Business Explorer (BEx), SAP BW's suite of front-end BI tools, supports decision-making for various user types. However, some companies have the need to integrate with other front-end tools, because they want to leverage existing IT investments or because they want to cover specific scenarios.

SAP has implemented several industry standards to create open access interfaces that allow third-party tools to connect to SAP BW, browse metadata and master data, and retrieve data from the underlying data warehouse or ODS. These standards are:

• OLE DB for OLAP (ODBO)
• The OLAP BAPI
• XML for Analysis

These three standards provide third-party vendors different interface options to request and visualize data from BW, processed through the BW OLAP engine.

SAP's open access interfaces are transparent to end users, but two groups on your BW team need to have some knowledge of them: IT and query designers. For the IT team, it is important to know the options, requirements, and limitations of the respective interfaces and certified third-party reporting tools when determining a strategy for integrating a third-party front-end with BW. This helps to shorten the software selection process significantly and to set the appropriate expectations of the tool's capabilities.

Query designers need a good understanding of the SAP BW information architecture and its interface options, as it provides them with additional flexibility for data access. This is important, since the requirements for a reporting solution are diverse and depend on the specific customer situation.

OLE DB for OLAP (Object Linking and Embedding for Databases for Online Analytical Processing), a Microsoft specification, was published with SAP BW Release 1.2. ODBO is used to access relational and multi-dimensional data regardless of the database. The data access is realized via ADO MD (ActiveX Data Objects Multidimensional), which enables straightforward access to multi-dimensional data using a multi-dimensional data provider (MDP). OLE DB and ADO form the core of Microsoft's Universal Data Access (UDA) standard, which is designed to provide access to all types of data through a single data access model.

With OLAP BAPIs (Business Application Programming Interfaces), applications can use the various available options of the interface to access data in BW and to connect to the BW server regardless of their OLAP architecture. Typically, these options are functions to browse BW data such as GetCubes or GetDimensions, or to fetch data using statements such as GetCell Data, or GetAxis Info. These functions are specified in the interface description and implemented by the third-party tool. Published with SAP BW 2.0, OLAP BAPI provides direct access via the BAPI library to enable platform-independent access to the OLAP BAPI (in contrast to ODBO, which requires a Microsoft Windows platform). Communication takes place via an RFC (remote function call).

XML for Analysis (XML/A) standardizes the access to analytical data sources and advances the concepts of ODBO by providing universal access to any data source over the Internet (using the SOAP, XML, and HTTP standards). Built on SAP Web Application Server technology, SAP BW (from Release 3.0 on) leverages the Web service architecture to expose its XML/A service.

Third-party front-end tools communicate with SAP BW via MDX (multi-dimensional expressions), a language developed by Microsoft used for queries on multi-dimensional data. An MDX query returns a multi-dimensional result set (dataset) that consists of axis data and cell data.

The three interfaces offered by SAP BW allow third-party tools to send query requests to the MDX processor on the BW application server. Figure 1 shows how the requests are processed, what the underlying architecture looks like, and which protocols are used.

Figure 1

How SAP BW processes an MDX query

Using the OLAP engine, third-party tools can access the whole spectrum of InfoProviders in SAP BW. These InfoProviders either contain the data objects themselves (InfoCube, ODS object, or InfoObject), or reporting-relevant views of data objects (MultiProvider, RemoteCube, or InfoSet). As of SAP BW 3.0, third-party administrators can have better access to Business Content, since it is no longer necessary to define a query before being able to access the InfoProvider. A “virtual query” allows direct access to the InfoProvider and its key figures and characteristics.

Preparing for Third-Party Access

The ODBO interface provides the capability to query multi-dimensional result sets by executing MDX statements. To enable third-party administrators to query through the ODBO interface, BW ODBO front-end components (the ODBO client) must be installed on the client PC. (BW serves as the data provider and the certified third-party tool serves as the data consumer.) Additionally, BEx and SAP GUI (including add-ons such as the ODBO provider) need to be installed on the client machine to facilitate authentication to the BW server and to allow the query definition. To activate the BEx query for ODBO, the respective settings have to be made in the Query Properties window of the BEx Query Designer screen (Figure 2).

