- Prioritized List of Improvements
- Highlights of User Feedback

Name of Reviewer: | Ray Ortigas
Current Trail Author(s): | Ann Wollrath, Jim Waldo
Was the author contacted? | No If yes, Date:
Comments:

#### Prioritized List of Improvements/Corrections:

Priority Scale:
(1-5)

1 = immediate attention required
3 = fix in next public push (2-3 weeks)
5 = when you get a chance...

1. At there is a reference to "JNDI", but nowhere in the tutorial is this acronym ever explained.

   priority (1-5): 4

2. Should add a link to security trail for running RMI example, since it uses a policy file.

   priority (1-5): 3

3. Should point out that the RemoteException must be declared in the throws clause of every method in a Remote interface (any interface that extends Remote).

   priority (1-5): 3

4. Applets and RMI? A few users are asking about it; maybe we should take a look at it, although I doubt this is a worthy topic to pursue.

   priority (1-5): 5

5. Note that trailing slash is needed when running example and passing directories as parameters.

   priority (1-5): 4

6. Add a note about unsetting CLASSPATH on Windows (merely "set CLASSPATH=" as opposed to "unset CLASSPATH" on Solaris).

   priority (1-5): 3

#### Highlights of User Feedback:

- Date: 16 Jan 1999

  I am currently working on a problem involving RMI. I am faced with a problem that whenever the network load is high, some kind of timeout occurs and 'NoRouteToHost' exception is thrown. I want to change the settings in RMI so that this timeout period is increased.

- Date: 30 Mar 1999

  Over the past few weeks I've spent quite a bit of time in the RMI trail of the Java Tutorial (March 12, 1999 edition) and I feel there are some very serious problems that should be addressed.

  I sincerely don't mean to sound critical in this e-mail -- overall I think the Java Tutorial is a terrific piece of work -- but the RMI trail needs some fixing up (IMHO). If you'd like to speak with me about any of these issues, you can reach me at: W:(602) 607-4995 or H:(602) 813-4452.

  I'm sorry about the length of this message but I've tried to be complete and clear.

  First, I'd like to direct your attention to the section entitled, "Build a JAR File of Interface Classes", at "/rmi/compiling.html". The second-to-last paragraph in that section begins with this statement:

  "When you build either server- or client-side classes with the javac and rmic compilers, you generally need to specify where the resulting class files should reside so that they are network accessible."

  I believe this is a minor wording problem. Although it is necessary to specify a "network-accessible" location of class files before the client and server begin execution so that classes may be downloaded dynamically, it is *not* necessary to specify their network-accessible location at *build* time, as the statement above implies. I believe the statement above should read:

  "After you build either the server- or client-side classes with the javac and rmic compilers, you will need to ensure the resulting class files are placed in a network accessible location."

  The same paragraph also seems to indicate that it is entirely possible to use a "file:" URL when specifying where classes reside. Now, I'm not sure if the reference to the "file:" URL pertains to the location of class files at compile-time or runtime. I assume it refers to making the class files network-accessible at runtime. In other words, I interpret the reference to the "file:" URL to mean that classes can be made network-accessible using the "file:" URL rather than an "HTTP:" URL. Is this correct? I'll have more to say about this below.

  The last paragraph in the same section makes reference to the use of an HTTP server to download classes. It does not, however, indicate that an HTTP server is an absolute requirement for downloading classes. In fact, the Tutorial says, "RMI uses URL protocols supported by the Java platform..." I assume this includes the "file:" URL. In other words, my impression is that an HTTP server *can* be used but so long as a network connection is available, HTTP is not absolutely required. On the other hand, the Tutorial makes reference to a "simple HTTP server" (ftp://java.sun.com/pub/jdk1.1/rmi/class-server.zip). Does this mean HTTP *is* required? I recently posted this question to a few Java newsgroups, as well as the JDC, and some of the responses I received indicated that an HTTP server *MUST* be running on the machine from which classes will be downloaded. If this is so, the Java Tutorial should say so explicitly. If this is not the case, then it would be extremely helpful if the Tutorial provided a working example using the "file:" URL between two separate machines.

  I'd also like to direct your attention to the section entitled, "A Note about Security" on "rmi/running.html". I think it would be very helpful if the relationship between a "Permissions Policy" file and the use of the RMISecurityManager was described. What does the RMISecurityManager provide that the "Permissions Policy" file doesn't and vice versa? Do I need both the RMISecurityManager *and* a "Permissions Policy" file?

  The next section, entitled, "Start the Server", begins with this statement:

  "If you *do* start the rmiregistry and it *can* find your stub classes in CLASSPATH, it will not remember that the loaded stub class can be loaded from your server's code base, ..."

  Personally, I find this entire paragraph a bit confusing. I believe that somehow the notion of annotating a class is involved here but I really don't have a feel for it's relevance and the Tutorial does not even mention class annotation. I'd like to see a discussion on how class annotation is related to the java.rmi.server.codebase property and also a description of where the java.rmi.server.RMIClassLoader fits into the picture. What's the result if the java.rmi.server.codebase property is *not* set? When will the RMIClassLoader be used and when will it not be used?

  Ealier, I mentioned that it seemed to be possible (according to the Tutorial) to use a "file:" URL to dynamically load classes across the network. Again, in the "Start the Server" section of the Tutorial is an example that specifies a "file:" URL for the java.rmi.server.codebase property:

  java -Djava.rmi.server.codebase=file:/c:\home\ann\public_html\classes/ -Djava.rmi.server.hostname=zaphod.east.sun.com -Djava.security.policy=java.policy engine.ComputeEngine

  Once again, I'm assumming this means it is *not* necessary to have any form of HTTP server running. Is this correct?

- Date:
  User3's email

- Date:
  User4's email