be given a logical name of "address/Create" (the redundant "Address" is removed as a suffix). However, this only affects how the page is referenced in URLs; the template file will still be CreateAddress.tml, whether on the classpath, or as address/CreateAddress.tml (in the web context).</p><p><span>Tapestry actually creates multiple names for the name page: "address/Create" and "address/CreateAddress" are both synonymous. You can user either in Java code that refers to a page by n
ame, or as the page parameter of a PageLink.</span></p><h2 id="PageNavigation-ComponentEventRequests&Responses">Component Event Requests & Responses</h2><p>Main Article: <a href="component-events.html">Component Events</a></p><p>Component event requests may take the form of hyperlinks (<a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/EventLink.html">EventLink</a> or <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/ActionLink.html">ActionLink</a>) or form submissions (<a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/corelib/components/Form.html">Form</a>).</p><p>The value returned from an <a href="component-events.html">event handler method</a> controls the response sent to the client web browser.</p><p>The URL for a component event request identifies the name of the page, the nested id of the comp
onent, and the name of the event to trigger on the component (specified by the "event" parameter of EventLink, or "action" for an ActionLink). Further, a component event request may contain additional context information, which will be provided to the event handler method.</p><p>These URLs expose a bit of the internal structure of the application. Over time, as an application grows and is maintained, the ids of components may change. This means that component event request URLs should not be bookmarked. Fortunately, users will rarely have the chance to do so (see below).</p><h3 id="PageNavigation-1.Nullresponse">1. Null response</h3><p>If the event handler method returns no value, or returns null, then the current page (the page containing the component) will render the response.</p><p>A page render URL for the current page is created and sent to the client as a client side redirect. The client browser will automatically submit a new request to generate the page.</p><p>The user will
see the newly generated content in their browser. In addition, the URL in the browser's address bar will be a render request URL. Render request URLs are shorter and contain less application structure (for instance, they don't include component ids or event types). Render requests URLs are what your users will bookmark. The component event request URLs are transitory, meaningful only while the application is actively engaged, and not meant to be used in later sessions.</p><plain-text-body>public Object onAction(){
return null;
-}</pre>
-</div></div><h3 id="PageNavigation-2.Stringresponse">2. String response</h3><p>When a string is returned, it is expected to be the logical name of a page (as opposed to the page's fully qualified class name). As elsewhere, the name of the page is case insensitive.</p><p>Again, a render request URL will be constructed and sent to the client as a redirect.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">public String onAction(){
+}</plain-text-body><h3 id="PageNavigation-2.Stringresponse">2. String response</h3><p>When a string is returned, it is expected to be the logical name of a page (as opposed to the page's fully qualified class name). As elsewhere, the name of the page is case insensitive.</p><p>Again, a render request URL will be constructed and sent to the client as a redirect.</p><plain-text-body>public String onAction(){
return "Index";
-}</pre>
-</div></div><h3 id="PageNavigation-3.Classresponse">3. Class response</h3><p>When a class is returned, it is expected to be a page class. Returning a page class from an event handler is safer for refactoring than returning a page name.</p><p>As with other response types, a render request URL will be constructed and sent to the client as a redirect.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">public Object onAction(){
+}</plain-text-body><h3 id="PageNavigation-3.Classresponse">3. Class response</h3><p>When a class is returned, it is expected to be a page class. Returning a page class from an event handler is safer for refactoring than returning a page name.</p><p>As with other response types, a render request URL will be constructed and sent to the client as a redirect.</p><plain-text-body>public Object onAction(){
return Index.class
-}</pre>
-</div></div><h3 id="PageNavigation-4.Pageresponse">4. Page response</h3><p>You may also return an instance of a page, rather than the name or class of a page.</p><p>A page may be injected via the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/InjectPage.html">InjectPage</a> annotation.</p><p>Often, you will configure the page in some way before returning the page (examples below).</p><p>You can also return a component within the page, but this will generate a runtime warning (unless you are doing a partial-page update via <a href="ajax-and-zones.html">Ajax</a>).</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">@InjectPage
+}</plain-text-body><h3 id="PageNavigation-4.Pageresponse">4. Page response</h3><p>You may also return an instance of a page, rather than the name or class of a page.</p><p>A page may be injected via the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/InjectPage.html">InjectPage</a> annotation.</p><p>Often, you will configure the page in some way before returning the page (examples below).</p><p>You can also return a component within the page, but this will generate a runtime warning (unless you are doing a partial-page update via <a href="ajax-and-zones.html">Ajax</a>).</p><plain-text-body>@InjectPage
private Index index;
public Object onAction(){
return index;
-}</pre>
-</div></div><h3 id="PageNavigation-5.HttpError">5. HttpError</h3><p>An event handler method may return a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/services/HttpError.html">HttpError</a> instance to send an error response to the client.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">public Object onAction(){
+}</plain-text-body><h3 id="PageNavigation-5.HttpError">5. HttpError</h3><p>An event handler method may return a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/services/HttpError.html">HttpError</a> instance to send an error response to the client.</p><plain-text-body>public Object onAction(){
return new HttpError(302, "The Error message);
-}</pre>
-</div></div><h3 id="PageNavigation-6.Linkresponse">6. Link response</h3><p>An event handler method may return a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/Link.html">Link</a> instance directly. The Link is converted into a URL and a client redirect to that URL is sent to the client.</p><p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ComponentResources.html">ComponentResources</a> object that is injected into your pages (and components) has methods for creating component links.</p><p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/services/PageRenderLinkSource.html">PageRenderLinkSource</a> service can be injected to allow links to other pages to be created (though that is rarely necessary, given the other options listed above).</p><h3 id="PageNavigation-7.Streamresponse">7. Stream response</h3><p>An event handler can als
o return a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/StreamResponse.html">StreamResponse</a> object, which encapsulates a stream to be sent directly to the client browser. This is useful for components that want to, say, generate an image or PDF and provide it to the client:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">public Object onAction(){
+}</plain-text-body><h3 id="PageNavigation-6.Linkresponse">6. Link response</h3><p>An event handler method may return a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/Link.html">Link</a> instance directly. The Link is converted into a URL and a client redirect to that URL is sent to the client.</p><p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ComponentResources.html">ComponentResources</a> object that is injected into your pages (and components) has methods for creating component links.</p><p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/services/PageRenderLinkSource.html">PageRenderLinkSource</a> service can be injected to allow links to other pages to be created (though that is rarely necessary, given the other options listed above).</p><h3 id="PageNavigation-7.Streamresponse">7. Stream response</h3><p>An event handler
can also return a <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/StreamResponse.html">StreamResponse</a> object, which encapsulates a stream to be sent directly to the client browser. This is useful for components that want to, say, generate an image or PDF and provide it to the client:</p><plain-text-body>public Object onAction(){
return new StreamResponse() {
@Override
public String getContentType() {
@@ -194,29 +95,24 @@ public Object onAction(){
response.setHeader("Content-Disposition", "attachment; filename=\"" + myFileName + "\"");
}
};
-}</pre>
