Consider an app that allows friends to record songs for each other. Any user can record a song and then "post" it to the web so that others can play it. TinyWebDB is the key component you'll need. It is an App Inventor component that let's your app store persistent data on the web and thus share data amongst phones and people. It is very much like TinyDB.The Web component lets your app talk to any web service.
TinyWebDB is for talking to special App Inventor web services that store data in the same format as TinyDB.
Where is the data stored?
0. In a browser, go to usfwebservice.appspot.com or customtinywebdb.appspot.com. If the page loads for either one of these, use it below.
1. First play around with writing to a database with TinyWebDB. Create a new app and add a TinyWebDB component and a "store" button. Set the ServiceURL to one of the URLS above. In the blocks editor, in StoreButton.Click, call TinyWebDB.StoreValue with some tag and value. Then open a browser to your appspot URL and see if your data is there.
2. Now play around with reading from a web database. Add a "get" button and a text box. Change the StoreValue so it stores what the user has put in textbox. Then in the GetButton.Click, call TinyWebDB.GetValue. Code the TinyWebDB.GotValue to put the data from the database into the textbox.
Now lets use it for real. Build a "Share your song" app.
0. Start with your song playback app. If you don't have one that works, have someone email you a zip file of their working version, and upload it into App Inventor.
1. Add a TinyWebDB to your app. Set the ServiceURL to an appspot url.
2. Now add the blocks to store a recorded song (musicNoteList) to the TinyWebDB. On the SaveButton.Click event, call TinyWebDB.StoreValue. Try it and open the browser to see if your data is at your appspot URL
4. Add another button that when clicked gets the current song at the web database. Remember, you'll need both a call to TinyWebDB.GetValue and you'll need to handle the TinyWebDB.GotValue function. In the GotValue, after you've retrieved the song, play it.
5. Test: Get a partner and each of you download one of your apps. See if you can play each others' songs.