Structuring Components Specifications using Dependencies among the Runtime Environments

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1 Vol. 99 No. 72 SS99-7 [ ] : : : kaiya@jaist.ac.jp ochimizu@jaist.ac.jp Java RMI RMI / Java Z Structuring Components Specifications using Dependencies among the Runtime Environments Haruhiko Kaiya Koichiro Ochimizu School of Information Science Japan Advanced Institute of Science and Technology, HOKURIKU 1-1, Asahidai, Tatsunokuchi-machi, Nomi-gun, Ishikawa, JAPAN, Phone: Fax: kaiya@acm.org ochimizu@jaist.ac.jp kaiya/ Abstract When we develop a software system with a resuable component, we should refer not only to its own specification, e.g. its signatures and constraints of input, output and internal values, but also to the relationships between the component and external environments. But the specification with such additional information tends to be a large document, hence it is too hard to read and maintain its descriptions. In this paper, we specify an external environment for RMI, Remote Method Invovation Components in Java using Z notation. And we also introduce a way to simplying and generalizing its specification. As a result, we can systematically describe the specification of any remote objects. Key words reusable component, runtime environment, Java, RMI, Z notation

2 1 A B [1] [2] Java RMI [3] Z [4] RMI [5] [5] RMI RMI RMI 2 RMI Applet , 2, 3 RMI 1 appletviewer RMI 1: ( ) C A http RMI B 2: RMI httpd ( ) 2 httpd httpd RMI httpd ( www ) RMI httpd RMI RMI [3, p.28] 3 httpd httpd RMI 18

3 A http RMI B Report ::= OK Exception sayhello 3: RMI httpd ( ) out! : String; rep! : Report ΞHelloImpl; SecurityManager out! =message; Applet RMI Applet- SecurityManager Actions ::= CCONNETCT CREAD dlhost RMI cldhost slfhost AppletSecurityManager checktable : Actions B dlhost, cldhost, slfhost : Host checktable CCONNECT =(dlhost = cldhost) checktable CREAD = false. 3.2 : HelloImpl class HelloImpl extends UnicastRemoteObject implements Hello HelloImpl HelloImpl message : String SecurityManager 23 SecurityManager 3.3 : Naming public final class Naming extends Object public static Remote lookup(string name) public static void rebind(string name, Remote obj) nmhost Naming lookuptable : String Remote nmhost : Host rebind Naming.rebind n? : String; o? : Remote; rep! : Report Naming; SecurityManager dlhost = nmhost lookuptable n?=o?; dom lookuptable {n?} dlhost nmhost = dom lookuptable lookup 19

4 Naming.lookup shost? : String; sname? : String r! : Remote; rep! : Report ΞNaming; SecurityManager cldhost = shost? (checktable CCONNETCT slfhost = dlhost) sname? dom lookuptable lookuptable sname? =r! sname? dom lookuptable θnaming = θnaming (checktable CCONNETCT slfhost = dlhost) 3.4 AppletSecurityManager sayhello [SecurityManager/ AppletSecurityManager] out! =message sayhello SecurityManager ( 3 ) Naming.rebind Naming.lookup dlhost = nmhost nmhost = shost? n? =sname? o? =r! 1 Naming.rebind Naming.lookup slfhost = dlhost n? =sname? o? =r! 4 3 RMI ResType ::= Strage FileSystemR FileSystemW Port 4.1 AppletSecurityManager HelloImpl HelloImpl message : String ResType sayhello 1 out! : String; rep! : Report ΞHelloImpl SecurityManager[a/message] (out!, Strage) =message SecurityManager[a/message] AppletSecurityManager AppletSecurityManager a : String ResType dlhost, cldhost, slfhost : Host x : String a =(x, Strage) x : String a (x, FileSystemR) x : String a (x, FileSystemW). 1 20

5 [SecurityManager /AppletSecurityManager] 4.2 FSReadSecurityManager a : String ResType dlhost, cldhost, slfhost : Host [1] Bertrand Meyer. The Next Software Breakthrough. COMPUTER, Vol. 30, No. 7, pp , Jul IEEE/CS. [2] Tommy Thorn. Programming languages for mobile code. ACM Computing Surveys, Vol. 29, No. 3, pp , Sep [3] Sun Microsystems, Inc. Java Remote Method Invocation Specification, Feb Revision 1.4, JDK1.1 FCS. [4] J. M. Spivey. The Z Notation, A Reference Manual, Second Edition. Prentice Hall, spivey.oriel.ox.ac.uk/ mike/zrm/. [5],.., Vol. 98, No. 439, pp. 7 14, Dec SS x : String a =(x, Strage) x : String a =(x, FileSystemR) x : String a (x, FileSystemW). readfile 2 HelloImp.readfile [SecurityManager /FSReadSecurityManager] HelloImp.readfile [SecurityManager /AppletSecurityManager] 5 RMI 2 21

6 : 1 // $ :35:57+09 kaiya Exp $ 2 3 import java.rmi.*; 4 5 public interface Hello extends Remote{ 6 public String sayhello() throws java.rmi.remoteexception; 7 } 8 1 // $ :35:57+09 kaiya Exp $ 2 3 import java.rmi.*; 4 import java.rmi.server.unicastremoteobject; 5 import java.net.*; 6 7 public class HelloImpl extends UnicastRemoteObject implements Hello{ 8 int cnt=0; 9 10 public HelloImpl() throws RemoteException{ 11 super(); 12 } public String sayhello() throws RemoteException{ 15 cnt++; 16 System.err.println(cnt+": Hello Jaist!"); 17 return "Hello Jaist!"; 18 } public static void main(string args[]){ 21 String n=args.length>0? args[0]: "hello"; 22 try{ 23 System.setSecurityManager(new RMISecurityManager()); 24 }catch(exception e){ 25 System.err.println("can not set SM, "+e); 26 } try{ 29 HelloImpl h=new HelloImpl(); 30 Naming.rebind(n, h); 31 System.out.println(n+" ready as hello"); 32 }catch(remoteexception re){ 33 System.out.println("RemoteException "); 34 }catch(malformedurlexception e){ 35 System.out.println("URL Excetion "); 36 } 37 } 38 } 39 Applet html 1 <html> 2 <title>hello jaist</title> 3 <applet codebase="." code="helloapplet" width=200 height=100> 4 <param name=server value=rmi > 5 <param name=service value=jaist> 6 </applet> 7 </html> Applet java 1 // $ :35:57+09 kaiya Exp $ 2 import java.awt.*; 3 import java.rmi.*; 4 import java.applet.*; 5 6 public class HelloApplet extends Applet{ 7 String message="", serv; 8 public void init(){ 9 try{ 10 serv="rmi://"+getparameter("server")+"/"+getparameter("service"); 11 Hello obj=(hello)naming.lookup(serv); 12 message=obj.sayhello(); 13 }catch(exception e){ 14 System.out.println(""+e); 15 } 16 } 17 public void paint(graphics g){ 18 // System.err.println(message); 19 g.drawstring(serv+" said, ", 0, 10); 20 g.drawstring(message, 0, 20); 21 } 22 } 23 22

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