learning notes

SAS - Tip of Using SAS/Access to ODBC

2011-04-22T16:59:00.001+08:00

Usually we will use below syntax to connect a ODBC data source as SAS library.

LIBNAME sql_server ODBC DSN=TheSQLServer USER=sas PASSWORD=S@s123  SCHEMA=dbo;

But sometimes, especially while we are using SAS Enterprise Guide, it will not work and the system will report a ODBC driver not found error. To prevent this error from happening, we have to use the NOPROMPT option to declare the connection string manually.

LIBNAME sql_server ODBC NOPROMPT="DRIVER=SQL SERVER NATIVE CLIENT 10.0;SERVER=theSQLServerHost;DATABASE=databaseName;uid=sas;pwd=S@s123;" SCHEMA=dbo;

SAS - Applying ACT to Objects

2011-02-11T13:35:00.001+08:00

An example code for applying ACT to certain objects such like dataset and/or library.

%macro applyACT(objName, objType, actName, metaUser, metaPass, metaServer=localhost, metaPort=8561);

options metauser="&metaUser"
              metapass="&metaPass"
              metaserver="&metaServer"
              metaport=&metaPort
              metarepository=Foundation;

filename request temp ;
filename response temp ;

data _null_ ;
   length type $32 t_uri act_uri ace_uri $ 17 line $ 100 ;
   file request ;

   line="omsobj:&objType?@Name='&objName'";
   rc=metadata_resolve(line,type,t_uri) ;
   
   line="omsobj:AccessControlTemplate?@Name='&actName'";
   rc=metadata_resolve(line,type,act_uri) ;
       
    line="omsobj:AccessControlEntry?AccessControlEntry[/Objects/&objType[@Name='&objName']]";
    rc=metadata_resolve(line,type,ace_uri) ;
      
    put "" ;
    put "" ;

    line="<&objType Id='"|| strip(t_uri)|| "' >";
    put line ;
    put "" ;
    line=cats("") ;
    put line ;
    if strip(ace_uri) <> '' then
        do;
            line=cats("") ;
           put line ;
        end;
    put "";
    put "" ;

    if strip(ace_uri) <> '' then
        do; 
            line=cats("") ;
            put line ;
            line=cats("") ;
            put line ;
            line=cats("") ;
            put line ;
            line=cats("") ;
            put line ;
 end;
         
    /* uncomment below for SAS 9.1.3 */
    * put "" ;
    put "" ;
 
    /* uncomment below for SAS 9.1.3 */
    * put "$METAREPOSITORY" ;
    put "SAS" ;
    put "402654208" ;
    put "" ;
    put "" ;
run ;

proc metadata verbose header=full
    in=request
    out=response ;
run ;

%mend;

/* to apply ACT [TestACT] to Lib [TestLib] */
%applyACT(TestLib, SASLibrary, Test_ACT, sasadm, sasadm);

/* to apply ACT [TestACT] to Dataset [TestTable] */
%applyACT(TestTable, PhysicalTable, Test_ACT, sasadm, sasadm);

Groovy - Sample Code of Modifying SAS SPK package

2010-12-30T16:59:00.000+08:00

def ant = new AntBuilder(); 

def path = 'C:\\Temp\\Test'
def orig = "${path}\\Orig"
def chng = "${path}\\Chng"
def tmpf = "${path}\\Temp"
def datf = "${path}\\Data"

def mappings = [:]
new File("${datf}\\table.csv").withReader { r ->
    def data = r.readLine()
    while (data != null) {
        def tdata = data.split(',')
        mappings[tdata[1]] = tdata[2]
        data = r.readLine()
    }
}

ant.delete(file: chng)
ant.mkdir(dir: chng)

ant.delete(file: tmpf)
ant.mkdir(dir: tmpf)

def pfolder = new File(orig)
pfolder.eachFile { theFile ->
  
  def tempFolder = "${tmpf}\\${theFile.name}"
  
  ant.mkdir(dir: tempFolder)
  ant.unzip(src: theFile.path, dest: tempFolder,  overwrite:"true")

  ant.move(file: "${tempFolder}\\MetadataExport.xml", tofile: "${tempFolder}\\MetadataExport_old.xml")

  def mf = new File("${tempFolder}\\MetadataExport_old.xml")
  def mfn = new File("${tempFolder}\\MetadataExport.xml")

  mfn.withWriter('UTF-8') { o ->
    mf.withReader('UTF-8') { r ->
      def temp = r.readLine()
      while (temp != null) {
        temp = temp.replaceAll(/PhysicalTable[ ]Id=\"[0-9A-Z]{8}\.[0-9A-Z]{8}\"/, { 
            def tt = it.substring(18, 35)            
            println tt
            return "PhysicalTable Id=\"${mappings[tt]}"
        })
        temp = temp.replaceAll(/\!SAS[A-Z]{3}+/, { return it + '2'})
        temp = temp.replaceAll(/[A-Za-z]+[ ]Lib/, { return it + ' CI'})
        temp = temp.replaceAll(/SASMain/, { return it + ' CI'})
        temp = temp.replaceAll(/SAS Data Integration Studio Custom Tree/, { return 'CI Project'})
        o.write(temp + '\n')
        temp = r.readLine()
      }
    }
  }
  ant.delete(file: "${tempFolder}\\MetadataExport_old.xml")
  ant.zip(destfile: "${chng}\\${theFile.name}", basedir: "${tempFolder}")
}

Thought - My Next Major Programming Language

2010-10-27T17:23:00.001+08:00

I have been using Java as my major programming language for a decade (partially for work, partially for personal interest.) And now, I think it should be the time to pick up an alternative to "repowering" my passion as well as to extend my career if any.

The criteria to choose the language are only a few; mainly it must be interesting to learn and the underlying design principles have to fit my personal taste. Second, it should be good at solving at least one kind of domain problems. And finally, it will be nice if it is a platform independent language or a platform-crossing language. JVM only languages are not considered so far (though I really like the syntax design of Groovy), because it is more like to use another kind of Java in a degree.

Here comes some candidates:

JavaScript/HTML5 - the keys of Web.
Objective-C - quite attracting because it is the native language of iOS platform.
Ruby - the fundamental of the Web development rock star framework.
Smalltalk - seems fun to learn.
Perl - useful and powerful.
Python - seems an elegant language.
C - persistence and everywhere.
Clojure - kinda curious.
Go - does it really the real "next C"?
ActionScript - just in case...

SAS - IOM JDBC Driver Data Type Mapping

2010-09-07T23:40:00.004+08:00

Seems like that there are only a few SQL data types supported in SAS 9.2 IOM JDBC driver.
For example, only CHAR, CHARACTER, VARCHAR, INT, INTEGER, SMALLINT, FLOAT, DOUBLE and DATETIME can be used in a table creation statement; therefore, the corresponding Java data types (mapped from previous SQL data types) are as well kinda lacking.

Following is the SQL/Java data type mapping table which is according to my recent test result:

SQL Data Type	Java Data Type
DATETIME	java.sql.Timestamp
INTEGER	java.lang.Integer
CHAR, CHARACTER, VARCHAR	java.lang.String
INT, SMALLINT, FLOAT, DOUBLE	java.lang.Double

* I really don't know why INT and SMALLINT are mapped to Java Double, but they are!

Groovy - Using GroovyWS as Web Service Client

2010-08-31T15:20:00.000+08:00

It looks very simple to use GroovyWS, but actually, in my case, it's somehow a little tricky to successfully use it.

In the beginning, I always get a

ClassCastException: org.apache.xerces.jaxp.DocumentBuilderFactoryImpl cannot be cast to javax.xml.parsers.DocumentBuilderFactory

if I just simply declare groovyws module in my maven project dependencies.

After googling awhile, I finally found this article and understood what's the cause of ClassCastException, and resulting to manually adjust the project dependencies to solve this problem.

