Hello Jay

Hello Jay


How to Build a GraphQL API using Spring Boot


In this tutorial we will build a Pokemon API that consumes data from a Postgres database, with a simple endpoint that performs a search by id.

Postgres setup

If you already have Postgres installed locally, you can skip this part, otherwise the easiest way to do it is by running a Docker image. Just install Docker and then:

docker run -p5432:5432 -d postgres:11.4-alpine

This command will start a Postgres instance on port 5432 with default user postgres and default database postgres.

Spring Boot setup

We will start by creating the initial project files using Spring Initializr. I’ve selected:

  • Gradle
  • Java
  • Spring Boot 2.1.6
  • Spring Web Starter
  • Spring Data JPA
  • PostgreSQL Driver

Besides Spring dependencies, we need to add the GraphQL libraries:

  • GraphQL Spring Boot Starter: will automatically create an /graphqlendpoint
  • GraphQL Spring Boot Starter Test: for our unit tests
  • GraphQL Java Tools: from its own documentation: “maps fields on your GraphQL objects to methods and properties on your java objects”. This library requires version 1.3.* of Kotlin, so you need to create a gradle.properties file on the project root directory with content:

Database connection

After adding the dependencies, you can edit the src/main/resources/application.properties file to add the Postgres configuration. If you are using the Docker command above to start Postgres locally, your file should be like this:

## PostgreSQL

#drop n create table again, good for testing, comment this in production

Run your application to test if everything is working so far: ./gradlew bootRun.

GraphQL Schema

GraphQL has a great schema language that adds type declatarations to its request and return values and couples this to the API implementation. Which means that what you declare on the schema must be implemented.

If we want to add an endpoint to search a pokemon by its id we should declare on src/main/resources/schema.graphqls file:

type Pokemon {
    id: ID!
    name: String!

type Query {
    pokemon(id: ID!): Pokemon

Our next step now must be the database search of a Pokemon instance by its id, or else the application won’t run.

Query resolver

The declared schema expects to returns a Pokemon type that contains required attributes id and name.

To our application, that means Pokemon is a Java class with id and nameproperties but also a database table. We can use javax.persistenceannotations to automatically map Pokemon to database table with columns id and name:

@Table(name = "pokemon")
public class Pokemon {

    public Pokemon(final Long id, final String name) {
        this.id = id;
        this.name = name;

    public Long id;

    public String name;

The other expected class should be a Spring Bean that implements GraphQLQueryResolver interface and should have a method with name getPokemon, that matches the parameters and response exactly like we defined in the scheme:

public class Query implements GraphQLQueryResolver {

    public Pokemon getPokemon(Long id) {
        return new Pokemon(1L, "Pikachu");

We can now perform an request at our new endpoint to check if its response is our Pikachu.


GraphiQL configures an endpoint at our API that allow us to test any query. In our project it will run on address <a href="http://localhost:8080/graphiql" target="_blank">http://localhost:8080/graphiql</a>.

The left column is where we should write the queries, and the right column is the results. For example, if we enter the query:

# Searches a Pokemon with id 25 and returns its field 'name'
query {
  pokemon(id: 25){

We should expect the result on right column:

  "data": {
    "pokemon": {
      "name": "Pikachu"

So far it doesn’t matter which parameter id we pass because we’ve fixed the response object, but now we will implement a database search.

Fetch Pokemons from database

Currently our application is not doing a real database search but returning a fixed instance. Let’s now implement this part.

First we create a PokemonRepository interface that extends JpaRepository:

public interface PokemonRepository extends JpaRepository<Pokemon, Long> {

Then we change our Query class to autowire this bean and perform the real database fetch:

public class Query implements GraphQLQueryResolver {

    private PokemonRepository repository;

    public Pokemon getPokemon(Long id) {
        // Not returning a fixed instance anymore
        return repository.findById(id).orElse(null);

Unit test

Our automated test will make use of GraphQLTestTemplate class which allow us to enter a query and verify its response. For example, if we want to test the search pokemon by id query, we first have to create a file in src/test/resources with this query:

# src/test/resources/get-pokemon-by-id.graphql
query {
    pokemon(id: "1") {

The test class should be annotated with @GraphQLTest so it can resolve the GraphQLTestTemplate instance, and PokemonRepository should be annotated with @MockBean so we can mock its response using Mockito.

public class DemoApplicationTests {

    private GraphQLTestTemplate graphQLTestTemplate;

    private PokemonRepository pokemonRepository;

    public void getById() throws IOException {
        Pokemon pokemon = new Pokemon(1L, "Pikachu");

        GraphQLResponse response =

        assertEquals("1", response.get("$.data.pokemon.id"));
        assertEquals("Pikachu", response.get("$.data.pokemon.name"));

Basically the scenario we are testing here is the following:

  • Given the repository returns a pikachu when called the findByIdmethod
  • When we query GraphQL Api with get-pokemon-by-id.graphql
  • Then we expect the response to be a JSON containing the pikachu from repository


The challenge of implementing a GraphQL Api using Spring Boot relies mostly in the configuration and small details of Spring Boot functionality. Overall I think the integration works very well, specially the GraphQL Java Tools that enforces the code implementation.

