In previous posts (see here) I've covered various aspects of logging in ADF and in conjunction with a presentation delivered at the UK Oracle Users Group, I'm continuing the trend with an article on the new Click History functionality within 12c.
So What is Click History?
Basically the feature relates to instrumentation that is built into the ADF framework which, when switched on, continuously reports the actions that users have taken within the UI. This mostly relates to physical clicks on UI elements such as buttons and tabs, but it also reports scrolling events, graph draws and more. Why is it useful? Well the point is that it can help answer that particular question - "What did you do before you got the error?" You can see how you could leverage this in a feedback or error reporting function in a UI where the information is extracted and automatically bundled with other useful information for the Support staff to have a look at.
Each Click History record provides information about the component, region and view that reported the event, along with key information about the application, the user and the DSID (Diagnostic Session ID).
Here's a screen shot from some in-application diagnostics that I've developed as an small example. In this case the history is being dumped and read into the actual application UI. This is something I'll cover doing in a follow up article.
Enabling Click History
As I mentioned Click History is part of the framework in 12c, however, it's not switched on for every application by default. There will be a performance overhead for any kind of tracing like this so we want to be explicit about choosing to use it.
In your application itself you need to make 2 small changes:
- Create a new web.xml context parameter with the name oracle.adf.view.faces.context.ENABLE_ADF_EXECUTION_CONTEXT_PROVIDER and set the value to true.
- Add an extra library reference to your /WEB-INF/ weblogic.xml file (create this if you don't have one already). Here's the reference you need:
Assuming that you have a correctly configured Weblogic domain that has been extended with JRF this library will already be defined for you.
So in your application, that's basically it. However, we then need to do a little work on the server to configure the server side parameters for this, specifically how much space should be devoted to the Click History buffer. To explain, Click History has a logical circular buffer of a specified size. As the buffer fills up then new records will be written from the start again and the older records discarded. When you want to look at the history, then you have to dump this buffer, but we'll come to that later.
Server Side Configuration of Click History
Switching Click History On or Off
Although individual applications enable Click History, the server also has to be told to pay attention. This is very simple to do as it is controlled by switching a particular logger (oracle.clickhistory.EUM) to the NOTIFICATION level. This can be done from Enterprise Manager, or from the Weblogic scripting tool, WLST. Here, I'll show you how to do it from the command line using WLST, I think you can probably work out how to do it though EM yourself.
So, with WLST running:
The value of INCIDENT_ERROR indicates that the facility is OFF, so we can set it on with the following command:
If you've not encountered the setLogLevel command in WLST before, just issue help('setLogLevel') from the WLST command line to view the options and what they mean.
Viewing the Click History Buffer
Unlike a normal logging message we can't view the Click History output directly in EM, instead we need to explicitly dump the buffer to the console, or more usually a file. As I mentioned we can also do this in code which is something I'll cover in another article. So for now, let's look at how to do that from WLST:
Again you can issue the help() command in WLST for more information about the options on executeDump(), but in this case I'm just taking the simple option of dumping the data to a file.. Inside the file you'll see the output containing all of the lines of Click History information like this:
[2013-11-20T09:08:53.332+00:00] [AdminServer] [NOTIFICATION]  [oracle.clickhistory.EUM]
[tid: 120][userId: alice] [ecid: 67ea61aa-dde8-4e35-afa2-a75a24c8a820-00001769,0]
[CLICK_COMPTYPE: oracle.adf.RichShowDetailItem] [APP: SummitProductionDeploy]
[DSID: 0000K9ohwuNFw000jzwkno1IYTfR00000X] [CLICK_VIEWID: /index]
[CLICK_REGIONVIEWID: /customer-task-flow-definition/Customers] [CLICK_STARTTIME: 1384938532808]
[CLICK_RENDERTYPE: oracle.adf.rich.Item] [CLICK_TYPE: disclosure]
[CLICK_COMPCLIENTID: pt1:r1:0:sdi2] [CLICK_WINDOWID: w0] [CLICK_REGIONVIEWNAME: ]
[CLICK_COMPDISPLAYNAME: Orders Dashboard]
It's pretty easy to parse this by eye...
Configuring the Click History Buffer Size
You can view the initial size of the circular buffer by issuing the following WLST command:
This will return a chunk of information, including the all important buffer size. (some information omitted here for space reasons):
Handler Name: apps-clickhistory-handler
To change the buffer size from the value of 880640bytes it's another WLST command:
So that's the basics of Click History - enjoy.