         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    4.0.0

    cc.ceks
    autojmp
    1.0
    jar

    autojmp
    http://ceks.cc

    
        UTF-8
    

    
        
            junit
            junit
            3.8.1
            test
        
        
            org.codehaus.groovy
            groovy
            1.8.0-beta-1
        
        
            org.codehaus.groovy.modules
            groovyws
            0.5.2
            
                
                    xerces
                    xercesImpl
                
                
                    xerces
                    xmlParserAPIs
                
                
                    xml-apis
                    xml-apis
                
                
                    xalan
                    xalan
                
                
                    xalan
                    serializer
                
                
                    org.apache.ws.commons.axiom
                    axiom-impl
                
                
                    org.apache.ws.commons.axiom
                    axiom-api
                
                
                    xom
                    xom
                
            
        
        
            org.bouncycastle
            bcprov-ext-jdk16
            1.45
        
        
            javax.xml.soap
            saaj-impl
            1.3
        
        
            org.codehaus.woodstox
            wstx-asl
            3.2.9
            
                
                    stax
                    stax-api
                
            
        
        
            commons-cli
            commons-cli
            1.2
        
        
            org.codehaus.groovy.modules.scriptom
            scriptom
            1.6.0
        
        
            net.sf.jacob-project
            jacob
            1.14.3
            jar

SAS - Output DataSet as JSON

2010-08-13T18:05:00.002+08:00

This example converts a SAS dataset to JSON notation strings and output to STDOUT; change the line 8 to any specific file names to write the result to the file instantly.

LIBNAME EDA ORACLE  PATH=XE  SCHEMA=EDA  USER=eda  PASSWORD=eda;
DATA WAT;
    SET EDA.WAT;
 KEEP PRODUCT_NAME SPEC_FILE LOT_ID WAFER_ID SITE_ID ATT1 ATT2 ATT3;
 WHERE LOT_ID like 'P0M78.1';
RUN;
DATA _NULL_;
    file print PS=32767;
    set WAT end=lastrec;
    if _N_ eq 1 then do;
        put '[';
    end;
    put '{"productName":"' PRODUCT_NAME '",';
    put '"lotId":"' LOT_ID '",';
    put '"waferId":' WAFER_ID ',';
    put '"siteId":"' SITE_ID '",';
    put '"specFile":"' SPEC_FILE '",';
    put '"attrs": [';
    put '{"attr1":' ATT1 '},';
    put '{"attr2":' ATT2 '},';
    put '{"attr3":' ATT3 '}]}';

    if lastrec eq 1 then do;
        put ']';
    end;
    else do;
        put ',';
    end;
RUN;

Another example from Wade H. Van Buskirk.

Oracle - Change the Service Listening Ports of TNS Listener

2010-08-11T11:04:00.001+08:00

Since version 9, Oracle database pre-bundled a XML DB serves both on port 8080 (HTTP) and 2020 (FTP). To change the default ports, we could use follow command in SQLPlus:

call dbms_xdb.cfg_update(updateXML(dbms_xdb.cfg_get(), '/xdbconfig/sysconfig/protocolconfig/httpconfig/http-port/text()', 9090));
commit;
exec dbms_xdb.cfg_refresh;

call dbms_xdb.cfg_update(updateXML(dbms_xdb.cfg_get(), '/xdbconfig/sysconfig/protocolconfig/ftpconfig/ftp-port/text()', 9091));
commit;
exec dbms_xdb.cfg_refresh;

SAS - Connect to SAS Shared Service with SAS JDBC Driver

2010-08-09T18:52:00.004+08:00

Code snippet relative to connect to SAS Shared Service with SAS JDBC driver

Connection conn = null;
try {
    Class.forName("com.sas.net.sharenet.ShareNetDriver");
    conn = DriverManager.getConnection("jdbc:sharenet://localhost:8551",
                                       "USER_NAME", "PASSWORD");
    DatabaseMetaData dma = conn.getMetaData();
    System.out.println("Connected to " + dma.getURL());
    System.out.println("Driver " + dma.getDriverName());
    System.out.println("Version " + dma.getDriverVersion());
} catch (Exception e) {
    e.printStackTrace();
} finally {
    try {
        if (null != conn) conn.close();
    } catch (SQLException e) {}
}

Grails - Tips of Using Metro Plugin

2010-07-29T14:16:00.002+08:00

Metro Integration
Two ways to integrate web services into your grails application with Metro plugin:

Do nothing, then Metro plugin will register jax-ws spring configuration (com.sun.xml.ws.transport.http.servlet.GrailsWsServlet) to web.xml.
Place self-defined sun.jaxws.xml in web-app/WEB-INF folder, and copy generated Java source files to src/java. Then Metro plugin will register com.sun.xml.ws.transport.http.servlet.WSServletContextListener to web.xml.

Enabling MTOM Support
To enable MTOM support is basically simple, what we have to do is to declare a @MTOM annotation in your service classes, and use relative @XmlMimeTypes to annotate the MIME types we need to each web method's parameters if any.
But here is one thing needs to be additionally took care of. It is, if the grails application not only serves as a Web Service server, but also a web application as well. In order to prevent the upload multi-part attachment from mixing up by grails, we need to exclude the url-pattern we used for all web services from grails' UrlMappingsFilter (it means to add the url pattern to the excludes list in UrlMapping.groovy file.)

class UrlMappings {

 static excludes = ["/services/*"]
    
 static mappings = {
  "/$controller/$action?/$id?"{
   constraints {
    // apply constraints here
   }
  }

  "/" (view: '/')
  "500"(view:'/error')
 }
}

Grails - Metro Plugin Modification for Grails 1.3.3

2010-07-27T09:08:00.002+08:00

Though it isn't listed in official Grails plugin list and kinda out dated, there is indeed a Metro plugin available on dev.java.net.

Metro Plugin for Grails Framework

To adopt the plugin to Grails 1.3.3 applications, I tweaked the plugin source a little bit to make it work again. Following is the change:

import org.codehaus.groovy.grails.compiler.support.*
import groovy.xml.DOMBuilder
import groovy.xml.dom.DOMCategory
import groovy.xml.StreamingMarkupBuilder

class MetroGrailsPlugin {
//    def dependsOn = []

    def author = "Martin Grebac"
    def authorEmail = "martin.grebac@sun.com"
    def title = "Add METRO Web Service support to services built with Grails framework."
    def description = '''\
METRO plugin allows applications developed with Grails framework to expose service 
classes as SOAP Web Services. It uses the SOAP implementation from METRO (includes JAX-WS).
'''
    def documentation = "http://jax-ws-commons.dev.java.net/grails/"
    def version = '1.0.2'
    def loadAfter = ['services']
    def watchedResources = ["file:./grails-app/services/**/*Service.groovy",
                            "file:./plugins/*/grails-app/services/**/*Service.groovy",
                            "file:./src/java/**/*.java",
                            "file:./src/groovy/**/*.groovy"]

    def doWithSpring = {
        File f = new File("grails-app/conf/spring/resources.xml")
        println "Generating " + f

        def output = new FileOutputStream(f)

        def xml = new StreamingMarkupBuilder().bind {
            mkp.xmlDeclaration()
            mkp.declareNamespace(wss: "http://jax-ws.dev.java.net/spring/servlet")
            mkp.declareNamespace(ws: "http://jax-ws.dev.java.net/spring/core")
            mkp.declareNamespace(sp: "http://www.springframework.org/schema/beans")
            mkp.declareNamespace(xsi: "http://www.w3.org/2001/XMLSchema-instance")

            String classDir = "target/classes" //"${userHome}/.grails/${grailsVersion}/projects/${appName}/classes"
            new File(classDir).mkdir()
            String sourceDir = "target/generated-java-source"
            new File(sourceDir).mkdir()
            String wsdlDir = "web-app/WEB-INF/wsdl"
            new File(wsdlDir).mkdir()

            //def pName
            sp.beans('xsi:schemaLocation': "http://jax-ws.dev.java.net/spring/core http://jax-ws.dev.java.net/spring/core.xsd http://jax-ws.dev.java.net/spring/servlet http://jax-ws.dev.java.net/spring/servlet.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd") {
                def clazz = application?.allClasses as List
                clazz.unique().each { cl ->
                    java.lang.annotation.Annotation a = cl?.getAnnotation(javax.jws.WebService.class)
                    if (a) {
                        def String shortName = cl.name
                        println "Generating spring configuration for: ${shortName}"

                        if (shortName?.contains('.')) {
                            shortName = shortName.substring(shortName.lastIndexOf('.') + 1, shortName.size())
                        }
                        //pName = shortName

