B2B Integration : A Practical Guide to Collaborative E-commerce

214 B2B Integration — A Practical Guide to Collaborative E-commerce
8.1. What is Middleware?
The term 'middleware' is actually a misnomer to a large degree.
Middleware has typically been defined as distributed software that
resides in the middle of a client/server system providing a uniform
'conduit' for client applications to communicate with a server. The
truth is that many middleware products manage, contain and share
business and application logic, operating more as a server than as
'middleware'.
Traditional middleware technologies include message oriented
middleware (MOM), TP monitors and distributed object technology,
though a 'purer' type of middleware would be communication conduits
such as TCP/IP, DCE and RPC. Middleware products provide a highlevel
abstraction through an API that shields a developer from the
complexities of heterogeneous platforms and architectures.
In order to accomplish the transfer of information, most middleware
will follow a standard set of functions as under:
• The sending application formats the information into a message
buffer using a process called marshalling.
• The sending application must identify the location of the receiving
application or service. The destination can be specified several ways
including:
1. Hard coding;
2. Initialization file; and
3. Middleware naming service such as JNDI or UDDI.
• The sending application must initiate a network communications
session with the destination application.
• The sending application must transfer the message buffer to the
receiving application.
• The receiving application must receive the message buffer.
• The receiving application must extract and interpret the information
in the message using a process called unmarshalling.
• If a response is required, then the receiving application must generate
a response and repeat the communication process to send a message
back to the sender.