Databases Reference
In-Depth Information
You will learn more about Active Data and push-based mechanisms in the
Understanding message flow
section, later in this chapter.
ChangeList
A
ChangeList
is an Active Data Payload that includes the changes produced by
a specific
ViewSet
.
The ChangeList is in XML format, which normally includes the following:
•
index:
A sequence number of a ChangeList. When a report is first
rendered, a
ViewSet
will be opened with a Snapshot. Any further Data
Object changes may trigger a ChangeList generated with incremental index
numbers starting from one. The index will increment by one as any new
changes come.
•
viewsetID:
A unique identifier for a particular
ViewSet
, the index, and
viewsetID
together identify the ChangeList.
•
Group:
A container to hold ChangeList records.
•
Record:
An XML element representing a row in the updated query result of
a
ViewSet
. A
Record
contains a transaction type
(insert, update,
upsert
, and
delete)
, Data Object field references, and contents.
Let us look at a
ChangeList
example, which is produced by a
ViewSet
of
the
Employees
Data Object.