Thanks for reading. If you liked this post, share it with all of your programming buddies!

Further reading

Spring & Hibernate for Beginners (includes Spring Boot)

Spring Framework Master Class - Learn Spring the Modern Way!

Master Microservices with Spring Boot and Spring Cloud

Spring Boot and OAuth2: Getting the Authorization Code

Monitor Your Java Apps with Spring Boot Actuator

An Introduction to Spring Boot

How to build GraphQL APIs with Kotlin, Spring Boot, and MongoDB?

Build a Rest API with Spring Boot using MySQL and JPA

Angular 8 + Spring Boot 2.2: Build a CRUD App Today!

Spring Boot vs. Spring MVC vs. Spring: How Do They Compare?

Top 4 Spring Annotations for Java Developer in 2019

#spring-boot #java #graphql #docker

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How to Build a GraphQL API using Spring Boot
Were  Joyce

Were Joyce


Spring Boot Authorization Tutorial: Secure an API (Java)

Learn how to use Spring Boot, Java, and Auth0 to secure a feature-complete API. Learn how to use Auth0 to implement authorization in Spring Boot.

Learn how to secure an API with the world’s most popular Java framework and Auth0.

So far, you’ve built an API that allows anyone to read and write data. It’s time to tighten the security, so only users with the menu-admin role can create, update, and delete menu items.

Authentication vs. Authorization

To know what a user can do, you first need to know who the user is. This is known as authentication. It is often done by asking for a set of credentials, such as username & password. Once verified, the client gets information about the identity and access of the user.

To implement these Identity and Access Management (IAM) tasks easily, you can use OAuth 2.0, an authorization framework, and OpenID Connect (OIDC), a simple identity layer on top of it.

OAuth encapsulates access information in an access token. In turn, OpenID Connect encapsulates identity information in an ID token. The authentication server can send these two tokens to the client application initiating the process. When the user requests a protected API endpoint, it must send the access token along with the request.

You won’t have to worry about implementing OAuth, OpenID Connect, or an authentication server. Instead, you’ll use Auth0.

Auth0 is a flexible, drop-in solution to add authentication and authorization services to your applications. Your team and organization can avoid the cost, time, and risk that comes with building your own solution. Also, there are tons of docs and SDKs for you to get started and integrate Auth0 in your stack easily.

#spring boot authorization tutorial: secure an api (java) #spring boot #api (java) #authorization #spring boot authorization tutorial #api

Sival Alethea

Sival Alethea


APIs for Beginners - How to use an API (Full Course / Tutorial)

What is an API? Learn all about APIs (Application Programming Interfaces) in this full tutorial for beginners. You will learn what APIs do, why APIs exist, and the many benefits of APIs. APIs are used all the time in programming and web development so it is important to understand how to use them.

You will also get hands-on experience with a few popular web APIs. As long as you know the absolute basics of coding and the web, you’ll have no problem following along.
⭐️ Unit 1 - What is an API
⌨️ Video 1 - Welcome (0:00:00)
⌨️ Video 2 - Defining Interface (0:03:57)
⌨️ Video 3 - Defining API (0:07:51)
⌨️ Video 4 - Remote APIs (0:12:55)
⌨️ Video 5 - How the web works (0:17:04)
⌨️ Video 6 - RESTful API Constraint Scavenger Hunt (0:22:00)

⭐️ Unit 2 - Exploring APIs
⌨️ Video 1 - Exploring an API online (0:27:36)
⌨️ Video 2 - Using an API from the command line (0:44:30)
⌨️ Video 3 - Using Postman to explore APIs (0:53:56)
⌨️ Video 4 - Please please Mr. Postman (1:03:33)
⌨️ Video 5 - Using Helper Libraries (JavaScript) (1:14:41)
⌨️ Video 6 - Using Helper Libraries (Python) (1:24:40)

⭐️ Unit 3 - Using APIs
⌨️ Video 1 - Introducing the project (1:34:18)
⌨️ Video 2 - Flask app (1:36:07)
⌨️ Video 3 - Dealing with API Limits (1:50:00)
⌨️ Video 4 - JavaScript Single Page Application (1:54:27)
⌨️ Video 5 - Moar JavaScript and Recap (2:07:53)
⌨️ Video 6 - Review (2:18:03)
📺 The video in this post was made by freeCodeCamp.org
The origin of the article: https://www.youtube.com/watch?v=GZvSYJDk-us&list=PLWKjhJtqVAblfum5WiQblKPwIbqYXkDoC&index=5
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Thanks for visiting and watching! Please don’t forget to leave a like, comment and share!

