B2B Integration : A Practical Guide to Collaborative E-commerce

82 B2B Integration — A Practical Guide to Collaborative E-commerce
from application-to-application. With most middleware, 'wrappers' are
developed (distributed objects) or messages queues employed (MOM)
to provide a uniform communication standard between APIs.
Invoking API functions from applications developed in different
programming languages requires an application broker in between to do
the data type conversion. This makes the calling application errorprone,
which now has to deal with all kinds of interoperability issues,
including hard-to-find problems such as pointers and terminating nulls.
Most of the APIs do not allow for customization of the application
interface to better suit the needs of the user. Furthermore, API level
integration makes the application tightly coupled, which has some
serious drawbacks. These drawbacks are discussed later in the chapter
under the heading Application Oriented Integration and B2BL
3.4.2. Remote Procedure Calls (RPCs)
RPCs provide a high-level communications paradigm for network
applications using which the applications can invoke procedure
calls across a network, irrespective of the underlying network. RPCs
enable communication and integration of local and remote applications
on a procedure or method level. They allow local applications to draw
on the resources of remote systems and can set up cause-and-effect
events.
The independence from the transportation layer feature of RPC
makes it very useful in B2Bi as it can integrate cross-organization
applications irrespective of the underlying networking mechanisms.
Further, RPCs also hide other technical details of making a remote call
such as parameter marshaling and context management.
The current implementations of RPC include: Common Object
Request Broker Architecture (CORBA), Java's Remote Method
Invocation (RMI) and Microsoft's Distributed Component Object Model
(DCOM).
How to make a remote procedure call?
RPCs enable programs to call or execute predefined functions in the
same system or a remote system. Before we discuss how to make a