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This Concept Map, created with IHMC CmapTools, has information related to: Chapter 5, Middleware Software that provides a programming model above the basic building blocks of processes and message passing is called middleware. The middleware layer uses protocols based on messages between processes to provide its higher level abstractions such as remote invocations and events. An important aspect of middleware is the provision of location transparency and independence from the details of communication protocols, operating systems and computer hardware. Some forms of middleware allow the separate components to be written in different programming languages. includes Location Transparency In RPC, the client that calls a procedure cannot tell whether the procedure runs in the same process or in a different process, possibly on a different computer. In RMI the object making the invocation cannot tell whether the object it invokes is local or not and does not need to know. Also in distributed event based programs, the objects generating events and the objects that receive notifications of those events need not to be aware of one anothers' locations., Remote procedure call Model allows client programs to call procedures in server programs running in separate processes and generally in different computers from the client. which The event based programming model allows objects to receive notification of the events at other objects in which they have registered interest. This model has been exted to allow distributed event based programs to be written., Remote procedure call Model allows client programs to call procedures in server programs running in separate processes and generally in different computers from the client. which The object-based programming model was extended to allow objects in different processes to communicate with one another by means of remote method invocation (RMI). RMI is an extension of local method invocation that allows an object living in one process to invoke the methods of an object living in another process., Middleware Software that provides a programming model above the basic building blocks of processes and message passing is called middleware. The middleware layer uses protocols based on messages between processes to provide its higher level abstractions such as remote invocations and events. An important aspect of middleware is the provision of location transparency and independence from the details of communication protocols, operating systems and computer hardware. Some forms of middleware allow the separate components to be written in different programming languages. includes Heterogeneity Applies to all of the following: networks Internet protocols mask the differences between networks computer hardware e.g. data types such as integers can be represented differently operating systems e.g. the API to IP differs from one OS to another programming languages data structures (arrays, records) can be represented differently implementations by different developers they need agreed standards so as to be able to interwork Middleware provides a programming abstraction and masks the heterogeneity of networks etc.