#apis #apis for beginners #how to use an api #apis for beginners - how to use an api #application programming interfaces #learn all about apis

Top 10 API Security Threats Every API Team Should Know

As more and more data is exposed via APIs either as API-first companies or for the explosion of single page apps/JAMStack, API security can no longer be an afterthought. The hard part about APIs is that it provides direct access to large amounts of data while bypassing browser precautions. Instead of worrying about SQL injection and XSS issues, you should be concerned about the bad actor who was able to paginate through all your customer records and their data.

Typical prevention mechanisms like Captchas and browser fingerprinting won’t work since APIs by design need to handle a very large number of API accesses even by a single customer. So where do you start? The first thing is to put yourself in the shoes of a hacker and then instrument your APIs to detect and block common attacks along with unknown unknowns for zero-day exploits. Some of these are on the OWASP Security API list, but not all.

Insecure pagination and resource limits

Most APIs provide access to resources that are lists of entities such as /users or /widgets. A client such as a browser would typically filter and paginate through this list to limit the number items returned to a client like so:

First Call: GET /items?skip=0&take=10 
Second Call: GET /items?skip=10&take=10

However, if that entity has any PII or other information, then a hacker could scrape that endpoint to get a dump of all entities in your database. This could be most dangerous if those entities accidently exposed PII or other sensitive information, but could also be dangerous in providing competitors or others with adoption and usage stats for your business or provide scammers with a way to get large email lists. See how Venmo data was scraped

A naive protection mechanism would be to check the take count and throw an error if greater than 100 or 1000. The problem with this is two-fold:

  1. For data APIs, legitimate customers may need to fetch and sync a large number of records such as via cron jobs. Artificially small pagination limits can force your API to be very chatty decreasing overall throughput. Max limits are to ensure memory and scalability requirements are met (and prevent certain DDoS attacks), not to guarantee security.
  2. This offers zero protection to a hacker that writes a simple script that sleeps a random delay between repeated accesses.
skip = 0
while True:    response = requests.post('https://api.acmeinc.com/widgets?take=10&skip=' + skip),                      headers={'Authorization': 'Bearer' + ' ' + sys.argv[1]})    print("Fetched 10 items")    sleep(randint(100,1000))    skip += 10

How to secure against pagination attacks

To secure against pagination attacks, you should track how many items of a single resource are accessed within a certain time period for each user or API key rather than just at the request level. By tracking API resource access at the user level, you can block a user or API key once they hit a threshold such as “touched 1,000,000 items in a one hour period”. This is dependent on your API use case and can even be dependent on their subscription with you. Like a Captcha, this can slow down the speed that a hacker can exploit your API, like a Captcha if they have to create a new user account manually to create a new API key.

Insecure API key generation

Most APIs are protected by some sort of API key or JWT (JSON Web Token). This provides a natural way to track and protect your API as API security tools can detect abnormal API behavior and block access to an API key automatically. However, hackers will want to outsmart these mechanisms by generating and using a large pool of API keys from a large number of users just like a web hacker would use a large pool of IP addresses to circumvent DDoS protection.

How to secure against API key pools

The easiest way to secure against these types of attacks is by requiring a human to sign up for your service and generate API keys. Bot traffic can be prevented with things like Captcha and 2-Factor Authentication. Unless there is a legitimate business case, new users who sign up for your service should not have the ability to generate API keys programmatically. Instead, only trusted customers should have the ability to generate API keys programmatically. Go one step further and ensure any anomaly detection for abnormal behavior is done at the user and account level, not just for each API key.

Accidental key exposure

APIs are used in a way that increases the probability credentials are leaked:

  1. APIs are expected to be accessed over indefinite time periods, which increases the probability that a hacker obtains a valid API key that’s not expired. You save that API key in a server environment variable and forget about it. This is a drastic contrast to a user logging into an interactive website where the session expires after a short duration.
  2. The consumer of an API has direct access to the credentials such as when debugging via Postman or CURL. It only takes a single developer to accidently copy/pastes the CURL command containing the API key into a public forum like in GitHub Issues or Stack Overflow.
  3. API keys are usually bearer tokens without requiring any other identifying information. APIs cannot leverage things like one-time use tokens or 2-factor authentication.

