plugin-llm

A plugin that provides an MCP (Model Context Protocol) Streamable HTTP client. It sends prompts to LLM services (default: quarkus-chat-ui-claude) and retrieves responses.

What is MCP (Model Context Protocol)?

MCP is a protocol that standardizes communication with LLM services. It uses JSON-RPC over HTTP to invoke tools and send prompts.

plugin-llm implements MCP's "Streamable HTTP Transport" (protocol version 2025-03-26).

Usage

Basic Prompt Sending

# Usage example in workflow YAML
states:
  ask-llm:
    code:
      - action: setUrl
        args: ["http://192.168.5.15:8090"]
      - action: prompt
        args: ["Please write a script to check this server's status"]

@Action Methods

Action	Arguments	Description
setUrl	"http://host:port"	Set the MCP server base URL. Changing this resets the session
prompt	"prompt text"	Send a prompt and return the LLM response
status	none	Get MCP server status
listTools	none	Get list of available MCP tools

Argument Formats

Arguments accept the following formats:

• Quoted string: "http://localhost:8090"
• JSON array: ["http://localhost:8090"]
• Bare string: http://localhost:8090

Internal Operation

Session Management

1. MCP session is initialized on the first prompt call
2. Session ID is obtained via initialize request (response header Mcp-Session-Id)
3. Subsequent requests include the session ID
4. Session is reset when URL is changed via setUrl

Communication Flow

LlmActor                         MCP Server
   |                                  |
   |-- initialize (JSON-RPC) -------->|
   |<-- session-id (header) ----------|
   |                                  |
   |-- notifications/initialized ---->|
   |                                  |
   |-- tools/call: sendPrompt ------->|
   |<-- result: {content: [{text}]} --|

HTTP Configuration

Setting	Value
Connection timeout	10 seconds
Request timeout	5 minutes
Content-Type	application/json
Accept	application/json, text/event-stream

Response Extraction

Extracts entries with type: "text" from the result.content array in the MCP response and concatenates the text to return.

{
  "result": {
    "content": [
      {"type": "text", "text": "Here is the script..."}
    ]
  }
}

Real-time Output

When an output listener is set, callbacks are invoked in real-time upon response reception.

llmActor.setOutputListener(text -> System.out.println("[LLM] " + text));

Default Settings

Setting	Default Value
Base URL	http://localhost:8090/mcp
Protocol version	2025-03-26
MCP version	1.0

Library Dependencies

• JDK java.net.http.HttpClient (built-in) - No external HTTP dependencies
• No dependencies on other plugins