Node.js Module

Node.js is an open-source and cross-platform JavaScript runtime environment.

Node.js runs the V8 JavaScript engine, the core of Google Chrome, outside of the browser. This allows Node.js to be very performant.

A Node.js app runs in a single process, without creating a new thread for every request. Node.js provides a set of asynchronous I/O primitives in its standard library that prevent JavaScript code from blocking and generally, libraries in Node.js are written using non-blocking paradigms, making blocking behavior the exception rather than the norm.

Lianja Cloud Data Services Node module

Lianja Cloud Server includes a Node.js module lianjaclouddataservices enabling Node.js applications to connect to a local or remote Lianja Cloud Server and perform a variety of operations.

Installing the Lianja Cloud Data Services Node module

The simplest way to use the Node.js module module is by creating a symbolic link using "npm link".

On Windows:

cd C:\lianja\cloudserver\tenants\public\wwwroot\library\LianjaWebFramework\LianjaCloudDataServices\node\
npm link

On Linux:

cd /opt/lianja/cloudserver/tenants/public/wwwroot/library/LianjaWebFramework/LianjaCloudDataServices/node/
npm link

Testing the installation:

On Windows:

cd C:\lianja\cloudserver\tenants\public\wwwroot\library\LianjaWebFramework\LianjaCloudDataServices\node\lianjaclouddataservices\
node test.js

On Linux:

cd /opt/lianja/cloudserver/tenants/public/wwwroot/library/LianjaWebFramework/LianjaCloudDataServices/node/lianjaclouddataservices/
node test.js

On MacOS:

cd /Users/shared/Lianja/cloudserver/tenants/public/wwwroot/library/LianjaWebFramework/LianjaCloudDataServices/node/lianjaclouddataservices
node test.js

Using the Lianja Cloud Data Services module in Node Applications

Load the module into your Node.js application

const Lianja = require("Lianjaclouddataservices")

Exported functions. All are asynchronous returning a "Promise" (see example usage below).

See OData URIs for details of OData URIs and OData Operators for all the OData operators.

Module Methods

Function	Description
Lianja.login(host, user, password)	Login and connect to to a local or remote Cloud Server. To connect locally specify the host as http: //localhost:8001
Lianja.logout()	Logout from the local or remote Cloud Server.
Lianja.evaluate(expr)	Evaluates LianjaScript expression and returns the result asynchronously.
Lianja.evaluatePython(expr)	Evaluates Python expression and returns the result asynchronously.
Lianja.evaluateJavaScript(expr)	Evaluates JavaScript expression and returns the result asynchronously.
Lianja.fetch(url)	Fetches data from the server using an .rsp, .pysp or .jssp server side page. Use fetch() to retrieve custom data from the server.
Lianja.OData_Create(url, data)	See ODATA_CREATE()
Lianja.OData_Read(url)	See ODATA_READ()
Lianja.OData_ReadHTML(url)	See See ODATA_READ()
Lianja.OData_ReadJSON(url)	See See ODATA_READ()
Lianja.OData_ReadImage(url)	See See ODATA_READ()
Lianja.OData_Update(url, data)	See ODATA_UPDATE()
Lianja.OData_UpdateHTML(url, text)	See ODATA_UPDATE()
Lianja.OData_UpdateJSON(url, jsontext)
Lianja.OData_Delete(url, data)	See ODATA_DELETE()

//
// Lianja Node.js module test
//
// On windows:
//
// cd C:\lianja\cloudserver\tenants\public\wwwroot\library\LianjaWebFramework\LianjaCloudDataServices\node\
// npm link
// cd C:\lianja\cloudserver\tenants\public\wwwroot\library\LianjaWebFramework\LianjaCloudDataServices\node\lianjaclouddataservices\
// node test.js
//
// on Linux:
//
// cd /opt/lianja/cloudserver/tenants/public/wwwroot/library/LianjaWebFramework/LianjaCloudDataServices/node/
// npm link
// cd /opt/lianja/cloudserver/tenants/public/wwwroot/library/LianjaWebFramework/LianjaCloudDataServices/node/lianjaclouddataservices/
// node test.js
//
// on MacOS:
//
// cd /Users/shared/Lianja/cloudserver/tenants/public/wwwroot/library/LianjaWebFramework/LianjaCloudDataServices/node/lianjaclouddataservices/
// node test.js
//
 
const Lianja = require("lianjaclouddataservices");
 
// All Lianja methods are asynchronous as required by Node.js
 
var rc = Lianja.login("admin", "admin").then(ok =>
{
	console.log("Lianja.login() - " + (ok ? "successful" : "failed"));
	if (ok) performOperations()
});
 
function performOperations()
{
	Lianja.evaluate("username()").then(result => 
	{
		console.log("username - " + result);
	});
 
	Lianja.evaluate("etos(date()) + ' ' + time()").then(result => 
	{
		console.log("Lianja.evaluate() - " + result);
	});
 
	Lianja.OData_Read("/southwind/employees?$top=1").then(result => 
	{
		console.log("Lianja.OData_Read()");
		console.log(result);	
	});
 
	Lianja.OData_ReadHTML("/southwind/employees?$select=notes&$filter=lastname eq 'Buchanan'").then(result => 
	{
		console.log("Lianja.OData_ReadHTML()");
		console.log(result);	
	});
 
	Lianja.OData_ReadImage("/southwind/employees?$select=photo&$filter=lastname eq 'Buchanan'").then(result => 
	{
		console.log("Lianja.OData_ReadImage()");
		console.log("size="+result.length);	
	});	
};