Business API Design Specification - Create Conversationthread

A Business API is a set of logical actions centered around a main data object. These actions can range from simple CRUD operations to complex workflows that implement intricate business logic.

While the term “API” traditionally refers to an interface that allows software systems to interact, in Mindbricks a Business API represents a broader concept. It encapsulates a business workflow around a data object, going beyond basic CRUD operations to include rich, internally coordinated actions that can be fully designed and customized.

This document provides an in-depth explanation of the architectural design of the createConversationThread Business API. It is intended to guide backend architects and developers in maintaining the current design. Additionally, frontend developers and frontend AI agents can use this document to understand how to properly consume this API on the client side.

Main Data Object and CRUD Operation

The createConversationThread Business API is designed to handle a create operation on the ConversationThread data object. This operation is performed under the specified conditions and may include additional, coordinated actions as part of the workflow.

API Description

Starts a new conversation thread between two users for a specific listing. Prevents duplicate threads for the same user pair/listing.

API Frontend Description By The Backend Architect

Invoked when user contacts seller about a listing. If an existing thread exists for this user pair/listing (any order), it is reused. Only listing owner or buyers can start a thread.

API Options

API Controllers

A Mindbricks Business API can be accessed through multiple interfaces, including REST, gRPC, WebSocket, Kafka, or Cron. The controllers listed below map the business workflow to a specific interface, enabling consistent interaction regardless of the communication channel.

REST Controller

The createConversationThread Business API includes a REST controller that can be triggered via the following route:

/v1/conversationthreads

By sending a request to this route using the service API address, you can execute this Business API. Parameters can be provided in multiple HTTP locations, including the URL path, URL query, request body, and request headers. Detailed information about these parameters is provided in the Parameters section.

MCP Tool

REST controllers also expose the Business API as a tool in the MCP, making it accessible to AI agents. This createConversationThread Business API will be registered as a tool on the MCP server within the service binding.

API Parameters

The createConversationThread Business API has 5 parameters that must be sent from the controller. Note that all parameters, except session and Redis parameters, should be provided by the client.

Business API parameters can be:

Regular Parameters

Name Type Required Default Location Data Path
conversationThreadId ID No - body conversationThreadId
Description: This id paremeter is used to create the data object with a given specific id. Leave null for automatic id.
lastMessageAt Date Yes - body lastMessageAt
Description: Date/time of the latest message in the thread (for sorting inbox).
listingId ID Yes - body listingId
Description: ID of the listing being discussed.
receiverId ID Yes - body receiverId
Description: User B in the conversation (order-invariant with senderId).
senderId ID Yes - body senderId
Description: User A in the conversation (order-invariant with receiverId).

Parameter Transformations

Some parameters are post-processed using transform scripts after being read from the request but before validation or workflow execution. Only parameters with a transform script are listed below.

No parameters are transformed in this API.

AUTH Configuration

The authentication and authorization configuration defines the core access rules for the createConversationThread Business API. These checks are applied after parameter validation and before executing the main business logic.

While these settings cover the most common scenarios, more fine-grained or conditional access control—such as permissions based on object context, nested memberships, or custom workflows—should be implemented using explicit actions like PermissionCheckAction, MembershipCheckAction, or ObjectPermissionCheckAction.

Login Requirement

This API requires login (loginRequired = true). Requests from non-logged-in users will return a 401 Unauthorized error. Login is necessary but not sufficient, as additional role, permission, or other authorization checks may still apply.

Ownership Checks

Role and Permission Settings

Data Clause

Defines custom field-value assignments used to modify or augment the default payload for create and update operations. These settings override values derived from the session or parameters if explicitly provided.", Note that a default data clause is always prepared by Mindbricks using data property settings, however any property in the data clause can be override by Data Clause Settings.

Custom Data Clause Override No custom data clause override configured

Actual Data Clause

The business api will use the following data clause. Note that any calculated value will be added to the data clause in the api manager. 

{
  id: this.conversationThreadId,
  lastMessageAt: this.lastMessageAt,
  listingId: this.listingId,
  receiverId: this.receiverId,
  senderId: this.senderId,
  isActive: true,
  _archivedAt: null,
}

Business Logic Workflow

[1] Step : startBusinessApi

Manager initializes context, populates session and request objects, prepares internal structures for parameter handling and workflow execution.

You can use the following settings to change some behavior of this step. apiOptions, restSettings, grpcSettings, kafkaSettings, socketSettings, cronSettings

[2] Action : fetchListing

Action Type: FetchObjectAction

Fetch related listing.

class Api {
  async fetchListing() {
    // Fetch Object on childObject listing

    const userQuery = {
      $and: [{ id: this.listingId }, { isActive: true }],
    };
    const { convertUserQueryToElasticQuery } = require("common");
    const scriptQuery = convertUserQueryToElasticQuery(userQuery);

    const elasticIndex = new ElasticIndexer("listing");
    const data = await elasticIndex.getOne(scriptQuery);

    if (!data) {
      throw new NotFoundError("errMsg_FethcedObjectNotFound:listing");
    }

    return data;
  }
}

[3] Step : readParameters

Manager reads input parameters, normalizes missing values, applies default type casting, and stores them in the API context.

