Ralph's Open Source Blog

With JEE6 and JSF2 we finally have the great feature of bookmarkable URLs. This fixes one of the most awful faults of JSF that pages were not bookmarkable. An application can now become bookmarkable with some modifications. (See details about bookrmarkble URLs in Ryan Lubke’s Blog)

In a JSF web application you will usually have a <h:command link> or <h:commandbutton> like this:

<h:commandLink action="#{workflowController.load()}">
    <h:outputTextvalue="My action link" />
</h:commandLink>

In this example the action method returns a navigation outcome. Since JSF2 this action outcome can be also a jsf page URL (e.g /page/my_page.xhml), so no more explicit navigation rule is necessary. But the result is not bookmarkable.

To replace this with a bookmarkable URL you can replace the JSF component with the new  <h:link>. See the following example:

<h:link outcome="#{workflowController.load()}">
    <f:param name="id" value="#{workitem.item['$uniqueid']}"/>
    <h:outputText value="My action link" />
</h:link>

The trick here is, that the link is extended with a URL query param ‘id’.  Now the HTML outcome of the JSF component will look like this.

<a href="http://localhost:8080/myapp/page/my_page.xhtml?id=1">My action Link</a>

The result is simmilar to a <h:commandLink> with the difference that the URL is now set to the browsers URL. So far this new link can be bookmarked, but it is not automatically working. To resolve this new URL you have to customize your jsf page to evaluate the new query param (in this example my_page.xhml).

You can add the following metadata tag to extract the ID.

<h:head>
 <f:metadata>
 <f:viewParam name="id" value="#{workflowController.deepLinkId}" />
 </f:metadata>
</h:head>

In my example I have a method ‘getDeepLinkId’ in my workflowController Bean. The method just loads the corresponding object into my controller.

public void setDeepLinkId(String adeepLinkId) {
 this.deepLinkId = adeepLinkId;
   if (deepLinkId != null && !deepLinkId.isEmpty()) {
       // load the business object....
       this.load(deepLinkId);
       // finally destroy the deepLinkId to avoid a reload on the next
       // post event
       deepLinkId = null; // !
    }
 }

This method is necessary so in case the bookmarkable URL is requested later from a user we load the corresponding Object before we load the page.

That’s it.

h:command Buttons

The bookmarkable URLs can become a little bit tricky if you have more complex action methods. For example I used in a h:commandButton like this:

<h:commandButton action="#{workflowController.process}" value="My button">
 <f:setPropertyActionListener
    target="#{workflowController.workitem.item['$ActivityID']}"
     value="#{activity.item['numactivityid']}" />
</h:commandButton>

This is a case where replacing <h:commandButton> with <h:button> will not work out of the box. This is because the outcome property can not evaluate the action result which can – in my case – also become null. To solve this the navigation rules come back into the game. You can achieve the same result as shown in the first example with a navigation rule placed in the faces-config.xml. See the following example:

<navigation-rule>
   <navigation-case>
   <from-outcome>workitem</from-outcome>
   <to-view-id>/page/my_page.xhtml</to-view-id>
   <redirect>
     <view-param>
       <name>id</name>
       <value>#{workflowController.workitem.item['$uniqueid']}</value>
     </view-param>
   </redirect>
 </navigation-case>
</navigation-rule>

Now I moved the param ‘id’ out to the navigation rule with the identifier ‘workitem’. If my action result form the h:commandButton is ‘workitem’ the navigation rule computes the bookmarkable URL:

<a href="http://localhost:8080/myapp/page/my_page.xhtml?id=1">My action Link</a>

I hope this short examples will help you to build bookmakrable jsf applications.

If you start developing a business application you have two different approaches. In the first one – and this is the typically one – you start with the modelling of business objects. For example you have a “car” which can be easily modeled in a business object. You have a “buyer” and a “seller” which can be also simply stored into separated data tables. That’s it! It looks so easy to develop a business applications like in this example for a “used car dealer”. What you do is to describe the real things from the surrounding world into objects using a programming language of your choice. Today we have a lot of frameworks to map the real world things into databases and object orientated application frameworks. This all works well – at a glance. But as we all know, the real world is anything but simple. And in the moment when you realize that “used cars”, “sellers” and “buyers” have more complex relationships you need new objects like a “sales contract” and a “driver‘s license”. A “credit agreement” and a “warranty”. And you see that the things of the real world are not so easy as they seems to be in the first time.

A complete different approach to develop a business application is to get rid of the things of the real world. In this case you don’t look for what the persons do with the things. But you look for why they do the things they do. Now you are looking at the process behind the things in our real world – the business process. In the example of our “used car dealer” you can see a buyer showing interest in a car – his desire to buy. You see the dealer who tries to regulate the payment and all the things which can happen when you buy or sell a car.

Now when you try to model this in your business application your thoughts revolve around what people do and what happened during the entire process. And this is the idea of a business process application or a workflow application. Talking about the objects and data tables as we do in the beginning we now need objects like “events”, “activities”, “process states”, “actors” and “time ranges”. This is more abstract because we are now looking behind the things in your visible world. The funny part of this developing is, that you will realize that it does no longer matter if your seller sells cars or flowers or if you buyer is interested in a used car or a holiday travel. Your application becomes more abstract and you begin to model the real abstraction of the world.

When you start developing a business application in the second way you don’t ask your customer what the things are he what’s to save into a database. You ask him why he need an application to do his work better.

Take a look at our open source project Imixs-Workflow. It maybe can help you to get on that way.