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Design concepts
Learn about HCL Link services, projects, flows, maps and schemas.
Schemas
Schemas specify the format of data witin HCL Link maps and flows.
Schemas
Use the schema designer to define, modify, and view schemas. A schema describes the syntax, structure, and semantics of your data.
Type properties
Group properties
Group subclass
Properties of group subclasses

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.
- 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.
  - Schemas
    Use the schema designer to define, modify, and view schemas. A schema describes the syntax, structure, and semantics of your data.
    - About schemas
      A schema defines the contents of at least one input that you intend to map or one output you intend to map.
    - Subtypes
    - Schema hierarchy
    - Defining data
    - Objects, types, and classes
    - Testing part of a schema
      You can test a schema by generating test data for an item or a group. The schema designer creates source and compiled maps that generate and validate the test data. The test-data-generation map automatically runs and produces a text file with the sample data. After that, the test-data-validation map automatically runs on the sample data file.
    - Type properties
      - Defining type properties
      - Basic type properties
      - Item properties
      - Group properties
        Group subclass
        Properties of group subclasses
        Choice group components
        Unordered group components
        Sequence group formats
        Explicit format
        Implicit format
        Specifying a delimiter
        Defining exclude characters
        During map run time, the data validation process uses the Exclude Character List group property to define a set of characters that are not allowed to exist in the data stream as data content.
        Escaping an excluded character in the data content
        Select Release exclude characters when you configure the exclude character list to enable the release character to escape excluded characters. When enabled, a release character that precedes an excluded character in data content escapes the excluded character, and the data content passes validation. Likewise, Link precedes an excluded character with the release character when building the output stream.
      - XML properties in the schema
    - Item restrictions
    - Components
    - Partitioning
    - Type inheritance
    - Error detection
    - Error recovery
    - Schema analyzer
    - Distinguishable objects
    - Return codes and error messages
- 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.

Properties of group subclasses

The distinction between Sequence and Choice group subclasses is that Choice groups have no Partition or Format properties.

Type syntax properties such as Initiator, Terminator, Release, and Empty can be applied to Choice groups. If a release character is defined, by default it applies to the Terminator.