Question

I hope this question belongs here. I am developing a web application for a client. It involves creating appointments/quotes for tradesman and need some advice.

Basically there are products that can be added to a quote created on the webapp. I want to be able to select the quote on the mobile app from a smartphone a fill out the quote.

The problem I face is that because there might not always be internet connectivity I need to store quote data offline on the device so that it can be synchronised when there is internet.

Here is the process using the mobile app:

1. User gets appointments from web application and stores them (preferably in a database)
2. Even with no connection user can then fill out quote on the appointment.
3. User saves quote
4. Mobile app automatically sends new quote to web application (if connection)
5. When internet is available user manually synchronises data

The web application takes care of creating appointments and managing the products. The mobile device stores it’s own copy of the products and simply just a reference to the quote.

So the user can see a list of appointments. Selects the appointment and then begins to add products.

appointments

appointment_id

description

products

id

description

quote

id

appointment_id

product_id

The web application has been developed in PHP.

I’d like to take advantage of HTML5’s offline storage for the mobile app as I’m a web developer and don’t have time on this project to learn a native language (i.e objective-C). I’ve read in a couple of places that web SQL database is not going to be continued so I’m not really sure what my options are.

Also for code in thinking HTML5 and JavaScript, so probably using jQTouch or jQuery Moble.

If anyone has any suggestions or recommendations for me that would be great!

Answer 1

I have a jQuery Mobile app which stores data off-line. Users push completed records up to a web service when connected (the app also uses the off-line capabilities in HTML5). This uses Web SQL (which is SQLite in WebKit and Opera) in Mobile Safari, and works well on the principal devices (iPad / iPhone) but is also fully functional in Chrome and Safari on the desktop (I haven’t tried Opera, but obviously it wouldn’t work in Firefox or IE).

A few considerations:

• As you point out, Web SQL has a somewhat uncertain future. You might want to look at IndexedDB instead, although depending on the browsers you need to support Web SQL might just be fine.
• Local database size is limited, but you should be OK if you “purge” data flagged as complete and submitted every so often (I think it’s 5MB per db or thereabouts, so quite considerable).
• My app talks to a SOAP web service via ajax, and we’re all on the same domain. You may need to look at CORS / reverse proxies and such if domains are going to differ
• I don’t like fiddling with XML in Javascript, but XMLObjectifier makes that side of things easier (parses XML into JSON objects)