-</div></div><p> </p><h3 id="PageNavigation-8.URLresponse">8. URL response</h3><p>A java.net.URL response is handled as a client redirect to an external URL. (In Tapestry 5.3.x and earlier this only works for non-Ajax requests.)</p><h3 id="PageNavigation-9.Objectresponse">9. Object response</h3><p>Any other type of object returned from an event handler method is an error.</p><h2 id="PageNavigation-PageRenderRequests">Page Render Requests</h2><p>Render requests are simpler in structure and behavior than component event requests. In the simplest case, the URL is simply the logical name of the page.</p><p>Pages may have an <em>activation context</em>. The activation context represents persistent information about the state of the page. In practical terms, the activation context is usually the id of some database-persistent object.</p><p>When a page has an activation context, the values of the context are appended to the URL path. For example, in <code>http://www.example.com/my
app/foo/bar</code> the "myapp" part is the servlet context (usually the name of your app), and the "foo/bar" part is the activation context, with "foo" being the first activation parameter and "bar" being the second.</p><p>It is common for most pages to not have any activation context.</p><p>The activation context may be explicitly set when the render request link is created (the PageLink component has a context parameter for this purpose).</p><p>When no explicit activation context is provided, the page itself is queried for its activation context. This querying takes the form of an event trigger. The event name is "passivate" (as we'll see shortly, there's a corresponding "activate"). The return value of the method is used as the context. For example:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">public class ProductDetail
+}</plain-text-body><p> </p><h3 id="PageNavigation-8.URLresponse">8. URL response</h3><p>A java.net.URL response is handled as a client redirect to an external URL. (In Tapestry 5.3.x and earlier this only works for non-Ajax requests.)</p><h3 id="PageNavigation-9.Objectresponse">9. Object response</h3><p>Any other type of object returned from an event handler method is an error.</p><h2 id="PageNavigation-PageRenderRequests">Page Render Requests</h2><p>Render requests are simpler in structure and behavior than component event requests. In the simplest case, the URL is simply the logical name of the page.</p><p>Pages may have an <em>activation context</em>. The activation context represents persistent information about the state of the page. In practical terms, the activation context is usually the id of some database-persistent object.</p><p>When a page has an activation context, the values of the context are appended to the URL path. For example, in <code>http://www.example
.com/myapp/foo/bar</code> the "myapp" part is the servlet context (usually the name of your app), and the "foo/bar" part is the activation context, with "foo" being the first activation parameter and "bar" being the second.</p><p>It is common for most pages to not have any activation context.</p><p>The activation context may be explicitly set when the render request link is created (the PageLink component has a context parameter for this purpose).</p><p>When no explicit activation context is provided, the page itself is queried for its activation context. This querying takes the form of an event trigger. The event name is "passivate" (as we'll see shortly, there's a corresponding "activate"). The return value of the method is used as the context. For example:</p><parameter ac:name="">java</parameter><plain-text-body>public class ProductDetail
{
private Product product;
. . .
long onPassivate() { return product.getId(); }
}
-</pre>
-</div></div><p>The activation context may consist of a series of values, in which case the return value of the method should be an array or a List.</p><div class="confluence-information-macro confluence-information-macro-information"><span class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div class="confluence-information-macro-body"><p>Note: If you are using the <a href="hibernate-user-guide.html">tapestry-hibernate</a> integration library and your passivate context is a Hibernate entity, then you can just use the entity itself, not its id. Tapestry will automatically extract the entity's id into the URL, and convert it back for the "activate" event handler method.</p></div></div><h2 id="PageNavigation-Pageactivation">Page activation</h2><p>When a page render request arrives, the page is <em>activated</em> before it is rendered.</p><div class="navmenu" style="float:right; background:#eee; margin:3px; padding:0 1em">
-<p> <strong>JumpStart Demos:</strong><br clear="none">
- <a class="external-link" href="http://jumpstart.doublenegative.com.au/jumpstart/examples/navigation/onactivateandonpassivate/3" rel="nofollow">onActivate and onPassivate</a><br clear="none">
- <a class="external-link" href="http://jumpstart.doublenegative.com.au/jumpstart/examples/infrastructure/handlingabadcontext/1" rel="nofollow">Handling A Bad Context</a></p></div>Activation serves two purposes:<ul><li>It allows the page to restore its internal state from data encoded into the URL (the activation context discussed above).</li><li>It provides coarse approach to validating access to the page.</li></ul><p>The later case – validation – is generally concerned with user identity and access; if you have pages that may only be accessed by certain users, you may use the page's activate event handler for verifying that access.</p><p>Page activation uses Tapestry's <em>Component Event</em> mechanism. See <a href="component-events.html">Component Events</a> for details.</p><p>A page's activate event handler mirrors its passivate handler:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> private Product product;
+</plain-text-body><p>The activation context may consist of a series of values, in which case the return value of the method should be an array or a List.</p><rich-text-body><p>Note: If you are using the <a href="hibernate-user-guide.html">tapestry-hibernate</a> integration library and your passivate context is a Hibernate entity, then you can just use the entity itself, not its id. Tapestry will automatically extract the entity's id into the URL, and convert it back for the "activate" event handler method.</p></rich-text-body><h2 id="PageNavigation-Pageactivation">Page activation</h2><p>When a page render request arrives, the page is <em>activated</em> before it is rendered.<plain-text-body>{float:right|background=#eee|padding=0 1em}
+ *JumpStart Demos:*
+ [onActivate and onPassivate|http://jumpstart.doublenegative.com.au/jumpstart/examples/navigation/onactivateandonpassivate/3]
+ [Handling A Bad Context|http://jumpstart.doublenegative.com.au/jumpstart/examples/infrastructure/handlingabadcontext/1]
+{float}</plain-text-body>Activation serves two purposes:</p><ul><li>It allows the page to restore its internal state from data encoded into the URL (the activation context discussed above).</li><li>It provides coarse approach to validating access to the page.</li></ul><p>The later case – validation – is generally concerned with user identity and access; if you have pages that may only be accessed by certain users, you may use the page's activate event handler for verifying that access.</p><p>Page activation uses Tapestry's <em>Component Event</em> mechanism. See <a href="component-events.html">Component Events</a> for details.</p><p>A page's activate event handler mirrors its passivate handler:</p><parameter ac:name="">java</parameter><plain-text-body> private Product product;
. . .
void onActivate(long productId)
{
product = productDAO.getById(productId);
}
. . .
-</pre>
-</div></div><p>Here's the relevant part: when the page renders, it is likely to include more component event request URLs (links and forms). The component event requests for those links and forms will <em>also</em> start by activating the page, before performing other work. This forms an unbroken chain of requests that include the same activation context.</p><p>To some degree, this same effect could be accomplished using a <a href="persistent-page-data.html">persistent page value</a>, but that requires an active servlet session, and the result is not bookmarkable.</p><p>Your activate event handler, like any event handler, may also return a value, which is treated identically to a return value of a component event method. This technique is commonly used as a simple access validation mechanism.</p><p>You sometimes need to handle multiple page activation scenarios in one page class. You could create multiple activate event handler methods with different arguments (see the "Multiple Me
thod Matches" section at <a href="component-events.html">Component Events</a> for details), but if you do so, you should generally return <code>true</code> from each to avoid having more than one activation event handler method from being called for each page request. However, a better approach is to create one method with an EventContext argument. Tapestry will populate the EventContext argument with all of the activation parameters, and the EventContext's <code>get</code> method will retrieve and coerce each parameter to the desired type. For example:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> . . .
