This is a demo project to connect an MCP client to an MCP Server, both implemented using the Spring MCP library.

The client connects to a running instance of Ollama, and by default uses the Llama 3.1 model, but can in theory use any LLM model compatible with MCP tools.

This is built using Java 24. Lower versions of Java will also probably work, but I have not tested. This is also built with Spring 3.5.

This demo application contains a MCP Server which is connected to a database, for a Hospital. It contains three tables, doctors, patients, and appointments. We would like to perform CRUD operations on these tables. That is, create patients and doctors and make appointments. To do this we expose multiple MCP Tools to the MCP Client that allows it to perform the desired database operations via natural language requests from a user.

graph TD
    User[User]
    ClientApp[Client App]
    Ollama[Ollama]
    ServerApp[Server App]
    DB[Database]

    User -->|HTTP: port 8081| ClientApp
    ClientApp -->|HTTP: port 11434| Ollama
    ClientApp -->|HTTP: port 8080| ServerApp
    ServerApp --> DB

Setup requires 4 components

1. PostgreSql database
2. Ollama instance
3. MCP Server app
4. MCP Client app

We can start Ollama in docker (doesn't have to be dockerized, but it is simplest.)

docker run -d  -v ollama:/root/.ollama -p 11434:11434 --name ollama ollama/ollama

The MCP server contains tools that perform operations on a PostgreSQL database. The database can be started by running

docker compose up --build

which will use Flyway to build, modify the tables, and sets up the database on default port 5432.

MCP Server can be run from the mcp-server module directory with the command:

mvn spring-boot:run

By default, this will run on port 8080.

MCP Client can be run from the mcp-client module directory with the command:

mvn spring-boot:run

The client runs on port 8081.

We can send POST requests to our MCP app (the client). Examples below:

Create a doctor record.

curl -X POST -H 'Content-Type: application/json' -d \
'{"message":"Create a doctor with first name Gregory, last name House. His specialization is diagnostics."}' \
http://localhost:8081/tool

Create a patient record.

curl -X POST -H 'Content-Type: application/json' -d \
'{"message": "create a patient record with first name Bob and last name Jones. Email is bobjones@email.ccc, and the phone number is 090-123-567-432."}' \
http://localhost:8081/tool

Create an appointment.

curl -X POST -H 'Content-Type: application/json' -d \
'{"message":"Create an appointment for the doctor with id 1, and patient with id 1, where the time of the appointment is 2025/08/25 at 3:15 PM"}' \
http://localhost:8081/tool

Delete a doctor (Cascades to appointments)

curl -X POST -H 'Content-Type: application/json' -d \
'{"message":"Delete the doctor record which has id 1."}' \
http://localhost:8081/tool