Hi Kumar,
The Three-tier Architecture includes three layers in order to extract the data from the various database and store data in the qlikview data file, apply the business logic and develop the data model using QVD files and finally create the dashboard by using the second layer as a binary load which helps the business user to analyse and process the data.
1. Load (Extract Layer and QVD Layer)
2. Transform ( QlikMart Layer)
3. Presentation (Presentation Layer)
Load:
This tier connect any database by OLEDB or ODBC connection (like MySql, SQL and Oracle) or third party tool (like Salesforce connector) to get the raw data from source tables and store it in the QVD (Qlikview Data) file. We can use this QVD files for all application in that domain. For example, customer, employees and other master data can become common QVDs over a period of time thus saving load times and memory resources.
TRANSFORM:
In this tier, QVD is transform in the business logic and requirement of the business and data model is created with either snowflake or star schema.
A star schema has one fact table and is associated with numerous dimensions table and depicts a star.
Snowflake schema, very large dimension tables are normalized into multiple tables. Every dimension table is associated with sub dimension table.
In this tier, use the QVDs generated from the first tier, inline load, resident load and external files in order to achieve the business logic.
Example:
Master Calendar, Mapping table, Aggregation calculation, Rename or create new field and any external files if necessary.
Sales:
LOAD x as y, * FROM Sales.qvd (qvd);
PRESENTATION:
This tier contains the Binary load of the "second tier file", apply application or data security if necessary and set of QlikView documents used to provide the data to the end user.
The binary statement is used for loading the access and data parts of a QlikView document. It does not load the layout information. Only one binary statement is allowed in the script and it can only be put as the first statement of a script.
Dashboard is a data visualization tool that displays the current status of metrics and key performance indicators (KPIs) for an enterprise. Dashboard contains different filters, widgets and KPIs which help the business users to easily analyse and process the data in order to identity the business failover and achievements.
Example: Binary customer_transform.qvw;
Advantage of Three Tier Architecture: Increased performance:
o QVD file makes the transform to load the data 100 times faster than loading it from the database.
Flexibility:
o More flexible since it used binary load in presentation layer, so the transform can be used in many dashboard.
Easy to maintain:
o We do separate the qvd generator files for each data source for east to maintenance. Since if one of them doesn’t work it’s easier to pinpoint as well as u don’t have to take down all data sources while fixing it.
Reusability:
o QVD and transform files can be used in many applications.
Hope it will helpful to understand clearly about Architectures.
