Develop Reference

How to verify if a servlet processing is really doing non-blocking io?

I am trying to receive an http request using non-blocking io, then make another http request to another server using non-blocking io, and return some response, here is the code for my servlet:
package learn;
import java.io.IOException;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.TimeUnit;
import javax.servlet.AsyncContext;
import javax.servlet.ReadListener;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.InvocationCallback;
import javax.ws.rs.core.Response;
import org.jboss.resteasy.client.jaxrs.ResteasyClientBuilder;
#WebServlet(urlPatterns = {"/async"}, asyncSupported = true)
public class AsyncProcessing extends HttpServlet {
private static final long serialVersionUID = -535924906221872329L;
public CompletableFuture<String> readRequestAsync(final HttpServletRequest req) {
final CompletableFuture<String> request = new CompletableFuture<>();
final StringBuilder httpRequestData = new StringBuilder();
try (ServletInputStream inputStream = req.getInputStream()){
inputStream.setReadListener(new ReadListener() {
final int BUFFER_SIZE = 4*1024;
final byte buffer[] = new byte[BUFFER_SIZE];
#Override
public void onError(Throwable t) {
request.completeExceptionally(t);
}
#Override
public void onDataAvailable() {
if(inputStream.isFinished()) return;
System.out.println("----------------------------------------");
System.out.println("onDataAvailable: " + Thread.currentThread().getName());
try {
while(inputStream.isReady()) {
int length = inputStream.read(buffer);
httpRequestData.append(new String(buffer, 0, length));
}
} catch (IOException ex) {
request.completeExceptionally(ex);
}
}
#Override
public void onAllDataRead() throws IOException {
try {
request.complete(httpRequestData.toString());
}
catch(Exception e) {
request.completeExceptionally(e);
}
}
});
} catch (IOException e) {
request.completeExceptionally(e);
}
return request;
}
private Client createAsyncHttpClient() {
ResteasyClientBuilder restEasyClientBuilder = (ResteasyClientBuilder)ClientBuilder.newBuilder();
return restEasyClientBuilder.useAsyncHttpEngine().connectTimeout(640, TimeUnit.SECONDS).build();
}
public CompletableFuture<Response> process(String httpRequest){
System.out.println("----------------------------------------");
System.out.println("process: " + Thread.currentThread());
CompletableFuture<Response> futureResponse = new CompletableFuture<>();
Client client = createAsyncHttpClient();
client.target("http://localhost:3000").request().async().get(new InvocationCallback<Response>() {
#Override
public void completed(Response response) {
System.out.println("----------------------------------------");
System.out.println("completed: " + Thread.currentThread());
futureResponse.complete(response);
}
#Override
public void failed(Throwable throwable) {
System.out.println(throwable);
futureResponse.completeExceptionally(throwable);
}
});
return futureResponse;
}
public CompletableFuture<Integer> outputResponseAsync(Response httpResponseData, HttpServletResponse resp){
System.out.println("----------------------------------------");
System.out.println("outputResponseAsync: " + Thread.currentThread().getName());
CompletableFuture<Integer> total = new CompletableFuture<>();
try (ServletOutputStream outputStream = resp.getOutputStream()){
outputStream.setWriteListener(new WriteListener() {
#Override
public void onWritePossible() throws IOException {
System.out.println("----------------------------------------");
System.out.println("onWritePossible: " + Thread.currentThread().getName());
outputStream.print(httpResponseData.getStatus());
total.complete(httpResponseData.getLength());
}
#Override
public void onError(Throwable t) {
System.out.println(t);
total.completeExceptionally(t);
}
});
} catch (IOException e) {
System.out.println(e);
total.completeExceptionally(e);
}
return total;
}
#Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
System.out.println("----------------------------------------");
System.out.println("doGet: " + Thread.currentThread().getName());
final AsyncContext asyncContext = req.startAsync();
readRequestAsync(req)
.thenCompose(this::process)
.thenCompose(httpResponseData -> outputResponseAsync(httpResponseData, resp))
.thenAccept(a -> asyncContext.complete());
}
}
The server at http://localhost:3000 is an http server written in node which just returns a response after 27 seconds, i would like to make a request to the node server and while this request is being processed i would want to make another http request to the servlet to see if the same thread is being used. Currently i'm trying to use payara 5.194 to do this but even if i set the two thread pools to have one thread the app server seems to create another threads. So, i would like to know from your knowledge if this servlet is really doing non-blocking io and not blocking at any time, also it would be amazing if i could do some experiment to ensure this. I think it's important to point out that the class ServletInputStream is a subclass of InputStream, so i really don't know if this is non-blocking io. Thank you.