+</plain-text-body><p>Here's the relevant part: when the page renders, it is likely to include more component event request URLs (links and forms). The component event requests for those links and forms will <em>also</em> start by activating the page, before performing other work. This forms an unbroken chain of requests that include the same activation context.</p><p>To some degree, this same effect could be accomplished using a <a href="persistent-page-data.html">persistent page value</a>, but that requires an active servlet session, and the result is not bookmarkable.</p><p>Your activate event handler, like any event handler, may also return a value, which is treated identically to a return value of a component event method. This technique is commonly used as a simple access validation mechanism.</p><p>You sometimes need to handle multiple page activation scenarios in one page class. You could create multiple activate event handler methods with different arguments (see the "Multi
ple Method Matches" section at <a href="component-events.html">Component Events</a> for details), but if you do so, you should generally return <code>true</code> from each to avoid having more than one activation event handler method from being called for each page request. However, a better approach is to create one method with an EventContext argument. Tapestry will populate the EventContext argument with all of the activation parameters, and the EventContext's <code>get</code> method will retrieve and coerce each parameter to the desired type. For example:</p><parameter ac:name="">java</parameter><plain-text-body> . . .
void onActivate(EventContext eventContext) {
@@ -235,14 +131,10 @@ public Object onAction(){
}
. . .
-</pre>
-</div></div><h2 id="PageNavigation-PageNavigationPatterns">Page Navigation Patterns</h2><p>This combination of action links and context and page context can be put together in any number of ways.</p><p>Let's take a typical master/detail relationship using the concept of a product catalog page. In this example, the ProductListing page is a list of products, and the ProductDetails page must display the details for a specific product.</p><h3 id="PageNavigation-Pattern1:Componenteventrequests/PersistentData">Pattern 1: Component event requests / Persistent Data</h3><p>In this pattern, the ProductListing page uses action events and a persistent field on the ProductDetails page.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>ProductListing.html</b></div><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> <t:loop source="products" value="product">
+</plain-text-body><h2 id="PageNavigation-PageNavigationPatterns">Page Navigation Patterns</h2><p>This combination of action links and context and page context can be put together in any number of ways.</p><p>Let's take a typical master/detail relationship using the concept of a product catalog page. In this example, the ProductListing page is a list of products, and the ProductDetails page must display the details for a specific product.</p><h3 id="PageNavigation-Pattern1:Componenteventrequests/PersistentData">Pattern 1: Component event requests / Persistent Data</h3><p>In this pattern, the ProductListing page uses action events and a persistent field on the ProductDetails page.</p><parameter ac:name="">java</parameter><parameter ac:name="title">ProductListing.html</parameter><plain-text-body> <t:loop source="products" value="product">
<a t:type="actionlink" t:id="select" context="product.id">${product.name}</a>
</t:loop>
-</pre>
-</div></div><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>ProductListing.java</b></div><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> @InjectPage
+</plain-text-body><parameter ac:name="">java</parameter><parameter ac:name="title">ProductListing.java</parameter><plain-text-body> @InjectPage
private ProductDetails details;
Object onActionFromSelect(long productId)
@@ -251,9 +143,7 @@ public Object onAction(){
return details;
}
-</pre>
-</div></div><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>ProductDetails.java</b></div><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> @Inject
+</plain-text-body><parameter ac:name="">java</parameter><parameter ac:name="title">ProductDetails.java</parameter><plain-text-body> @Inject
private ProductDAO dao;
private Product product;
@@ -267,9 +157,7 @@ public Object onAction(){
{
product = dao.getById(productId);
}
-</pre>
-</div></div><p>This is a minimal approach, perhaps good enough for a prototype.</p><p>When the user clicks a link, the component event request URL will initially be something like "http://.../productlisting.select/99" and the final render request URL will be something like "http://.../productdetails". Notice that the product id ("99") does not appear in the render request URL.</p><p>This pattern has the following drawbacks:</p><ul><li>It requires a session (to store the productId field between requests).</li><li>It may fail if the ProductDetails page is accessed before a valid product id is set.</li><li>The URL does not indicate the identity of the product; if the user bookmarks the URL and comes back later, they will trigger the previous case (no valid product id).</li></ul><p><span class="confluence-anchor-link" id="PageNavigation-activationpattern"></span></p><h3 id="PageNavigation-Pattern2:ComponentEventRequests/NoPersistentData">Pattern 2: Component Event Requests / No Persiste
nt Data</h3><p>We can improve the previous example without changing the ProductListing page, using a passivation and activation context to avoid the session and make the links more bookmarkable.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>ProductDetails.java</b></div><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> @Inject
+</plain-text-body><p>This is a minimal approach, perhaps good enough for a prototype.</p><p>When the user clicks a link, the component event request URL will initially be something like "http://.../productlisting.select/99" and the final render request URL will be something like "http://.../productdetails". Notice that the product id ("99") does not appear in the render request URL.</p><p>This pattern has the following drawbacks:</p><ul><li>It requires a session (to store the productId field between requests).</li><li>It may fail if the ProductDetails page is accessed before a valid product id is set.</li><li>The URL does not indicate the identity of the product; if the user bookmarks the URL and comes back later, they will trigger the previous case (no valid product id).</li></ul><p><parameter ac:name="">activationpattern</parameter></p><h3 id="PageNavigation-Pattern2:ComponentEventRequests/NoPersistentData">Pattern 2: Component Event Requests / No Persistent Data</h3><p>We can imp
rove the previous example without changing the ProductListing page, using a passivation and activation context to avoid the session and make the links more bookmarkable.</p><parameter ac:name="">java</parameter><parameter ac:name="title">ProductDetails.java</parameter><plain-text-body> @Inject
private ProductDAO dao;
private Product product;
@@ -286,17 +174,11 @@ public Object onAction(){
}
long onPassivate() { return productId; }
-</pre>
-</div></div><p>This change ensures that the render request URL will include the product id, i.e., "http://.../productdetails/99".</p><p>It has the advantage that the connection from page to page occurs in type-safe Java code, inside the onActionFromSelect method of ProductListing. It has the disadvantage that clicking a link requires two round trips to the server.</p><h3 id="PageNavigation-Pattern3:RenderRequestsOnly">Pattern 3: Render Requests Only</h3><p>This is the most common version of this master/detail relationship.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>ProductListing.html</b></div><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> <t:loop source="products" value="product">
+</plain-text-body><p>This change ensures that the render request URL will include the product id, i.e., "http://.../productdetails/99".</p><p>It has the advantage that the connection from page to page occurs in type-safe Java code, inside the onActionFromSelect method of ProductListing. It has the disadvantage that clicking a link requires two round trips to the server.</p><h3 id="PageNavigation-Pattern3:RenderRequestsOnly">Pattern 3: Render Requests Only</h3><p>This is the most common version of this master/detail relationship.</p><parameter ac:name="">java</parameter><parameter ac:name="title">ProductListing.html</parameter><plain-text-body> <t:loop source="products" value="product">
<a t:type="pagelink" page="productdetails" context="product.id">${product.name}</a>
</t:loop>
-</pre>
-</div></div><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>ProductListing.java</b></div><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">No code is needed to support the link.
