CincomSmalltalkWiki: Adding a Simple Web Server Interface

Sometimes you have an application where it would be nice - either on the internet or on the intranet - to add a small server interface to your application. What do I mean by this? Visit this page. See the set of icons at the top? Those provide ways of sending a simple HTTP based message from the browser to a locally running application. What's the simplest way that could work? Why not leverage a simple web browser, but not one running on port 80?

Makes it easy to do simple integration with any browser
Makes it easy for end users to take advantage of you do this in VisualWorks. First, load VisualWave Server. Not Wave developer, and not web toolkit - we are after something much simpler here.

Second, create a new subclass of class WebResponder, and implement the #answerFor: method. This method is where your server will grab the message from the browser and figure out what it means. So say you have a link in the browser that looks like this:

http://localhost:8777/myApp?arguementsGoHere

in the answerFor: method, grab the arguements this way:

answerFor: aWebRequest
     arguments := aWebRequest uri query.
     "put code for doing something with those arguments here"

That's about it. You can parse the arguments easily and have your application integrated with a web browser right away. The next question might be, how does one create the server and the interface programmatically? That's also pretty easy:

createServer
     server := self createWaveServer.
     self createResponderFor: server.
     server startOn: 'localhost'.


createWaveServer
     server := TinyHttpServer newMinimal.
     server service trapErrors: true.
     server autoStart: false.
     server port: 8777.
     server hostname: 'localhost'.
     ^server

createResponderFor: server
     | responder resolver |
     responder := MyResponderSubclass new.
     resolver := server service resolver.
     resolver atPath: 'myApp' put: responder.

The nice thing is, this server has no other interfaces - not an echo, not a launch, nothing - there's really no way to access it's services other than the limited route you give it. You'll want to add some sanity checking and some error handling; look at the BottomFeeder bundle (package RSS-Server) in the public repository for an example implementation that does that.

Try it out and see how simple it really is!