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Is it difficult to make a mainly stateless web application with Wicket?

Answer 1

+4 A:

When building stateless pages with Wicket, you do lose most 'smart' built-in components, for example paginated tables and trees.

I think this is less an issue for sites, blogs and the like, which usually have a fairly simpler navigation model and don't use this kind of 'rich' component, and use stateless-server-friendly, Javascript-based components/effects, like jQuery-UI or YUI instead.

Some things you'll do differently, like pagination. For example, instead of using built-in pagination components, you'll have to make your own mechanism, using page parameters and stateless links:

HomePage.html

<html xmlns:wicket="http://wicket.apache.org"&gt;
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
  <div class="container">

    <div wicket:id="posts">
      <h2 wicket:id="title"></h2>
      <p wicket:id="content"></p>
      Posted on <span wicket:id="date"></span>
    </div>

    <div>
      <a wicket:id="recentPosts">&lt;&lt; Recent posts</a>
      <a wicket:id="previousPosts">Previous posts &gt;&gt;</a>
    </div>

  </div>
</body>
</html>

HomePage.java

package wishminimal.ui.home;

import java.util.Iterator;

import org.apache.wicket.PageParameters;
import org.apache.wicket.devutils.stateless.StatelessComponent;
import org.apache.wicket.extensions.markup.html.repeater.data.table.ISortableDataProvider;
import org.apache.wicket.extensions.markup.html.repeater.util.SortableDataProvider;
import org.apache.wicket.markup.html.WebPage;
import org.apache.wicket.markup.html.basic.Label;
import org.apache.wicket.markup.html.link.BookmarkablePageLink;
import org.apache.wicket.markup.repeater.Item;
import org.apache.wicket.markup.repeater.data.DataView;
import org.apache.wicket.model.CompoundPropertyModel;
import org.apache.wicket.model.IModel;
import org.apache.wicket.spring.injection.annot.SpringBean;

import wishminimal.dao.PostDAO;
import wishminimal.entity.Post;

@StatelessComponent
public class HomePage extends WebPage {

    @SpringBean
    PostDAO postDAO;

    ISortableDataProvider<Post> dataProvider = new SortableDataProvider<Post>() {
    public Iterator<? extends Post> iterator(int first, int count) {
        return postDAO.findAll(first, count).iterator();
    }
    public int size() {
        return postDAO.countAll();
    }
    public IModel<Post> model(Post object) {
        return new CompoundPropertyModel<Post>(object);
    }
    };

    public HomePage(PageParameters params) {
    final int currentPage = params.getAsInteger("p", 0);

    final DataView<Post> dataView = new DataView<Post>("posts", dataProvider, 10) {
        @Override
        protected void populateItem(Item<Post> item) {
        item.add(new Label("title"));
        item.add(new Label("content"));
        item.add(new Label("date"));
        }
    };
    dataView.setCurrentPage(currentPage);
    add(dataView);

    add(new BookmarkablePageLink<Void>("recentPosts", getClass(), new PageParameters("p=" + (currentPage - 1))) {
        @Override
        public boolean isVisible() {
        return currentPage > 0;
        }
    });
    add(new BookmarkablePageLink<Void>("previousPosts", getClass(), new PageParameters("p=" + (currentPage + 1))) {
        @Override
        public boolean isVisible() {
        return currentPage < dataView.getPageCount();
        }
    });
    }
}

While this is much less convenient than stateful Wicket, I still find much better than say, stateless JSF or Struts :)

tetsuo 2010-08-09 15:29:01

Thank you for taking the time to write that incredibly useful example! :-)

John 2010-08-09 16:49:52

Answer 2

+1 A:

To make pages stateless, i do the following:

Use bookmarkable pages
Use stateless forms in all cases
To pass data across pages, i use page parameters as the only constructor in the pages
Use bookmarkable links

Regards.

joshua 2010-08-11 06:30:24

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Is it difficult to make a mainly stateless web application with Wicket?

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