The SmartPlant schema must be allowed to evolve because the scope of what the schema defines will change over time. This document describes the rules for modifying the SmartPlant schema (and indirectly, all of the component schemas). Unless explicitly stated otherwise, all of the rules defined in this document apply to both the meta-schema and the SmartPlant schema.
The schema evolution rules support four software schema configurations. In the following four examples, Tool 1 and Tool 2 represent applications written to integrate with the SmartPlant schema. The schema version number has two parts (X.X), where the first number is the schema as it was released by Hexagon. The second part is optional and indicates support for customized changes made by the user.
The schema version for a tool indicates the version of the SmartPlant schema against which the tool adapter was written. Including the asterisk (*) indicates that the metadata (for example, a map file) used by that tool has been updated to the latest set of user-specified customizations and delivered by the SmartPlant schema. Because all four configuration examples include the asterisk, you can conclude that the metadata used by the adapter has been updated to work against the latest SmartPlant schema.
Configuration 1 is the simplest case. All of the tools and the SmartPlant schema are written against the same version of the schema, and there should be no issues.
Configuration 1: All tools (adapters) and the SmartPlant schema on the same version
A new version of the SmartPlant schema has been loaded in configuration 2. However, each of the tools is running with its adapter written to work against the previous version. In this configuration, the new SmartPlant schema cannot include any changes that would prevent the old tool adapters from working with the new SmartPlant schema.
Configuration 2: Tools are on an older version of the schema than the SmartPlant schema
New versions of Tool 1 and Tool 2 have been loaded in configuration 3. These tools have adapters that were written against a version of the SmartPlant schema that is newer than what is currently loaded. The tool adapters must support backward compatibility, and they will have less functionality against the older, loaded version of the SmartPlant schema.
Configuration 3: Tools are on a newer version of the schema than the SmartPlant schema
Configuration 4 is the worst-case scenario. Some of the tool adapters are working against a schema version that is older than the loaded schema, and some of the tools are working against a newer schema version than the loaded schema.
Configuration 4: Tools are on both older and newer versions of the schema than the SmartPlant schema