Zend_ProgressBar_Adapter_JsPull is the opposite of jsPush, as it requires to pull for new updates, instead of pushing updates out to the browsers. Generally you should use the adapter with the persistence option of the Zend_ProgressBar. On notify, the adapter sends a JSON string to the browser, which looks exactly like the JSON string which is send by the jsPush adapter. The only difference is, that it contains an additional parameter, finished, which is either FALSE when update() is called or TRUE, when finish() is called. You can set the adapter options either via the set*() methods or give an array or a Zend_Config instance with options as first parameter to the constructor. The available options are: exitAfterSend: Exits the current request after the data were send to the browser. Default is TRUE.