Lecture 4 - Remote Invocation

What is remote invocation?

A process that invokes an operation in another process via message sending.

What are the three dominant paradigms of remote invocation?

Request-reply protocols, Remote Procedure Call (RPC), and Remote Method Invocation (RMI).

What is a request-reply protocol?

A pattern on top of message passing that supports two-way exchange of messages, commonly used in client-server architecture.

What does RPC stand for?

Remote Procedure Call.

How does RPC function?

Client programs call procedures transparently in a server program, typically across different machines.

What is RMI?

Remote Method Invocation, which is RPC for object-oriented programming languages, mainly Java.

What is the role of the client in request-reply protocols?

The client makes a request to the server, which performs an operation and replies with the result.

What are some common implementations of request-reply protocols?

UDP and TCP.

What are message identifiers in request-reply protocols?

Unique IDs assigned to all requests to identify them.

What is a failure scenario in request-reply protocols?

Examples include client not connecting to the server, request not reaching the server, or server crashing during execution.

What happens when a client times out in request-reply protocols?

The client resends the request if the result does not arrive in time.

What is HTTP?

HyperText Transfer Protocol, an example of a request-reply protocol used for web pages.

What are common HTTP methods?

GET, HEAD, PUT, POST, DELETE.

What does a 200 status code indicate in HTTP?

Success.

What is REST?

Representational State Transfer, a modern remote invocation method via HTTP.

What does REST focus on?

Client transfers a representation of the state of a resource to the server, often in JSON format.

What is the service interface in RPC?

It abstracts the communication, allowing clients to call functions without knowing their implementation.

What is the purpose of IDL in RPC?

Interface Definition Language is used to define interfaces for RPC.

What are the components of an RPC client?

Client program, client stub procedure, and communication module.

What is a stub procedure in RPC?

A proxy that marshals the procedure ID and arguments to the server.

What is the role of the dispatcher in RPC?

It selects the appropriate stub to call based on the procedure ID.

What are some popular RPC implementations?

Sun RPC, DCE RPC, XML-RPC, JSON-RPC, gRPC, Apache Thrift.

What is the main focus of Remote Method Invocation (RMI)?

RPC on objects using object-oriented programming, primarily in Java.

What are the two main concepts of RMI?

Remote object references and remote interfaces.

What are popular implementations of RMI?

Java RMI and CORBA (Common Object Broker Architecture).