Re: question about RPC

On May 22, 2015, at 3:53 AM, Stuart Dallas wrote:

On Fri, 22 May 2015 at 07:20 Jeffry Killen <jekillen@prodigy.net> wrote: This may be a bit off topic but I begin with understanding of php and doing synchronous and async queries generated by javascript on the client side. Recently I resurrected a home built server and installed FreeBSD. Since I have been doing probably as much javascript as php, I have been interested in exploring node.js. My question is academic How is a simple query from a client like Firefox to an http server using php to process the request different from RPC? (I have been looking at Wikipedia article on RPC: http://en.wikipedia.org/wiki/Remote_procedure_call) I have written call back functions that are invoke from a window opened in javascript that call functions in the opening window. And as well, calling a server side script generally involves calling functions and methods and sending a result back to the client. For instance, there may be a form that is used to compose and execute a query of the server's data base server (MySQL, Postgres, etc) and the result is assembled and sent back to the client for display. How is this different from formal RPC? Now there is Apache Thrift with bindings to node.js (and other languages), which seems to imply that php can hand off requests to a node.js server, that might in turn satisfy a client request. (node.js is server side javascript) Right now I wouldn't do anything outside of localhost with node.js because it looks like asking for a whole lot of trouble if used over public network. Are there any academic thoughts on this? Generally speaking, RPC (as a concept) is simply "making a request to a remote server and receiving the results." The term originated with distributed systems with technologies such as CORBA. Essentially RPC describes the format of the request before it hits the transport mechanism (HTTP, 0MQ, TCP, whatever), and there are several different standards. XMLRPC is another technology that does RPC defined using XML over HTTP: http://en.wikipedia.org/wiki/XML-RPC. The main distinguishing feature of an RPC against simply using, for example, a REST service is that the client does not necessarily know that it's calling a remote procedure. That fact is hidden by a class or library that wraps the remote call in a local function. Doing RPC over public networks is acceptable so long as you use SSL to protect the data and authentication to prevent unauthorised access. This is generally not a bad idea even within a private network, because there really is no such thing as a private network! I hope that helps expand on what RPC is and why it's different from submitting a form on a web page. -Stuart

So, the class or library would be local to but separate from the client itself? As if, say, javascript had to call a function in another application to make an async request to a server. This is a bit subtile for me. It appears to be another layer between the application layer and the transport layer. Thank you for your reply JK