                        wss.binding(url: "/services/${shortName}") {
                            wss.service {
                                ws.service(bean: "#${shortName}")
                            }
                        }
                        sp.bean(id: "${shortName}", 'class': "${cl.name}")

                        String[] attrs = ["-classpath",
                                classDir,
                                "-d",
                                classDir,
                                "-keep",
                                "-wsdl",
                                "-r",
                                wsdlDir,
                                "-s",
                                sourceDir,
                                "${cl.name}"
                        ]
                        com.sun.tools.ws.WsGen.doMain(attrs);
                    }
                }
            }
        }
        output << xml.toString()
        output.close()
    }

    def doWithApplicationContext = { ctx ->

//        /*
//        //          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
//          xmlns:ws="http://jax-ws.dev.java.net/spring/core"
//          xmlns:wss="http://jax-ws.dev.java.net/spring/servlet">
//
//            
//              
//                  
//              
//             
//            
//            
//        
//        */
//        
    }

    def doWithWebDescriptor = { xml ->

        def jaxwsdesc = new File("web-app/WEB-INF/sun-jaxws.xml")

        def servlets = xml.servlet[0]
        def servletMappings = xml.'servlet-mapping'[0]
        def listeners = xml.listener[0]

        if (jaxwsdesc.exists()) {

            //plain jax-ws way
            def reader = new FileReader(jaxwsdesc)

            def doc = DOMBuilder.parse(reader)
            def endpoints = doc.documentElement

            listeners + {
                listener {
                    'listener-class'('com.sun.xml.ws.transport.http.servlet.WSServletContextListener')
                }
            }

            use(DOMCategory) {
                def endpointset = endpoints.'endpoint'
                endpointset.each { endpoint -> processEndpoint(endpoint, servlets, servletMappings) }
            }

        } else {

            // spring-way
            println "Creating jax-ws spring configuration in web.xml."

            servlets + {
                servlet {
                    'servlet-name'('jaxws-servlet')
                    'servlet-class'("com.sun.xml.ws.transport.http.servlet.GrailsWsServlet") //WSSpringServlet
                }
            }

            servletMappings + {
                'servlet-mapping' {
                    'servlet-name'('jaxws-servlet')
                    'url-pattern'('/services/*')
                }
            }

        }

    }

    def processEndpoint(endpoint, servlets, servletMappings) {
        def name = endpoint.'@name'
        def impl = endpoint.'@implementation'
        def url = endpoint.'@url-pattern'

        println "Processing web.xml for endpoint: " + name + " | " + impl + " | " + url

        // Pure jax-ws way
        servlets + {
            servlet {
                'servlet-name'(name)
                'servlet-class'("com.sun.xml.ws.transport.http.servlet.WSServlet")
                'load-on-startup'(1)
            }
        }

        servletMappings + {
            'servlet-mapping' {
                'servlet-name'(name)
                'url-pattern'(url)
            }
        }

    }

    def doWithDynamicMethods = { ctx ->
//        println "DOWITHDYNMETHODS" + ctx
    }

    def onChange = { event ->
//        println "ONCHANGE" + event
    }

    def onApplicationChange = { event ->
//        println "ONAPPCHANGE" + event        
    }
}

Mac OS X - Useful Tips

2010-07-26T12:16:00.000+08:00

Absolutely useful:

Terminal Tips and Tricks For Mac OS X

Grails - Using Liquibase for Database Migration

2010-07-09T16:18:00.005+08:00

Here are the discussions about the usage of Liquibase as database migration tool for Grails applications, quite useful:

Liquibase usage and alternatives

In my case, I just change a little bit of the code example to suit both of development mode and production mode.

Liquibase liquibase = null
try {
    def c = dataSource.getConnection()
    if (c == null) {
        throw new RuntimeException("No database connection available!")
    }
    def database = DatabaseFactory
                     .getInstance()
                     .findCorrectDatabaseImplementation(c)
    def fileOpener = null
    environments {
        production {
            fileOpener = new ClassLoaderFileOpener()
        }
    }
    if (!fileOpener) fileOpener = new GrailsFileOpener()
    liquibase = new Liquibase("changelog.xml", fileOpener, database)
    liquibase.update(null)
} finally {
    if (liquibase && liquibase.database) {
        liquibase.database.close()
    }
}

And, of course, the event hook to copy relative files before creating war is also required:

eventCreateWarStart = { warName, stagingDir ->
    ant.copy(todir:"${stagingDir}/WEB-INF/classes", overwrite: true) {
        fileset(dir:"grails-app/migrations", includes:"**")
    }
}

Grails - Taglib in Services

2010-07-09T16:14:00.003+08:00

Using taglib functions in services

Mac OS X - Changing Windows Domain Password from Mac OS X

2010-06-22T12:58:00.001+08:00

How do I change my windows domain password from Mac OS X?

Grails - Some Findings of Table-Per-Hierarchy in GORM

2010-04-08T23:18:00.002+08:00

Finding 1:
Seems like there is a bug in both Grails 1.2.* and 1.3.0 RC1, which causes that customized discriminator column name doesn't work well. Grails will always try to create the customized column with varchar(-1).

After fighting with this problem for several hours, I finally found a work-around:

class Parent {

    String name
    String gender
    int age

    static mapping = {
        discriminator column: [name:'level', length:50]
    }

    static constraints = {
  
    }
}

class Child extends Parent {

    static mapping = {
        discriminator 'child'
    }

    static constraints = {
     
    }
}

class Grandchild extends Parent {

    static mapping = {
        discriminator 'grandchild'
    }

    static constraints = {
    }
}

But, there is another problem: that discriminator value won't affect in the Parent class.

Finding 2:
Abstract classes will fail table-per-hierarchy declaration; therefore, just declare it as a class to ensure it will work as your wish.

Project Euler - P22

2010-02-09T18:01:00.000+08:00

Problem 22

Groovy Code

final int BASE = 64 // the ASCII code of the character previous to 'A'
def total = 0, subtotal = 0
def names = []

def file = new File("names.txt")
file.withReader { r ->
  r.readLine().split(",").each {
    names << it.replace("\"", "")
  }
}
names.sort().eachWithIndex { name, index ->
  subtotal = 0
  name.toCharArray().each { c ->
    subtotal += (c - BASE)
  }
  total += (subtotal * (index + 1))
}

println "Total -> ${total}"

Project Euler - P21

2010-02-09T17:41:00.000+08:00

Problem 21

Groovy Code

static final def PRIMES = [1, 2, 3, 5, 7, 9, ...] // prime list

static final int MAX = 10000

def amicables = []
int a1 = 1, a2, temp, sum1, sum2

MAX.times {
  if (!(a1 in PRIMES || a1 in amicables)) {
    sum1 = 1
    temp = 1
    (a1/2).times {
      temp++
      if (a1 % temp == 0) sum1 += temp
    }
    if (sum1 > a1) {
      a2 = sum1
      sum2 = 1
      temp = 1
      (a2/2).times {
        temp++
        if (a2 % temp == 0) sum2 += temp
      }
      if (sum2 == a1) {
        println ("found $a1, $a2")
        amicables << a1
        amicables << a2
      }
    }
  }
  a1++
}

println ("sum of all amicables under $MAX = ${amicables.sum()}")

Project Euler - P20

2010-02-09T17:11:00.000+08:00

Problem 20

Groovy Code

static final int TIME = 100

def multiple(s, n, i) {
  s[i] = Character.forDigit(n % 10, 10)
  return (int) (n / 10)
}

def strPowerR = '1'
def strTemp = new char[2048]
int level = 2
int intTemp = 0
int intOverflow = 0

Arrays.fill strTemp, Character.forDigit(0, 10)
strTemp[0] = Character.forDigit(1, 10)
(TIME - 1).times {
  strPowerR.toCharArray().eachWithIndex { item, index ->
    intTemp = Character.digit(item, 10)
    intTemp = (intTemp * level) + (intOverflow % 10)
    intOverflow = ((int)intOverflow/10) + multiple(strTemp, intTemp, index)
  }
  if (intOverflow > 0) {
    String strTemp2 = String.valueOf(intOverflow)
    strTemp2.toCharArray().eachWithIndex { item, index ->
      strTemp[strPowerR.length() + strTemp2.length() - index - 1] = item
    }
    intOverflow = 0
  }
  strPowerR = String.valueOf('a' + strTemp).replace('0', ' ').trim().replace(' ', '0').substring(1) // trim right
  level++
}

println ("${TIME}! = ${strPowerR.reverse()}")

intTemp = 0
strPowerR.toCharArray().each {
  intTemp += Character.digit(it, 10)
}

println ("Sum of all digit character of ${TIME}! = ${intTemp}")

