Conversation Memory & State Management

Version: ≥5.5.x

Overview

Conversation Memory (IConversationMemory) is the heart of EDDI's stateful architecture. It's a Java object that represents the complete state of a conversation, including history, user data, context, and intermediate processing results. This object is passed through the entire Lifecycle Pipeline, with each task reading from and writing to it.

What is Conversation Memory?

Think of Conversation Memory as a living document that captures everything about a conversation:

• Who: User ID and bot ID

• What: All messages exchanged (both user inputs and bot outputs)

• When: Timestamp of each interaction

• Context: Data passed from external systems (user profile, session info, etc.)

• State: Current processing stage (READY, IN_PROGRESS, ENDED, etc.)

• Properties: Extracted and stored data (user preferences, entities, variables)

• History: Complete record of all previous conversation steps

Key Concepts

1. Conversation Steps

A conversation is divided into steps, where each step represents one complete interaction cycle:

Step 1: User says "Hello" → Bot responds "Hi, how can I help?"
Step 2: User says "What's the weather?" → Bot responds "The weather is sunny, 75°F"
Step 3: ...

Each step contains:

• Input: What the user said

• Actions: Actions triggered by behavior rules

• Data: Results from lifecycle tasks (parsed expressions, API responses, LLM outputs)

• Output: Bot's response

2. Current Step vs Previous Steps

IWritableConversationStep getCurrentStep();  // The step being processed right now
IConversationStepStack getPreviousSteps();    // All completed steps (history)

• Current Step: Writable, being built during lifecycle execution

• Previous Steps: Read-only, provides conversation history

3. Memory Scopes

EDDI supports different scopes for storing data:

Scope	Lifetime	Use Case
step	Single interaction	Temporary data needed only for this response
conversation	Entire conversation	User preferences, extracted entities (persists across steps)
longTerm	Across conversations	User profile data that should persist between sessions

4. Undo/Redo Support

Conversation Memory supports undo/redo operations:

void undoLastStep();       // Go back to previous step
boolean isUndoAvailable(); // Check if undo is possible
void redoLastStep();       // Re-apply undone step
boolean isRedoAvailable(); // Check if redo is possible

This enables scenarios like:

• User makes a mistake and wants to go back

• Testing different conversation paths

• Debugging bot behavior

Conversation Memory Structure

Core Properties

public interface IConversationMemory {
    // Identity
    String getConversationId();
    String getBotId();
    Integer getBotVersion();
    String getUserId();
    
    // State
    ConversationState getConversationState();
    void setConversationState(ConversationState state);
    
    // Steps
    IWritableConversationStep getCurrentStep();
    IConversationStepStack getPreviousSteps();
    IConversationStepStack getAllSteps();
    int size();  // Total number of steps
    
    // Properties
    IConversationProperties getConversationProperties();
    
    // Output
    List<ConversationOutput> getConversationOutputs();
    
    // History management
    void undoLastStep();
    void redoLastStep();
    Stack<IConversationStep> getRedoCache();
}

Conversation States

public enum ConversationState {
    READY,           // Bot is ready to process next input
    IN_PROGRESS,     // Currently processing a message
    EXECUTION_INTERRUPTED,  // Processing was interrupted
    ERROR,           // An error occurred
    ENDED            // Conversation has ended
}

How Lifecycle Tasks Use Memory

Each lifecycle task follows this pattern:

@Override
public void execute(IConversationMemory memory, Object component) {
    // 1. Read from memory
    String userInput = memory.getCurrentStep().getLatestData("input").getResult();
    
    // 2. Perform task logic
    String processed = process(userInput);
    
    // 3. Write results back to memory
    IData<String> data = dataFactory.createData("output", processed);
    memory.getCurrentStep().storeData(data);
}

Example: Behavior Rules Task

// Reads conversation memory to check conditions
IData<List<String>> expressionsData = 
    memory.getCurrentStep().getLatestData("expressions");

// If conditions match, stores actions in memory
memory.getCurrentStep().storeData(
    dataFactory.createData("actions", List.of("welcome_action"))
);

Example: LangChain Task

// Reads conversation history
List<IConversationStep> history = memory.getPreviousSteps().getAllSteps();

// Calls LLM with history
String llmResponse = langChainService.chat(history, currentInput);

// Stores LLM response in memory
memory.getCurrentStep().storeData(
    dataFactory.createData("llmResponse", llmResponse)
);

Example: HTTP Calls Task

// Reads context from memory for request
String userId = memory.getConversationProperties()
    .get("context.userId");

// Makes API call
JsonObject response = httpClient.get("/users/" + userId);

// Stores response for use in output templates
memory.getCurrentStep().storeData(
    dataFactory.createData("userProfile", response)
);

Accessing Memory in Configurations

In Output Templates (Thymeleaf)

<!-- Access current input -->
You said: [[${memory.current.input}]]

<!-- Access previous step data -->
Previously, you mentioned: [[${memory.previous.userPreference}]]

<!-- Access context data -->
Welcome, [[${memory.current.context.userName}]]!

