Defining Data Sources

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In addition to the Dimensions and Measures, another key element to define in the models with O3 Designer are the Data Sources.

Using the Data Sources that you include in the model definition, O3 obtains the data necessary for the creation of the Cube corresponding to the model. The data is used to create the Dimensions and hierarchies as well as in the calculation of the Measures.

When working with public dimensions, the data sources are only needed to build the dimensions along with their corresponding hierarchies because these modesl contain no measures. More information can be obtained in this tutorial.

O3 builds cubes in two main stages:

Building of Metadata (the dimensions and their hierarchies)
Loading of measures (the loading of numeric values)

Each record read in stage 2, has the values for the measures and the value for the key of each one of the dimensions. If there's a record that in the value corresponding to a dimension has an element that is not included in the hierarchy (it wasn't in the sources used to build metadata) three things may happen depending on the Error Mode defined in the General Tab of the properties pane:

IGNORE: the record is ignored
ABORT: the building is aborted
APPEND: the element is added to the dimension and the record is included in the cube

Data Sources have two different functions:

Defining the access to data repositories for obtaining data
Declaring the fields for use in the definition of Dimensions and Measures

O3 handles two types of fields, depending on whether they come from the data source or they are created based on expressions on the previous ones:

Basic Fields	These come directly from the data sources (text files, SQL queries, etc.)
Virtual Fields	These are calculated with expressions based on the previous ones

A model can contain multiple data sources of the same type or different types.

Data Sources are identified in the Design Tree by the different branches. These branches include:

	File System, define text files stored in the file system	See Text Data Sources
	SQL Queries, define database connections to query them using SQL	See SQL Data Sources
	Scripts, define scripted sources using a java-like scripting language called Bean Shell	See Script Data Sources
	XML, define XML data sources	See XML Data Sources
	Web Services, define connections to Web Services	See Web Data Sources

The Virtual Fields panel can be accessed by clicking on the Sources element in the Dessign Tree.

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