Hold on to it. This is going to be a rant about what I am thinking about ideas to post, but also an update about the web application Social KPI.
I am working on a few ideas that I would like to write about. But I am not sure. Lately I have been working on microservice architecture project and that had helped me to design Social KPI application. I would like to hear from my followers if they are interested in any particular topic that I should cover. Currently most of the interests are around Spring boot and microservices. That is too specific, but also equally too big of a topic to cover. I have covered bits and pieces of Spring boot.
Here are a few ideas that I have in mind that I would like to post about:
Spring boot in android applications.
How to use Spring boot and deploy in cloud infrastructure
What is chaos engineering?
Android application and details
Microservices and Service-to-Service authentication
Udemy course for Spring boot and microservices.
Please leave a comment if you want me to cover something new.
Where are we with Social KPI application?
So last, I posted about this application was back in May Twitter Client. After that there had been some progress as I did figure out how to use social login for authentication purposes, but it had not been added in the application. I will be reviving the work on this project and will try to contribute daily for 30-60 minutes. As part of my planning process, I will add here the tasks that need to be finished:
Add Social login UI for the application
Add UI Pages for displaying Social KPI reports and user navigation
Connecting front-end to back-end REST APIs through clients.
Use of Jasper reports for graphical reports.
These are the 4 big stories I am planning to finish by the end of October. Once I have all the code completed, I will launch the application through Heroku.
So I have talked about blockchain previously here. I will not be indulging in details about what is blockchain. But I will show how to build blockchain using Spring boot.
What will you need
IntelliJ
Java 8
Spring boot
Gradle
What is blockchain?
In short, blockchain is chain of records which are called blocks, containing any kind of data or transactions in these records. They are chained together using hashes.
Build a blockchain
We will need two model classes: one each for block and for transaction. We will also need a spring rest controller to provide 3 APIs for mining, transaction, and chaining. The heart of this blockchain will be a utility class to provide us Proof of work. If you don’t know what is Proof of work, then you can revisit the article I have linked in this post where I explained the algorithm used in building a blockchain, is called as Proof of work.
Model Classes
Each block will contain an index, timestamp, transactions, proof, and a hash for previous block. This model class will look like below:
package com.betterjavacode.blockchain.model;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.hash.Hashing;
import java.nio.charset.StandardCharsets;
import java.util.List;
public class Block
{
public Block()
{
}
private Long index;
private Long timestamp;
private List<Transaction> transactionList;
private Long proof;
private String previousBlockHash;
public static final Long GENESIS_BLOCK_PROOF = 100L;
public static final String GENESIS_BLOCK_PREV_HASH = "1";
public Long getIndex()
{
return index;
}
public String getPreviousBlockHash()
{
return previousBlockHash;
}
public Long getProof()
{
return proof;
}
public List<Transaction> getTransactionList()
{
return transactionList;
}
public Block(Builder builder)
{
this.index = builder.index;
this.timestamp = builder.timestamp;
this.transactionList = builder.transactionList;
this.proof = builder.proof;
this.previousBlockHash = builder.previousBlockHash;
}
public static class Builder
{
private Long index;
private Long timestamp;
private List<Transaction> transactionList;
private Long proof;
private String previousBlockHash;
public Builder setIndex(Long index)
{
this.index = index;
return this;
}
public Builder setTimestamp(Long timestamp)
{
this.timestamp = timestamp;
return this;
}
public Builder setTransactionList(List<Transaction> transactionList)
{
this.transactionList = transactionList;
return this;
}
public Builder setProof(Long proof)
{
this.proof = proof;
return this;
}
public Builder setPreviousBlockHash(String previousBlockHash)
{
this.previousBlockHash = previousBlockHash;
return this;
}
public Block build()
{
return new Block(this);
}
}
public String hash(ObjectMapper mapper) throws JsonProcessingException
{
String json = mapper.writeValueAsString(this);
return Hashing.sha256().hashString(json, StandardCharsets.UTF_8).toString();
}
}
It will look like below when we have some transaction
We will write a rest controller to retrieve the chain, mine or add a transaction. A REST controller for transactions will do a POST request to add a transaction to chain. Our REST controller will look like below:
package com.betterjavacode.blockchain.controller;
