Zend_ProgressBarIntroductionZend_ProgressBar is a component to create and update progressbars in different environments. It consists of a single backend, which outputs the progress through one of the multiple adapters. On every update, it takes an absolute value and optionally a status message, and then calls the adapter with some precalculated values like percentage and estimated time left. Basic Usage of Zend_ProgressbarZend_ProgressBar is quite easy in its usage. You simply create a new instance of Zend_Progressbar, defining a min- and a max-value, and choose an adapter to output the data. If you want to process a file, you would do something like:
In the first step, an instance of Zend_ProgressBar is created, with a specific adapter, a min-value of 0 and a max-value of the total filesize. Then a file is processed and in every loop the progressbar is updated with the current byte count. At the end of the loop, the progressbar status is set to finished. You can also call the update() method of Zend_ProgressBar without arguments, which just recalculates ETA and notifies the adapter. This is useful when there is no data update but you want the progressbar to be updated. Persistent progressIf you want the progressbar to be persistent over multiple requests, you can give the name of a session namespace as fourth argument to the constructor. In that case, the progressbar will not notify the adapter within the constructor, but only when you call update() or finish(). Also the current value, the status text and the start time for ETA calculation will be fetched in the next request run again. Standard adaptersZend_ProgressBar comes with the following three adapters: Zend_ProgressBar_Adapter_ConsoleZend_ProgressBar_Adapter_Console is a text-based adapter for terminals. It can automatically detect terminal widths but supports custom widths as well. You can define which elements are displayed with the progressbar and as well customize the order of them. You can also define the style of the progressbar itself.
You can set the adapter options either via the
Zend_ProgressBar_Adapter_JsPushZend_ProgressBar_Adapter_JsPush is an adapter which let's you update a progressbar in a browser via Javascript Push. This means that no second connection is required to gather the status about a running process, but that the process itself sends its status directly to the browser.
You can set the adapter options either via the
The usage of this adapter is quite simple. First you create a progressbar
in your browser, either with JavaScript or previously created with plain
HTML. Then you define the update method and optionally the finish method
in JavaScript, both taking a json object as single argument. Then you
call a webpage with the long-running process in a hidden
Example #1 Basic example for the client-side stuff This example illustrates a basic setup of HTML, CSS and JavaScript for the JsPush adapter
This will create a simple container with a black border and a
block which indicates the current process. You should not hide
the Instead of creating your custom progressbar, you may want to use one of the available JavaScript libraries like Dojo, jQuery etc. For example, there are:
Zend_ProgressBar_Adapter_JsPullZend_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:
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