Hi,
The bid is for the following implementation of your requirements:
1. Build the project as a django project that would run on the web hosting you have, but that requires python and django support, please, check with your hosting provider.
2. Implement IMAP Idle monitoring on the web hosting server for the mail box instead of using cron, every decent imap server supports this. IMAP Idle gives almost instant notifications, it's used by all modern mail clients. Cron job is an option too if you insist on it.
3. Send notifications using, email or http - matched from the database by device id
each device have settings
message , type of notification mail/http get or post
with default preconfigure url and optional url override per device.
4. Simple admin interface - web based with administrative login.
Can add/edit/delete devices and their options.
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Extra things that can be done but are not easy to do:
5. Collect statistics per device
6. Implement notifications rate limit - if the power starts to go up and down don't get flooded with messages, same if you have a failing sensor giving a random data.
Regards,
Alex