Project Euler - P19

2010-02-05T16:45:00.000+08:00

Problem 19

Groovy Code

class D {
  int year
  int month
  int day
  public int getV() {
    return year * 10000 + month * 100 + day
  }
}

def count = 0
def d = new D(year:1900, month:1, day:7) // the first Sunday in 20th century
while (d.v < 20001231) {
  d.day += 7
  if (d.day > 28) {
    // need to roll
    switch (d.month) {
      case 1:
      case 3:
      case 5:
      case 7:
      case 8:
      case 10:
      case 12:
        if (d.day > 31) {
          d.day -= 31
          d.month += 1
        }
        break
      case 4:
      case 6:
      case 9:
      case 11:
        if (d.day > 30) {
          d.day -= 30
          d.month += 1
        }
        break
      case 2:
        if ((d.year % 4 == 0) && (d.year % 400 == 0 || !(d.year % 100 == 0))) {
          // leap year
          if (d.day > 29) {
            d.day -= 29
            d.month += 1
          }
        } else {
          d.day -= 28
          d.month += 1
        }
        break
    }
    if (d.month > 12) {
      d.month = 1
      d.year++
    }
    if (d.year > 1900 && d.day == 1) {
      println(d.v)
      count++
    }
  }
}
println ("Found ${count} Sundays!")

Project Euler - P18

2010-02-05T16:11:00.000+08:00

Problem 18

Groovy Code

class Spot {
  int value
  Spot left, right

  public String toString() { value }

  public static int calPath(s) {
    int ls = s.value
    int rs = s.value
    ls = ls + (s.left ? calPath(s.left) : 0)
    rs = rs + (s.right ? calPath(s.right) : 0)
    return Math.max(ls, rs)
  }
}

def TRI = [[75],
           [95,64],
           [17,47,82],
           [18,35,87,10],
           [20, 4,82,47,65],
           [19, 1,23,75, 3,34],
           [88, 2,77,73, 7,63,67],
           [99,65,04,28,06,16,70,92],
           [41,41,26,56,83,40,80,70,33],
           [41,48,72,33,47,32,37,16,94,29],
           [53,71,44,65,25,43,91,52,97,51,14],
           [70,11,33,28,77,73,17,78,39,68,17,57],
           [91,71,52,38,17,14,91,43,58,50,27,29,48],
           [63,66,04,68,89,53,67,30,73,16,69,87,40,31],
           [ 4,62,98,27,23, 9,70,98,73,93,38,53,60, 4,23]]

def root  = null
def spots = []
def cRow, pRow = null
def a, b, c, d

TRI.each { tRow ->
  cRow = []
  spots << cRow
  tRow.eachWithIndex { v, i ->
    a = new Spot(value:v)
    cRow << a
    if (pRow) {
      if (i < pRow.size()) {
        pRow[i].left = a
      }
      if (i > 0) {
        pRow[i - 1].right = a
      }
    }
  }
  if (tRow.size() == 1) root = a
  pRow = cRow
}

println ("Max -> ${Spot.calPath(root)}")

Project Euler - P17

2010-02-05T13:42:00.000+08:00

Problem 17

Groovy Code

def N = [0:'', 1:'one', 2:'two', 3:'three', 4:'four', 5:'five', 6:'six', 7:'seven', 8:'eight', 9:'nine', 10:'ten',
         11:'eleven', 12:'twelve', 13:'thirteen', 14:'fourteen', 15:'fifteen', 16:'sixteen', 17:'seventeen', 18:'eighteen', 19:'nineteen', 20:'twenty',
         30:'thirty', 40:'forty', 50:'fifty', 60:'sixty', 70:'seventy', 80:'eighty', 90:'ninety', 100:'hundred', 1000:'thousand']

int count = 0
int c
int x, y, z, w

def s = new StringBuilder()

1000.times {
  c = it + 1
  if (N.containsKey(c)) {
    if (c >= 100)
        s.append(N[1])
    s.append(N[c])
  } else {
    x = (int) c / 100
    w = (int) c % 100
    y = (int) w / 10
    z = (int) w % 10
    if (x > 0) {
      s.append(N[x])
      s.append(N[100])
      if (y > 0 || z > 0 || w > 0) {
        s.append('and')     // and
      }
    }
    if (N.containsKey(w)) {
      s.append(N[w])
    } else {
      if (y > 0) s.append(N[y * 10])
      if (z > 0) s.append(N[z])
    }
  }
  println(s)
  count += s.length()
  s.delete(0, s.length())
}
println("Total characters: ${count}")

Project Euler - P16

2010-02-05T11:48:00.001+08:00

Problem 16

Groovy Code

static final int TIME = 1000
static final int BASE = 2

def add(s, n, i) {
  s[i] = Character.forDigit(n % 10, 10)
  return (int) (n / 10)
}

def strPowerR = '1'
def strTemp = new char[1024]
int intTemp = 0
int intOverflow = 0

Arrays.fill strTemp, Character.forDigit(0, 10)
strTemp[0] = Character.forDigit(1, 10)
TIME.times {
  strPowerR.toCharArray().eachWithIndex { item, index ->
    intTemp = Character.digit(item, 10)
    intTemp = (intTemp * BASE) + (intOverflow % 10)
    intOverflow = ((int)intOverflow/10) + add(strTemp, intTemp, index)
  }
  if (intOverflow > 0) {
    String strTemp2 = String.valueOf(intOverflow)
    strTemp2.toCharArray().eachWithIndex { item, index ->
      strTemp[strPowerR.length() + strTemp2.length() - index - 1] = item
    }
    intOverflow = 0
  }
  strPowerR = String.valueOf('a' + strTemp).replace('0', ' ').trim().replace(' ', '0').substring(1) // trim right
}

println ("Power(${BASE}, ${TIME}) = ${strPowerR.reverse()}")

intTemp = 0
strPowerR.toCharArray().each {
  intTemp += Character.digit(it, 10)
}

println ("Sum of all digit character of Power(${BASE}, ${TIME}) = ${intTemp}")

Project Euler - P15

2010-02-05T07:45:00.000+08:00

Problem 15

C Code

#define MAX (20)

typedef struct _node {
    int v;
    struct _node *a;
    struct _node *b; 
} node;

static long long unsigned int count = 0;

void new_node(node* n, int i, int j) {
    n->v = i * 100 + j + 1;
}

void find_path(node* n) {
    if (!n->a && !n->b) {
        count++;
        return;
    }
    if (n->a) {
        if (n->b) {
            find_path(n->b);
        }
        find_path(n->a);
    } else {
        if(n->b) find_path(n->b);
    }
}

int main(void) {
    const int BOUNDARY = MAX + 1;
    node  m[BOUNDARY * BOUNDARY] = {0};
    node* pn = NULL;
    int i = 0, j = 0;

    printf("given %d X %d matrix\n", MAX, MAX);

    for (i = 0; i < BOUNDARY; i++) {
        for (j = 0; j < BOUNDARY; j++) {
            pn = m + i * BOUNDARY + j;
            if (0 == pn->v) 
                new_node(pn, i, j);
            if (j < MAX) {
                pn->b = m + i * BOUNDARY + j + 1;
                if (0 == pn->b->v) new_node(pn->b, i, j + 1);
            }
            if (i < MAX - 1) {
                pn->a = m + (i + 1) * BOUNDARY + j;
                if (0 == pn->a->v) new_node(pn->a, i + 1, j);
            }
        }
    }
    
    printf("start...\n", count);

    pn = m;
    find_path(pn);

    printf("result-> %llu\n", count);

    return EXIT_SUCCESS;
}

Groovy Code

class Node {

  static pathCount = 0

  String name
  int    weight = 0
  Node   downward, rightward

  public String toString() { name }

  static def newInstance(i, j) {
    def n = new Node()
    n.name = "Node ${i}:${j}"
    n.weight = i * 100 + j
    n
  }

  static def calPathAll(n) {
    if (n.downward) {
      if (n.rightward) {
        calPathAll(n.rightward)
      }
      calPathAll(n.downward)
    } else {
      if (n.rightward) calPathAll(n.rightward)
    }
    if (!n.downward && !n.rightward) pathCount++
  }

