Woonsan on Open Source Software

• https://github.com/woonsanko/recipe-for-hippo-db-migration

• The client is requesting a page which maps to a page configuration which is composed of a root HstComponents, "Parent"
• The "Parent" component has two child components, "LeftChild" and "RightChild". These two child components are siblings.
• At the time, the client is submitting a form included in the HstComponent, "RightChild".

1. Client requests to HST-2 container.
2. Because the client is submitting a form by an action URL, the container invokes doAction() of "RightChild".
3. The container redirects to a render page.
   (Because the container aggregates multiple components in a page, the action phase should be separated from the render phase of all components. HST-2 container's aggregation implies the PRG pattern. [2])
4. Client requests to the render page.
5. The container invokes doBeforeRender() of each component. The invocation order of doBeforeRender() is from parent to child. The invocation order between siblings is not specified.
6. The container dispatches to the render path of each component. The dispatch order of render page of component is from child to parent. The invocation order between siblings is not specified.
7. A parent component's render page can include the rendered content of a child component.
8. The container writes the aggregated content to the client.

• Because the action phase request and render phase request are separated in HST-2 request processing, the web application framework should not assume that the request would be shared between the two phases.
  For example, when you use SimpleFormController of Spring Web MVC Framework with a form view page and a validator, if a user enters invalid information in the form, the dispatcher would render the form view again with some validation error information. Internally, this information is stored in a ModelAndView object to be rendered in the render phase. This cannot work in HST-2 request processing because the requests are not shared between action phase and render phase.
  Therefore, that kind of shared information between action phase and render phase should be passed correctly between two separate request processing phases by bridging solutions.
• By the way, because HST request and response objects are just extended objects to the default HttpServletRequest and HttpServletResponse, the other bridging integration stuffs could be easier than expected in other technologies such as Apache Portals Bridge. [3]

2.2. A very simple bridging solution: SimpleDispatcherHstComponent

package org.hippoecm.hst.component.support;

public class SimpleDispatcherHstComponent extends GenericHstComponent {
    public static final String LIFECYCLE_PHASE_ATTRIBUTE = SimpleDispatcherHstComponent.class.getName() + ".lifecycle.phase";
    public static final String BEFORE_RENDER_PHASE = "BEFORE_RENDER_PHASE";
    public static final String DISPATCH_PATH_PARAM_NAME = "dispatch-path";
    public static final String BEFORE_RENDER_PATH_PARAM_NAME = "before-render-path";
    public static final String RENDER_PATH_PARAM_NAME = "render-path";
    public static final String ACTION_PATH_PARAM_NAME = "action-path";

    @Override
    public void doAction(HstRequest request, HstResponse response) throws HstComponentException {
        doDispatch(getDispatchPathParameter(request, request.getLifecyclePhase()), request, response);
    }

    @Override
    public void doBeforeRender(HstRequest request, HstResponse response) throws HstComponentException {
        request.setAttribute(LIFECYCLE_PHASE_ATTRIBUTE, BEFORE_RENDER_PHASE);
        String dispatchPath = getDispatchPathParameter(request, request.getLifecyclePhase());
    
        if (dispatchPath != null) {
            response.setRenderPath(dispatchPath);
        }

        try {
            doDispatch(getDispatchPathParameter(request, BEFORE_RENDER_PHASE), request, response);

        } finally {
            request.removeAttribute(LIFECYCLE_PHASE_ATTRIBUTE);
        }
    }

    protected void doDispatch(String dispatchPath, HstRequest request, HstResponse response) throws HstComponentException {
        if (dispatchPath != null) {
            try {
                getServletConfig().getServletContext().getRequestDispatcher(dispatchPath).include(request, response);
            } catch (ServletException e) {
                throw new HstComponentException(e);
            } catch (IOException e) {
                throw new HstComponentException(e);
            }
        }
    }

    protected String getDispatchPathParameter(HstRequest request, String lifecyclePhase) {
        String dispatchPath = null;
    
        if (BEFORE_RENDER_PHASE.equals(lifecyclePhase)) {
            dispatchPath = getParameter(BEFORE_RENDER_PATH_PARAM_NAME, request, null);
        } else if (HstRequest.RENDER_PHASE.equals(lifecyclePhase)) {
            dispatchPath = getParameter(RENDER_PATH_PARAM_NAME, request, null);
        } else if (HstRequest.ACTION_PHASE.equals(lifecyclePhase)) {
            dispatchPath = getParameter(ACTION_PATH_PARAM_NAME, request, null);
        }
    
        if (dispatchPath == null) {
            dispatchPath = getParameter(DISPATCH_PATH_PARAM_NAME, request, null);
        }
    
        if (dispatchPath != null) {
            if (dispatchPath.charAt(0) != '/') {
                dispatchPath = new StringBuilder(dispatchPath.length() + 1).append('/').append(dispatchPath).toString();
            }
        }
    
        return dispatchPath;
    }

    protected String getParameter(String name, HstRequest request, String defaultValue) {
        String value = (String) this.getComponentConfiguration().getParameter(name, request.getRequestContext().getResolvedSiteMapItem());
        return (value != null ? value : defaultValue);
    }
}