-</pre>
-</div></div><div class="code panel pdl" style="border-width: 1px;"><div class="codeHeader panelHeader pdl" style="border-bottom-width: 1px;"><b>ProductDetails.java</b></div><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> @Inject
+</plain-text-body><parameter ac:name="">java</parameter><parameter ac:name="title">ProductListing.java</parameter><plain-text-body>No code is needed to support the link.
+</plain-text-body><parameter ac:name="">java</parameter><parameter ac:name="title">ProductDetails.java</parameter><plain-text-body> @Inject
private ProductDAO dao;
private Product product;
@@ -311,8 +193,7 @@ public Object onAction(){
}
long onPassivate() { return productId; }
-</pre>
-</div></div><p>The setProductId() method is no longer needed.</p><h3 id="PageNavigation-Limitations">Limitations</h3><p>As your application's workflow expands, you may find that there is not a reasonable way to avoid storing some data persistently between requests, outside of the page activation context. For example, if from the ProductDetails page, the user is allowed to navigate to related pages and then back to ProductDetails, it starts to become necessary to keep passing that product id around from page to page to page.</p><p>At some point, persistent values make more sense. Tapestry has several persistence strategies available, including one that stores data in URL query parameters. See <a href="persistent-page-data.html">Persistent Page Data</a> for details.</p></div>
+</plain-text-body><p>The setProductId() method is no longer needed.</p><h3 id="PageNavigation-Limitations">Limitations</h3><p>As your application's workflow expands, you may find that there is not a reasonable way to avoid storing some data persistently between requests, outside of the page activation context. For example, if from the ProductDetails page, the user is allowed to navigate to related pages and then back to ProductDetails, it starts to become necessary to keep passing that product id around from page to page to page.</p><p>At some point, persistent values make more sense. Tapestry has several persistence strategies available, including one that stores data in URL query parameters. See <a href="persistent-page-data.html">Persistent Page Data</a> for details.</p></div>
</div>
<div class="clearer"></div>
Modified: websites/production/tapestry/content/parallel-execution.html
==============================================================================
--- websites/production/tapestry/content/parallel-execution.html (original)
+++ websites/production/tapestry/content/parallel-execution.html Sat Sep 16 02:22:40 2017
@@ -27,14 +27,6 @@
</title>
<link type="text/css" rel="stylesheet" href="/resources/space.css" />
- <link href='/resources/highlighter/styles/shCoreCXF.css' rel='stylesheet' type='text/css' />
- <link href='/resources/highlighter/styles/shThemeCXF.css' rel='stylesheet' type='text/css' />
- <script src='/resources/highlighter/scripts/shCore.js' type='text/javascript'></script>
- <script src='/resources/highlighter/scripts/shBrushJava.js' type='text/javascript'></script>
- <script>
- SyntaxHighlighter.defaults['toolbar'] = false;
- SyntaxHighlighter.all();
- </script>
<link href="/styles/style.css" rel="stylesheet" type="text/css"/>
@@ -75,11 +67,7 @@
</div>
<div id="content">
- <div id="ConfluenceContent"><p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ioc/services/ParallelExecutor.html">ParallelExecutor</a> service allows a computation to occur in parallel.</p><p>It can be used in two ways. First, with an explicit <a class="external-link" href="http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/Future.html" rel="nofollow">Future</a>:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> Future<String> future = executor.invoke(new Invokable<String>() { ... });</pre>
-</div></div><p>The executor will submit the Invokable to a thread pool for execution in the background.</p><p>The ultimate value of the Invokable is available by invoking <code>get()</code> on the Future; this will block until the value is ready.</p><p>Other methods on Future can cancel the execution, or get the value only if it is ready within a timeout.</p><p>The thread pool is started automatically as needed, and will shutdown when the Registry itself is shutdown.</p><p>Another alternative will return an object proxy, not a Future:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> RSSFeed feed = executor.invoke(RSSFeed.class, new Invokable<RSSFeed>() { ... });</pre>
-</div></div><p>This only works if the type is an interface. A proxy for the interface is created around the Future object; any invocation on the proxy will invoke get() on the Future (that is, will block until the value is computed).</p><h1 id="ParallelExecution-Configuration">Configuration</h1><p>The behavior of the ParallelExecutor can be tuned with global configuration symbols.</p><p>Java constants for the configuration symbols are defined in <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ioc/IOCSymbols.html">IOCSymbols</a>.</p><h3 id="ParallelExecution-tapestry.thread-pool-enabled">tapestry.thread-pool-enabled</h3><p>If true, the default, then the thread pool will operate. If false, then ParallelExecutor's implementation changes to invoke the Invokable immediately, not in a pooled thread. This is useful in environments, such as <a class="external-link" href="http://code.google.com/appengine/" rel="nofollow">Google App Engine</a>,
that do not support the creation of threads and thread pools.</p><h3 id="ParallelExecution-tapestry.thread-pool.core-pool-size">tapestry.thread-pool.core-pool-size</h3><p>Minimum size of the thread pool. Defaults to 3.</p><h3 id="ParallelExecution-tapestry.thread-pool.max-pool-size">tapestry.thread-pool.max-pool-size</h3><p>Maximum number of threads (active or inactive) in the thread pool. Defaults to 20.</p><h3 id="ParallelExecution-tapestry.thread-pool.keep-alive">tapestry.thread-pool.keep-alive</h3><p>Time to keep waiting threads alive. Defaults to "1 m" (one minute).</p><h3 id="ParallelExecution-tapestry.thread-pool.queue-size">tapestry.thread-pool.queue-size</h3><p>
+ <div id="ConfluenceContent"><p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ioc/services/ParallelExecutor.html">ParallelExecutor</a> service allows a computation to occur in parallel.</p><p>It can be used in two ways. First, with an explicit <a class="external-link" href="http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/Future.html" rel="nofollow">Future</a>:</p><parameter ac:name="">java</parameter><plain-text-body> Future<String> future = executor.invoke(new Invokable<String>() { ... });</plain-text-body><p>The executor will submit the Invokable to a thread pool for execution in the background.</p><p>The ultimate value of the Invokable is available by invoking <code>get()</code> on the Future; this will block until the value is ready.</p><p>Other methods on Future can cancel the execution, or get the value only if it is ready within a timeout.</p><p>The thread pool is started automat
ically as needed, and will shutdown when the Registry itself is shutdown.</p><p>Another alternative will return an object proxy, not a Future:</p><parameter ac:name="">java</parameter><plain-text-body> RSSFeed feed = executor.invoke(RSSFeed.class, new Invokable<RSSFeed>() { ... });</plain-text-body><p>This only works if the type is an interface. A proxy for the interface is created around the Future object; any invocation on the proxy will invoke get() on the Future (that is, will block until the value is computed).</p><h1 id="ParallelExecution-Configuration">Configuration</h1><p>The behavior of the ParallelExecutor can be tuned with global configuration symbols.</p><p>Java constants for the configuration symbols are defined in <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/ioc/IOCSymbols.html">IOCSymbols</a>.</p><h3 id="ParallelExecution-tapestry.thread-pool-enabled">tapestry.thread-pool-enabled</h3><p>If true, the default, th