Servlet for receive and share streaming data

I have three programs (a-b-c): a starts b that handles c, when c ends a restarts b. I can only change b, but it is unstable because it is restarted. I was thinking of solving my problems with a servlet service that receives b data and errors and displays them on a web page immediately. I tried two ways: 1. Receive data in a Thread parallel to the servlet and share it with it (I did not succeed); 2. Receive data from a client and share it with ServletContext and refresh the page with sent event but skip lines, even with retry: 100, and repeat the last one when there are no new data. Is there a way to send data to all servlet clients only when they are new? Is there a better solution considering that b is restarted and that I have to limit the ports used?
--UPDATE--
Servlet.java
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
#WebServlet(name = "Servlet", urlPatterns = {"/Servlet", "/test"})
public class Servlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setHeader("Connection", "keep-alive");
response.setContentType("text/event-stream");
response.setCharacterEncoding("UTF-8");
response.setHeader("Cache-Control", "no-cache");
String datain = request.getParameter("StringIn");
String dataold = request.getParameter("StringOld");
PrintWriter writer = response.getWriter();
if (datain == null) {
boolean test = getServletContext().getAttribute("actualData").equals(request.getParameter("StringOld"));
if (!test) {
writer.write("data: " + getServletContext().getAttribute("actualData") +"\n\n");
writer.write("retry: 500");
}
else {
writer.write("data: \n\n");
writer.write("retry: 1000");
}
}
else {
getServletContext().setAttribute("actualData", datain);
writer.write("data receive!\n\n");
}
writer.flush();
writer.close();
}
}
Script index.jsp
var eventSource = null;
var oldmessage = "";
var path = "http://localhost:8080/Servlet?StringaOld=";
function start() {
eventSource = new EventSource(path + oldmessage);
eventSource.onopen = function () {
};
eventSource.onmessage = function (message) {
var mex = message.data;
message.data = null;
if (mex != null) {
oldmex = mex;
testo.value += mex + "\n";
}
};
eventSource.onerror = function (error) {
eventSource = new EventSource(path + encodeURI(oldmessage));
};
Start.disabled = true;
}
function stop() {
eventSource.close();
Start.disabled = false;
}

cookies giving unusual values along with set values in servlet

I have set cookies in a servlet class and read those cookies values in another servlet class. In another servlet class along with the set cookies values, I am getting some unusual values.
My Home.java servlet class results set ::
first result
Hello JSESSIONID, Hello A502A7144AE035ED9B1A2549F5C7B74B
Hello first_name, Hello RACHEL
Hello last_name, Hello KIM
second result
Hello JSESSIONID, Hello A502A7144AE035ED9B1A2549F5C7B74B
Hello first_name, Hello CAIRO
Hello last_name, Hello SENGAL
in both the results I am getting the set cookies values and names but along with them I am getting JSESSIONID and A502A7144AE035ED9B1A2549F5C7B74B. I can't understand from where do these cookies values are appearing? How can I remove this? Why are these values appearing?
My code :
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class Authenticate
*/
#WebServlet("/Authenticate")
public class Authenticate extends HttpServlet {
private static final long serialVersionUID = 1L;
public Authenticate() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
#Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
try
{
// Set response content type
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String firstname = request.getParameter("firstname");
String lastname = request.getParameter("lastname");
out.print("Welcome "+ firstname);
// Create cookies for first and last names.
Cookie f_name = new Cookie("first_name", firstname);
Cookie l_name = new Cookie("last_name", lastname);
// Add both the cookies in the response header.
response.addCookie( f_name );
response.addCookie( l_name );
//creating submit button
out.print("<form action='Home' method='post' >");
out.print("<input type='submit' value='cookie click' />");
out.print("</form>");
out.close();
}
catch(Exception ex)
{
System.out.println("exception occured");
System.out.println(ex.toString());
}
}
}
Code for Home servlet
#WebServlet("/Home")
public class Home extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* #see HttpServlet#HttpServlet()
*/
public Home() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
Cookie ck[] = request.getCookies();
if (ck != null) {
for (int i = 0; i < ck.length; i++) {
out.print("Hello " + ck[i].getName() + ", ");
out.print("Hello " + ck[i].getValue());
out.print("<br />");
}
}
out.close();
} catch (Exception e) {
System.out.println(e);
}
}
}

Apache Felix Filter Issue

I'm developing an Apache Sling WCMS application. I need to filter all requests sent to the server and set some headers in response object. I implemented filter and bundle activator class according to Felix Http Filter Sample and installed as bundle to sling.
Fileter class:
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class HeaderFilter implements Filter {
private final String name;
public HeaderFilter(String name) {
this.name = name;
}
public void init(FilterConfig config) throws ServletException {
doLog("Init with config [" + config + "]");
}
public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
throws IOException, ServletException {
try {
HttpServletResponse response = (HttpServletResponse) res;
HttpServletRequest request = (HttpServletRequest) req;
doLog("Filter request [" + request + "]");
response.setHeader("Cache-Control", "no-cache");
response.setHeader("Expires", "-1");
chain.doFilter(req, response);
} catch (Exception e) {
e.printStackTrace();
}
}
public void destroy() {
doLog("Destroyed filter");
}
private void doLog(String message) {
System.out.println("## [" + this.name + "] " + message);
}
}
Bundle Activator class:
import org.apache.felix.http.api.ExtHttpService;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.framework.ServiceReference;
import org.osgi.util.tracker.ServiceTracker;
import java.util.Dictionary;
import java.util.Hashtable;
public class Activator implements BundleActivator {
private ServiceTracker tracker;
private HeaderFilter filter1 = new HeaderFilter("filter1");
Dictionary hashTable = new Hashtable<Object, Object>();
public void start(BundleContext context) throws Exception {
try {
this.tracker = new ServiceTracker(context, ExtHttpService.class.getName(), null) {
#Override
public Object addingService(ServiceReference ref) {
Object service = super.addingService(ref);
serviceAdded((ExtHttpService) service);
return service;
}
#Override
public void removedService(ServiceReference ref, Object service) {
serviceRemoved((ExtHttpService) service);
super.removedService(ref, service);
}
};
this.tracker.open();
} catch (Exception e) {
e.printStackTrace();
}
}
public void stop(BundleContext context)
throws Exception {
this.tracker.close();
}
private void serviceAdded(ExtHttpService service) {
try {
hashTable.put("filter.scope", new String[]{"request", "forward", "include"});
service.registerFilter(this.filter1, ".*", hashTable, 0, null);
} catch (Exception e) {
e.printStackTrace();
}
}
private void serviceRemoved(ExtHttpService service) {
service.unregisterFilter(this.filter1);
}
}
The is a problem with the code above. It's not working and no request will be filtered.
Any help is appreciated in advance.

Note that you can implement this in a much simpler way using Sling Filters implemented as OSGi Declarative Services (DS).
You'll then just need a few annotations in your Filter, no Activator and the correct pom.xml setup for the Maven plugins that handle the DS annotations.
The documentation is at https://sling.apache.org/documentation/the-sling-engine/filters.html and it points to the NoPropertyFilter example from the Sling integration tests.

I found that my filter is not tracked by the service tracker, so by passing parameter 'true' to tracker.open() the filter was tracked:
this.tracker.open(true);

