TEX Predefined Events

EDM Trigger Schema specification version 0.2 2017-11-30

Predefined events

Predefined events is events genarated by the EDM system if certain conditions apply.

Addressing such events from XPX is done via XPX pseudo-constants. An XPX pseudo-constant is for example model open modes like "XPXRW".

---------------------------------------------------------------------------
-- the system recognized events is proposed to define as INTEGER XPX pseudo constants
-- then we can expand range of trigger events without enhancing grammar
-- declaration can be assumed as something like:
---------------------------------------------------------------------------
trigger_source = ENUMERATION OF(
        XPX_Create_Instance,      -- raised after entity is created
        XPX_Delete_Instance,      -- raised before an entity is deleted
        XPX_Read_Instance,        -- any attribute is accessed
        XPX_Write_Instance,       -- any attribute is modified
 
        XPX_Pre_Set_Attribute,      -- raised before specified attribute is assigned (do we need PRE/POST?)
        XPX_Post_Set_Attribute,     -- raised after specified attribute is assigned (do we need PRE/POST?)
        XPX_Pre_Unset_Attribute,    -- raised before an attribute is set to UNSET
        XPX_Post_Unset_Attribute,   -- raised after an attribute is set to UNSET
        XPX_Read_Attribute,         -- any attribute is accessed
 
        XPX_Create_Model,       -- raised after model is created
        XPX_Delete_Model,       -- raised before model is deleted
        XPX_Read_Model,         -- raised if any data in model accessed (pre)
        XPX_Write_Model,        -- raised if any data in model written (pre)
 
        XPX_Commit_Write_Transaction,       -- raised just before write transaction committed (what about tx levels?)
        XPX_Abort_Write_Transaction,        -- raised just before write transaction aborted(what about tx levels?)
 
    );

Comments from @Former user (Deleted):

(3) what is XPX_Read_Instance?

Only read any attribute in getAttr functions? What's about getAttrs? getAggr where the instance is element? To avoid ambiguity I think it should be defined a set of edmi functions that raised this and other events.

(4) XPX_Pre_Set_Attribute, XPX_Post_Set_Attribute, XPX_Pre_Unset_Attribute and XPX_Post_Unset_Attribute

xpx_change_attribute would be enough for me

It should be subtypes of XPXEVENT to specify different types of attribute changes (with old and new values, ref. to instance, for aggregates initialize/insert/add/delete element and its index,..)

(5) For tracking would be nice to have events like this:

xpx_event_user_logged_in, xpx_event_user_logged_out

xpx_model_open, xpx_model_closed, xpx_model_converted (copied), xpx_model_validated, xpx_model_content_deleted, xpx_model_renamed

xpx_db_started, xpx_db_stopped, xpx_db_backup

xpx_schema_defined, xpx_schema_deleted (for EXPRESS, XPX, QEX, VALIDATION,..)