RMI required?
Vrunda Joshi
Ranch Hand
Posts: 104
posted 11 years ago
hi all,
i am preparing for the exam..and i am using the HFSJ book..i absolutely don't have any background in RMI..so i am finding it difficult to understand the last chapter besides patterns..do i need to understand rmi before reading the last chapter or taking exam?
thanks in advance
-vrunda
i am preparing for the exam..and i am using the HFSJ book..i absolutely don't have any background in RMI..so i am finding it difficult to understand the last chapter besides patterns..do i need to understand rmi before reading the last chapter or taking exam?
thanks in advance
-vrunda
Bryan Basham
author
Ranch Hand
Ranch Hand
Posts: 199
posted 11 years ago
Hello Vrunda,
You do not need to know how RMI works, but you do need to know what RMI does. RMI is Java infrastructure and APIs that allow distributed method calls. In a little more detail: a client program on machine X calls method calcShippingCosts() on a remote object on machine Y. What RMI does is that there is a proxy object on the client that includes the calcShippingCosts() method. The client calls this method on the proxy object. The proxy then converts the method call into a TCP/IP message to the remote JVM. The TCP message is read by the remote JVM and forwards the call to the remote object. The remote object performs the calculation and returns the result to the remote JVM. The remote JVM converts the result into a return message to the client-side proxy object. The proxy object converts the TCP response message into a Java value which is then returned to the client object as the result of its calcShippingCosts() method call.
So, what does this mean for the SCWCD exam? Basically, what you need to know is that a BusinessDelegate is the pattern which hides the details of dealing with making remote method calls. RMI is a "behind the scenes" aspect of the pattern.
HTH,
Bryan
You do not need to know how RMI works, but you do need to know what RMI does. RMI is Java infrastructure and APIs that allow distributed method calls. In a little more detail: a client program on machine X calls method calcShippingCosts() on a remote object on machine Y. What RMI does is that there is a proxy object on the client that includes the calcShippingCosts() method. The client calls this method on the proxy object. The proxy then converts the method call into a TCP/IP message to the remote JVM. The TCP message is read by the remote JVM and forwards the call to the remote object. The remote object performs the calculation and returns the result to the remote JVM. The remote JVM converts the result into a return message to the client-side proxy object. The proxy object converts the TCP response message into a Java value which is then returned to the client object as the result of its calcShippingCosts() method call.
So, what does this mean for the SCWCD exam? Basically, what you need to know is that a BusinessDelegate is the pattern which hides the details of dealing with making remote method calls. RMI is a "behind the scenes" aspect of the pattern.
HTH,
Bryan