}


def MAX = 2 + 1
def nodes = new Node[MAX][MAX]
def i = 0, j = 0

//initiate node matrix
(MAX).times {
  j = 0
  (MAX).times {
    if (!nodes[i][j]) {
      nodes[i][j] = Node.newInstance(i, j)
    }
    def c = nodes[i][j]
    nodes[i][j] = c
    if (i != MAX - 1) {
      if (!nodes[i + 1][j]) {
        nodes[i + 1][j] = Node.newInstance(i + 1, j)
      }
      def a = nodes[i + 1][j]
      if (c.weight < a.weight) c.downward = a
    } else {
      c.downward = null
    }
    if (j != MAX - 1) {
      if (!nodes[i][j + 1]) {
        nodes[i][j + 1] = Node.newInstance(i, j + 1)
      }
      def b = nodes[i][j + 1]
      if (c.weight < b.weight) c.rightward = b
    } else {
      c.rightward = null
    }
    j++
  }
  i++
}

Node.calPathAll(nodes[0][0]) // calculate from node 0:0
println("Found ${nodes[0][0].pathCount} possible paths.")

English - Class Notes 05

2009-12-31T11:30:00.000+08:00

Vocabulary

rural: not in a city; in the countryside.
amateur: not professional.
elaborate: complex or fancy.
barter: to exchange.
embezzle: to steal money that you are responsible for or that belongs to your employer.
bounce: if a cheque bounces, or a bank bounces it, the bank refuses to accept it because there is not enough money in the account.
endorse: to write your name on the back of a cheque so that it can be paid into a bank account.
loan shark: a person who lends money at very high rates of interest.
frugal, stingy, pennysaver: using only as much money or food as is necessary.
solvent: having enough money to pay your debts; not in debt.
insolvent: not having enough money to pay your debts; not in debt.
overdrawn: of a person 人 having taken more money out of your bank account than you have in it.
postdated: in banking, postdated refers to checks which have been written by the maker for a date in the future.

English - Class Notes 04

2009-12-16T08:51:00.000+08:00

Numbers

Temperature

1 °C: one degree Celsius
1 °F: one degree Fahrenheit

Time, for example 08:00

8 o'clock on the dot
8 o'clock sharp

Fraction/Ratio

1/4: one over four
1/3: one third
2/3: two thirds
4:1: four to one

Currency

123,456: one hundred twenty-three thousand four hundred and fifty-six
1,234.56: one thousand and two hundred thirty-four point five six
1,000: one grand

Space

1 m²: one square metre

Java - Some Fundamental Concepts

2009-12-04T10:03:00.003+08:00

Method declaration in an interface,

Correct:

abstract void doStuff();
protected abstract void doStuff();

Incorrect:

public abstract static void doStuff();
private abstract void doStuff();
final abstract void doStuff();

Overloading & Overriding,

Cans:
- Instance method can be overloaded.
- Instance method can be overriden.
- Static method can be overloaded.
- Constructor can be overloaded.
Cants:
- Static method can't be overriden.
- Constructor can't be overriden.
- Instance field can't be overloaded.
- Instance field can't be overriden.

A constructor may only access final or static attributes, therefore following is incorrect.

class Base { 
     private int value; 
      
     Base (int v) { 
         value = v; 
     } 
  
     public int getValue() { 
         return value; 
     } 
 } 
  
 public class Derived extends Base { 
     int currentValue = 1; 
  
     public Derived() { 
         super(currentValue); 
         currentValue++; 
     } 
 }

An assert statement can take any one of following two forms, method call isn't allowed:

assert Expression1; 
assert Expression1 : Expression2;

Inheritance and abstract modifier, following are correct

Method could be declared as abstract in a child.
Class could be declared as abstract even if it doesn't have any abstract method.
Static method can be overloaded.

Implementation of an interface, following code snippet isn't correct because all interface methods are default public methods.

interface Useable { 
   void doIt(); 
} 
  
public class Test implements Useable {    
   public Test(){} 
   void doIt() {} 
}

Notification in threads

If a thread issues a notifyAll on an object without having acquired the lock for the object Java throws an IllegalMonitorStateException.

Appropriate uses for Assertion statements

Should be used to validate private method parameters.
Should be used to check for cases that should never occur.

Interface and abstract constructors

Abstract classes have constructors, and those constructors are always called when a concrete subclass is instantiated using the new operator.

Java - Classes Comparison

2009-12-04T01:08:00.001+08:00

Hashtable v.s. HashMap

Hashtable: Synchronized
HashMap: Non synchronized

StringBuffer v.s. StringBuilder

StringBuffer: Synchronized
StringBuilder: Non synchronized

List v.s. Set

List: Allow duplicate elements
Set: Not allow duplicate elements

C - pthread_cond_timedwait_relative_np example

2009-11-16T18:35:00.001+08:00

Follow up of previous post, try to simulate the sigtimedwait method due to the fact that the method is lacked in OS X.

BTW, ldd is also not found, just use otool -L for an alternative.

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>
#include <signal.h>

#define SIG_A          (SIGUSR2 - 0)
#define SIG_B          (SIGUSR2 - 1)
#define SIG_C          (SIGQUIT)

#define S  1
#define F  0

#define TIMES 10

/*
 * data structure
 */
typedef struct _proc {
    char            name[2];
    int             data;
    pthread_t       thread;
    pthread_mutex_t lock;
    pthread_cond_t  cond;
    long int        waits;
    sigset_t        sigset;
} PROC;

/*
 * variables
 */

static PROC *listener;

/*
 * methods
 */
void _exec_and_wait(void* args) {
    PROC *proc = (PROC*) args;
    static struct timespec time_to_wait = {0, 0};
    // signal version
    int recSignal;
    while(proc->data < 999) {
        if (0 == sigwait(&proc->sigset, &recSignal)) {
            pthread_mutex_lock(&proc->lock);
            switch (recSignal) {
                case SIG_A:
                    printf("proc[%s] receive SIG_A\n", proc->name);
                    proc->data++;
                break;
                case SIG_B:
                    printf("proc[%s] receive SIG_B\n", proc->name);
                    proc->data += 5;
                break;
                case SIG_C:
                    printf("proc[%s] receive SIG_C\n", proc->name);
                    proc->data += 999;
                break;
                default:
                    printf("proc[%s] receive unknow signal [%d]\n", proc->name, recSignal);
            }
            pthread_mutex_unlock(&proc->lock);
        } else {
            printf("proc[%s] fail to receive signal [%d]\n", proc->name);
        }
    }
    printf("proc[%s] finished\n", proc->name);
}

void _exec_to_signal(void* args) {
    PROC *proc = (PROC*) args;
    static struct timespec time_to_wait = {0, 0};
    int sig_sending;
 
    if (listener != NULL) {
        srand(time(NULL));
        time_to_wait.tv_sec = proc->waits;
        while(proc->data < TIMES) {
            pthread_mutex_lock(&proc->lock);
            pthread_cond_timedwait_relative_np(&proc->cond, &proc->lock, &time_to_wait);
            sig_sending = (rand() % 2 > 0) ? SIG_A : SIG_B;
            printf("proc[%s] is sending signal[%d]\n", proc->name, sig_sending);
            pthread_kill(listener->thread, sig_sending);
            proc->data++;
            pthread_mutex_unlock(&proc->lock);
        }
        printf("proc[%s] is sending signal[%d]\n", proc->name, SIG_C);
        pthread_kill(listener->thread, SIG_C); // to terminate listener
    } else {
        printf("proc[%s] is aborting signal[%d], due to no listener registered\n", proc->name, SIG_A);
 }
 printf("proc[%s] finished\n", proc->name);
}

int _init_proc(PROC *proc, void *(*routine) (void *)) {
    pthread_attr_t attr;
    //
    printf("try to init proc [%s]\n", proc->name);
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    //
    pthread_mutex_init(&proc->lock, NULL);
    pthread_cond_init(&proc->cond, NULL);
    //
    pthread_create(&proc->thread, &attr, routine, (void*) proc);
    pthread_attr_destroy(&attr);
    //
    return S;
}

int _init_signal_proc(PROC *proc, void *(*routine) (void *)) {
    pthread_attr_t attr;
    //
    printf("try to init proc [%s]\n", proc->name);
    //
    sigemptyset(&proc->sigset);
    sigaddset(&proc->sigset, SIG_A);
    sigaddset(&proc->sigset, SIG_B);
    sigaddset(&proc->sigset, SIG_C);
    pthread_sigmask(SIG_BLOCK, &(proc->sigset), NULL);
    //
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    //
    pthread_mutex_init(&proc->lock, NULL);
    //
    pthread_create(&proc->thread, &attr, routine, (void*) proc);
    pthread_attr_destroy(&attr);
    //
    return S;
}