en the thread pool will operate. If false, then ParallelExecutor's implementation changes to invoke the Invokable immediately, not in a pooled thread. This is useful in environments, such as <a class="external-link" href="http://code.google.com/appengine/" rel="nofollow">Google App Engine</a>, that do not support the creation of threads and thread pools.</p><h3 id="ParallelExecution-tapestry.thread-pool.core-pool-size">tapestry.thread-pool.core-pool-size</h3><p>Minimum size of the thread pool. Defaults to 3.</p><h3 id="ParallelExecution-tapestry.thread-pool.max-pool-size">tapestry.thread-pool.max-pool-size</h3><p>Maximum number of threads (active or inactive) in the thread pool. Defaults to 20.</p><h3 id="ParallelExecution-tapestry.thread-pool.keep-alive">tapestry.thread-pool.keep-alive</h3><p>Time to keep waiting threads alive. Defaults to "1 m" (one minute).</p><h3 id="ParallelExecution-tapestry.thread-pool.queue-size">tapestry.thread-pool.queue-size</h3><p>
</p><div class="confluence-information-macro confluence-information-macro-information"><p class="title">Added in 5.3</p><span class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div class="confluence-information-macro-body">
</div></div>
Modified: websites/production/tapestry/content/parameter-type-coercion.html
==============================================================================
--- websites/production/tapestry/content/parameter-type-coercion.html (original)
+++ websites/production/tapestry/content/parameter-type-coercion.html Sat Sep 16 02:22:40 2017
@@ -27,14 +27,6 @@
</title>
<link type="text/css" rel="stylesheet" href="/resources/space.css" />
- <link href='/resources/highlighter/styles/shCoreCXF.css' rel='stylesheet' type='text/css' />
- <link href='/resources/highlighter/styles/shThemeCXF.css' rel='stylesheet' type='text/css' />
- <script src='/resources/highlighter/scripts/shCore.js' type='text/javascript'></script>
- <script src='/resources/highlighter/scripts/shBrushJava.js' type='text/javascript'></script>
- <script>
- SyntaxHighlighter.defaults['toolbar'] = false;
- SyntaxHighlighter.all();
- </script>
<link href="/styles/style.css" rel="stylesheet" type="text/css"/>
@@ -44,13 +36,26 @@
<div class="wrapper bs">
- <div id="navigation"><div class="nav"><ul class="alternate"><li><a href="index.html">Home</a></li><li><a href="getting-started.html">Getting Started</a></li><li><a href="documentation.html">Documentation</a></li><li><a href="download.html">Download</a></li><li><a href="about.html">About</a></li><li><a class="external-link" href="http://www.apache.org/licenses/LICENSE-2.0">License</a></li><li><a href="community.html">Community</a></li><li><a class="external-link" href="http://www.apache.org/security/">Security</a></li><li><a class="external-link" href="http://www.apache.org/">Apache</a></li><li><a class="external-link" href="http://www.apache.org/foundation/sponsorship.html">Sponsorship</a></li><li><a class="external-link" href="http://www.apache.org/foundation/thanks.html">Thanks</a></li></ul></div></div>
+ <div id="navigation"><div class="nav"><ul class="alternate"><li><a href="index.html">Home</a></li><li><a href="getting-started.html">Getting Started</a></li><li><a href="documentation.html">Documentation</a></li><li><a href="download.html">Download</a></li><li><a href="about.html">About</a></li><li><a class="external-link" href="http://www.apache.org/licenses/LICENSE-2.0">License</a></li><li><a href="community.html">Community</a></li><li><a class="external-link" href="http://www.apache.org/security/">Security</a></li><li><a class="external-link" href="http://www.apache.org/">Apache</a></li><li><a class="external-link" href="http://www.apache.org/foundation/sponsorship.html">Sponsorship</a></li><li><a class="external-link" href="http://www.apache.org/foundation/thanks.html">Thanks</a></li></ul></div>
+
+</div>
<div id="top">
- <div id="smallbanner"><div class="searchbox" style="float:right;margin: .3em 1em .1em 1em"><span style="color: #999; font-size: 90%">Tapestry docs, issues, wikis & blogs:</span><form enctype="application/x-www-form-urlencoded" method="get" action="http://tapestry.apache.org/search.html">
- <input type="text" name="q">
- <input type="submit" value="Search">
-</form></div><div class="emblem" style="float:left"><p><a href="index.html"><span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image confluence-external-resource" src="http://tapestry.apache.org/images/tapestry_small.png" data-image-src="http://tapestry.apache.org/images/tapestry_small.png"></span></a></p></div><div class="title" style="float:left; margin: 0 0 0 3em"><h1 id="SmallBanner-PageTitle">Parameter Type Coercion</h1></div></div>
+ <div id="smallbanner"><div class="searchbox" style="float:right;margin: .3em 1em .1em 1em"><span style="color: #999; font-size: 90%">Tapestry docs, issues, wikis & blogs:</span>
+<form enctype="application/x-www-form-urlencoded" method="get" action="http://tapestry.apache.org/search.html">
+ <input type="text" name="q">
+ <input type="submit" value="Search">
+</form>
+
+</div>
+
+
+<div class="emblem" style="float:left"><p><a href="index.html"><span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image confluence-external-resource" src="http://tapestry.apache.org/images/tapestry_small.png" data-image-src="http://tapestry.apache.org/images/tapestry_small.png"></span></a></p></div>
+
+
+<div class="title" style="float:left; margin: 0 0 0 3em"><h1 id="SmallBanner-PageTitle">Parameter Type Coercion</h1></div>
+
+</div>
<div class="clearer"></div>
</div>
@@ -62,44 +67,7 @@
</div>
<div id="content">
- <div id="ConfluenceContent"><p><strong style="text-align: justify;">Type Coercion</strong><span style="color: rgb(0,0,0);"> is the conversion of one type of object to a new object of a different type with similar content. Tapestry frequently must coerce objects from one type to another. A common example is the coercion of a string into an integer or a double.</span></p><p>See <a href="type-coercion.html">Type Coercer Service</a> for the list of build-in coercions.</p><h2 id="ParameterTypeCoercion-ParameterTypeCoercions">Parameter Type Coercions</h2><div class="aui-label" style="float:right" title="Related Articles"><h3>Related Articles</h3><ul class="content-by-label"><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="type-coercion.html">Type Coercion</a>
- </div> </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="parameter-type-coercion.html">Parameter Type Coercion</a>
- </div> </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="enum-parameter-recipe.html">Enum Parameter Recipe</a>
- </div> </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="supporting-informal-parameters.html">Supporting Informal Parameters</a>
- </div> </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="default-parameter.html">Default Parameter</a>
- </div> </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="component-parameters.html">Component Parameters</a>
- </div> </li></ul></div><p>Tapestry automatically handles type coercions for <a href="component-parameters.html">component parameters</a>.</p><p>Type coercions occur when a value passed into a parameter (as bound in a template or in an annotation) does not match the type of the parameter.</p><p>For example, consider the Count component:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;">public class Count
