Data Object

A Data Object is an internal data structure that represents the business data in the BAM server. Like the concept of the database tables, a Data Object has a flat structure, which includes fields with primitive data types, such as string, integer, float, date time, and so on. It can also include calculated fields and lookup fields, which reference to other Data Objects using foreign keys. The Data Object field cannot be defined using complex data types, such as arrays, objects, and so on.

The following screenshot depicts the Employees Data Object layout, which is defined using simple primitive data types, such as string, integer, and timestamp:

Data Objects are managed in the in-memory data cache to meet the needs of high volume data processing, and get persistent in the BAM database schema automatically. In the current release, Oracle BAM supports the following RDBMS as its persistence store: Oracle Database, IBM DB2, and Microsoft SQL server.

More Data Object details will be covered in Chapter 2,Designing your First Data Objects and Reports.

ViewSet

A ViewSet is an object that represents a query to a given Data Object. A ViewSet provides an abstraction layer that decouples the View design and underlying data model, which allows multiple reports to share the same Data Object.

In BAM, a ViewSet is defined using an XML schema, which can contain the following elements:

To understand this concept, let's take a look at an example that represents the query to the Employee Data Object that you saw before.

In this ViewSet definition, the dataset attribute specifies the database table (_Employees) that is used to persist the Data Object (Employee). The DatasetField and AggregateField elements specify the _Sales_Area data field and the aggregate SUM(_Sales_Number) that can be used to construct the query to the _Employees dataset.

ViewSets can also be sorted, filtered, and applied row-level securities. More topics related to ViewSet will be covered in the next chapter.

View

A View is a rendered result set, which is generated by opening one or a collection of ViewSets. The following is a sample of the 3D bar chart View that shows the number of orders, grouped by its status:

The list of View types supported in BAM 11g R1 include the following:

You will learn more about these View types in Chapter 4, .

Snapshot

A Snapshot is a query result set created by a ViewSet. When a report is first rendered, a ViewSet is opened to generate the initial result, which is called a Snapshot. The XML representation of the Snapshot is then transformed to DHTML using View-specific XSL, and sent to the client along with JavaScript.

Snapshots are cached in the BAM Server. So, every time the same report is opened in another browser session, the Snapshot will be retrieved, and sent back to the client without generating from scratch, which helps improve the report rendering performance.

Snapshots can be used to generate static Views. To produce dynamic Views, or in other words, to render a report that can reflect the data changes in real time, you will need a push-based mechanism called Active Data, which we will look at next.

Active Data

Active Data is the continuous stream of changes that the ViewSet can produce. Once a report is first rendered with a Snapshot, any subsequent changes to the Snapshot of the ViewSet will be captured at the server side, and pushed back to the client. This is what we call a push-based mechanism.

A push-based mechanism is an efficient way of delivering real-time notifications to the client. Unlike the polling approach, in which clients need to consistently send requests to the server, Active Data allows the server to send the changed data in an incremental way, instead of transferring all the report data to the client, and thus can provide significant advantages, such as the following:

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:

Let us look at a ChangeList example, which is produced by a ViewSet of the Employees Data Object.

The key points that you can see from the example are: