OLaaS: OLAP as a Service

Online Analytics Processing (OLAP) is utilised to develop multidimensional operations enabling queries and visualisation for Business Intelligence (BI). Most of the OLAP systems come with a tightly integrated user interface for querying and visualisation of data without the core OLAP operations exposed as an API. Advanced BI applications can be developed and composed to create complex workflows if the OLAP operations are available as an API. In addition, a Web Service based API would enable applications to use Service Oriented Architecture for Big Data Analytics and also easily be deployed on a Cloud. This paper documents the design and prototyping of an OLAP based Platform as a Service, termed OLAP as a Service (OLaaS). OLaaS exposes the core OLAP operations of OLAP Cube design, Slicing, Dicing, Rollup and Drilldown and data retrieval as RESTful Web Services for application programming and composition. Syntax and parsing logic for the Web Service call parameters is developed and an engine for Multidimensional Query (MDX) construction for the OLAP operations is developed. The Web Services are designed to use an existing OLAP engine for running the generated MDX queries. For flexibility and processing huge data sizes, data movement is allowed to be programmed using source and destination database sources set as parameters to the developed OLAP operation services. The designed OLaaS services are implemented in Java and integrated with the open-source Mondrian OLAP engine Olap4j. Standard OLAP Cube data is used to test and validate the OLaaS and its OLAP services. The prototyped OLaaS services have successfully passed the testing and validation. The performance of the services is evaluated on the test data and is found that the overhead of the REST request parsing and MDX query generation is comparable with the standalone MDX query processing time.