Model Granularity

Table of Contents
  1. Introduction
  2. Granularities
  3. Meta-model
  4. API
  5. Storage

Introduction

Tree-ware allows fine-grained (set/get) access to individual fields in a model. Other services (in a tree-ware based system) may not be able to handle this fine field-level granularity. So tree-ware supports coarser granularities. Different granularities can be chosen for different parts of the model tree.

Granularities

  • field: this is the default level if granularity is not specified.
  • entity: not yet supported. an entity is the atomic unit.
  • sub_tree: a sub-tree is the atomic unit.

Meta-model

Granularity can only be specified for composition-fields. The definition for composition-fields supports an optional granularity field:

{
  "name": "settings",
  "type": "composition",
  "granularity": "sub_tree"
}

As mentioned previously, granularity defaults to field if not specified.

API

The API cannot support the specified granularity in some cases. For example, individual fields cannot be created; the minimum granularity for creation is an entity. And the get-API is able to support field level granularity irrespective of the granularity specified in the meta-model. The following table indicates what the API is able to support.

API Operation Meta-Model Granularity API Granularity
CREATE field Entity
  entity Entity
  sub_tree Sub-tree
UPDATE field Field
  entity Entity
  sub_tree Sub-tree
DELETE field Entity
  entity Entity
  sub_tree Sub-tree
get field Only fields specified in the request must be returned
  entity All fields in entity must be returned if the request specifies none
  sub_tree All fields in sub-tree must be returned if the request specifies none

Storage

Granularity is implemented completely in the API layer and has no impact on storage. The model is stored the same way for all granularities.