THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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In most cases, each component class will have a corresponding component template. However, it is also possible for a component class to emit all of its markup itself, without using a template.
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In this example, just like the first one, the component's only job is to write out a fixed message. The @BeginRender annotation is a type of render phase annotation
, a method annotation that instructs Tapestry when and under what circumstances to invoke methods of your class.
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In previous versions of Tapestry there was also the concept of a start page configured with the tapestry.start-page-name configuration symbol (defaults to "start"). If a page with a name as configured with that symbol exists at the root level, this page is used as the root URL. This has precedence over an existing Index page. If for example you have a page class com.example.myapp.pages.Start it will map to /.
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Component classes are monitored for changes by the framework. Classes are reloaded when changed. This allows you to build your application with a speed approaching that of a scripting environment, without sacrificing any of the power of the Java platform.
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Unless an instance variable is decorated with an annotation, it will be a transient instance variable. This means that its value resets to its default value at the end of reach request (when the page is detached from the request
).
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Never initialize an instance field to a mutable object at the point of declaration. If this is done, the instance created from that initializer becomes the default value for that field and is reused inside the component on every request. This could cause state to inadvertently be shared between different sessions in an application. |
| Deprecated | ||
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| For Tapestry 5.1 and earlier, in the rare event that you have a variable that can keep its value between requests and you would like to defeat that reset logic, then you can add a @Retain annotation to the field. You should take care that no client-specific data is stored into such a field, since on a later request the same page instance may be used for a different user. Likewise, on a later request for the same client, a different page instance may be used. |
Use persistent fields to hold client-specific information from one request to the next.
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Components often contain other components. Components inside another component's template are called embedded components. The containing component's template will contain special elements, in the Tapestry namespace, identifying where the the embedded components go.
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