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Glossary

A complete reference of terms used throughout apptor flow documentation and the platform itself.

A​

Actor The runtime unit responsible for executing a specific node type. Each actor type has its own thread pool configured in flow-config.json. Actors communicate via internal message queues and execute asynchronously.

Active Version The workflow version currently deployed to an environment. When a workflow is executed, the active version for the specified environment is used.

A2UI (AI-to-UI) apptor's proprietary system where an AI Task node can generate interactive UI components directly inside a chat interface. The AI produces structured component definitions that the frontend renders dynamically. Supports 24 component types.

API Key A machine-to-machine authentication credential in the format apk_{keyId}_{secret}. Sent as the X-API-Key HTTP header. API Keys are scoped to an organization, can have rate limits, expiry dates, and are assigned roles/permissions.

B​

Boundary Event A node that attaches to another node (usually a subprocess or user task) and triggers on a timeout or error condition. Controlled by the cancel_activity flag.

C​

Call Agent A node type that invokes an external AI agent by reference. Used to modularize AI logic into reusable agent definitions.

Call Process A node type that asynchronously invokes another workflow by its process ID. Useful for triggering sub-workflows without waiting for their completion.

Connection A directed edge between two nodes in a workflow diagram. Has a type: sequenceFlow, trueFlow, falseFlow, successFlow, errorFlow, timeoutFlow, or toolConnection.

Condition Expression A JUEL expression used on trueFlow and falseFlow connections to determine routing. Syntax: ${variableName == 'value'}. Only valid on connection properties — NOT in node property values.

Correlation Key An optional string attached to a process instance that enables an event-driven workflow to be resumed. An intermediate catch event waits for an inbound message matching a specific correlation key.

D​

Dead Letter Queue A storage area for messages that failed to be processed by the execution engine after exhausting retries. Managed via the admin dashboard at /admin/dead-letter-queue.

Domain Task A node type that executes a domain action from a vertical integration. Connects to a domain model (e.g., CRM, HRIS) via a provider mapping and executes operations like "create contact" or "get employee record".

E​

Environment A deployment context within an organization. The two built-in environments are DEVELOPMENT and PRODUCTION. Workflows have separate active versions per environment.

Error Flow A connection type taken when a node execution throws an unhandled error. Enables workflow-level error handling without code.

Execution A single run of a workflow. Also called a process instance. Each execution has isolated state stored in the process_instance table, with individual node_instance records per step.

Event Subscription A database record that captures a suspended workflow waiting for an external event. Stored in event_subscription and matched by message_or_signal_ref + correlation_key.

F​

Flow Definition The complete JSON definition of a workflow, including all nodes, connections, properties, and metadata. Stored as processText in the process_version table.

Flow Link See Connection.

G​

Gateway A routing decision point in a workflow. apptor flow supports exclusive gateways (one path), inclusive gateways (multiple paths), parallel gateways (all paths), and event-based gateways.

GoJS The JavaScript diagramming library used to power the visual workflow designer in the browser. All node rendering, connection drawing, and layout management is handled by GoJS.

I​

If/Else Node A conditional branching node. Has a trueFlow and falseFlow outgoing connection. Conditions are JUEL expressions evaluated at runtime.

Input Node A node type that pauses workflow execution and renders a form to the user. Execution resumes when the user submits the form. Supports field types: textbox, textarea, number, date, select, checkbox, radio, file, form.

Integration A configured connection to an external system (REST API, database, email provider, SMS provider, etc.). Integrations are managed per organization and referenced by nodes via connectionId properties.

J​

JUEL Java Unified Expression Language. The expression engine used for evaluating conditions in If/Else and Loop nodes. Expression syntax: ${expression}. Example: ${status == 'approved' && amount > 1000}.

L​

LangChain4j The Java AI framework used by the AI Task handler to connect to LLM providers, manage tool calling, handle streaming, and manage conversation memory.

Loop Node A node type that repeats execution of a sub-graph based on a condition. Supports standard loops (condition-based) and multi-instance loops (collection-based).

M​

Memory Action A node type that reads or writes conversation memory entries. Used to persist context across workflow executions for long-running AI conversations.

MCP (Model Context Protocol) A tool integration protocol that allows AI models to call external tools via a standardized interface. The Tool node supports MCP connections via mcpConnectionId.