+ <div id="ConfluenceContent"><p><strong style="text-align: justify;">Type Coercion</strong><span style="color: rgb(0,0,0);"> is the conversion of one type of object to a new object of a different type with similar content. Tapestry frequently must coerce objects from one type to another. A common example is the coercion of a string into an integer or a double.</span></p><p>See <a href="type-coercion.html">Type Coercer Service</a> for the list of build-in coercions.</p><h2 id="ParameterTypeCoercion-ParameterTypeCoercions">Parameter Type Coercions</h2><parameter ac:name="style">float:right</parameter><parameter ac:name="title">Related Articles</parameter><parameter ac:name="class">aui-label</parameter><rich-text-body><parameter ac:name="showLabels">false</parameter><parameter ac:name="showSpace">false</parameter><parameter ac:name="title">Related Articles</parameter><parameter ac:name="cql">label in ("coercion","parameters") and space = currentSpace()</parame
ter></rich-text-body><p>Tapestry automatically handles type coercions for <a href="component-parameters.html">component parameters</a>.</p><p>Type coercions occur when a value passed into a parameter (as bound in a template or in an annotation) does not match the type of the parameter.</p><p>For example, consider the Count component:</p><parameter ac:name="language">java</parameter><plain-text-body>public class Count
{
@Parameter
private int start = 1;
@@ -111,11 +79,8 @@
private int value;
. . .
-</pre>
-</div></div><p>Here, the type of all three parameters is <code>int</code>.</p><p>However, it is likely that the component will be used as so:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
-<pre class="brush: java; gutter: false; theme: Default" style="font-size:12px;"> Merry Christmas: <t:count end="3"> Ho! </t:count>
-</pre>
-</div></div><p>A bare whole number is interpreted by the prop binding prefix as a <code>long</code>. So this is the <em>long</em> value 3.</p><p>Tapestry will automatically coerce the bound value, a <code>long</code>, to the parameter's type, <code>int</code>. This may be a lossy coercion (if the <code>long</code> represents a number larger than can be stored in an <code>int</code>).</p><h2 id="ParameterTypeCoercion-TypeCoercerService">TypeCoercer Service</h2><p>Main Article: <a href="type-coercion.html">Type Coercion</a></p><p>The TypeCoercer service is responsible for this type coercion. This service is part of the <a href="ioc.html">tapestry-ioc</a> module. The service is quite extensible, allowing for new types and coercions to be added easily. The TapestryModule contributes a few additional coercions into the TypeCoercer service.</p></div>
+</plain-text-body><p>Here, the type of all three parameters is <code>int</code>.</p><p>However, it is likely that the component will be used as so:</p><parameter ac:name="language">java</parameter><plain-text-body> Merry Christmas: <t:count end="3"> Ho! </t:count>
+</plain-text-body><p>A bare whole number is interpreted by the prop binding prefix as a <code>long</code>. So this is the <em>long</em> value 3.</p><p>Tapestry will automatically coerce the bound value, a <code>long</code>, to the parameter's type, <code>int</code>. This may be a lossy coercion (if the <code>long</code> represents a number larger than can be stored in an <code>int</code>).</p><h2 id="ParameterTypeCoercion-TypeCoercerService">TypeCoercer Service</h2><p>Main Article: <a href="type-coercion.html">Type Coercion</a></p><p>The TypeCoercer service is responsible for this type coercion. This service is part of the <a href="ioc.html">tapestry-ioc</a> module. The service is quite extensible, allowing for new types and coercions to be added easily. The TapestryModule contributes a few additional coercions into the TypeCoercer service.</p></div>
</div>
<div class="clearer"></div>
Modified: websites/production/tapestry/content/performance-and-clustering.html
==============================================================================
--- websites/production/tapestry/content/performance-and-clustering.html (original)
+++ websites/production/tapestry/content/performance-and-clustering.html Sat Sep 16 02:22:40 2017
@@ -36,13 +36,26 @@
<div class="wrapper bs">
- <div id="navigation"><div class="nav"><ul class="alternate"><li><a href="index.html">Home</a></li><li><a href="getting-started.html">Getting Started</a></li><li><a href="documentation.html">Documentation</a></li><li><a href="download.html">Download</a></li><li><a href="about.html">About</a></li><li><a class="external-link" href="http://www.apache.org/licenses/LICENSE-2.0">License</a></li><li><a href="community.html">Community</a></li><li><a class="external-link" href="http://www.apache.org/security/">Security</a></li><li><a class="external-link" href="http://www.apache.org/">Apache</a></li><li><a class="external-link" href="http://www.apache.org/foundation/sponsorship.html">Sponsorship</a></li><li><a class="external-link" href="http://www.apache.org/foundation/thanks.html">Thanks</a></li></ul></div></div>
+ <div id="navigation"><div class="nav"><ul class="alternate"><li><a href="index.html">Home</a></li><li><a href="getting-started.html">Getting Started</a></li><li><a href="documentation.html">Documentation</a></li><li><a href="download.html">Download</a></li><li><a href="about.html">About</a></li><li><a class="external-link" href="http://www.apache.org/licenses/LICENSE-2.0">License</a></li><li><a href="community.html">Community</a></li><li><a class="external-link" href="http://www.apache.org/security/">Security</a></li><li><a class="external-link" href="http://www.apache.org/">Apache</a></li><li><a class="external-link" href="http://www.apache.org/foundation/sponsorship.html">Sponsorship</a></li><li><a class="external-link" href="http://www.apache.org/foundation/thanks.html">Thanks</a></li></ul></div>
+
+</div>
<div id="top">
- <div id="smallbanner"><div class="searchbox" style="float:right;margin: .3em 1em .1em 1em"><span style="color: #999; font-size: 90%">Tapestry docs, issues, wikis & blogs:</span><form enctype="application/x-www-form-urlencoded" method="get" action="http://tapestry.apache.org/search.html">
- <input type="text" name="q">
- <input type="submit" value="Search">
-</form></div><div class="emblem" style="float:left"><p><a href="index.html"><span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image confluence-external-resource" src="http://tapestry.apache.org/images/tapestry_small.png" data-image-src="http://tapestry.apache.org/images/tapestry_small.png"></span></a></p></div><div class="title" style="float:left; margin: 0 0 0 3em"><h1 id="SmallBanner-PageTitle">Performance and Clustering</h1></div></div>
+ <div id="smallbanner"><div class="searchbox" style="float:right;margin: .3em 1em .1em 1em"><span style="color: #999; font-size: 90%">Tapestry docs, issues, wikis & blogs:</span>
+<form enctype="application/x-www-form-urlencoded" method="get" action="http://tapestry.apache.org/search.html">
+ <input type="text" name="q">
+ <input type="submit" value="Search">
+</form>
+
+</div>
+
+
+<div class="emblem" style="float:left"><p><a href="index.html"><span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image confluence-external-resource" src="http://tapestry.apache.org/images/tapestry_small.png" data-image-src="http://tapestry.apache.org/images/tapestry_small.png"></span></a></p></div>
+
+
+<div class="title" style="float:left; margin: 0 0 0 3em"><h1 id="SmallBanner-PageTitle">Performance and Clustering</h1></div>
+
+</div>
<div class="clearer"></div>
</div>
@@ -54,51 +67,7 @@
</div>
