Skip to main content

Categories

Categories are the top-level groupings that organize Shelf Elements. There are two built-in categories: Assets and Messages.

What Are Categories?​

Categories provide the first level of organization in the Shelf. They separate two distinct types of content that can be stored and reused.

Built-in Categories​

layline.io provides two Categories:

CategoryPurposeContents
AssetsReusable Asset configurationsConnections, Services, Formats, Processors, and other Asset types
MessagesData format definitionsMessage schemas, format definitions, and data structure templates

These Categories are fixed and cannot be created, renamed, or deleted.

Assets Category​

The Assets Category contains copies of Project Assets that have been saved to the Shelf for reuse. This includes:

  • Connections — Database connections, API endpoints, file system configurations
  • Services — HTTP services, email configurations, message queue connections
  • Formats — Data format definitions and parsing configurations
  • Processors — Flow processors and transformation logic
  • Other Asset Types — Any Asset that can be copied from a Project

When you copy an Asset from a Project and paste it into the Shelf, it is stored in the Assets Category within a Folder you select or create.

Messages Category​

The Messages Category contains copies of messages that have been saved to the Shelf for later investigation or reuse.

What Are Messages?​

Messages are generic runtime structures created by layline.io at runtime. They hold data that is read from data sources or travels through the system. The structure of messages is completely dynamic and based on a combination of all defined data formats (through format definitions, data dictionary, etc.).

Where Do Shelf Messages Come From?​

Messages that are pasted into the Shelf are usually taken from:

  • Audit trail — Historical message records from processed data
  • Service function execution results — Messages returned from function calls (see Engine State → Services → Functions)

Using Shelf Messages​

Copy a Message from the Shelf and paste it wherever message pasting is supported. A common use case is pasting into the Engine State when executing service functions.

Selecting a Category​

  1. Navigate to the Shelf tab
  2. Click on Assets or Messages in the left sidebar
  3. The middle panel updates to show Folders within that Category
  4. The selected Category is highlighted

Category Icons​

Each Category has a distinct icon for quick visual identification:

  • Assets — Cube/box icon (representing packaged configurations)
  • Messages — Document/message icon (representing data formats)

Organizing Within Categories​

Since Categories are fixed, all organization happens at the Folder level:

  • Create Folders within Categories to group related Elements
  • Use clear, descriptive Folder names
  • Consider organizing by project, environment, or function

See Folders for detailed guidance on Folder organization.

Copying Between Projects​

The key benefit of Categories is that they enable cross-project reuse:

  1. Assets — Copy an Asset from Project A, paste to Shelf, then copy from Shelf and paste into Project B
  2. Messages — Copy a Message definition from one context, save to Shelf, reuse in multiple Projects

The Category structure (Assets vs Messages) remains consistent across all Projects.

Best Practices​

  1. Use both Categories — Don't store everything in one Category; use Assets for configurations and Messages for data formats
  2. Create meaningful Folders — Since you can't create Categories, invest in good Folder structure
  3. Name consistently — Use the same naming patterns across Categories
  4. Review periodically — Clean up unused Elements in both Categories

See Also​

  • Folders — Organizing Elements within Categories
  • Elements — The Assets and Messages stored in Categories
  • Shelf Overview — Introduction to the Shelf concept