Multi-tenant The architecture pattern where a single deployment of apptor flow serves multiple organizations, with complete data isolation between them enforced by organizationId on every entity.

N​

Node A single step in a workflow. Every node has a type, name, optional timeout/retry configuration, and type-specific properties. See Node Reference.

Node Handler The Java class in apptor-flow-core that implements the execution logic for a specific node type. Each handler extends AbstractNodeHandler.

Node Instance A runtime record of a node's execution within a specific process instance. Tracks status, variables, start/end time, and iteration count. Stored in the node_instance table.

NodeType The Java enum in apptor-flow-sdk that defines all supported node types. The type field of every node maps to a NodeType constant.

O​

Organization The top-level multi-tenancy boundary. All data is scoped to an organization. A user can belong to one or more organizations.

Output Node A node type that renders a message or data to the user. Execution continues immediately — it does not wait for user interaction. Supports display types: info, success, warning, error, message.

P​

Permission A granular capability flag in the format RESOURCE_ACTION (e.g., WORKFLOW_EXECUTE). Permissions are assigned to roles. Users and API keys are assigned roles.

Process The data entity representing a workflow definition. A process has an ID, name, and multiple versions. Also referred to as a "workflow" in the UI.

Process Instance See Execution.

Process Text The raw JSON string stored in process_version.process_text that defines the workflow's nodes, connections, and configuration.

Published Workflow A workflow made accessible via a public URL (/w/{urlSlug} or /public/{urlSlug}). Public workflows can be executed without authentication. They render as a form, chat interface, or custom display.

R​

RAG (Retrieval-Augmented Generation) The technique of injecting relevant document chunks into an LLM's context at query time. apptor flow supports RAG through its Knowledge Base (vector store), accessible via the Knowledge Base Tool node.

Role A named set of permissions. Roles are assigned to users and API keys. Examples: Admin, Developer, Viewer.

Retry A per-node configuration that automatically re-executes a failed node up to maxAttempts times with a configurable delay between attempts. Properties: maxAttempts, delay, delayUom.

S​

Script Task A node type that executes custom code (JavaScript or Python) via GraalVM's Polyglot API. Full access to workflow variables.

Secret An encrypted key-value store entry (name, value) scoped to an organization. Secrets are referenced in node properties using {env.SECRET_NAME} syntax and never exposed in logs.

Service Task The umbrella node type for external integrations. Subtypes: REST API, SQL, Send Email, Send SMS.

Set Variable A node type that creates or updates named variables in the execution context using declarative key-value mappings. Supports expression-based values.

Subprocess A node type that embeds a child workflow definition within the parent workflow. The subprocess runs as a nested execution and can pass variables to/from the parent.

Success Flow A connection type taken when a node completes successfully. Used alongside errorFlow and timeoutFlow for explicit result routing.

T​

Template Variable A variable interpolated into a string property using {variableName} syntax. Resolved by TemplateVariableResolver before the property value is used. Example: Hello {firstName}, your order {orderId} is ready.

Timeout A per-node configuration that triggers a timeoutFlow connection if the node does not complete within the specified duration. Properties: duration, uom (Seconds/Minutes/Hours/Days), action.

Timeout Flow A connection type taken when a node exceeds its configured timeout duration.

Tool Node A node type that exposes an operation (email, SQL, REST API, MCP, knowledge base, web search, file manager) as a tool available to an AI Task node via tool calling.

Tool Connection The connection type used to link a Tool node to an AI Task node. This link registers the tool with the AI agent for tool calling.

Trigger A mechanism that starts a workflow execution. Types include API call, webhook, schedule, and event.

V​

Variable A named value in the workflow execution context. Created by nodes as output, consumed by nodes as input or in property expressions. Variables are scoped to the execution instance.

Vertical Integration A domain-specific integration model that maps abstract business operations (e.g., "create a contact") to provider-specific implementations (e.g., Salesforce, HubSpot). Managed via the Domain Task node.

Voice Task A node type that handles automated voice calls using Twilio for telephony and OpenAI voice models for speech-to-text and text-to-speech.

W​

WebSocket The real-time communication channel used for chat-based workflow interactions. Endpoint: /ws/chat/{processInstanceId}.

Workflow See Process.

Workflow Version A snapshot of a workflow definition at a point in time. Versions have a version_number, state_cd (draft/published), and are associated with an environment.