<div id="content">
- <div id="ConfluenceContent"><p>Tapestry has a great <strong>performance</strong> story to tell. It's designed to take advantage of the speed of the modern JVM: no reflection, built to support a high level of concurrency without contention, and clean, lightweight code paths. In addition, there is built-in integrated GZIP content compression, far-future expires headers on static resources, JavaScript aggregation and minification, and an intentionally lightweight use of the HTTPSession. The result is a blistering fast framework. See <a class="external-link" href="http://tapestry.apache.org/2011/06/13/tapestrys-performance-tested.html">Tapestry's Performance Tested</a> for some objective numbers.</p><div class="aui-label" style="float:right" title="Related Articles"><h3>Related Articles</h3><ul class="content-by-label"><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="performance-and-clustering.html">Performance and Clustering</a>
- </div> </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="session-storage.html">Session Storage</a>
- </div> </li><li>
- <div>
- <span class="icon aui-icon aui-icon-small aui-iconfont-page-default" title="Page">Page:</span>
- </div>
- <div class="details">
- <a href="persistent-page-data.html">Persistent Page Data</a>
- </div> </li></ul></div><h2 id="PerformanceandClustering-PerformanceTips">Performance Tips</h2><p>But even with all of Tapestry's built-in speediness, to really get top performance you'll need to be sure you're not hamstringing Tapestry. As a start, use the following checklist:</p><ul><li>Ensure (be absolutely sure) that <a href="configuration.html">Production Mode</a> is turned on in production.</li><li>Minimize the use of the HTTPSession (see below), especially if you're using clustering.</li><li>Set <a href="configuration.html">tapestry.clustered-sessions</a> to "false" if you aren't using clustering.</li><li>Organize your JavaScript files into <a href="legacy-javascript.html">JavaScriptStacks</a>.</li><li>Ensure that your static resources (images, CSS, JavaScript) are being cached by the browser.<ul><li>Use "asset:" or "context:" <a href="component-parameters.html">binding prefixes</a> for all links to static resources (images, CSS, JavaScript).</li><li>Make sure that your
firewall, proxy server, load balancer, front-end web servers, and app servers all allow caching of static resources.</li><li>Ensure "cache-control" and "vary" HTTP headers are set correctly for your static resources.</li><li>Use a client-based tool (like Firebug) to examine the requests that your browser makes as you navigate through the site. You should <em>not</em> see repeated requests for static resources.</li></ul></li><li>Consider using a <a class="external-link" href="http://en.wikipedia.org/wiki/Content_delivery_network" rel="nofollow">Content Delivery Network</a> for static parts of your site.</li></ul><p>After all of the above issues are addressed, if you still have performance problems, they probably aren't related to Tapestry.</p><h2 id="PerformanceandClustering-ClusteringversusStickySessions">Clustering versus Sticky Sessions</h2><p>For web applications, <strong>clustering</strong> is a load-balancing technique in which multiple application servers are set up to behave
as one big server. Generally this requires replicating HttpSession data across the servers, to ensure that a user's web interactions will continue without interruption regardless of which server handles the next request. Session replication achieves very high reliability, but it incurs an extra performance cost (due to the serializing and deserializing of session data and the extra network traffic required).</p><p>In contrast, <strong>Sticky Sessions</strong> (also called <em>session persistence</em> or <em>sticky persistence</em>) is a load balancing technique in which each session is assigned to a particular server for the duration of the session. This approach doesn't require copying HTTPSession data between servers, so it's very scalable. But if a server goes down, all of its sessions are lost.</p><p>In general, the sticky sessions approach is the way to go when possible (that is, when performance is more important than session survival). It represents a much more efficient use
of resources ... you are scaling <em>out</em> not <em>up</em>, which is always cheaper. It also means that you don't have to be as careful about what goes into the HTTPSession.</p><p><em>For details on setting up clustering and sticky sessions, see the documentation of whatever load balancer you are using.</em></p><h2 id="PerformanceandClustering-Clustering">Clustering</h2><p>Tapestry is designed to be "a good citizen" of an application server that supports clustering. It is careful about what it writes into the HttpSession. The framework understands that the server that receives a request may not be the same one that rendered the page initially; this knowledge affects many code paths, and it guides the approach Tapestry takes to caching page and component properties.</p><p>Your part is to properly manage the objects put into the HttpSession (via @SessionAttribute, @SessionState or @Persist; see <a href="session-storage.html">Session Storage</a>):</p><ul><li>Don't store anything i
n the session that you don't have to. Principally this means minimizing the use of @Persist (see <a href="page-navigation.html">Page Activation</a> and <a href="using-select-with-a-list.html">Using Select With a List</a>), storing only IDs in the session rather than whole entities.</li><li>Where possible, persist only objects that are immutable (i.e., String, or a primitive or wrapper type).</li><li>Only put <em>serializable</em> objects into the session.</li><li>Make use of the @ImmutableSessionPersistedObject annotation and OptimizedSessionPersistedObject interface (both described below).</li></ul><p>Again, Tapestry is a good citizen, but from the application server's point of view, it's just another servlet application. The heavy lifting here is application server specific.</p><p></p><h2 id="PerformanceandClustering-ClusteringIssues">Clustering Issues</h2>
-
-<p>The Servlet API was designed with the intention that there would be only a modest amount of server-side state, and that the stored values would be individual numbers and strings, and thus, immutable.</p>
-
-<p>However, many web applications do not use the HttpSession this way, instead storing large, mutable objects in the session. This is not a problem for single servers, but in a cluster, anything stored in the session must be serialized to a bytestream and distributed to other servers within the cluster, and restored there.</p>
-
-<p>Most application servers perform that serialization and distribution whenever HttpSession.setAttribute() is called. This creates a data consistency problem for mutable objects, because if you read a mutable session object, change its state, but <em>don't</em> invoke setAttribute(), the changes will be isolated to just a single server in the cluster.</p>
-
-<p>Tapestry attempts to solve this: any session-persisted object that is read during a request will be re-stored back into the HttpSession at the end of the request. This ensures that changed internal state of those mutable objects is properly replicated around the cluster.</p>
-
-<p>But while this solution solves the data consistency problem, it does so at the expense of performance, since all of those calls to setAttribute() result in extra session data being replicated needlessly if the internal state of the mutable object hasn't changed.</p>
-
-<p>Tapestry has solutions to this, too:</p>
-
