Client/Server Architecture and Data Access - Microsoft SQL Server 2008 Analysis Services - page 566

. XML for Analysis (XML/A) defines methods of access to multidimensional data and

online analytical processing (OLAP) metadata.

NOTE
Analysis Services supports both IPv4 and IPv6. The default is IPv4, but you can change
the configuration of your server to use IPv6 or to use both IPv4 and IPv6.

XML for Analysis Application Layer

SOAP Presentation Protocol Layer

TCP Transport Protocol Layer

IPv4 IPv6 Network Protocol Layer

FIGURE 31.1

The protocol stack.

SOAP defines an XML-based format for the exchange of messages between applications.
The SOAP specification defines a standard way of invoking objects, rules for defining and
transferring data types, and methods of handling errors. This messaging framework is
highly extensible and is independent of implementation-specific semantics such as the
programming model. SOAP version 1.1 can use any transport protocol, including TCP, to
transfer its messages and attachments.

Proposed by Microsoft and Hyperion Solutions, XML/A is an open standard for communi-
cation between an OLAP server and client applications. It is built on top of SOAP to trans-
fer data, including multidimensional data, between a client and a server.

Using Binary XML and Compression for Data Access

XML/A and SOAP are standard text-based protocols that significantly simplify implemen-
tation of both client and server message exchange. However, you might have to pay for
this simplification with a performance hit because of the workload needed to transfer and
decode the text messages. Analysis Services deals with this problem by transferring some
of the data in binary format and compressing the data before it goes through the wire.
Clients can transfer information to the server and vice versa in three modes:

. Text format —Plain text requests and responses using XML/A and SOAP protocols.

. Binary format —Tags of XML elements and attributes are encoded in binary format;

numeric values are not converted to strings but are transferred as is over the wire.
This solves a number of problems: Content going over the wire is less verbose;
parsing of XML is easier and faster; and most important, the precision of numeric