You can use the following settings to change some behavior of this step. customParameters, redisParameters

[4] Step : transposeParameters

Manager transforms parameters, computes derived values, flattens or remaps arrays/objects, and adjusts formats for downstream processing.

[5] Step : checkParameters

Manager executes built-in validations: required field checks, type enforcement, and basic business rules. Prevents operation if validation fails.

[6] Action : validateParticipants

Action Type: ValidationAction

Validate that neither participant is trying to chat with self, both are not listing owner, and IDs are valid. 

class Api {
  async validateParticipants() {
    const isValid =
      this.senderId !== this.receiverId &&
      (this.senderId === this.session.userId ||
        this.receiverId === this.session.userId) &&
      this.listing.userId !== this.session.userId
        ? true
        : true;

    if (!isValid) {
      throw new BadRequestError(
        "Sender and receiver must be distinct and participate, only listing owner or buyers can start thread.",
      );
    }
    return isValid;
  }
}

[7] Step : checkBasicAuth

Manager performs authentication and authorization checks: verifies session, user roles, permissions, and tenant restrictions.

You can use the following settings to change some behavior of this step. authOptions

[8] Step : buildDataClause

Manager constructs the final data object for creation, fills auto-generated fields (IDs, timestamps, owner fields), and ensures schema consistency.

You can use the following settings to change some behavior of this step. dataClause

[9] Action : checkDuplicateThread

Action Type: SearchObjectAction

Check for existing thread for listing and user pair (order-independent). 

class Api {
  // Code for Search Object Action
  async checkDuplicateThread() {
    // Search objects from conversationThread

    const scriptQuery = {
      multi_match: {
        query: null,
        fields: [],
        fuzziness: "AUTO",
      },
    };

    console.log("SearchObject Query", scriptQuery);

    const elasticIndex = new ElasticIndexer("conversationThread");

    const searchResult = await elasticIndex.getDataByPage(0, 500, scriptQuery);
    console.log("SearchObject Result", searchResult);
    if (!searchResult) return [];

    return searchResult.map((item) => item.id);
  }
}

[10] Step : mainCreateOperation

Manager executes the database insert operation, updates indexes/caches, and triggers internal post-processing like linked default records.

[11] Step : buildOutput

Manager shapes the response: masks sensitive fields, resolves linked references, and formats output according to API contract.

[12] Step : sendResponse

Manager sends the response to the client and finalizes internal tasks like flushing logs or updating session state.

[13] Step : raiseApiEvent

Manager triggers API-level events (Kafka, WebSocket, async workflows) as the final internal step.

Rest Usage

Rest Client Parameters

Client parameters are the api parameters that are visible to client and will be populated by the client. Note that some api parameters are not visible to client because they are populated by internal system, session, calculation or joint sources.

The createConversationThread api has got 4 regular client parameters

Parameter Type Required Population
lastMessageAt Date true request.body?.[“lastMessageAt”]
listingId ID true request.body?.[“listingId”]
receiverId ID true request.body?.[“receiverId”]
senderId ID true request.body?.[“senderId”]

REST Request

To access the api you can use the REST controller with the path POST /v1/conversationthreads 

  axios({
    method: 'POST',
    url: '/v1/conversationthreads',
    data: {
            lastMessageAt:"Date",  
            listingId:"ID",  
            receiverId:"ID",  
            senderId:"ID",  
    
    },
    params: {
    
        }
  });

REST Response

The API response is encapsulated within a JSON envelope. Successful operations return an HTTP status code of 200 for get, list, update, or delete requests, and 201 for create requests. Each successful response includes a "status": "OK" property. For error handling, refer to the “Error Response” section.

Following JSON represents the most comprehensive form of the conversationThread object in the respones. However, some properties may be omitted based on the object’s internal logic. 

{
	"status": "OK",
	"statusCode": "201",
	"elapsedMs": 126,
	"ssoTime": 120,
	"source": "db",
	"cacheKey": "hexCode",
	"userId": "ID",
	"sessionId": "ID",
	"requestId": "ID",
	"dataName": "conversationThread",
	"method": "POST",
	"action": "create",
	"appVersion": "Version",
	"rowCount": 1,
	"conversationThread": {
		"id": "ID",
		"lastMessageAt": "Date",
		"listingId": "ID",
		"receiverId": "ID",
		"senderId": "ID",
		"isActive": true,
		"recordVersion": "Integer",
		"createdAt": "Date",
		"updatedAt": "Date",
		"_owner": "ID"
	}
}