<%-- contactdispatch.jsp --%>
<%!
private static String[] formFields = {"name","email","textarea"};

private void doBeforeRender(HstRequest request, HstResponse response) throws HstComponentException {
    HttpSession session = request.getSession(true);
    FormMap formMap = (FormMap) session.getAttribute("contactdispatch:formMap");
    if (formMap == null) {
        formMap = new FormMap();
        session.setAttribute("contactdispatch:formMap", formMap);
    }
    request.setAttribute("form", formMap);
}

private void doAction(HstRequest request, HstResponse response) throws HstComponentException {
    HttpSession session = request.getSession(true);
    FormMap formMap = new FormMap(request, formFields);
    session.setAttribute("contactdispatch:formMap", formMap);
    // Do a really simple validation:
    if (formMap.getField("email") != null && formMap.getField("email").contains("@")) {
        // success
        // do your business logic
        // possible do a redirect to a thankyou page: do not use directly response.sendRedirect;
        HstSiteMapItem item = request.getRequestContext().getResolvedSiteMapItem().getHstSiteMapItem().getChild("thankyou");
        if (item != null) {
            sendRedirect(request, response, item.getId());
        } else {
            log.warn("Cannot redirect because siteMapItem not found. ");
        }
    } else {
        // validation failed. Persist form map, and add possible error messages to the formMap
        formMap.addMessage("email", "Email address must contain '@'");
    }
}

private void sendRedirect(HstRequest request, HstResponse response, String redirectToSiteMapItemId) {
    HstLinkCreator linkCreator = request.getRequestContext().getHstLinkCreator();
    HstSiteMap siteMap = request.getRequestContext().getResolvedSiteMapItem().getHstSiteMapItem().getHstSiteMap();
    HstLink link = linkCreator.create(siteMap.getSiteMapItemById(redirectToSiteMapItemId));
    StringBuffer url = new StringBuffer();
    for (String elem : link.getPathElements()) {
        String enc = response.encodeURL(elem);
        url.append("/").append(enc);
    }
    String urlString = ((HstResponse) response).createNavigationalURL(url.toString()).toString();
    try {
        response.sendRedirect(urlString);
    } catch (IOException e) {
        throw new HstComponentException("Could not redirect. ",e);
    }
}
%>

<%
HstRequest hstRequest = (HstRequest) request;
HstResponse hstResponse = (HstResponse) response;

String hstRequestLifecyclePhase = hstRequest.getLifecyclePhase();
String dispatchLifecyclePhase = (String) hstRequest.getAttribute(SimpleDispatcherHstComponent.LIFECYCLE_PHASE_ATTRIBUTE);

if (HstRequest.ACTION_PHASE.equals(hstRequestLifecyclePhase)) {
    doAction(hstRequest, hstResponse);
} else if (SimpleDispatcherHstComponent.BEFORE_RENDER_PHASE.equals(dispatchLifecyclePhase)) {
    doBeforeRender(hstRequest, hstResponse);
} else if (HstRequest.RENDER_PHASE.equals(hstRequestLifecyclePhase)) {
%>
<div>
    <form method="POST" name="myform" action="<hst:actionURL/>">
    <input type="hidden" name="previous" value="${form.previous}"/>
    <br/>
    <table>
        <tr>
            <td>Name</td>
            <td><input type="text" name="name" value="${form.value['name']}" /></td>
            <td><font style="color:red">${form.message['name']}</font></td>
        </tr>
        <tr>
            <td>Email</td>
            <td><input type="text" name="email" value="${form.value['email']}"/></td>
            <td><font style="color:red">${form.message['email']}</font></td>
        </tr>
        <tr>
            <td>Text</td>
            <td><textarea name="textarea">${form.value['textarea']}</textarea></td>
            <td><font style="color:red">${form.message['textarea']}</font></td>
        </tr>
        <tr>
            <td>
                <c:if test="${form.previous != null}">
                  <input type="submit" name="prev" value="prev"/>
                </c:if>
            </td>
            <td><input type="submit" value="send"/></td>
        </tr>
    </table>
    </form>
</div>
<% } %>

<%
if (HstRequest.ACTION_PHASE.equals(hstRequestLifecyclePhase)) {
    doAction(hstRequest, hstResponse);
} else if (SimpleDispatcherHstComponent.BEFORE_RENDER_PHASE.equals(dispatchLifecyclePhase)) {
    doBeforeRender(hstRequest, hstResponse);
} else if (HstRequest.RENDER_PHASE.equals(hstRequestLifecyclePhase)) {
%>
//...
<%
}
%>