Mark Baker wrote:
> Sure, but your service oriented approach also has to define those
> things *and* the operations. That's extra agreement that my solution
> doesn't require, because my solution reuses existing pervasively
> understood operations. I'd call that simpler.
Last time I looked it took more than zero lines of code to make an HTTP service
implementation respond to a particular HTTP operation in any particular
language. That's not "free". There is always code to write. The question is,
where is the most bang for the buck in the lines of code that you do write.
Are
you implementing an API interface or are you implementing an API entry point?
In a Java Servlet, I have to implement the API entry point for each operation.
I have to look at the request parameters using call backs on API objects. I
have to call things to set the mime-type of the returned value and I have to
"write" the returned data out to the client.
In a Java RMI service I have
public int add( int a1, int a2 ) {
return a1 + a2;
}
in a Java servlet I have at a minimum these lines to get started.
public void doGet( HttpServletRequest req, HttpServletResponse res ) {
parameter1 = getInitParameter("path.to.resources");
String path = req.getPathInfo(); // get resource name.
ServletOutputStream out = res.getOutputStream();
res.setContentType("...");
out.write(...);
}
The programming model and the mechanism are at a much lower level from the
programmers perspective. If I'm using Java, why would I want to do so many
type
conversion/mappings to just make things work?
In the newest incantations of Java Enterprise Edition, one can use annotations
to indicate that some class is a service and that some of the methods are
actually service operations. So, the lines typed (which is pretty much a
tracking point for number of errors per application), are less than before, and
from my experience both JEE and Jini/RMI have a much reduced labor compared to
a
HTTP programming environment such as the servlet model in Java.
Gregg Wonderly
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