Introduction
TIC 4TIC4.0 uses the JSON format as by default because it allows us to express an array of subjects (for several subsubjectssub-subjects) or observed properties (for different combinations of timestamps, pom, pomt, names, etc). JSON is also the default file format for many protocols such as REST and MQTT extensively used to share data or publish IoT data. These arrays give us a high flexibility thanks to the hierarchical structure. Other hierarchical structures, such as XML, are possible in TIC 4TIC4.0 like XML but we recommend using JSON as default.
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A flat format is more suitable for low-level implementation like PLCs or software code. JSON is better for sharing extensive messages. Both are valid in TIC 4TIC4.0.
Message Validation
It is a process to check if the message complies TIC4.0 schema. The validations are made based on a JSON Schema. The schema doesn't limit the content to TIC 4TIC4.0, but if the attribute is a TIC 4TIC4.0 attribute the Schema will check if the format is TIC 4TIC4.0.
JSON SCHEMA
Basic rules
All subjects are arrays
All concepts are not arrays
All observed properties are arrays and contain at least the timestamp.
JSON schema validates the type of the “key” (objects and values), if exists in the registered sample and in the schema will verify is the type is the same (boolean, string, real, etc), if it doesn't exist in one of them will not be considered, you will not get any error. The JSON TIC40 schema can be extended with proprietary extra information as TIC4.0 doesn't limit the content of the message with new proprietary content.
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Custom validations
Arrays of Subjects, with more than one array element in the message, need to have a unique “arrayid”.
Arrays of “observed properties” need to have always a unique combination of name, pom, pomt, reference, unit and timestamp. These fields are optional but if exist it needs a unique combination.
“pom” https://tic40.atlassian.net/wiki/spaces/TIC40Definitions/pages/8618041/TIC4.0+Semantic#Where-in-the-subject-(device-or-process) , “pomt” https://tic40.atlassian.net/wiki/spaces/TIC40Definitions/pages/8618041/TIC4.0+Semantic#Where%2FWhen-in-the-timeline-%E2%80%9Cpomt%E2%80%9D%3A, needs to have the expected values. pom: input, iinput, ioutput, output; pomt : schedule, proposal, request, estimated, planned, actual, performed, historic. For the observed properties the “name”, “reference” and “unit” values can have any value as they will be
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identified by #name#, #reference#, #unit# and
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#qualifier# in the flat name path.