Key in Request Token is null or blank- Brick red Social Auth

I need to import contacts to the enable my web app users to send invitation to his/her friends from my site, I am using SocioAuth Open source API to get this done, I have written 2 servlets to get this done I am pasting the code of my servlet. when I deployed the app in my Ec2 instance, I am getting an exception saying "Key in request token is null or blank in the line number 27 of the NewSocialAuthentication,
package com.auth.actions;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.brickred.socialauth.AuthProvider;
import org.brickred.socialauth.AuthProviderFactory;
public class NewSocialAuthentication extends HttpServlet{
/**
*
*/
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("Coming to doGet of NewSocialApp..");
#SuppressWarnings("unused")
PrintWriter out = response.getWriter();
String socialAppId = request.getParameter("id");
System.out.println("SocialAppId: "+socialAppId);
AuthProvider provider;
try {
provider = AuthProviderFactory.getInstance(socialAppId);
String returnToUrl = "http://ec2-50-19-118-108.compute-1.amazonaws.com/SocialAuthNew6/return";
System.out.println("Return URL..." + returnToUrl);
String urlString = provider.getLoginRedirectURL(returnToUrl);
System.out.println("URLString: "+urlString);
request.getSession().setAttribute("SocialAuth", provider);
response.sendRedirect(response.encodeRedirectURL(urlString));
} catch (Exception e) {
System.out.println("Exception...");
e.printStackTrace();
}
}
}
package com.auth.actions;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.brickred.socialauth.AuthProvider;
import org.brickred.socialauth.Contact;
import org.brickred.socialauth.Profile;
import org.brickred.socialauth.util.*;
public class ReturnServlet extends HttpServlet{
/**
*
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("Coming to doGet of Return Servlet..");
try{
AuthProvider provider = (AuthProvider)request.getSession().getAttribute("SocialAuth");//this the line is rising exception
Profile p = provider.verifyResponse(request);
System.out.println(p.getFirstName());
List<Contact> contactsList = provider.getContactList();
for(int i=0;i<contactsList.size();i++){
response.setContentType("text/html");
PrintWriter out = response.getWriter();
System.out.println(contactsList.get(i).getFirstName()+" : "+contactsList.get(i).getLastName());
out.println(contactsList.get(i).getFirstName());
out.println(contactsList.get(i).getLastName());
}
}
catch(Exception e){
e.printStackTrace();
}
}
}

This is the servlet which redirects to the email service provider
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.brickred.socialauth.AuthProvider;
import org.brickred.socialauth.AuthProviderFactory;
/**
* Servlet implementation class NewSocialAuthentication
*/
public class NewSocialAuthentication extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* #see HttpServlet#HttpServlet()
*/
public NewSocialAuthentication() {
super();
// TODO Auto-generated constructor stub
}
/**
* #see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
#Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
#SuppressWarnings("unused")
PrintWriter out = response.getWriter();
String socialAppId = request.getParameter("id");
System.out.println("SocialAppId: "+socialAppId);
AuthProvider provider;
try {
provider = AuthProviderFactory.getInstance(socialAppId);
//String returnToUrl = "http://ec2-50-16-183-101.compute-1.amazonaws.com/SocialAuthNew/return";
String returnToUrl = "u r returning url ";
System.out.println("Return URL..." + returnToUrl);
String urlString = provider.getLoginRedirectURL(returnToUrl);
System.out.println("URLString: "+urlString);
request.getSession().setAttribute("SocialAuth", provider);
response.sendRedirect(response.encodeRedirectURL(urlString));
} catch (Exception e) {
System.out.println("Exception...");
e.printStackTrace();
}
}
/**
* #see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
#Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}
the return url would look like this I have embedded in the jsp
<%# page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<%#page import="org.brickred.socialauth.AuthProvider" %>
<%#page import="org.brickred.socialauth.Contact" %>
<%#page import="org.brickred.socialauth.AuthProvider" %>
<%#page import="org.brickred.socialauth.Profile" %>
<%#page import="java.util.*" %>
Insert title here
CONTACT LIST
<%
try{
AuthProvider provider = (AuthProvider)request.getSession().getAttribute("SocialAuth");
try{
System.out.println(provider.getContactList());
}
catch(Exception e){
System.out.println("Exception Encountered..");
}
Profile p = provider.verifyResponse(request);
List contactsList = provider.getContactList();
%>
Hello, <%= p.getFirstName() %>
Contact List
First Name
Email
<%
for(int i=0;i
"/><%= contactsList.get(i).getFirstName() %><%= contactsList.get(i).getEmail() %>
<%
}
%>
</table>
<input type="submit" value="GET CONTACTS"/>
</form>
<%
}
catch(Exception e){
e.printStackTrace();
}
%>