/*
 *  main
 */
int main(int argc, char** argv)
{
    int  result_a = 0, result_b = 0;
    PROC proc_a, proc_b;

    strcpy(proc_a.name, "A\0");
    proc_a.data = 0;
    proc_a.waits = 1L;

    strcpy(proc_b.name, "B\0");
    proc_b.data = 0;
    proc_b.waits = 800L;

    listener = &proc_b;

    if (!_init_proc(&proc_a, _exec_to_signal))
        printf("Fail to init proc [%s]\n", proc_a.name);
    /* */
    if (!_init_signal_proc(&proc_b, _exec_and_wait))
        printf("Fail to init proc [%s]\n", proc_b.name);
 
    /* */
    pthread_join(proc_a.thread, (void*) &result_a);
    pthread_join(proc_b.thread, (void*) &result_b);

    return (EXIT_SUCCESS);
}

C - pthread_cond_timedwait example

2009-11-13T11:22:00.003+08:00

Follow up: try to use pthread_cond_timedwait_relative_np on OS X.

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <errno.h>
#include <unistd.h>
#include <time.h>

#define S  1
#define F  0

#define TIMES 10

/*
 * data structure
 */
typedef struct _proc {
    char            name[2];
    int             data;
    pthread_t       thread;
    pthread_mutex_t lock;
    pthread_cond_t  cond;
    long int        waits;
} PROC;

void _exec_and_wait(void* args) {
    static struct timespec time_to_wait = {0, 0};
    PROC *proc = (PROC*) args;

    while(proc->data < TIMES) {
        time_to_wait.tv_sec = time(NULL) + proc->waits;
        pthread_mutex_lock(&proc->lock);
        pthread_cond_timedwait(&proc->cond, &proc->lock, &time_to_wait);
        proc->data++;
        printf("increase proc[%s] data to [%d]\n", proc->name, proc->data);
        pthread_mutex_unlock(&proc->lock);
    }
}

int _init_proc(PROC *proc, void *(*routine) (void *)) {
    pthread_attr_t attr;
    //
    printf("try to init proc [%s]\n", proc->name);
    pthread_attr_init(&attr);
    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
    //
    pthread_mutex_init(&proc->lock, NULL);
    pthread_cond_init(&proc->cond, NULL);
    //
    pthread_create(&proc->thread, &attr, routine, (void*) proc);
    pthread_attr_destroy(&attr);
    //
    return S;
}

/*
 *  main
 */
int main(int argc, char** argv)
{
    int  result_a = 0, result_b = 0;
    PROC proc_a, proc_b;

    strcpy(proc_a.name, "A\0");
    proc_a.data = 0;
    proc_a.waits = 2L;

    strcpy(proc_b.name, "B\0");
    proc_b.data = 0;
    proc_b.waits = 1L;

    if (!_init_proc(&proc_a, _exec_and_wait))
        printf("Fail to init proc [%s]\n", proc_a.name);
    /* */
    if (!_init_proc(&proc_b, _exec_and_wait))
        printf("Fail to init proc [%s]\n", proc_b.name);
    /* */
    pthread_join(proc_a.thread, (void*) &result_a);
    pthread_join(proc_b.thread, (void*) &result_b);

    return (EXIT_SUCCESS);
}

AIX - Memory Allocation Segmentation Fault

2009-11-10T10:22:00.000+08:00

Once again, there were segmentation faults occurred during the execution of my AIX porting application. After digging into the call stacks of the application, I found that it crashed frequently while allocating or dellocating small size of memories. No matter what the stack size I assigned to the system, it kept crashed.

Then I spent few hours refering to the official AIX porting guidelines and finally got some hints on section 4.2 page 169. On AIX, there are many different memory allocation policies implemented as different allocators. Depends on the design of your applications, it is adjustable to change to any suitable allocator simply by declaring a environment variable, MALLOCTYPE. Therefore I had a try to test different allocators, and the result was quite positive.

P.S. the allocator I chose was MALLOCTYPE=buckets, which was optimized for applications that require large numbers of small allocation requests.

English - Class Notes 03

2009-11-10T09:54:00.000+08:00

Some conjuctions

because + n.c.
since + n.c.
so + n.c.
due to the fact that + n.c.
due to + n.p.
because of + n.p.

Some phrases

have to vs must
- have to: outside authority.
- must: self motivated.
humble vs modest
- humble: soft of negative.
- modest: kinda positive.
dynamic similar to lively
had better similar to shall similar to should similar to could
luggage equals to baggage

Some vocabularies

filial: connected with the way children behave towards their parents.
Filippino: means belonging or relating to the Philippines, or to its people or culture.
wind chill factor: a phenomenon called the Wind Chill factor makes us feel colder in winter than the air temperature really is.
punctually: if you are punctual, you do something or arrive somewhere at the right time and are not late.
etiquette: is a set of customs and rules for polite behaviour, especially among a particular class of people or in a particular profession.
netiquette: is the set of rules and customs that it is considered polite to follow when you are communicating by means of e-mail or the Internet.
manner: the way that sth is done or happens.

AIX - Multithread Program Segmentation Fault

2009-11-06T18:14:00.001+08:00

Recently I encountered some difficulties to porting pthread base multithreading program to AIX platform. The problem was, one of my multithreaded programs always crashed due to unknown segmentation faults. Spent few days on testing and debugging, finally I found below useful information by google's help:

Reference

This says, to prevent our multithreaded program from crashing by segmentation faults, we need to set an environment variable, AIXTHREAD_STK, to change default thread stack size. Or, we could use the pthread_attr_setstacksize() sub-routine alternatively.

Then I changed the environment variable AIXTHREAD_STK to a larger number, and thankfully it did worked.

English - Class Note 02

2009-10-22T14:13:00.002+08:00

Was Ving & Ved
Saying was ving to emphasize what was doing during previous period, and saying ved to emphasize the presented result.

was Ving -
I was working on the software development project at that time.
Ved -
I worked for the company few years ago.

V = Ving
Sometimes using v is the same as ving

I work on the project = I am working on the project
I live in Taipei = I am living in Taipei

hope & wish
Using hope ... can for something which is possible. On the other hand, using wish ... could for which impossible.

I hope I can and maybe be I will.
I wish I could but I can't.

Verb choosing

mail letters
deliver good
courier package

Punctuations

. - full stop, add two spaces
, - pause, add one space
; - between full stop and pause, add one space
- - minor additional information, add one space

Additional

Golden Gate Bridge is a suspension bridge

C - Macro

2009-10-15T10:46:00.001+08:00

Some example of C macro usages:

Literal/Number declaration


#define PI 3.14159

Code Fragment I : Code Fragment Delcaration


#define pf(str)     printf(str)

Code Fragment II : Variable Parameters


#define pf(str, ...)  printf(str, __VA_ARGS__)

Code Fragment III : Parameter as String


#define run(method)  printf("Runing %s\n", #method); \ 
                     method();

Code Fragment IV : Parameter Variation


#define pf(method)  method##_debug("debug was called"); \ 
                    method##_info("info was called");

English - Class Notes 01

2009-10-13T15:46:00.001+08:00

habit & hobby

habit stands for what you used to do.
hobby stands for what you are interesting in.

nice to meet you

In response, says you too, same here, likewise or for me too.
The difference between nice to meet you and nice meeting you
- Nice to meet you usually be used at the beginning of an encounter.
- Nice meeting you commonly be used as farewell.

