The template is the part where the static portions (plain text/HTML) of
the web page needs to be provided, that will be rendered by Tapestry
unaltered. In addition to providing the static portions of the page,
the template is also used to provide placeholder tags for the dynamic
portions of the page. The placeholder tags are XML-like (no scripting
here!); in other words every open tag should have a matching close tag.
The placeholder tags are identified by a unique user-provided id
specified using a special markup tag attribute,
jwcid, as
shown in the
<span> tag in our example template. It
is the
jwcid attribute of the placeholder tag that is of
importance to Tapestry; the placeholder tag itself is irrelevant, it
could have as well been
<xyz> in our example. But
the
<span> tag was chosen instead, so the page can
be previewed properly outside the context of a Tapestry application.
The
jwcid attribute instructs Tapestry that an instance of
a JWC, declared in the specification below, is to be created and
plugged in place of the placeholder tag. The placeholder tag can have
attributes other than
jwcid. How Tapestry interprets and
treats these attributes is dependent on the specification of the
component that will be plugged in. Some components (like the one we
have used in our Home Page) instruct the framework to silently filter
out the irrelevant attributes of the placeholder tag and its enclosing
body when it is rendered. Thus our
user JWC, when
rendered, will not render the text "
User Name"
enclosed by the placeholder tag. Please see "Tapestry Component
Reference" under "Documentation" on
Tapestry's home page for more information
on the core component specifications. In any case, the newly created
instance of JWC is assigned the user-specified id (
user in
our example) that may be used later to reference this JWC. The
template, as one can see, is for the most part plain HTML except for
the XML-like placeholder tags. This allows a page designer with no
programming knowledge, a more natural undertaker of the task to build
and maintain web pages, to easily take over the responsibility of
building and maintaining the template through the life of the
application.