Greetings from the Edge: Using javaobj in DATA Step

Transcript Greetings from the Edge: Using javaobj in DATA Step

Greetings from the Edge: Using javaobj in DATA Step

Richard A. DeVenezia Independent Consultant

SAS is a registered trademark or trademark of SAS Institute Inc. in the USA and other countries. ® indicates USA registration. Other brand and product names are registered trademarks or Trademarks of their respective companies.

Overview

 SAS Version 9 DATA Step has experimental syntax for interfacing with objects •

Java

, Hash, HashIter  Demonstration by way of examples.

Java is ...

 java.sun.com

“The Java 2 Platform provides robust end-to-end solutions for networked applications as well as a trusted standard for embedded applications”

 Widespread  Networked  Applications • Analysis and management

Component Interface is ...

 support.sas.com/rnd/...

“DATA Step Component Interface provides a mechanism for accessing predefined component objects from within a DATA Step program.”  Instantiate • Create an object •

declare Type var, var = _new_

 Access •

var.method()

javaobj is ...

 DATA Step  Experimental  Part of broader initiative • Component Interface • Object Dot Syntax

Java development

 Free kit •

java.sun.com/j2se

• compiler, packager and loader

javac, jar, java

• Runtime Environment • Online training  Tutorials • numerous web sites and publications

The edge

 New or experimental  Where two things come together

SAS session

 Version 9 • CLASSPATH environment variable

-set CLASSPATH myPath;%CLASSPATH%

 Version 9.1

• jreoptions SAS option

-jreoptions ( -Djava.class.path=myPath;%CLASSPATH% -Dsas.jre.version=jrePath )

Default JRE is installed at shared\JRE\1.4.1

A little birdie

 Version 9.1

Proc JAVAINFO



--log--

java.version = 1.4.1

java.vm.version = 1.4.1-b21 java.home = c:\opt\sas\shared\JRE\1.4.1

java.class.path = ...

Java coding pattern - variables

public class

Class

{ private double

variable

; public double get Variable () { return this.

variable

; } public void set

Variable

(double

variable

) { this.

variable

; } }

 java.sun.com/docs/codeconv /html/CodeConvTOC.doc.html

Java coding pattern - methods

public class

Class

{ public

methodNameAsVerb

(args...) {...} }

 java.sun.com/docs/codeconv /html/CodeConvTOC.doc.html

Declare statement



declare javaobj var ('Class' [,arg-1[,…[,arg-N]]) ;

- or  

declare javaobj var; var = _NEW_ javaobj ('Class' [,arg-1[,…[,arg-N]]) ;



Accessing methods and fields

 public

Type method ( args …) {…}



obj.

call

Type

Method ( ‘

method ’, args …, return );

 public

Type field ;



obj.

[get|set]

Type

Field (

‘ field ’, value );

HelloSAS.java

HelloSAS.sas

data _null_; length message $200; declare javaobj j (’HelloSAS'); j.callStringMethod ('getMessage', message); put message=; run; --- log - message=Hello SAS Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

Gotchas

 Classes are cached per SAS session  Did you recompile a Java class?

• Restart SAS  Signature Types • pass double, String, javaobj • return double, String

SystemProperties.class

import java.util.Enumeration; public class SystemProperties { private Enumeration e; public SystemProperties () { e = System.getProperties().propertyNames(); } public String return getProperty () { if (e.hasMoreElements()) { String p = (String) e.nextElement(); p + "=" + System.getProperty(p) ; } else { return null ; } } } Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

SystemProperties.sas

data _null_; dcl javaobj j (’ SystemProperties '); length s $200; j.callStringMethod (' getProperty ', s); do while ( s ne '' ); run; ...

… put s; j.callStringMethod ('getProperty', s); end; --- log -- java.vm.version=1.4.2_03-b02 java.vm.vendor=Sun Microsystems Inc.

Exceptions

  Always check, handle and clear

exceptionDescribe(1)

•

write exceptions to stdout or console



exceptionCheck(rc)

•

did an exception occur ?



exceptionClear()

•

Object persistence

 Intra DATA Step ? No • javaobj is gone when DATA Step ends • obj.delete() recommended  Birdie:

“An instantiated javaobj creates a JNI reference which will not be garbage collected. The reference needs to be explicitly deleted.”