import com.betterjavacode.blockchain.model.Block;
import com.betterjavacode.blockchain.model.Transaction;
import com.betterjavacode.blockchain.response.ChainResponse;
import com.betterjavacode.blockchain.response.MineResponse;
import com.betterjavacode.blockchain.response.TransactionResponse;
import com.betterjavacode.blockchain.service.Blockchain;
import com.betterjavacode.blockchain.util.BlockProofOfWorkGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import javax.validation.Valid;
import java.math.BigDecimal;
import java.util.UUID;
@RestController
@RequestMapping("/")
public class BlockchainController
{
@Autowired
private Blockchain blockchain;
@Autowired
private ObjectMapper objectMapper;
public static final String NODE_ID = UUID.randomUUID().toString().replace("-","");
public static final String NODE_ACCOUNT_ADDRESS = "0";
public static final BigDecimal MINING_CASH_REWARDS = BigDecimal.ONE;
@GetMapping("mine")
public MineResponse mine() throws JsonProcessingException
{
// Calculate Proof of work
Block lastBlock = blockchain.lastBlock();
Long lastProof = lastBlock.getProof();
Long proof = BlockProofOfWorkGenerator.proofOfWork(lastProof);
// Reward the miner by adding a transaction
blockchain.addTransaction(NODE_ACCOUNT_ADDRESS, NODE_ID, MINING_CASH_REWARDS);
// Add the new block to the chain
Block newBlock = blockchain.createBlock(proof, lastBlock.hash(objectMapper));
return new MineResponse.Builder().message("New Block Added").index(newBlock.getIndex()).transactions(newBlock.getTransactionList())
.proof(newBlock.getProof()).previousHash(newBlock.getPreviousBlockHash()).build();
}
@GetMapping("chain")
public ChainResponse fullChain()
{
return new ChainResponse.Builder().chain(blockchain.getChain()).length(blockchain.getChain().size()).build();
}
@PostMapping("transactions")
public TransactionResponse newTransaction(@RequestBody @Valid Transaction transaction)
{
Long index = blockchain.addTransaction(transaction.getSender(), transaction.getRecipient(), transaction.getAmount());
return new TransactionResponse.Builder().index(index).build();
}
}
Transaction POST call basically adds the transaction to the list and returns the index of the block to which the transaction will be added to.
Proof of work
We will discuss how we have implemented the proof of work here. This will be the heart of entire blockchain that we have built.
When new blocks are mined on the blockchain, a proof of work algorithm is used to verify if the block is justifiable. Simple idea of Proof of Work is to find a number which solves a problem. This number must be difficult to find, but easy to verify by network.
Example – Hash of an integer multiplied by another integer must end in a particular number. In our implementation for this algorithm, we verify the proof is valid as below:
public static boolean validProof(Long lastProof, Long proof)
{
String s = "" + lastProof + "" + proof;
String sha256 = Hashing.sha256().hashString(s, StandardCharsets.UTF_8).toString();
return sha256.endsWith(PROOF_OF_WORK);
}
This is the algorithm that miners try to solve fastest and whoever solves it first and compact manner gets rewarded with a coin as part of the transaction.
Swagger API
So now once we build our implementation and run the Spring Boot Application, I can access it through Swagger APIs. These APIs are as below:
/transactions – Creates a new transaction in the block
/mine – mines the new block
/chain – returns the full blockchain
Conclusion
In this post, we showed how to understand a blockchain by implementing one in Spring boot. Remember, one thing that I have not described is the consensus algorithm to verify the chain, though I have implemented that in my class Blockchain.
In this post, I will show how to use social login in a Spring Boot application. So we build an application, but we use a form-based login which is the most basic and most insecure authentication mechanism out there. How do we get over this hunch and use the latest more secure mechanism?
Social login – Tada.
Yes, with an increasing number of social networks, it has become increasingly popular and easier to build an OAuth based login mechanism using social networks. In other words, spring boot offers a solution with a social login plugin and in this post, we will show how to use social login to authenticate your users.
What will you need
IntelliJ
Java 8
Twitter/Facebook/Google/Linkedin/Github accounts
Spring Boot
Gradle
Spring Social Core
Spring offers a spring-social-core project that contains APIs to connect to user’s social accounts. Nevertheless, this library includes a connect framework that offers a solution to manage connections with social service providers. It offers support for OAuth1a and OAuth2. The simplest way to understand this library is that you create a connection factory for each social provider. A connection factory locator finds a factory to create a Sign In Provider. I will provide more details as we go along in implementing this module.
