Design a remote object table that can support distributed garbage collection as well as translating between local and remote object references. Give an example involving several remote objects and proxies at various sites to illustrate the use of the table. Show what happens when an invocation causes a new proxy to be created. Then show what happens when one of the proxies becomes unreachable

Question

What will be an ideal response?

Answer 1

The table will have three columns containing the local reference and the remote reference of a remote object and the virtual machines that currently have proxies for that remote object. There will be one row in the table for each remote object exported at the site and one row for each proxy held at the site.


To illustrate its use, suppose that there are 3 sites with the following exported remote objects: S1: A1, A2, A3 S2: B1, B2; S3: C1;


and that proxies for A1 are held at S2 and S3; a proxy for B1 is held at S3. Then the tables hold the following information:.





Now suppose that C1(at S3) invokes a method in B1 causing it to return a reference to B2. The table at S2 adds the holder S3 to the entry for B2 and the table at S3 adds a new entry for the proxy of B2.


Suppose that the proxy for A1 at S3 becomes unreachab