Warning:
JavaScript is turned OFF. None of the links on this page will work until it is reactivated.
If you need help turning JavaScript On, click here.
This Concept Map, created with IHMC CmapTools, has information related to: ch.5, a collection of objects, some of which can recieve both local and remote invocation those that can receive remote invocations are called remote objects objects need to know the remote object reference of an object in another process in order to invoke its methods. How do they get it?the remote interface specifies which methods can be invoked remotely example ????, remote object invocation Invocation semantics are Local invocations are executed exactly once Remote invocations cannot achieve this. Why not? the Request-reply protocol can apply fault-tolerance measures, cobra marshals data for use by recipients that have prior knowledge of the types of its components. It uses an IDL specification of the data types Java serializes data to include information about the types of its contents, allowing the recipient to reconstruct it. It uses reflection to do this., cobra provides it provides remote object invocation between a client program written in one language and a serverprogram written in another language, programming languages is data structures (arrays, records) can be represented differently, Local invocations are executed exactly once Remote invocations cannot achieve this. Why not? the Request-reply protocol can apply fault-tolerance measures failure models Maybe, At-least-once and At-most-once can suffer from crash failures when the server containing the remote object fails.Maybe - if no reply, the client does not know if method was executed or not. At-least-once - the client gets a result (and the method was executed at least once) or an exception (no result) arbitrary failures. If the invocation message is retransmitted, the remote object may execute the method more than once, possibly causing wrong values to be stored or returned. if idempotent operations are used, arbitrary failures will not occur At-most-once - the client gets a result (and the method was executed exactly once) or an exception (instead of a result, in which case, the method was executed once or not at all), remote object invocation is objects that can recieve remote invocation, Heterogeneity applies to operating system, remote interface is specified by an interface definition language (or IDL), A Middleware programming model is remote object invocation, distributed object model contains a collection of objects, some of which can recieve both local and remote invocation those that can receive remote invocations are called remote objects objects need to know the remote object reference of an object in another process in order to invoke its methods. How do they get it?the remote interface specifies which methods can be invoked remotely, Heterogeneity applies to programming languages, Heterogeneity applies to Networks, Heterogeneity applies to computer hardware, remote object invocation methods is defined remote interface, remote interface specifies the methods of an object available for remote invocation, Heterogeneity applies to Implementation by diff. developers, operating system is the API to IP differs from one OS to another, a remote object reference must be unique in the distributed system and over time. It should not be reused after the object is deleted. why not? the first two fields locate the object unless migration or re-activation in a new process can happen the fourth field identifies the object within the process its interface tells the receiver what methods it has (e.g. class Method) a remote object reference is created by a remote reference module when a reference is passed as argument or result to another process it will be stored in the corresponding proxy it will be passed in request messages to identify the remote object whose method is to be invoked, Implementation by diff. developers is they need agreed standards so as to be able to interwork