C - Using wchar_t on Windows platform

2009-10-08T18:15:00.003+08:00

The wchar_t Data Type

wchar_t represents the "wide char" data type in Windows platform, which aims to be capable of storing 2-byte format Unicode characters. To declare constant literals to wchar_t datatype, just put an L before it:

const wchar_t *pGreeting = L"Hello World";

Reference:
The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)
C++, wchar_t, Unicode and all that stuff

AIX - XL C/C++ compiler options for share objects

2009-10-02T14:20:00.001+08:00

To generate shared libraries for runtime dynamic linking on AIX with XL C/C++ compiler, must use -G & -qmkshrobj options.

xlc -G -qmkshrobj shrobj.c -o libshrobj.so

And, for runtime linking to the generated shared library, must use -brtl option.

xlc main.c -brtl -lshrobj

Knowledge - Big Endian & Little Endian

2009-10-01T09:23:00.002+08:00

There are two kinds of design architecture for memory storage: Big Endian & Little Endian. Some references are listed as blew:

AIX - Compiling GCC programming with XLC

2009-09-29T11:39:00.003+08:00

Some reference here:

C - Get File Length

2009-09-15T17:49:00.007+08:00

Code Snippet to Know File Length

#include <stdlib.h>

fseek (fileName, 0L, SEEK_END);  
len = ftell (fileName);  
fseek (fileName, len, SEEK_SET);

Project Euler - P14

2009-09-14T19:46:00.003+08:00

Problem 14

C Code

#define MAX 1000000
int main(void) {
 unsigned int n = 2, current = n, solution = 0;
 int max_count = 1, count;

 for (; n <= MAX; n++) {
  count = 1;
  current = n;
  while (current != 1) {
   if (current % 2 == 1) {
    current = 3 * current + 1;
   } else {
    current /= 2;
   }
   count++;
  }
  if (max_count < count) {
   max_count = count;
   solution = n;
  }
 }

 printf("The max chain (%d) found in %u is started by %u", max_count, MAX, solution);

 return EXIT_SUCCESS;

}

C - Inline Functions

2009-09-14T18:11:00.002+08:00

Inline in C

The inline keyword would suggest compiler to translate the declared function as inlined program in order to reduce corresponding efforts of the method call executions.

Inline Functions in C

C - Variable Declarations

2009-09-08T15:07:00.003+08:00

Quick Note : The First Rule of C Variable Declaration

Variable definitions must be at top of blocks for ANSI C. @_@

Reference:
typedef 跟採用全域變數的問題

C - Memory

2009-09-08T13:58:00.002+08:00

Memory Manipulation

To master C/C++ programming language, a well understanding of memory manipulation is the fundamental prerequisite. Till now, I finally understand why most C/C++ books always use chapters to explain relative topics. It does matters!

Some reference as blow:
#pragma pack directive
Data Structure Alignment

C - Win32 Header File Issue

2009-09-01T19:31:00.006+08:00

Quick Note: Solving Header File Conflict in Win32 Platform

If encountering a 'fd_set' : 'struct' type redefinition issue during the compile of socket related programs on win32 platform. Remember to use following macro to solve the header file conflict.

WIN32_LEAN_AND_MEAN

Reference: here.

C - IDE

2009-09-01T14:02:00.009+08:00

C/C++ IDE

I had spent some times trying to find an C/C++ IDE for multi-platform programming (both on Linux and Windows), unfortunately no suitable solution was found.

Code::Blocks is currently the best to me, but still not that well as I expected.

Hoping IntelliJ's C/C++ plugin could keep development and improving, it is really the best IDE I have ever used. :)

