Self-Describing Data
Self-describing data is data that has been annotated by the producer, so all consumers can interpret and use the data properly. Every message and every message field consists of self-describing data. Self-Describing Data presents the annotations that augment data so it is self-describing.
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Element |
Description |
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Field Annotations
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type |
Producers must designate the type of every message field. Rendezvous software uses a set of wire-format datatype designations to characterize data by type and size. For example, the type |
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count (number of elements) |
Producers must specify the length of all array data—that is, the number of elements in an array. |
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field name |
Producers can label the fields of a message with names. Consumers use field names to select specific fields from messages. |
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field identifier |
Producers can label the fields of a message with numeric identifiers. Consumers can use field identifiers to select specific fields from messages. All field identifiers in a message must be unique within that message. |
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Message Annotations
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subject name |
Producers must label every outbound message with a send subject name (also called the send subject name), which describes its content and destination set. |
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reply subject name |
Producers can label an outbound message with a reply subject name, to which consumers can send reply messages. |