6.7 The Delivery Processor

Once again, we’re going to borrow from the code we wrote in Chapter 5, ​Tweeting Bird Feeder​. We’re going to copy the serial monitoring and SQLite database connectivity instructions and enhance the script with additional functionality. First, we’re going to add the ability to scan a database containing known tracking numbers of packages in transit. When a delivery notification is received via the XBee/FTDI serial port connection, we will wait several minutes before iterating over the tracking numbers to determine which package was delivered. This delay can sometimes take an hour or more with some couriers. In the case of the US Post Office, it can take up to a day, making lookups on USPS deliveries impractical for our more immediate needs.

After scanning and polling the tracking numbers with the appropriate courier’s web services, we will add any courier delivery validation information to our delivery notification email message. If an error occurs with the tracking number lookup or if there were no confirmed deliveries of the tracking numbers we iterated upon, we will say that in the body of the message as well.

Finally, we will use Gmail to send our message to the intended recipient. If you don’t have a Gmail account, you will need to create one for this project. Alternatively, if you have SMTP outbound mail access via a different server, you’re welcome to substitute Gmail’s SMTP gateway with your own. Before we can write any Python code, though, we will need to create our database structures to store delivery events, tracking numbers, package descriptions, and confirmations.