I have encountered tons of problems, some small, some large while building XP-Dev.com as a web software as a service (SaaS). To be honest, I was a little too naive and didn’t foresee some of these issues, and I really do hope it will help someone out there who’s thinking of building a SaaS for the masses.
1. Case Sensitivity
Case sensitivity of your unique keys is really important. For example, when you’re building a user database, you need to consider whether User1 is the same as uSeR1 and vice versa. Do note that email addresses are case in-sensitive and you’ll need to be able to cope with that in your application code. If you’re hosting your application on a Linux box, do remember that in general, Unix filesystems are case sensitive, and if you had a directory for User1 on your server, you could have another directory for uSeR1 as well.
On the database side, MySQL has a small bug nifty feature that will actually help you solve this headache a little. If you declare a column as a VARCHAR, searches on it are case insensitive, i.e. if you search for uSeR1, you will get back User1.
If you’re finding some weirdness around Hibernate, MySQL and case sensitivity, do have a look at by past blog about it.
2. Internationalization and Unicode
Just build everything on UTF-8, from the beginning, on each-and-every-file, on each-and-every-request. It will save you a whole load of headache later on when you’re considering releasing your SaaS to the non-english speaking world (and that’s a HUGE motha-** of a world that you don’t want to miss out on).
Use UTF-8 database tables. Depending on your installation, you’ll find that MySQL uses latin1, and that doesn’t bode too well with them accented and asian characters. The trick is to use the ‘CHARACTER SET‘ option when creating your database, and setting ‘charset=utf8‘ when creating tables.
Do use the awesome W3C HTML Validator to ensure that web browsers are reading your SaaS using the correct encoding:
3. Login/Register Lifecycle
Ahh yes, authentication! There’s a ton of research put into answering the question ‘How do I authenticate users on a website ?’. But my gripe is not about the authentication itself – it’s about doing the right thing after authentication.
Here’s a common scenario – User1 visits http://example.com/some/private/service/ which is an authenticated service – i.e. User1 needs to login to example.com to be able to access it. The problem is that some SaaS out there immediately redirect User1 to their ‘dashboard‘ or ‘homepage‘ on example.com – http://example.com/userhomepage.
This will frustrate users as they have to:
Remember the initial URL http://example.com/some/private/service/
Retype http://example.com/some/private/service/ in the browser’s address bar
The same applied if the user has not even registered for your SaaS.
The solution here seems pretty obvious – keep track of the last URL that a user hit before reaching your authentication pages, and upon successful registration or authentication, just redirect the user back to the original URL.
Most web frameworks will have support for this functionality in one form or another. Do look it up and get it in before the site goes live.
4. URLs and Permalinks
Keep everything in nice encapsulated URLs. This is a subjective area (that has been debated to an extent that it’s no longer funny), but I think having URLs that do not contain query paramaters are:
Easier to remember
Search engine/SEO friendly
Cleaner to regenerate in code
For example, instead of having:
You could instead have:
If you’re using a modern web server like Apache, Nginx or Lighttpd, they all provide some mechanism of rewriting URLs so you don’t have to modify your code too much.
5. Application Level Permissions Layers
Most SaaS are essentially database driven applications, and they all access the database under a single user. In some complicated setups, this can actually go to 2 users – one for reading and one for writing. An even more complicated setup, each user of the SaaS will have a database login.
All of these are essentially not enough.
And here’s why – in a world where a normalised database structure is all the hype, there’s a high degree of certainty that data for User1 sits on the same table as data for User2. As far as I know most databases don’t really have row level permissioning and hence, having to rely on your database as your permission layer just does not work.
There is one setup where I thought that it might work – give each user a new table or database. But clearly this is a solution that simply won’t scale.
So, what’s the alternative ? Embed it into your application code. The decorator or facade patterns are extremely powerful for implementing this. Moreover, you can do complex permissioning, for e.g. User1 can read the business object during weekends, but not when User2 is logged in at the same time. OK, fine – ts a bad example, but you get the point.
Why bother going through all this trouble ? Well, here’s a generic use case:
MyCalendar app is a web SaaS online calendar offering. Each user can have multiple calendars, and they are all private to the user. To retrieve a calendar, all a user has to do is visit http://example.com/calendar/<calendar id>/ where calendar id is an identifier on a database table.
Say User1 has calendars with calendar ids 240, 252 and 362. If MyCalendar app didn’t have application level permissioning, User2 would happily be able to view all 3 of User1’s calendar.
So, the natural question to ask is “Do users actually try to do that ?”. YES! They will. I’m not sure whether they are curious, or looking for a security hole, but you will find some users exploring the URLs. What I mean by that is, say User2 has a calendar id of 5442. He/She will try to visit the URLs for calendar id 5440-5449, even though there are no direct links to those calendars that they can see (except 5442).
Using a database driven web framework like Rails and Django is all well and good, but remember to implement some application level permissioning if you have any private data.
There You Have It
5 simple tips that will save you a ton of hassle if you’re building an SaaS. As always, feedback is appreciated.