SAP BC was a joint venture between SAP and webMethods to develop an “integration” product. webMethods supplied the 4.x version of (then) B2B Integrator and SAP provided the knowledge for the creation of the SAP Adapter. SAP BC was provided free of charge to all those who used the SAP R/3 product. Your licensing determined if you should pay or not. You could download the product from SAP if you believed you needed it. It is currently no longer supported by SAP. SAP’s new integration product is XI (eXchange Infrastructure) which is itself part of the Netweaver component stack. It allows you to create interfaces to systems external to SAP R/3 in either Java which is executable by the SAP WebAS (web application server) and communicate with R/3 systems using ABAP interfaces executable by the ABAP Engine. ABAP is SAP’s programming language (note that SAP R/3 itself consists of components written in C and Java as well as ABAP). In light of the heavy amounts of money that SAP is contributing to the Netweaver development and marketing campaign, XI will become a major competitor to webMethods at least where there is already an SAP presence. The functionality of XI is already planned to replace the “messaging” between R/3 and SAP components that the Basis module currently performs (Basis allows for the creation of RFC’s and system connections in R/3). Indeed, it has already been used to link SAP’s SRM modules (EBP - enterprise buyer professional - and SUS - Supplier Self-Service).
However, given its relative newness to the world of integration, XI still has some kinks to work out. webMethods is the better choice when you want stable and reliable communications on realistic platforms. XI currently has a large footprint and only works reliably on big server iron.
In a nutshell, XI is a tool in SAP’s attempt to re-image their products as being SOA compliant. Currently, you can’t access any R/3 components using a service call (WSDL & SOAP, XMLRPC, etc…). You mut use a proprietary, point-to-point interface in a BAPI, IDOC, or RFC interface.
Hope that description helps you!