Create a Social Login Gradle Project
If you haven’t noticed from my blog posts, but I have switched from eclipse to IntelliJ for programming editor. Intellij is just smarter and easy to write code editor. So first create a Gradle project for spring boot. (Side note – if you are using IntelliJ ultimate edition, it offers a feature to create spring project.) We will be using the latest version of Spring Boot (2.0.3.RELEASE) to build this project.
I will explain each dependency added in Gradle file as we go along.
Create an entity class
We will be using a simple entity class for User with just one field name. This will look like below:
@JsonIgnoreProperties(ignoreUnknown = true)
public class User
{
public String name;
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
}
Create A Social Configuration to adapt Spring Social library
Firstly, we will implement an interface SocialConfigurer that Spring social library offers. For instance, as part of this implementation, we will create connection factories for different social service providers. Also for this module, we are using InMemoryUsersConnectionRepository. You can always implement a JDBC based database user connection repository. This class will look like below:
package com.betterjavacode.reusablesociallogin;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.*;
import org.springframework.core.env.Environment;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.security.crypto.encrypt.Encryptors;
import org.springframework.security.web.savedrequest.HttpSessionRequestCache;
import org.springframework.social.UserIdSource;
import org.springframework.social.config.annotation.ConnectionFactoryConfigurer;
import org.springframework.social.config.annotation.EnableSocial;
import org.springframework.social.config.annotation.SocialConfigurer;
import org.springframework.social.config.annotation.SocialConfigurerAdapter;
import org.springframework.social.connect.Connection;
import org.springframework.social.connect.ConnectionFactoryLocator;
import org.springframework.social.connect.ConnectionRepository;
import org.springframework.social.connect.UsersConnectionRepository;
import org.springframework.social.connect.jdbc.JdbcUsersConnectionRepository;
import org.springframework.social.connect.mem.InMemoryUsersConnectionRepository;
import org.springframework.social.connect.support.ConnectionFactoryRegistry;
import org.springframework.social.connect.web.ProviderSignInController;
import org.springframework.social.facebook.connect.FacebookConnectionFactory;
import org.springframework.social.github.connect.GitHubConnectionFactory;
import org.springframework.social.google.connect.GoogleConnectionFactory;
import org.springframework.social.linkedin.connect.LinkedInConnectionFactory;
import org.springframework.social.security.AuthenticationNameUserIdSource;
import org.springframework.social.twitter.api.Twitter;
import org.springframework.social.twitter.api.impl.TwitterTemplate;
import org.springframework.social.twitter.connect.TwitterConnectionFactory;
import javax.inject.Inject;
import javax.sql.DataSource;
@Configuration
@PropertySource("classpath:application.properties")
@EnableSocial
public class SocialConfig implements SocialConfigurer
{
@Autowired
private DataSource dataSource;
@Override
public void addConnectionFactories(ConnectionFactoryConfigurer connectionFactoryConfigurer, Environment environment)
{
connectionFactoryConfigurer.addConnectionFactory(new TwitterConnectionFactory(environment.getProperty("spring.social.twitter.consumerKey"), environment.getProperty("spring.social.twitter.consumerSecret")));
connectionFactoryConfigurer.addConnectionFactory(new FacebookConnectionFactory(environment.getProperty("spring.social.facebook.appId"),environment.getProperty("spring.social.facebook.appSecret")));
GoogleConnectionFactory googleConnectionFactory = new GoogleConnectionFactory(environment.getProperty("spring.social.google.appId"),environment.getProperty("spring.social.google.appSecret"));
googleConnectionFactory.setScope("profile");
connectionFactoryConfigurer.addConnectionFactory(googleConnectionFactory);
connectionFactoryConfigurer.addConnectionFactory(new GitHubConnectionFactory(environment.getProperty("spring.social.github.appId"), environment.getProperty("spring.social.github.appSecret")));
connectionFactoryConfigurer.addConnectionFactory(new LinkedInConnectionFactory(environment.getProperty("spring.social.linkedin.appId"), environment.getProperty("spring.social.linkedin.appSecret")));
}
@Override
public UserIdSource getUserIdSource()
{
return new UserIdSource() {
@Override
public String getUserId() {
Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
if (authentication == null) {
throw new IllegalStateException("Unable to get a ConnectionRepository: no user signed in");
}
return authentication.getName();
}
};
}
@Override
public UsersConnectionRepository getUsersConnectionRepository(ConnectionFactoryLocator connectionFactoryLocator)
{
InMemoryUsersConnectionRepository usersConnectionRepository = new InMemoryUsersConnectionRepository(
connectionFactoryLocator);
return usersConnectionRepository;
}
}
As you see in this class, I am referring to application.properties . The application.properties will look like below:
In other words, to get clientid and clientsecret , you will have to register your application with each social service provider. We will not be covering that in this post.