If a key is exposed due to user error, one may think you as the API provider has any blame. However, security is all about reducing surface area and risk. Treat your customer data as if it’s your own and help them by adding guards that prevent accidental key exposure.

How to prevent accidental key exposure

The easiest way to prevent key exposure is by leveraging two tokens rather than one. A refresh token is stored as an environment variable and can only be used to generate short lived access tokens. Unlike the refresh token, these short lived tokens can access the resources, but are time limited such as in hours or days.

The customer will store the refresh token with other API keys. Then your SDK will generate access tokens on SDK init or when the last access token expires. If a CURL command gets pasted into a GitHub issue, then a hacker would need to use it within hours reducing the attack vector (unless it was the actual refresh token which is low probability)

Exposure to DDoS attacks

APIs open up entirely new business models where customers can access your API platform programmatically. However, this can make DDoS protection tricky. Most DDoS protection is designed to absorb and reject a large number of requests from bad actors during DDoS attacks but still need to let the good ones through. This requires fingerprinting the HTTP requests to check against what looks like bot traffic. This is much harder for API products as all traffic looks like bot traffic and is not coming from a browser where things like cookies are present.

Stopping DDoS attacks

The magical part about APIs is almost every access requires an API Key. If a request doesn’t have an API key, you can automatically reject it which is lightweight on your servers (Ensure authentication is short circuited very early before later middleware like request JSON parsing). So then how do you handle authenticated requests? The easiest is to leverage rate limit counters for each API key such as to handle X requests per minute and reject those above the threshold with a 429 HTTP response. There are a variety of algorithms to do this such as leaky bucket and fixed window counters.

Incorrect server security

APIs are no different than web servers when it comes to good server hygiene. Data can be leaked due to misconfigured SSL certificate or allowing non-HTTPS traffic. For modern applications, there is very little reason to accept non-HTTPS requests, but a customer could mistakenly issue a non HTTP request from their application or CURL exposing the API key. APIs do not have the protection of a browser so things like HSTS or redirect to HTTPS offer no protection.

How to ensure proper SSL

Test your SSL implementation over at Qualys SSL Test or similar tool. You should also block all non-HTTP requests which can be done within your load balancer. You should also remove any HTTP headers scrub any error messages that leak implementation details. If your API is used only by your own apps or can only be accessed server-side, then review Authoritative guide to Cross-Origin Resource Sharing for REST APIs

Incorrect caching headers

APIs provide access to dynamic data that’s scoped to each API key. Any caching implementation should have the ability to scope to an API key to prevent cross-pollution. Even if you don’t cache anything in your infrastructure, you could expose your customers to security holes. If a customer with a proxy server was using multiple API keys such as one for development and one for production, then they could see cross-pollinated data.

#api management #api security #api best practices #api providers #security analytics #api management policies #api access tokens #api access #api security risks #api access keys

Autumn  Blick

Autumn Blick


Public ASX100 APIs: The Essential List

We’ve conducted some initial research into the public APIs of the ASX100 because we regularly have conversations about what others are doing with their APIs and what best practices look like. Being able to point to good local examples and explain what is happening in Australia is a key part of this conversation.


The method used for this initial research was to obtain a list of the ASX100 (as of 18 September 2020). Then work through each company looking at the following:

  1. Whether the company had a public API: this was found by googling “[company name] API” and “[company name] API developer” and “[company name] developer portal”. Sometimes the company’s website was navigated or searched.
  2. Some data points about the API were noted, such as the URL of the portal/documentation and the method they used to publish the API (portal, documentation, web page).
  3. Observations were recorded that piqued the interest of the researchers (you will find these below).
  4. Other notes were made to support future research.
  5. You will find a summary of the data in the infographic below.


With regards to how the APIs are shared:

#api #api-development #api-analytics #apis #api-integration #api-testing #api-security #api-gateway

Were  Joyce

Were Joyce


How to Download Files in Spring Boot

This post will show you how to download image from the local directory in Spring Boot.


This post is a continuation of the previous article…


First, as seen in the image above I target the filename along with the path location. In addition here I also set the header, mediatype for the body, and using InputStream.

In this case I made two returns, one of which I made a comment first. In the first return I made the return value is in the form of the image itself whose path we have targeted before, the following are the results:

Testing and Result 1

Testing and Result 2

#spring #spring-boot #rest-api #java #api #download files in spring boot