The 
pageContext
 object for the JSP page where the tag is located; this object can be used 
to access defined objects.
The 
parent
 tag handler for the enclosing action.
A tag handler may have additional properties, as any other JavaBean component.  These 
properties will have setters and getter methods, as described in the JavaBeans component 
specification, and used throughout the Java platform.
All attributes of a custom action must be JavaBeans component properties, although some 
properties may not be exposed as attributes in the Tag Library Descriptor.
Additional translation time information (
TagExtraInfo
) associated with the action 
indicates the name of the variables it introduces, their types and their scope. At specific 
moments (after processing the start tag; after processing the end tag), the JSP container can 
automatically synchronize the PageContext information with variables in the scripting 
language so they can be made available directly through the scripting elements.
5.4.2
Basic Protocol: Tag Interface
This section describes the 
Tag
 interface which defines the basic contract for all tag handlers. 
See Section 5.4.7 for a summary of the life cycle issues.
A tag handler has some 
properties
 that must be initialized before it can be used.  It is the 
responsibility of the JSP container to invoke the appropriate setter methods to initialize these 
properties.  Once properly set, these properties are expected to be persistent, so that if the 
JSP container ascertains that a property has already been set on a given tag handler instance, 
it needs not set it again. These properties include the properties in the Tag interface as well 
as other properties
Once initialized, the 
doStartTag
 and 
doEndTag
 methods can be invoked on the tag 
handler.  Between these invocations, the tag handler is assumed to hold a state that must be 
preserved.  After the 
doEndTag
 invocation, the tag handler is available for further 
invocations (and it is expected to have retained its properties). Once all invocations on the 
tag handler are completed, the 
release
 method is invoked on it.  Once a 
release
 method 
is invoked all properties are assumed to have been reset to an unspecified value.
Properties
All tag handlers must have the following properties: pageContext, and parent. When setting 
properties, the order is always 
pageContext and parent. 
The 
Tag
 interface specifies the setter 
methods for all properties, and the getter method for parent.
setPageContext(PageContext)
Sets the pageContext property of a tag handler.
setParent(Tag)
Sets the parent Tag for a tag handler. 
101
JavaServer Pages 1.1 Specification  
November 30, 1999




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