Tag Archives: JSF

Synchronizing access to CDI Conversations

If you are using CDI’s conversations you will most likely have come across the dreaded BusyConversationException. The CDI 1.0 specification states that the container must ensure that only one request at a time may be associated with the conversation by blocking or rejecting subsequent requests.

OpenWebBeans will immediately reassign and throw a BusyConversationException if the conversation is currently held by another request. Weld on the other hand uses a 1 second timeout to obtain a lock on the conversation before reassigning the request and throwing a BusyConversationException. Although this makes it less likely to occur, if you are dealing with multiple waiting requests or long running processes, you will still encounter them.
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Keeping focus on element with JSF 2 AJAX render

Anyone who has developed JSF 2 applications for any length of time, will have come across the issue that element focus may get lost when AJAX rendering is preformed.
So what is the cause of this? I have constructed a simple webapp to demonstrate the issue and show a potential solution.

One of the simplest possible scenario is a simple value change event that triggers a render on the following field:

     <h:outputLabel value="Input field: " />
     <h:inputText id="firstValue" value="#{sessionBean.firstValue}" tabindex="1">
        <f:ajax event="change" render="secondValue thirdValue" />
     </h:inputText>
     <h:outputLabel value="Render to Upper field: " />
     <h:inputText id="secondValue" value="#{sessionBean.secondValue}" tabindex="2" />

On the server side we are simply preforming a toUpper on the firstInput and assigning it to the secondValue. In this case implemented as a simple session scoped CDI bean, the underlying backing bean infrastructure has no influence on the response that JSF produces or how it is treated by the client.
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