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Design concepts
Learn about HCL Link services, projects, flows, maps and schemas.
Flows
A HCL Link flow is a transactional data flow comprised of processing nodes.
Introduction to Flows
This documentation describes how Flows can be run from REST API, listeners, or they can be scheduled.
Nodes
JSON Read Node
This documentation describes the function and use of the JSON Read Node.
Settings
This documentation describes the settings available for the JSON Read node.
Paths
Specifies as a table of paths to find in the input JSON document.

Design concepts
Learn about HCL Link services, projects, flows, maps and schemas.
- Introduction
  The documentation provided here defiens the main artifacts in HCL Link. It is necessar to understand what these artifacts are and the relationship between them.
- Services
  Service definitions define REST services and the endpoints of a service.
- Projects
  A project is a container for HCL Link artifacts.
- Flows
  A HCL Link flow is a transactional data flow comprised of processing nodes.
  - Introduction to Flows
    This documentation describes how Flows can be run from REST API, listeners, or they can be scheduled.
    - Nodes
      - Map Node
        A Map Node invokes an HCL Link map within a flow.
      - Flow Node
        A Flow node invokes a sub-flow within a flow.
      - Source and Target Nodes
        Source and Target Nodes provide HCL Link with an outside-in approach to developing integrations.
      - Request Node
        The Request Node has a single input request terminal and a single output response terminal.
      - Cache Read and Write Nodes
        Cache Read and Cache Write node functionality is described in this section.
      - Clone Node
        The Clone Node has one input and two output terminals.
      - Decision Node
        The Decision Node routes input data to the true, or false terminals depending upon the condition.
      - Fail Node
        The Fail Node causes the flow execution to fail.
      - Format Converter Node
        The Format Converter Node can be used to quickly convert data from one format to another.
      - JSON Read Node
        This documentation describes the function and use of the JSON Read Node.
        Settings
        This documentation describes the settings available for the JSON Read node.
        Paths
        Specifies as a table of paths to find in the input JSON document.
        Variable Scope
        Variable Scope specifies the target for the path expressions.
        Output Content
        Output Content specifies whether to propagate the input JSON document to the output, or whether to output a new JSON object that contains just the elements specified by the paths.
        Examples
        These examples show the functionality of JSON Read node.
      - JSON Transform Node
        The JSON Transform node is used to transform JSON documents from one form to another.
      - Java Node
        The Java Node invokes a Java class, thus performing user defined functionality based on the properties specified for the Java class to act on the input.
      - Join Node
        The Join Node gathers the individual results and appends to a single output file or terminal.
      - Log Node
        The Log Node logs the raw data from the node input into the file and propagates the data from the input to the output terminal.
      - Passthrough Node
        The Passthrough Node propagates data from the input to the output terminal.
      - REST Client Node
        The REST Client Node provides a simple and powerful way to access REST services.
      - Route Node
        The Route Node provides a way to route data conditionally to one or more outputs of the node. The node bases decisions by evaluating a condition for a flow variable and determining whether to send the data to output 1 or 2 or both, based on the result of the condition.
      - Sleep Node
        The Sleep Node suspends the execution of the flow for the specified number of milliseconds
      - Split Node
        A Split Node should be used when there is a need to split CSV data processing. This might occur when CSV data processing becomes excessively time consuming.
    - Terminals
    - Flow terminals
      Flow terminals represent the inputs and outputs to a flow. Every node has input and/or ouptut terminals.
    - Scheduled flows
      This documentation describes the options for defining the flow schedule.
    - Listener
      A Flow that has a Map node as its first node, and uses a File adapter for an input, can enable that node's input to be a Watch.
    - Flow audits
      Flow audits are a way to retrieve more verbose information about a flow instance.
    - Flow variables
      Flow Variables are process data variables that go along with the flow execution, accessible to all nodes in the flow while it is being executed under flow executor/engine context.
    - Create a flow
      Steps required to create a flow.
    - Running flows in the Designer
      When you develop a flow in the Flow Designer you can run the flow directly from the Designer either in Link, or on a different runtime environment.
- Maps
  A HCL Link map defines how to generate data that complies to a specific schema. A map can have any number of inputs and outputs.
- Schemas
  Schemas specify the format of data witin HCL Link maps and flows.
- Connections and Actions
  This documentation describes connections and actions.
- Files
  Files are used in various places within HCL Link. HCL Link allows files to be uploaded to the HCL Linkserver.
- Flow variables
  Flow variables provide a means of passing information throughout a flow instance without requiring that the information to be passed through data links. flow variables are name-value pairs that persist, unless deleted.
- Cache variables
  Cache variables provide a means of processing information throughout a flow instance without requiring that the information to be passed through data links.

Paths

Specifies as a table of paths to find in the input JSON document.

The table has two columns:

Path – The path or query expression that references elements in the JSON input document. Such expressions should comply with the syntax defined by Stefan Goessner's de-facto standard defined here: https://tools.ietf.org/id/draft-goessner-dispatch-jsonpath-00.html. Filter expressions are supported. The path might reference either a JSON text, numeric or boolean primitive, or can specify an object or array.
Variable/Key – The name of the flow variable or cache variable. If filtering the output, this also specifies the name of the field in the filtered output. The specified name can include flow variable references which are resolved when the flow is run. For example, if you specify "%_FLOWUUID_%_id" to prefix the name of the variable with the ID of the flow run.