The goal of this section is to give an overview of the CloudCare system for developers who are new to CloudCare. It should allow one’s first foray into the system to be as painless as possible by giving him or her a high level overview of the system.
On the frontend, CloudCare is a single page backbone.js app. The app, module, form, and case selection parts of the interface are rendered by backbone while the representation of the form itself is controlled by touchforms (described below).
/a/<domain>/cloudcare/apps/<urlPath> into the browser, the cloudcare_main view is called. This page loads the backbone app and perhaps bootstraps it with the currently selected app and case.
The Backbone Views¶
The backbone app consists of several
Backbone.Views subclasses. What follows is a brief description of several of the most important classes used in the CloudCare backbone app.
Renders the list of apps in the current domain on the left hand side of the page.
Renders the list of modules in the currently selected app on the left hand side of the page.
Renders the list of forms in the currently selected module on the left hand side of the page.
Renders the list of cases for the selected form. Note that this list is populated asynchronously.
Renders the table displaying the currently selected case’s properties.
AppView holds the module and form list views. It is also responsible for inserting the form html into the DOM. This html is constructed using JSON returned by the touchforms process and several js libs found in the
/touchforms/formplayer/static/formplayer/script/directory. This is kicked off by the AppView’s
_playFormmethod. AppView also inserts
cloudCareCases.CaseMainViews as necessary.
AppMainView (not to be confused with AppView) holds all of the other views and is the entry point for the application. Most of the applications event handling is set up inside AppMainView’s
initializemethod. The AppMainView has a router. Event handlers are set on this router to modify the state of the backbone application when the browser’s back button is used, or when the user enters a link to a certain part of the app (like a particular form) directly.
The backbone app is not responsible for processing the XFrom. This is done instead by our XForms player, touchforms. Touchforms runs as a separate process on our servers, and sends JSON to the backbone application representing the structure of the XForm. Touchforms is written in jython, and serves as a wrapper around the JavaRosa that powers our mobile applications.
What is it?¶
First of all, the “offline” part is a misnomer. This does not let you use CloudCare completely offline. We need a new name.
Normal CloudCare requires a round-trip request to the HQ touchforms daemon every time you answer/change a question in a form. This is how it can handle validation logic and conditional questions with the exact same behavior as on the phone. On high-latency or unreliable internet this is a major drag.
“Offline” CloudCare fixes this by running a local instance of the touchforms daemon. CloudCare (in the browser) communicates with this daemon for all matters of maintaining the xform session state. However, CloudCare still talks directly to HQ for other CloudCare operations, such as initial launch of a form, submitting the completed form, and everything outside a form session (case list/select, etc.). Also, the local daemon itself will call out to HQ as needed by the form, such as querying against the casedb. So you still need internet!
How does it work?¶
The touchforms daemon (i.e., the standard JavaRosa/CommCare core with a Jython wrapper) is packaged up as a standalone jar that can be run from pure Java. This requires bundling the Jython runtime. This jar is then served as a “Java Web Start” (aka JNLP) application (same as how you download and run WebEx).
When CloudCare is in offline mode, it will prompt you to download the app; once you do the app will auto-launch. CloudCare will poll the local port the app should be running on, and once its ready, will then initialize the form session and direct all touchforms queries to the local instance rather than HQ.
The app download should persist in a local application cache, so it will not have to be downloaded each time. The initial download is somewhat beefy (14MB) primarily due to the inclusion of the Jython runtime. It is possible we may be able to trim this down by removing unused stuff. When started, the app will automatically check for updates (though there may be a delay before the updates take effect). When updating, only the components that changed need to be re-downloaded (so unless we upgrade Jython, the big part of the download is a one-time cost).
When running, the daemon creates an icon in the systray. This is also where you terminate it.
How do I get it?¶
Offline mode for CloudCare is currently hidden until we better decide how to intergrate it, and give it some minimal testing. To access:
Go to the main CloudCare page, but don’t open any forms
Open the chrome dev console (
enableOffline()in the console
Note the new ‘Use Offline CloudCare’ checkbox on the left