By default when a flow enters a view state, it executes a client-side redirect before rendering the view. This approach is known as POST-REDIRECT-GET. It has the advantage of separating the form processing for one view from the rendering of the next view. As a result the browser Back and Refresh buttons work seamlessly without causing any browser warnings.
Normally the client-side redirect is transparent from a user's perspective. However, there are situations where POST-REDIRECT-GET may not bring the same benefits. For example a flow may be embedded on a page and driven via Ajax requests refreshing only the area of the page that belongs to the flow. Not only is it unnecessary to use client-side redirects in this case, it is also not the desired behavior with regards to keeping the surrounding content of the page intact.
The the section called “Handling Ajax Requests” explains how to do partial rendering during Ajax requests. The focus of this section is to explain how to control flow execution redirect behavior during Ajax requests. To indicate a flow should execute in "page embedded" mode all you need to do is append an extra parameter when launching the flow:
When launched in "page embedded" mode a flow will not issue flow execution redirects during Ajax requests. The mode=embedded parameter only needs to be passed when launching the flow. Your only other concern is to use Ajax requests and to render only the content required to update the portion of the page displaying the flow.
By default Web Flow does a client-side redirect upon entering every view state. However if you remain in the same view state -- for example a transition without a "to" attribute -- during an Ajax request there will not be a client-side redirect. This behavior should be quite familiar to Spring Web Flow 2 users. It is appropriate for a top-level flow that supports the browser back button while still taking advantage of Ajax and partial rendering for use cases where you remain in the same view such as form validation, paging trough search results, and others. However transitions to a new view state are always followed with a client-side redirect. That makes it impossible to embed a flow on a page or within a modal dialog and execute more than one view state without causing a full-page refresh. Hence if your use case requires embedding a flow you can launch it in "embedded" mode.
If you'd like to see examples of a flow embedded on a page and within a modal dialog please refer to the webflow-showcase project. You can check out the source code locally, build it as you would a Maven project, and import it into Eclipse:
cd some-directory svn co https://src.springframework.org/svn/spring-samples/webflow-showcase cd webflow-showcase mvn package # import into Eclipse