-<h3 id="PerformanceandClustering-@ImmutableSessionPersistedObjectAnnotation">@ImmutableSessionPersistedObject Annotation</h3>
-
-<p>Tapestry knows that Java's String, Number and Boolean classes are immutable. Immutable objects do not require a re-store into the session.</p>
-
-<p>You can mark your own session objects as immutable (and thus not requiring session replication) using the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/annotations/ImmutableSessionPersistedObject.html">ImmutableSessionPersistedObject</a> annotation.</p>
-
-<h3 id="PerformanceandClustering-OptimizedSessionPersistedObjectInterface">OptimizedSessionPersistedObject Interface</h3>
-
-<p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/OptimizedSessionPersistedObject">OptimizedSessionPersistedObject</a> interface allows an object to control this behavior. An object with this interface can track when its mutable state changes. Typically, you should extend from the <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/BaseOptimizedSessionPersistedObject.html">BaseOptimizedSessionPersistedObject</a> base class.</p>
-
-<h3 id="PerformanceandClustering-SessionPersistedObjectAnalyzerService">SessionPersistedObjectAnalyzer Service</h3>
-
-<p>The <a class="external-link" href="http://tapestry.apache.org/current/apidocs/org/apache/tapestry5/services/SessionPersistedObjectAnalyzer.html">SessionPersistedObjectAnalyzer</a> service is ultimately responsible for determining whether a session persisted object is dirty or not (dirty meaning in need of a restore into the session). This is an extensible service where new strategies, for new classes, can be introduced.</p></div>
+ <div id="ConfluenceContent"><p>Tapestry has a great <strong>performance</strong> story to tell. It's designed to take advantage of the speed of the modern JVM: no reflection, built to support a high level of concurrency without contention, and clean, lightweight code paths. In addition, there is built-in integrated GZIP content compression, far-future expires headers on static resources, JavaScript aggregation and minification, and an intentionally lightweight use of the HTTPSession. The result is a blistering fast framework. See <a class="external-link" href="http://tapestry.apache.org/2011/06/13/tapestrys-performance-tested.html">Tapestry's Performance Tested</a> for some objective numbers.</p><parameter ac:name="style">float:right</parameter><parameter ac:name="title">Related Articles</parameter><parameter ac:name="class">aui-label</parameter><rich-text-body><parameter ac:name="showLabels">false</parameter><parameter ac:name="showSpace">false</parameter><paramete
r ac:name="title">Related Articles</parameter><parameter ac:name="cql">label = "persistence" and space = currentSpace()</parameter></rich-text-body><h2 id="PerformanceandClustering-PerformanceTips">Performance Tips</h2><p>But even with all of Tapestry's built-in speediness, to really get top performance you'll need to be sure you're not hamstringing Tapestry. As a start, use the following checklist:</p><ul><li>Ensure (be absolutely sure) that <a href="configuration.html">Production Mode</a> is turned on in production.</li><li>Minimize the use of the HTTPSession (see below), especially if you're using clustering.</li><li>Set <a href="configuration.html">tapestry.clustered-sessions</a> to "false" if you aren't using clustering.</li><li>Organize your JavaScript files into <a href="legacy-javascript.html">JavaScriptStacks</a>.</li><li>Ensure that your static resources (images, CSS, JavaScript) are being cached by the browser.<ul><li>Use "asset:" or "context:" <a href="component-para
meters.html">binding prefixes</a> for all links to static resources (images, CSS, JavaScript).</li><li>Make sure that your firewall, proxy server, load balancer, front-end web servers, and app servers all allow caching of static resources.</li><li>Ensure "cache-control" and "vary" HTTP headers are set correctly for your static resources.</li><li>Use a client-based tool (like Firebug) to examine the requests that your browser makes as you navigate through the site. You should <em>not</em> see repeated requests for static resources.</li></ul></li><li>Consider using a <a class="external-link" href="http://en.wikipedia.org/wiki/Content_delivery_network" rel="nofollow">Content Delivery Network</a> for static parts of your site.</li></ul><p>After all of the above issues are addressed, if you still have performance problems, they probably aren't related to Tapestry.</p><h2 id="PerformanceandClustering-ClusteringversusStickySessions">Clustering versus Sticky Sessions</h2><p>For web applica
tions, <strong>clustering</strong> is a load-balancing technique in which multiple application servers are set up to behave as one big server. Generally this requires replicating HttpSession data across the servers, to ensure that a user's web interactions will continue without interruption regardless of which server handles the next request. Session replication achieves very high reliability, but it incurs an extra performance cost (due to the serializing and deserializing of session data and the extra network traffic required).</p><p>In contrast, <strong>Sticky Sessions</strong> (also called <em>session persistence</em> or <em>sticky persistence</em>) is a load balancing technique in which each session is assigned to a particular server for the duration of the session. This approach doesn't require copying HTTPSession data between servers, so it's very scalable. But if a server goes down, all of its sessions are lost.</p><p>In general, the sticky sessions approach is the way to go
when possible (that is, when performance is more important than session survival). It represents a much more efficient use of resources ... you are scaling <em>out</em> not <em>up</em>, which is always cheaper. It also means that you don't have to be as careful about what goes into the HTTPSession.</p><p><em>For details on setting up clustering and sticky sessions, see the documentation of whatever load balancer you are using.</em></p><h2 id="PerformanceandClustering-Clustering">Clustering</h2><p>Tapestry is designed to be "a good citizen" of an application server that supports clustering. It is careful about what it writes into the HttpSession. The framework understands that the server that receives a request may not be the same one that rendered the page initially; this knowledge affects many code paths, and it guides the approach Tapestry takes to caching page and component properties.</p><p>Your part is to properly manage the objects put into the HttpSession (via @SessionAttrib
ute, @SessionState or @Persist; see <a href="session-storage.html">Session Storage</a>):</p><ul><li>Don't store anything in the session that you don't have to. Principally this means minimizing the use of @Persist (see <a href="page-navigation.html">Page Activation</a> and <a href="using-select-with-a-list.html">Using Select With a List</a>), storing only IDs in the session rather than whole entities.</li><li>Where possible, persist only objects that are immutable (i.e., String, or a primitive or wrapper type).</li><li>Only put <em>serializable</em> objects into the session.</li><li>Make use of the @ImmutableSessionPersistedObject annotation and OptimizedSessionPersistedObject interface (both described below).</li></ul><p>Again, Tapestry is a good citizen, but from the application server's point of view, it's just another servlet application. The heavy lifting here is application server specific.</p><p><parameter ac:name=""><a href="clustering-issues.html">Clustering Issues</a><
/parameter></p></div>
</div>
<div class="clearer"></div>