LangChain4j in Jakarta EE and MicroProfile

This example demonstrates LangChain4J in a Jakarta EE / MicroProfile application on Open Liberty. The application is a chatbot built with LangChain4J and uses Jakarta CDI, Jakarta RESTful Web Services, Jakarta WebSocket, MicroProfile Config, MicroProfile Metrics, and MicroProfile OpenAPI features.

Prerequisites:

Java 21
Hugging Face API Key
- Sign up and log in to https://huggingface.co.
- Go to Access Tokens.
- Create a new access token with read role.

Environment Set Up

To run this example application, navigate to the jakartaee-microprofile-example directory:

cd langchain4j-examples/jakartaee-microprofile-example

Set the following environment variables:

export JAVA_HOME=<your Java 21 home path>
export HUGGING_FACE_API_KEY=<your Hugging Face read token>

Start the application

Use the Maven wrapper to start the application by using the Liberty dev mode:

./mvnw liberty:dev

Try out the application

Navigate to http://localhost:9080

At the prompt, try the following message examples:

```
What are large language models?
```
```
Which are the most used models?
```
```
show me the documentation
```

Try out other models

Navigate to the the OpenAPI UI URL for the following 3 REST APIs:

HuggingFaceLanguageModel
- Expand the GET /api/model/language API.
  1. Click the Try it out button.
  2. Type When was Hugging Face launched?, or any question, in the question field.
  3. Click the Execute button.
- Alternatively, run the following curl command from a command-line session:
  - ```
  curl 'http://localhost:9080/api/model/language?question=When%20was%20Hugging%20Face%20launched%3F'
```
HuggingFaceChatModel
- expand the GET /api/model/chat API
  1. Click the Try it out button.
  2. Type Which are the most used Large Language Models?, or any question, in the question field.
  3. Click the Execute button.
- Alternatively, run the following curl command from a command-line session:
  - ```
  curl 'http://localhost:9080/api/model/chat?userMessage=Which%20are%20the%20most%20used%20Large%20Language%20Models%3F' | jq
```
InProcessEmbeddingModel
- expand the GET /api/model/similarity API
  1. Click the Try it out button.
  2. Type I like Jakarta EE and MicroProfile., or any text, in the the text1 field.
  3. Type I like Python language., or any text, in the the text2 field.
  4. Click the Execute button.
- Alternatively, run the following curl command from a command-line session:
  - ```
  curl 'http://localhost:9080/api/model/similarity?text1=I%20like%20Jakarta%20EE%20and%20MicroProfile.&text2=I%20like%20Python%20language.' | jq
```

Running the tests

Because you started Liberty in dev mode, you can run the provided tests by pressing the enter/return key from the command-line session where you started dev mode.

If the tests pass, you see a similar output to the following example:

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running it.dev.langchan4j.example.ChatServiceIT
[INFO] ...
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.439 s...
[INFO] ...
[INFO] Running it.dev.langchan4j.example.ModelResourceIT
[INFO] Tests run: 3, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.733 s...
[INFO] 
[INFO] Results:
[INFO] 
[INFO] Tests run: 4, Failures: 0, Errors: 0, Skipped: 0

When you are done checking out the service, exit dev mode by pressing Ctrl+C in the command-line session where you ran Liberty, or by typing q and then pressing the enter/return key.