Is it a good practice to develop web-service and web-site in two different languages, on two different servers? E.g. right now I create a Java web-service running on Glassfish and Ruby on Rails presentation layer running in the same server.
I'd like to leave web-service on the same server but use Ruby 1.9, running in Passenger.
Is it a good idea? I don't have experience in architecture of web-apps.
Thanks.
If you write a contract first web service that consumes and produces XML, you can talk to any client that can make an HTTP GET or POST request in the appropriate format. SOAP or REST, doesn't matter.
I've written Java/Spring web services that started with an XSD. A Yahoo UI RIA client took the WSDL, made an HTTP POST to send the request document, and displayed the XML response in a nice data grid.
Technically, yes you can most certainly do that. That is one of the advantages of using WS. They are interoperable.
However, I would give some consideration to the thought if someone else were to maintain it and has expertise in only one of the two platforms (RoR or Java). It is always best to ask :-)
In terms of the architecture of the system, yes, this is a "good practice". By good, I mean that it achieves the goals, does no harm, and enforces separation of concerns.
I've been developing on an architecture that has a similar structure. The user interface is .NET and uses Java Web Services. That web services then are responsible for all interaction with the persistence media, third party components, etc.
I'd say in any system you should be working to abstract your user interface logic from your business logic. It's just good separation of concerns. Using web services to do that is just one way to achieve that goal. I'd recommend using web services in the case that you will re-use those business services in other use cases in your system.
One more thing; after using two different technologies on the UI and WS for the last 8 years, I've learned that most of the challenges are organizational, not technical. For example, it's harder to find those new developers that have both skills you're looking for to maintain your app. You end up having to find an expert on one and then train them on the other technology.
It depends on how similar they are.
If your web service basically mirrors your website in functionality - then it makes a lot of sense to reuse existing code and thus to make them the same thing on the same server.
Note - this is not the same thing as entangling tiers as your views are still separate from your business logic.
From the Ruby-on-Rails perspective, the "web service" and "web-site" are often interchangeable as they are exactly the same code, with only the view-template differing (html for the website, xml for the web service). If you build with a RESTful architecture in mind from the beginning, then you can achieve this with the minimum of duplication and with all application layers correctly decoupled.