Application revamp

README.md

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+# CartChain
+
+Proof of concept for an e-commerce API implementing blockchain technology by using a simple private chain (no mining)
+
+## How it works?
+
+The aim of this API is to manage a shopping cart of an ecommerce website. So, through it, the client will be
+able to request and create, update or delete any item in the current cart.
+
+Every action of the API will generate a new _Block_ on the _Blockchain_ in order to create a history and persist the
+information, so we can retrieve it later, but also keeps a history of which items have the user added to the cart.
+
+### Workflow
+
+The workflow of this API is as follows:
+
+* Create
+
+1. Create request is received
+2. Check if the `id` for a Cart is not already used
+    1. If it has been used we return error
+    2. If it has not been used, we create the cart with the given item and generates a new Block to add to the
+       Blockchain
+3. Add the new _Block_ to the _Blockchain_ with the current information of this Cart
+
+* Update
+
+1. Update request is received
+2. Check if the `id` for a Cart exists
+    1. If not exists return error
+    2. If exist retrieve it
+3. Update the items in the cart and generate a new Block with the information
+4. Add the new _Block_ to the _Blockchain_
+
+* Delete
+
+1. Delete request is received
+2. Check if the `id` for a Cart exists
+    1. If not exists return error
+    2. If exist retrieve it
+3. Remove cart information and create a new _Block_
+4. Add the new _Block_ to the _Blockchain_
+
+## Technical Considerations
+
+### Stack
+* [Java 17](https://openjdk.java.net/projects/jdk/17/)
+* [Gradle 7](https://docs.gradle.org/7.0/release-notes.html)
+* [Spring boot](https://spring.io/projects/spring-boot)
+* [Lombok](https://projectlombok.org/)
+* [Junit](https://junit.org/junit5/)
+* [JaCoCo](https://docs.gradle.org/current/userguide/jacoco_plugin.html)
+* [Docker](https://www.docker.com/)
+* [Make](https://www.gnu.org/software/make/manual/make.html)
+
+### Architecture
+
+This app is implemented using hexagonal architecture (ports & adapters) and DDD approach.
+
+The architecture helps to have a decoupled code and being easy to modify or extend it. Following diagram hints how this is achieved:
+
+![Architecture](hexagonal.png)
+
+More info at [Hexagonal Architecture](https://alistair.cockburn.us/hexagonal-architecture/)
+### Getting Started
+
+Within the [Makefile](Makefile) you can handle the entire flow to get everything up & running:
+
+1. Install `make` on your computer, if you do not already have it.
+2. Start the application: `make up`
+3. Run the application tests: `make test`
+
+Go to [localhost:8080/swagger-ui/index.html](http://localhost:8080/swagger-ui/index.html) to see the API description.
+
+As you can see on the [Makefile](Makefile) script and the [docker-Compose File](docker-compose.yml), the whole API
+is containerized with docker and the API is using the internal DNS to connect with the PostgreSQL instance.