<!-- Access HTTP call response -->
The weather is: [[${memory.current.httpCalls.weatherResponse.temperature}]]

<!-- Access LLM response -->
AI says: [[${memory.current.llmResponse}]]

In HTTP Call Body Templates

{
  "userId": "[[${memory.current.context.userId}]]",
  "message": "[[${memory.current.input}]]",
  "conversationId": "[[${memory.conversationId}]]"
}

In Behavior Rule Conditions

{
  "type": "contextmatcher",
  "configs": {
    "contextKey": "userName",
    "contextType": "string"
  }
}

Memory Persistence

Storage Mechanism

1. During Processing: Memory resides in Java heap (fast access)

2. After Each Step: Memory is serialized and saved to MongoDB

3. On Next Request: Memory is loaded from MongoDB and cached

Caching Strategy

Request → Check Cache → If Miss: Load from MongoDB → Execute Lifecycle → Save to MongoDB + Update Cache

EDDI uses Infinispan for distributed caching:

• Fast retrieval of frequently accessed conversations

• Reduced MongoDB load

• Supports horizontal scaling across multiple EDDI instances

MongoDB Structure

{
  "_id": "conversationId",
  "botId": "bot-123",
  "botVersion": 1,
  "userId": "user-456",
  "conversationState": "READY",
  "conversationSteps": [
    {
      "timestamp": 1699824000000,
      "data": [
        {"key": "input", "value": "Hello"},
        {"key": "expressions", "value": ["greeting(hello)"]},
        {"key": "actions", "value": ["welcome_action"]},
        {"key": "output", "value": ["Hi! How can I help you?"]}
      ]
    },
    // ... more steps
  ],
  "conversationProperties": {
    "userName": "John",
    "userPreference": "concise"
  },
  "redoCache": []
}

Best Practices

1. Use Appropriate Scopes

// ❌ Don't store temporary data in conversation scope
propertyInstruction.setScope("conversation");  // This persists!

// ✅ Use step scope for temporary data
propertyInstruction.setScope("step");  // Cleaned after this step

2. Clean Up Large Data

If you store large API responses, consider cleaning them after use:

{
  "postResponse": {
    "propertyInstructions": [
      {
        "name": "temperature",
        "fromObjectPath": "weatherResponse.current.temperature",
        "scope": "conversation"
      }
    ]
  }
}

Extract only what you need instead of storing the entire response.

3. Leverage History for Context

When calling LLMs, you can control how much history is sent:

{
  "parameters": {
    "sendConversation": "true",
    "includeFirstBotMessage": "true",
    "logSizeLimit": "10"  // Only last 10 messages
  }
}

4. Use Context for External Data

Pass data from your application via context instead of hardcoding:

// API Request
POST /bots/prod/mybot/conversation123
{
  "input": "What's my order status?",
  "context": {
    "userId": "user-789",
    "sessionId": "session-xyz"
  }
}

Then access in bot logic:

${memory.current.context.userId}

Memory Flow Example

Let's trace how memory flows through a complete conversation step:

1. User Request

POST /bots/prod/weatherbot/conv-123
{
  "input": "What's the weather in Paris?",
  "context": {
    "userId": "john-doe"
  }
}

2. Memory Initialization

IConversationMemory memory = loadOrCreateMemory("conv-123");
memory.getCurrentStep().storeData(
    dataFactory.createData("input", "What's the weather in Paris?")
);
memory.getConversationProperties().put(
    "context.userId", "john-doe"
);

3. Parser Task Execution

// Reads input
String input = memory.getCurrentStep().getLatestData("input").getResult();

// Parses input
List<String> expressions = parse(input);
// Result: ["question(what)", "entity(weather)", "location(paris)"]

// Stores in memory
memory.getCurrentStep().storeData(
    dataFactory.createData("expressions", expressions)
);

4. Behavior Rules Execution

// Reads expressions
List<String> expressions = memory.getCurrentStep()
    .getLatestData("expressions").getResult();

// Evaluates: if expressions contains "entity(weather)" → trigger "fetch_weather"
if (matchesRule(expressions, "entity(weather)")) {
    memory.getCurrentStep().storeData(
        dataFactory.createData("actions", List.of("fetch_weather"))
    );
}

5. HTTP Call Execution

// Reads action
List<String> actions = memory.getCurrentStep()
    .getLatestData("actions").getResult();

if (actions.contains("fetch_weather")) {
    // Extract location from expressions
    String location = extractLocation(expressions);  // "paris"
    
    // Make API call
    JsonObject weather = weatherApi.get(location);
    
    // Store response
    memory.getCurrentStep().storeData(
        dataFactory.createData("weatherData", weather)
    );
}

6. Output Generation

// Reads weather data
JsonObject weather = memory.getCurrentStep()
    .getLatestData("weatherData").getResult();

// Applies template
String output = applyTemplate(
    "The weather in [[${weatherData.location}]] is [[${weatherData.description}]]",
    memory
);
// Result: "The weather in Paris is sunny with 22°C"

// Stores output
memory.getCurrentStep().storeData(
    dataFactory.createData("output", List.of(output))
);

7. Memory Persistence

// Save to MongoDB
conversationMemoryStore.save(memory);

// Update cache
cache.put("conv-123", memory.getConversationState());

8. Response to User

{
  "conversationState": "READY",
  "conversationOutputs": [
    {
      "output": ["The weather in Paris is sunny with 22°C"],
      "actions": ["fetch_weather"]
    }
  ]
}

Advanced Topics

Accessing Nested Data

// In Java
IData<JsonObject> httpData = memory.getCurrentStep()
    .getLatestData("httpCalls.userProfile");
String userName = httpData.getResult().getString("name");

// In Thymeleaf
[[${memory.current.httpCalls.userProfile.name}]]

Iterating Over History

IConversationStepStack previousSteps = memory.getPreviousSteps();
for (IConversationStep step : previousSteps) {
    IData<String> inputData = step.getLatestData("input");
    if (inputData != null) {
        String pastInput = inputData.getResult();
        // Process historical input
    }
}

Conditional Memory Access

// In Thymeleaf, check if data exists
[(${memory.current.weatherData != null ? memory.current.weatherData.temperature : 'N/A'})]

Related Documentation

• Architecture Overview - Understanding the big picture

• Behavior Rules - Using memory in conditions

• Output Templating - Accessing memory in outputs

• HTTP Calls - Storing API responses in memory

• LangChain Integration - Using conversation history with LLMs