I've seen commercially available scripts that allow you to host THEIR scripts on THEIR web-server(s), so long as you pay X amount of dollars per month

I was wondering HOW you can use PHP to make something like this possible?

That's a much bigger problem than just a little PHP function you're asking for there.

A hosted software service could be ANYTHING!

I have quite a bit of experience in writing SaaS applications with PHP - but there is no one magic trick to know I'm afraid.

There are many possible ways of implementing such a scheme, and it really does depend on what the software does. Key things to remember are to make the software as configurable as possible to make it easier to "clone" instances of it with different properties. You should make such software very secure too, if you're hosting client scripts you don't want them being able to talk to eachother on your server!

In my experience, designing something to work as SaaS involves writing an application which takes parameters to run it - and those parameters govern the application's behaviour and data.

For example, I was hired to create a "hosted website" system which could be used to publish a clone of a site, tailored to each customer's name and branding, and accessed by different domains. Each site could have a different colour scheme and logo, and use the customer's name in copy text.

Rather than create a "site" which could be copied into a folder, and build a new apache VHost each time, I made a single piece of software which read the domain being accessed, loaded it's configuration from a MySQL database and served custom content to the user.

This means when we find a bug or want to update everything, rather than patch 200 customer sites, I simply update my code and all of the sites are patched in one fell swoop.

When doing this, take into consideration the possible scale of your application and code with that in mind. This is when you need to look at perhaps multiple servers, load balancers, primary, secondary, tertiary and more DNS servers, cache servers, database replication.... the list goes on.

I'm not saying it's incredibly difficult to do - but it's not trivial!

So are you talking about things like blogger.com. wordpress.com where it runs from a core script but it appears runs as an independent entity?

chris: that would be the product of this.

I thought I was asking a different question than before, looks like it's the same question... asked (again, however) due to a lack of an inability to fathom the components of it's construction.

What tripped me up was the idea of dealing with automation as far as a payment plan is concerned with SaaS.


Basically: "not CAN it be done with PHP?"

but How are the pros doing it?

Yes of course it can, all web applications run as independent entities anyway, each request from a different user agent creates an instance of the application (session) in the server memory space.
So it is only a small step to having the instance also have an independant database as well.

aroo-gah.

thank you.