[Jakarta-velocity Wiki] Update of "YmtdEmbeddedUsage" by WillGlassHusain

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The following page has been changed by WillGlassHusain:
http://wiki.apache.org/jakarta-velocity/YmtdEmbeddedUsage

New page:
== Embedded Usage ==


This is an example of using Velocity within an application.

{{{
    OutputStreamWriter writer = new OutputStreamWriter(output, encoding);
    Template template = RunTime.getTemplate(filename);
    template.merge( context, writer );
}}}


In other words, the above is translated into:
 1. Create a Writer.
 1. Ask the Velocity !RunTime to retrieve the Template.
 1. Merge the Context with the Template.

Velocity templates can contain '''any''' type of data. It can be XML, SQL,
HTML, plain text, internationalized text, anything. The parser is very
robust in terms of only parsing out what it cares about and ignoring the
rest. As demonstrated above, it is possible to embed Velocity's template
engine into any other Java code. The advantage of this is that it
provides users with a single template system for all sorts of uses.


For example, in the [http://java.sun.com/j2ee/blueprints/sample_application/index.html PetStore example] 
on the J2EE website, there is a !JavaBean which sends an
email confirmation when an order is complete. The unfortunate part about
this example is that in order to change the contents of the email, one
needs to edit Java code. Of course this example could have been done
differently to use a JSP based template as the base format. However, the
implementation of this is more difficult than simply creating a 
[http://www.working-dogs.com/turbine/cvsweb/index.cgi/turbine/src/java/org/apache/turbine/util/velocity/ Java object] 
which resides in the Context that can take as arguments the template to render.


Another example of this is the [http://jakarta.apache.org/velocity/texen.html Texen] 
and [http://jakarta.apache.org/velocity/anakia.html Anakia] tools
that come with Velocity. The advantage again is the ability to use
Velocity as an embedded tool to produce other useful applications that
are not bound strictly to a web application. While it is most likely
possible to do this with the JSP engine, it is significantly more
difficult to do so.


You make the decision.

YmtdTaglibs <- Previous | Next -> YmtdImplementation

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