Case for persistence

 Creating SAS Table from Q, a DBMS Query  Q  java.sql.ResultSet

• Two SAS Passes • 1. ResultSetMetaData, columns and types • 2. ResultsSet, rows  Without persistence, Q must be issued for each pass • not wanted

Persistence categories

 Intra SAS session • Object persists between DATA Steps in one SAS session • static fields and thread  Inter SAS session • Object persists between DATA Steps and SAS sessions • Remote method invocation - RMI  Require wrapper classes

Persistence via Static

 Static fields  java

public class Persist {static double x,y,z; }

 sas

data _null_; declare javaobj j ('Persist'); j.setStaticDoubleField('x',100); j.delete(); run; data _null_; declare javaobj j ('Persist'); j.getStaticDoubleField('x',x); j.delete(); put x=; run;

x=100

Persistence via Thread

 Runnable (R) • monitors its state • persists in Thread started by A  Adapter (A) • new Thread ( new R() ) . start () • methods grant access to R’s state • static fields persist across DATA Step -reference to R

Persistence via RMI

 Server process outside of SAS  DATA Step is client of server • via wrapper  Server allocates resources • Returns handles • Methods accessed by handle

DBMS servers

 Commercial  Open source • Postgresql • mySQL  JDBC • not an acronym (just like ess-a-ess) • trademark • 210 drivers listed at http://servlet.java.sun.com/products/jdbc/drivers

JDBC connection pattern

Class.forName(jdbcDriver); Connection con = DriverManager.getConnection

( URL, username, password );



jdbcDriver

“org.postgresql.Driver”



URL = “jdbc:postgresql://www.devenezia.com:5434/sesug03demo”



username = “sesug03demo”



Gateway - an RMI scheme

 Three classes  An Interface • GatewayInterface  An Implementation • GatewayManager  A Server • GatewayServer

GatewayInterface

 Declares methods

public int getConnectionHandle ( String driverClass, String databaseURL, String username, String password ) throws RemoteException; public int getStatementHandle (int cHandle) throws RemoteException; public int executeQuery (int handle, String sql) throws RemoteException; Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

GatewayManager

 Implements the Interface

public int getConnectionHandle ( { … { String driverClass, String databaseURL, String username, String password) throws RemoteException try System.out.println ("loading "+driverClass); Class.forName(driverClass); System.out.println ("connecting to "+databaseURL); con = DriverManager.getConnection (databaseURL, username, password); System.out.println ("connected"); } … Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

GatewayServer

 Hosts a GatewayManager

protected static final String RMI_NAME = "JDBC-GATEWAY-MANAGER

public static void main(String args[]){ … try { LocateRegistry.createRegistry(1099); GatewayManager manager = new GatewayManager (5); Naming.rebind (RMI_NAME, manager); } … System.out.println ( manager.getClass().getName() + " ready to manage " + 5 + " connections."); Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

DataStepGatewayAdapter

 Reimplements GatewayInterface • creates and uses delegate • performs typecasting where needed

public class DataStepGatewayAdapter { private GatewayInterface dbi; public DataStepGatewayAdapter() throws Exception { dbi=GatewayServer.getReferenceToPersistentManager (); } public int getStatementHandle (double cHandle) throws Exception { return dbi.getStatementHandle ( (int) cHandle); } Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

SAS macros

 Facilitate use of Gateway 

startServer



getConnectionHandle



getStatementHandle



jdbcLoadTable



Using the macros

 Reimplements GatewayInterface

%let jdbc_server_policy = gateway.policy; %let jdbc_driver = org.postgresql.Driver; %let db_url = jdbc:postgresql://www.devenezia.com:5434/sesug03demo; %let username = sesug03demo ; %let password = D3m0oeoe; %let cHandle =; %getConnectionHandle ( driver = &jdbc_driver , url = &db_url , user = &username , pass = &password , cHandle_mv = cHandle ); Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

Using the macros

%jdbcLoadTable ( cHandle=&cHandle, data=sashelp.zipcode, obs=20); %jdbcQuery ( cHandle=&cHandle, sql=SELECT * FROM ZIPCODE, out=WORK.ZIPCODE); Copyright © 2004 , Richard A. DeVenezia. All rights reserved.

Other tasks handled well by Java

 Directory listings  Archived file sets  Database connectivity  2D and 3D graphics  Open Office  XML  HTML parsing  and so much more

Conclusion

 Javaobj opens new horizons • Utilize problem solvers who work in Java  Hybrid solutions • Combine features of different technologies  Paper, slides and examples