Middleware Technologies [MCA II Yr, Anna University] by Roy Antony Arnold

• Client/Server applications are split across address spaces, physical machines, networks and operating systems.
• All NOSs offer peer-to-peer interfaces that let applications communicate using close to the wire send/receive semantics.
• Most NOSs provide some form of RPC middleware that hides the wire.
• An alternative type of model – message queueing or simple MOM – incredibly helpful in situations when the tight synchronization is not needed between the clients and servers.

Communication Stacks

• Each layer has a well-defined set of APIs and Protocols.
• With these mix-and-match can be done.
• Practically, an entire stack of from a single vendor.
• The lowest layer of the communication software belongs to the device drivers that provide an interface to several types of communication hardware adapters.
• Real products don’t have any notion of architectural boundaries or reference models – they just get a job done.
• At the lower layers, they interface to the hardware using MAC protocols defined by IEEE.
• The LLC provides a common interface to the MACs and a reliable link service for transmitting communication packets between two nodes.
• The transport layer provides end-to-end delivery service.