JAVA MW

Objective

The JAVA Middleware provides the ability to modernize existing API with SOAJS when this API is built using JAVA as a development language.

The middleware exposes several functionality and configuration that SOAJS offers and which can be consumed by the API upon initialization or during runtime when requests arrive.

This page explains the JAVA middleware; the functionality and configuration that it offers, how to install it and how to use it.

Scenario

How to Install
Features
1. Configuration
2. Functionality
How does it work
1. on init
2. on request
Using the Middleware
1. Initialization State
2. Runtime State
Examples
1. JAXRS Jersey Express

1- How to Install

The SOAJS Java middleware is open source and is available under Github, you can use the following reference to pull the source code → https://github.com/soajs/soajs.java

The middleware is also available as an NPM package and can be download for free.

SOAJS Java NPM Package

# install from npm
npm install soajs.java

2- Features

Once the middleware is initialized, the following functionality becomes available:

Function	Type	Input	Output	Remarks
getDatabases	Method	dbName (optional)	returns database object if dbName provided returns all core and tenant meta databases otherwise	Mongo Client Driver
getServiceConfig	Method	-	returns service configuration object	Services Config
getDeployer	Method	-	returns deployer object	Registry
getCustom	Method	-	returns custom object	Services Config
getResources	Method	resourceName (optional)	returns resource object if resourceName provided returns all resources otherwise	Registry
getServices	Method	serviceName (optional)	returns service object if serviceName provided returns all services otherwise	Service
getDaemons	Method	daemonName (optional)	returns daemon object if daemonName provided returns all daemons otherwise	Daemon
reload	Method	-	void (reload registry only)	Registry

This middleware functionality is accessible via the request that is made to the API. The middleware traps the request once it hits the API, injects its functionality and then hands it back to you to add your business logic.

3-How does it work

On Init

The Middleware requires the following environment variables to be set prior to starting your service

Environment Variable	Description	Example	Reference
SOAJS_REGISTRY_API	The location of the SOAJS API Gateway along with the maintenance port value that it is using in the environment where the service will run in	127.0.0.1:5000/	Environment Variables
SOAJS_ENV	environment code that this service will run in	DEV	Environment Variables

Once your service starts, the middleware will make a call to the SOAJS API Gateway and retrieve the registry of the environment, it will cache it in memory.

From this registry, it uses variable autoReloadRegistry (which represents the auto reload duration in seconds) and every time this value is met, the middleware automatically pulls the new version of the registry and updates its cached version.

On request

SOAJS midlleware augments your service by trapping all arriving requests and injecting additional data then hands the updated version of request to your business logic.

The following table illustrates the data that gets injected by the middleware on every request:

Property	Code Snippet	Description	Reference
Tenant	req.soajs.tenant tenant : { id : '', code : '' }	Represents the tenant that is making the call to the API.	Multitenancy
Key Device Geo	req.soajs[ key \| device \| geo ] key : { config : {}, iKey : '', eKey : '' }, device : '', geo : {}	Represents the key configuration which belongs to the tenant making the call to the API.	Security Services Config
Application	req.soajs.application application : { product : '', package : '', appId : '', acl : {}, acl_all_env : {} }	Represents the application information which belongs to the tenant making the call to the API.	Multitenancy Access Levels
Package	req.soajs.package package :{ acl :{}, acl_all_env : {} }	Represents the Productization that the tenant making the call to the API is using.	Productization Access Levels
URAC	req.soajs.urac urac : {}	Represents the User whose access token was found in the request.	URAC v2
Awareness	req.soajs.awareness awareness : { host : '', port : '', getHost : 'function' }	Represents the SOAJS API Gateway internal network host & port based on the environment where the API is deployed and running in.	Request

4- Using the Middleware

Once you download the middleware, simply instruct your application to use it by adding it as a library to the restful service as an external jar file soajs.java.jar OR using a POM.xml file

SOAJS Java Middleware as POM.xml

<dependency>
    <groupId>soajs</groupId>
    <artifactId>soajs.java</artifactId>
    <version>1.0.0</version>
</dependency>

Then make sure to initialize it in your servlet tag under web.xml as follow:

Initialize SOAJS Java Middleware

<init-param>
     <param-name>com.sun.jersey.spi.container.ContainerRequestFilters</param-name>
     <param-value>soajs.filters.SoajsContainerRequestFilter</param-value>
</init-param>

Consequently, anywhere in your web application you can wire your context to access the data and function that it offers

Example of Using the SOAJS Java Middleware

(@Context HttpHeaders headers)
headers.getRequestHeader("soajs")

5- Examples

JAXRS Jersey

The following code snippets shows a basic example built using Java and how the SOAJS Java Middleware was added to the code to augment the web server created.

Full Example on: https://github.com/soajs/soajs.java.jaxrs_jersey

Java Web App & SOAJS Java Middleware

package soajs.test.rest;

import java.util.List;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.Consumes;
import javax.ws.rs.DELETE;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.PUT;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.QueryParam;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
import org.json.JSONObject;

//Import Filters from SOAJS Java Middleware
import soajs.filters.SoajsRegistry;
import soajs.filters.SoajsRequestUtilities;

@Path("/hello")
public class Hello {

	//Invoke the middleware and use it in the App
    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public Response getTest( 
			@QueryParam("username") String username, 
			@QueryParam("lastname") String lastname
	) {
        
		JSONObject response = new JSONObject();
        
        response.put("message", "Hello, I am a JAVA service, you are [" + username + "] and your last name is : [" + lastname + "]");

        response.put("dbs", SoajsRegistry.getDatabases() );
        
        return Response.status(200).entity(response.toString()).build();
	}
    
	//Invoke the middleware and use it in the App
    @POST
    @Consumes(MediaType.APPLICATION_JSON)
    @Produces(MediaType.APPLICATION_JSON)
    public Response postTest(String data,
            @Context HttpHeaders headers,
            @Context HttpServletRequest httpServletRequest,
            @Context HttpServletResponse httpServletResponse
    ) {
        
		JSONObject soajs = new JSONObject();
        
		try{
            System.out.println("Post service reached: trying to fetch request header at SOAJS ...");
            System.out.println("Soajs request header length = [" + headers.getRequestHeader("soajs").size() + "]");
            
			soajs = new JSONObject(headers.getRequestHeader("soajs").get(0));
            
            String host = SoajsRequestUtilities.getHost(soajs);

            soajs.put("controller", host);

        }
		catch(Exception e){
            e.printStackTrace();
        }

        return Response.status(200).entity(soajs.toString()).build();
    }
}