I have a Silverlight Windows Phone 7 app that pulls data from a public API. I find myself doing much of the same thing over and over again:
In the UI, set a loading message or loading progress bar in place of where the content is
Get the content, which may be already in memory, cached in isolated file storage, or require an HTTP request
If the content can not be acquired (no network connection, etc), display an error message
If the content is acquired, display it in the UI
Keep the content in main memory for subsequent queries
The content that is displayed to the user can be taken directly from a data source, such as an ObservableCollection, or it may be a query on a data source.
I would like to factor out this repetitive process into a framework where ideally only the following needs to be specified:
Where to display the content in the UI
The UI elements to show while loading, on failure, and on success
The URI of the HTTP request
How to parse the HTTP response into the data structure that will kept in memory
The location of the file in isolated storage, if it exists
How to parse the file contents into the data structure that will be kept in memory
It may sound like a lot, but two strings, three FrameworkElements, and two methods is less than the overhead that I currently have.
Also, this needs to work for however the data is maintained in memory, and needs to work for direct collections and queries on those collections.
My questions are:
Has something like this already been implemented?
Are my thoughts about the topic above fundamentally wrong in some way?
Here is a design I'm thinking of:
There are two components, a View and a Model.
The View is given the FrameworkElements for loading, failure, and success. It is also given a reference to the corresponding Model. The View is a UserControl that is placed somewhere in the UI.
The Model a class that is given the URI for the data, a method of how to parse the data, and optionally a filename and how to parse the file. It is responsible for retrieving the data and notifying the View whenever the current status (loading/fail/success) changes. If the data downloaded from the network is different from the cache, the network data takes precedence. When the app closes or is tombstoned, the model writes the data to the cache.
How does that sound?
