1.4 Shared Definitions

If a Supplier is creating an IVES message that refers to the same real world entity in multiple locations within the document or within multiple documents then there a number of steps that can be taken to ensure that this data sharing is explicit in the IVES markup.

The shared entities should define a supplierSpecificId (see ) so that the shared elements are unambiguously referring to the same entity. This removes the potential duplication, but it does potentially leave you with a document that contains a lot of duplicate information. It also means that each successive definition of an entity would override the meta-data from an earlier definition which might also lead to inconsistencies.

If you want to remove the duplication, then one creates a definition element that defines the definitive description of an object. The definition element is held in the <IvesMessage> but outside the hierarchy of any particular <Event>.

Every time that a Supplier wants to refer to this definition then they use a reference element. The reference element can be used instead of an explicit inline definition for the object and is a pointer to the definition element. Consumers that are parsing an IVES message should then relate the data contained in the definition element to all reference elements that refer to it.

• The binding between a definition element and a reference element is via the supplierDefinitionId which is compulsory on both the definition element and the reference element.
• If you have a reference element that uses a supplierDefinitionId that is not resolveable to a definition element in the current document then the Consumer should use the most recently received matching definition element from an earlier document from the same Supplier. Consumers are under no obligation to be able to perform this operation, and if a Supplier is not aware that the Consumer that they are sending the reference element to is both able to perform the operation, and is also in possesion of the definition element then it is safer to always embed the current version of the appropriate definition elements in the same IVES document that contains the reference elements.
• If it is still not possible to resolve the definition object then the reference cannot be resolved and therefore the <Event> containing the reference cannot be utilised. This should be treated as an error condition and should be resolved, either by the Supplier providing the appropriate definition elements or by the Consumer making the decision to delete the reference elements and then re-parsing the IVES document.

The following list is all of the elements that support definition and reference objects:

• <VenueDefinition> () and <VenueReference> ()
  • <PerformanceSpaceDefinition> and <PerformanceSpaceReference>
• <ContactDefinition> () and <ContactReference> ()
• <PersonDefinition> () and <PersonReference> ()
• <GroupDefinition> () and <GroupReference> ()
• <LinkDefinition> () and <LinkReference> ()
• <DescriptionDefinition> () and <DescriptionReference> ()

It is also worth noting that references can be included in other definitions. For example, a <VenueDefinition> may contain <ContactReference> elements that point at <ContactDefinition>s which themselves contain <LinkReference> to <LinkDefinition> elements and so forth.