BServletView

Overview

A Servlet View is Niagara view that typically generates HTML.

Alternatives to extending BWebServlet are…

BServletView: used by developers who want to create Web Views on Components.
Java Servlets: create standard Java Servlets.

Please note…

BHxView extends BServletView and may be a preferred alternative. Click here for more information on creating Hx Views.
In Niagara 4’s new Open Web architecture, you can create client side views in JavaScript. You may find this a better alternative than traditional Server Side Servlet programming for User Interfaces.

A developer creates a Servlet View in the following way…

Extend javax.baja.sys.BServletView.
Override doGet or any other HTTP verb related methods to handle implementation.
Register the View as an Agent on the desired Niagara Type.

A few things to note about BServletView…

BServletView extends BSingleton. Therefore, there’s only ever one instance of a View.
BHxView extends BServletView.

Example

Here’s an example of a Servlet View that will be rendered in a web browser when the user navigates to the UserService. Please note, in this case the view is declared as an Agent on baja:UserService.

public final class BMyFirstServletView extends BServletView
{
  private BMyFirstServletView() {}
  public static final BMyFirstServletView INSTANCE = new BMyFirstServletView();

  @Override
  public Type getType() { return TYPE; }
  public static final Type TYPE = Sys.loadType(BMyFirstServletView.class);

  @Override
  public void doGet(WebOp op) throws Exception
  {
    op.getHtmlWriter()
      .w("<!DOCTYPE html>").nl()
      .w("<html>").nl()
      .w("<head></head>").nl()
      .w("<body>").nl()
      .w("<h1>Hello World!</h1>").nl()
      .w("</body></html>");
  }
}