Create a spring web security configuration
In this class, we will extend websecurityconfigureradapter and configure HTTP security as part of spring security implementation. We also add a bean to create Sign In Providers which are part of Spring Social. In addition, we will implement this Sign In Provider to provide a facility to users to sign in with their social provider.
As you see in this class, we have a bean ProviderSignInController which will use SocialSignInAdapter.
Implement a Sign In Adapter
Above all, this is the heart of our implementation where authentication will take place and the user will be assigned a role to access the application. The user will be redirected to the application if the user successfully authenticates. This class will look like below:
As you see in getAuthentication, we pass userId and roles for token-based authentication.
If the user has not signed up with a social provider before, he will be asked to sign up and will be redirected to the application after the first time sign up.
package com.betterjavacode.reusablesociallogin.social;
import com.betterjavacode.reusablesociallogin.entity.User;
import com.betterjavacode.reusablesociallogin.util.UserHelper;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.social.connect.Connection;
import org.springframework.social.connect.ConnectionSignUp;
import org.springframework.stereotype.Service;
@Service
public class SocialConnectionSignup implements ConnectionSignUp
{
@Autowired
UserHelper userHelper;
@Override
public String execute(Connection<?> connection)
{
User user = userHelper.getUser(connection);
return user.getName();
}
}
As you see in this class, we have Autowired a userHelper class, this class will have an implementation to get user details from each social provider.
Therefore, this UserHelper will look like below:
package com.betterjavacode.reusablesociallogin.util;
import com.betterjavacode.reusablesociallogin.entity.User;
import org.springframework.social.connect.Connection;
import org.springframework.social.facebook.api.Facebook;
import org.springframework.social.github.api.GitHub;
import org.springframework.social.google.api.Google;
import org.springframework.social.linkedin.api.LinkedIn;
import org.springframework.social.twitter.api.Twitter;
import org.springframework.stereotype.Component;
@Component
public class UserHelper
{
public User getUser(Connection<?> connection)
{
User user = null;
//get the connection type
ConnectionType type = ConnectionHelper.getConnectionType(connection);
if (type.equals(ConnectionType.TWITTER)) {
user = getTwitterUser(connection);
} else if (type.equals(ConnectionType.FACEBOOK)) {
user = getFacebookUser(connection);
} else if (type.equals(ConnectionType.GOOGLE)) {
user = getGoogleUser(connection);
} else if (type.equals(ConnectionType.GITHUB)) {
user = getGithubUser(connection);
} else if (type.equals(ConnectionType.LINKEDIN)){
user = getLinkedInUser(connection);
}
return user;
}
private User getTwitterUser(Connection<?> connection)
{
User user = new User();
Twitter twitterApi = (Twitter)connection.getApi();
String name = twitterApi.userOperations().getUserProfile().getName();
user.setName(name);
return user;
}
private User getFacebookUser(Connection<?> connection)
{
User user = new User();
Facebook facebookApi = (Facebook)connection.getApi();
String [] fields = { "name" };
User userProfile = facebookApi.fetchObject("me", User.class, fields);
String name = userProfile.getName();
user.setName(name);
return user;
}
private User getGoogleUser(Connection<?> connection)
{
User user = new User();
Google googleApi = (Google) connection.getApi();
String name = googleApi.plusOperations().getGoogleProfile().getDisplayName();
user.setName(name);
return user;
}
private User getGithubUser(Connection<?> connection)
{
User user = new User();
GitHub githubApi = (GitHub) connection.getApi();
String name = githubApi.userOperations().getUserProfile().getName();
user.setName(name);
return user;
}
private User getLinkedInUser(Connection<?> connection)
{
User user = new User();
LinkedIn linkedInApi = (LinkedIn) connection.getApi();
String name = linkedInApi.profileOperations().getUserProfile().getFirstName();
user.setName(name);
return user;
}
}
Implementing a controller and views
Similarly, the last piece in this puzzle is to add a controller and corresponding views so when the user accesses the application, the user will be challenged for authentication.
