appex

nodejs web services with the typescript programming language

install

npm install appex

• overview
• function signatures
  • http handler
  • json handler
• function visibility
• function routing

## overview

Appex is a nodejs web application and service framework built on top of the TypeScript programming language. Appex enables nodejs developers to expose typescript functions as http endpoints as well as generate meaningful service meta data for clients who consume them.

typescript

// program.ts

declare var require; 

// url: http://localhost:1337/
export function index (context:any): void { 
  
    context.response.write('home');

    context.response.end(); 
}

// url: http://localhost:1337/about
export function about (context:any): void { 
	
    context.response.write('about');

    context.response.end();
}

export module services {

    // url: http://localhost:1337/services/dir
    export function dir(context:any, path:string, callback:(contents:string[]) => void) {
        
        require('fs').readdir(path || './', (error, contents) => {
            
            callback(contents);

        });
    }
}

javascript

// app.js

var appex   = require('appex');

var runtime = appex.runtime ({ source : './program.ts', devmode : true });

require('http').createServer( function(request, response) {
    
    runtime(request, response);
    
}).listen(5444);

## function signatures

Appex supports two distinct function signatures. http handler signatures and json handler signatures.

### http handler signature

A http handler method can be created with the following function signature. The context argument contains the http request and response objects.

export function method(context:any) : void {

	context.response.write('hello world');
	
	context.response.end();

}

### json handler signature

A json handler function is a function which will automatically accept a HTTP POST'ed json string and pass it to the function as a object parameter. in addition, json handler functions also require that a response object be returned on the callback, which in turn will be passed back as a http response as a json string.

A http handler method can be created with the following function signature. The context argument contains the http request and response objects.

export function method(context:any, request:any, callback:(response:any) => void) {

	callback(request); // echo

}

## function routing

Appex creates url routing tables based on a function name and module scope. For example consider the following...

export function index   (context:any) { }

export function about   (context:any) { }

export function contact (context:any) { }

export module services.customers {

	export function insert(context:any) : void { }
	
	export function update(context:any) : void { }
	
	export function delete(context:any) : void { }
}

will create the following routes:

http://[host]:[port]/

http://[host]:[port]/about

http://[host]:[port]/contact

http://[host]:[port]/services/customers/insert

http://[host]:[port]/services/customers/update

http://[host]:[port]/services/customers/delete

## function visibility

Appex only exposes 'exported' functions over http. From this developers infer notions of public and private over http.

Consider the following example:

module private_module {

	export function public_method () {
	
		// this function is exported, but as this module is 
		
		// not exported, neither is this method.
	}
}

function private_function() {

	// this method is private
}

export function public_function   (context:any) { 

	private_function(); // ok
	
	private_module.public_method(); // ok
}

will result in the following routes.

http://[host]:[port]/public_function