Figure 2

Activating OLE DB for OLAP

To establish communication between third-party tools and SAP BW via the OLAP BAPI, several libraries and files are needed including SAP's main RFC library, which is available for different platforms.¹

To share reports over the Internet, SAP BW offers an XML/A-based BI Web service as of Release 3.0. This is automatically available once you install BW. Applications can access this service via Web protocols and data formats such as HTTP, XML, and SOAP without a special component installed at the client-side and with no need to worry about how each Web service is implemented. The Web service URL must have the following schema:

://:
/sap/bw/xml/soap/xmla


You can call up a description of the Web service via a URL with the following schema:

://:
/sap/bw/xml/soap/
xmla?wsdl

Certification of Third-Party Tools

While MDX provides flexibility, it might lead to the situation where each third-party vendor has its own way to express data sets. The challenge for SAP BW is to accommodate each method equally. Therefore, SAP's Integration and Certification Centers (ICCs) offer interface certification, which assures a pre-defined level of integration. ICCs check capabilities such as the connection of the client application to the SAP BW Server, the retrieval of data and master data (browsing InfoCubes, hierarchies, dimensions, and so on) and the accessing of transactional data (including drill-down capabilities).

However, certain issues arise when using third-party front-ends with SAP BW. The data models of the third-party products might differ from what SAP's interface offers, so you might have less integration in certain areas. For this reason, decision makers need to plan for a longer implementation time. Also, the support situation then becomes more complex, since you are dealing with multiple products and release cycles.

Nearly all major vendors of BI products have gained certification for at least one of their products for use with BW. Most of the third-party vendors' products are certified against the SAP BW ODBO interface, since this is closest to the original Microsoft OLE DB for OLAP specification. Supporting OLAP BAPI as a second choice requires the implementation of an SAP native interface, therefore resulting in higher effort for third-party vendors. At the moment, no certification is available for the SAP BW XML/A interface. This is because only a small number of tools capable of dealing with the new interface XML/A are currently available.

Access Methods

When selecting front-end tools, the first technical issue to consider is the type of implemented interface to access SAP BW data. Table 1 shows the differences among the three BW access standards.

Since information that can be accessed is the same for all interfaces, one of the most important technical differences between the three interface types is their platform availability. ODBO is limited to Windows platforms. This means that application servers or front-ends need to run in Windows, a condition met by most IT infrastructures. If you need support for other platforms such as UNIX or Linux, you should take a look at front-ends using OLAP BAPI or XML/A. Tests on these front-ends by the Business Application Research Center (BARC) show no differences in stability and performance among them if they are properly set up for your system.²

Level of Supported Functionality

Which third-party front-end you use might well depend on which BW functionalities it supports. Table 2 gives an overview of supported functionality and implemented open access interfaces for third-party front-ends recently tested by BARC. Some front-ends offer more functionality than the certification process requires. Support for SAP variables, attributes, and multiple hierarchies, for instance, is not imperative for certification, but can be useful in certain scenarios.

Table 2 shows that implemented interfaces and supported BW functionality vary significantly among third-party vendors.

1 A detailed list is provided in the SAP BW online documentation at https://help.sap.com/saphelp_bw31/helpdata/en/df/
ed8c3c59021315e10000000a114084/frameset.htm.

2 BARC is a European market research company with a focus on tool evaluations. The BARC report “Front-ends for SAP BW” offers organizations qualified support with the selection of front-ends certified for SAP BW. For ordering information, call +49-931-880651-0 or send a message by email to info@barc.de.

3 Four more vendors have certified tools for SAP BW: humanIT went bankrupt, mSE didn't want to be tested, Samsung hasn't been tested yet, and Viador stopped support for the interface.