However, we will add a login controller which will have three views for login, sociallogin and socialloginsuccess . This will look like below:
@Controller
public class LoginController
{
@RequestMapping(value="/login", method= RequestMethod.GET)
public String login(Model model)
{
return "login";
}
@RequestMapping(value ="/socialloginhome", method = RequestMethod.GET)
public String socialloginhome(Model model)
{
return "socialloginhome";
}
@RequestMapping(value="/socialloginsuccess", method= RequestMethod.GET)
public String socialloginsuccess(Model model)
{
return "socialloginsuccess";
}
}
Running the application
Once I build the application and run it, the flow will look like below:
You click on hereit will take you to social login screen as below:
I will choose Facebook and server-side code will redirect me to Facebook login screen. Once I enter my credentials, Facebook will redirect back me to my application as below:
Hence, we showed successful social authentication. Lastly, social login is part of any saas application you are building.
Conclusion
In conclusion, we showed how to create a social login module using the Spring boot social feature. Moreover, the code for this will be available to download here.
In this article, I will show how to achieve LDAP authentication using spring boot plugin for LDAP.
What you will need
Java 8
IntelliJ
Apache Directory Server
Apache Directory Studio
Spring Boot
Implementation
To use LDAP for authentication with Spring Boot, definitely set up a LDAP server and we will use Apache Directory Server in our case. I will not be showing “How to set up and add LDIF entries” as this is entirely different topic. But I have two users John Doe and James Hook in my LDAP repository. I will use those accounts to login.
Set up Spring Boot with LDAP dependencies
As part of implementing this, we will add following gradle dependencies:
For our task, spring-ldap-core and spring-security-ldap are important dependencies.
Rest Controller
We will create a simple rest controller that will display our sample page. This sample page will be secured and to access it, an user will have to authenticate.
package com.betterjavacode.SpringBootLdapApplication.Controllers;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HomeController
{
@GetMapping("/")
public String index()
{
return "Welcome to Spring Boot Ldap Application Page";
}
}
Security Configuration
We will add our security configuration by adding a WebSecurityConfig class that extends WebSecurityConfigurerAdapter.
Now if we look at this, when a user will launch the application, he will be challenged with a login form based on formLogin() . Once the user enters credentials, he will be redirected to home page.
The result for that will look like below:
Once the user enters credentials:
Conclusion
In this post, we showed how to use LDAP for authentication using Spring boot.
To use twitter data in my saas application, I was going to write my own custom Twitter client by doing a rest call. However, I found out Spring Boot offers a Twitter plugin that can be used to fetch Twitter data. Neat.
In this post, I will show some comparison of these two approaches and why one can choose over another:
Custom Twitter Client
So custom twitter client will be a standalone client which will build an HTTP entity with client secrets that are needed to authenticate with Twitter API. In this client, we will use restOperations to call API endpoint passing HTTP entity and the REST call will respond with Twitter Data Model.
There is nothing much wrong with this approach, except the fact that we will have to write an extra TwitterDataModel business object. Also, this business model should be created before we do the actual REST call.
Spring Boot Twitter Plugin
To use this plugin, first, we need to add the plugin in Gradle or maven like below:
Once we have this plugin, we can add an object of type Twitter in our code to call REST APIs.
This will look like below:
private final Twitter twitter;
public TwitterDataModel getTwitterData(long accountId)
{
String url = buildRestUrl(accountId);
ParameterizedTypeReference<HashMap<Long, TwitterDataModel>> responseType = new ParameterizedTypeReference<HashMap<Long, TwitterDataModel>>(){};
HttpEntity entity = buildHttpEntity(CLIENT_ID,CLIENT_SECRET);
Map<Long, TwitterDataModel> twitterDataModelMap = twitter.restOperations().exchange(url, HttpMethod.GET, entity, responseType).getBody();
Long keyForData = new Long(accountId);
TwitterDataModel twitterDataModel = twitterDataModelMap.get(keyForData);
return twitterDataModel;
}
public String buildRestUrl(long accountId)
{
return TWITTER_REST_ENDPOINT + accountId + TWITTER_REST_API;
}
The major advantage of this plugin is that we can get the data in Twitter Data Model that twitter offers. An then we can go on to use to handle our data.
Conclusion
In this post, I showed how we can use a Spring Boot Twitter social plugin to gather Twitter data.