Project Euler - P13

2009-08-07T08:15:00.001+08:00

Problem 13

Groovy Code

def matrix = [[37,107,287,533,902,102,798,797,998,220,837,590,246,510,135,740,250],
              [46,376,937,677,490,  9,712,648,124,896,970, 78, 50,417, 18,260,538],
              [74,324,986,199,524,741, 59,474,233,309,513, 58,123,726,617,309,629],
              [91,942,213,363,574,161,572,522,430,563,301,811, 72,406,154,908,250],
              [23, 67,588,207,539,346,171,171,980,310,421, 47,513,778, 63,246,676],
              [89,261,670,696,623,633,820,136,378,418,383,684,178,734,361,726,757],
              [28,112,879,812,849,979,408, 65,481,931,592,621,691,275,889,832,738],
              [44,274,228,917,432,520,321,923,589,422,876,796,487,670,272,189,318],
              [47,451,445,736,  1,306,439, 91,167,216,856,844,588,711,603,153,276],
              [70,386,486,105,843, 25,439,939,619,828,917,593,665,686,757,934,951],
              [62,176,457,141,856,560,629,502,157,223,196,586,755, 79,324,193,331],
              [64,906,352,462,741,904,929,101,432,445,813,822,663,347,944,758,178],
              [92,575,867,718,337,217,661,963,751,590,579,239,728,245,598,838,407],
              [58,203,565,325,359,399,  8,402,633,568,948,830,189,458,628,227,828],
              [80,181,199,384,826,282, 14,278,194,139,940,567,587,151,170, 94,390],
              [35,398,664,372,827,112,653,829,987,240,784,473, 53,190,104,293,586],
              [86,515,506,  6,295,864,861,532, 75,273,371,959,191,420,517,255,829],
              [71,693,888,707,715,466,499,115,593,487,603,532,921,714,970, 56,938],
              [54,370, 70,576,826,684,624,621,495,650, 76,471,787,294,438,377,604],
              [53,282,654,108,756,828,443,191,190,634,694, 37,855,217,779,295,145],
              [36,123,272,525,  0,296, 71, 75, 82,563,815,656,710,885,258,350,721],
              [45,876,576,172,410,976,447,339,110,607,218,265,236,877,223,636, 45],
              [17,423,706,905,851,860,660,448,207,621,209,813,287,860,733,969,412],
              [81,142,660,418, 86,830,619,328,460,811,191, 61,556,940,512,689,692],
              [51,934,325,451,728,388,641,918, 47, 49,293,215, 58,642,563, 49,483],
              [62,467,221,648,435, 76,201,727,918, 39,944,693,  4,732,956,340,691],
              [15,732,444,386,908,125,794,514, 89, 57,706,229,429,197,107,928,209],
              [55, 37,687,525,678,773, 91,862,540,744,969,844,508,330,393,682,126],
              [18,336,384,825,330,154,686,196,124,348,767,681,297,534,375,946,515],
              [80,386,287,592,878,490,201,521,685,554,828,717,201,219,257,766,954],
              [78,182,833,757,993,103,614,740,356,856,449, 95,527, 97,864,797,581],
              [16,726,320,100,436,897,842,553,539,920,931,837,441,497,806,860,984],
              [48,403, 98,129, 77,791,799, 88,218,795,327,364,475,675,590,848, 30],
              [87, 86,987,551,392,711,854,517, 78,544,161,852,424,320,693,150,332],
              [59,959,406,895,756,536,782,107, 74,926,966,537,676,326,235,447,210],
              [69,793,950,679,652,694,742,597,709,739,166,693,763, 42,633,987, 85],
              [41, 52,684,708,299, 85,211,399,427,365,734,116,182,760,315,  1,271],
              [65,378,607,361,501, 80,857,  9,149,939,512,557, 28,198,746,  4,375],
              [35,829, 35,317,434,717,326,932,123,578,154,982,629,742,552,737,307],
              [94,953,759,765,105,305,946,966, 67,683,156,574,377,167,401,875,275],
              [88,902,802,571,733,229,619,176,668,713,819,931,811, 48,770,190,271],
              [25,267,680,276, 78,  3, 13,678,680,992,525,463,401, 61,632,866,526],
              [36,270,218,540,497,705,585,629,946,580,636,237,993,140,746,255,962],
              [24, 74,486,908,231,174,977,792,365,466,257,246,923,322,810,917,141],
              [91,430,288,197,103,288,597,806,669,760,892,938,638,285, 25,333,403],
              [34,413, 65,578, 16,127,815,921,815,  5,561,868,836,468,420, 90,470],
              [23, 53, 81,172,816,430,487,623,791,969,842,487,255, 36,638,784,583],
              [11,487,696,932,154,902,810,424, 20,138,335,124,462,181,441,773,470],
              [63,783,299,490,636,259,666,498,587,618,221,225,225,512,486,764,533],
              [67,720,186,971,698,544,312,419,572,409,913,959,  8,952,310, 58,822],
              [95,548,255,300,263,520,781,532,296,796,249,481,641,953,868,218,774],
              [76, 85,327,132,285,723,110,424,803,456,124,867,697, 64,507,995,236],
              [37,774,242,535,411,291,684,276,865,538,926,205, 24,910,326,572,967],
              [23,701,913,275,725,675,285,653,248,258,265,463, 92,207, 58,596,522],
              [29,798,860,272,258,331,913,126,375,147,341,994,889,534,765,745,501],
              [18,495,701,454,879,288,984,856,827,726, 77,713,721,403,798,879,715],
              [38,298,203,783, 31,473,527,721,580,348,144,513,491,373,226,651,381],
              [34,829,543,829,199,918,180,278,916,522,431, 27,392,251,122,869,539],
              [40,957,953, 66,405,232,632,538, 44,100, 59,654,939,159,879,593,635],
              [29,746,152,185,502,371,307,642,255,121,183,693,803,580,388,584,903],
              [41,698,116,222, 72,977,186,158,236,678,424,689,157,993,532,961,922],
              [62,467,957,194,401,269, 43,877,107,275, 48,102,390,895,523,597,457],
              [23,189,706,772,547,915, 61,505,504,953,922,979,530,901,129,967,519],
              [86,188, 88,225,875,314,529,584, 99,251,203,829,  9,407,770,775,672],
              [11,306,739,708,304,724,483,816,533,873,502,340,845,647, 58, 77,308],
              [82,959,174,767,140,363,198,  8,187,129, 11,875,491,310,547,126,581],
              [97,623,331, 44,818,386,269,515,456,334,926,366,572,897,563,400,500],
              [42,846,280,183,517, 70,527,831,839,425,882,145,521,227,251,250,327],
              [55,121,603,546,981,200,581,762,165,212,827,652,751,691,296,897,789],
              [32,238,195,734,329,339,946,437,501,907,836,945,765,883,352,399,886],
              [75,506,164,965,184,775,180,738,168,837,861, 91,527,357,929,701,337],
              [62,177,842,752,192,623,401,942,399,639,168, 44,983,993,173,312,731],
              [32,924,185,707,147,349,566,916,674,687,634,660,915, 35,914,677,504],
              [99,518,671,430,235,219,628,894,890,102,423,325,116,913,619,626,622],
              [73,267,460,800,591,547,471,830,798,392,868,535,206,946,944,540,724],
              [76,841,822,524,674,417,161,514, 36,427,982,273,348, 55,556,214,818],
              [97,142,617,910,342,598,647,204,516,893,989,422,179,826, 88, 76,852],
              [87,783,646,182,799,346,313,767,754,307,809,363,333, 18,982,642, 90],
              [10,848,802,521,674,670,883,215,120,185,883,543,223,812,876,952,786],
              [71,329,612,474,782,464,538,636,993,  9, 49,310,363,619,763,878, 39],
              [62,184, 73,572,399,794,223,406,235,393,808,339,651,327,408, 11,116],
              [66,627,891,981,488, 87,797,941,876,876,144,230, 30,984,490,851,411],
              [60,661,826,293,682,836,764,744,779,239,180,335,110,989, 69,790,714],
              [85,786,944, 89,552,990,653,640,447,425,576, 83,659,976,645,795, 96],
              [66, 24,396,409,905,389,607,120,198,219,976, 47,599,490,197,230,297],
              [64,913,982,680, 32,973,156, 37,120, 41,377,903,785,566, 85, 89,252],
              [16,730,939,319,872,750,275,468,906,903,707,539,413, 42,652,315, 11],
              [94,809,377,245, 48,795,150,954,100,921,645,863,754,710,598,436,791],
              [78,639,167, 21,187,492,431,995,700,641,917,969,777,599, 28,300,699],
              [15,368,713,711,936,614,952,811,305,876,380,278,410,754,449,733, 78],
              [40,789,923,115,535,562,561,142,322,423,255, 33,685,442,488,917,353],
              [44,889,911,501,440,648, 20,369, 68, 63,960,672,322,193,204,149,535],
              [41,503,128,880,339,536, 53,299,340,368,  6,977,710,650,566,631,954],
              [81,234,880,673,210,146,739, 58,568,557,934,581,403,627,822,703,280],
              [82,616,570,773,948,327,592,232,845,941,706,525, 94,512,325,230,608],
              [22,918,802, 58,777,319,719,839,450,180,888, 72,429,661,980,811,197],
              [77,158,542,502, 16,545, 90,413,245,809,786,882,778,948,721,859,617],
              [72,107,838,435, 69,186,155,435,662,884, 62,257,473,692,284,509,516],
              [20,849,603,980,134,  1,723,930,671,666,823,555,245,252,804,609,722],
              [53,503,534,226,472,524,250,874, 54, 75,591,789,781,264,330,331,690]]

def p_sum = 0
def sum = []

for (int i = 16; i >= 0; i--) {
    def ts = (int) (p_sum + matrix.collect { it[i] }.sum())
    sum.add(0, ts % 1000)
    p_sum = (int) (ts / 1000)
}

if (p_sum > 0) {
    sum.add(0, p_sum)
}

print "sum -> "
sum.each {
    print it
}
println ""

Project Euler - P12

2009-08-07T08:14:00.000+08:00

Problem 12

Groovy Code

def tn = 1, n = 100
def r, max, c
def f = 0

while (f <= 500) {
    f = 0
    n++
    r = 1..n
    tn = r.sum()
    //r = 1..tn
    //r.each { f+= (tn % it == 0 ? 1 : 0) }
    c = 1
    max = tn
    def fn = "${n}th ${tn} : "
    while (c < max) {
        if (tn % c == 0) {
            max = (int)(tn / c)
            f += (max == c ? 1 : 2)
            //fn += "$c $max "
        }
        c++
    }
    fn += " --> $f"
    if (f > 100) {
       println fn
    }
}

println "${n}th triangle -> $tn"
println "factor size -> $f"

Project Euler - P11

2009-08-07T08:12:00.001+08:00

Problem 11

Groovy Code

def matrix = [[ 8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8],
              [49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  9, 56, 62,  0],
              [81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65],
              [52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91],
              [22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80],
              [24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50],
              [32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70],
              [67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21],
              [24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72],
              [21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95],
              [78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92],
              [16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57],
              [86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58],
              [19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40],
              [ 4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66],
              [88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69],
              [ 4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36],
              [20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16],
              [20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54],
              [ 1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48]]

def max = 0, sum = 1
for (int i = 0; i < matrix.size(); i++) {
    for (int j = 0; j < matrix[i].size(); j++) {
            if (matrix[i][j] == 0) continue
                for (int k = 0; k < 4; k++) {
                    sum = 0
                    switch (k) {
                            case 0:
                                    if (j > matrix.size() - 4) continue
                                        sum = matrix[i][j] * matrix[i][j + 1] * matrix[i][j + 2] * matrix[i][j + 3]
                                        break
                                case 1:
                                    if (i > matrix.size() - 4) continue
                                        sum = matrix[i][j] * matrix[i + 1][j] * matrix[i + 2][j] * matrix[i + 3][j]
                                        break
                                case 2:
                                    if (j > matrix.size() - 4 || i > matrix.size() - 4) continue
                                        sum = matrix[i][j] * matrix[i + 1][j + 1] * matrix[i + 2][j + 2] * matrix[i +
 3][j + 3]
                                        break
                                case 3:
                                    if (j < 3 || i >= matrix.size() - 4) continue
                                        sum = matrix[i][j] * matrix[i + 1][j - 1] * matrix[i + 2][j - 2] * matrix[i +
 3][j - 3]
                                        break
                        }
                        if (max < sum) {
                            max = sum
                                println "start from [$j, $i] direction [$k] current max -> $max"
                        }
                }
        }
}

Project Euler - P10

2009-08-07T08:09:00.003+08:00

Problem 10

Groovy Code

def primes = [2, 3, 5, 7, 11, 13, 17, 19]
def MAX = 2000000
double sum = primes.sum()
def i = primes.get(primes.size() - 1) + 2
while (MAX > i) {
 def found = true
 //def q = Math.sqrt(i)
 for (int x = 0; x < primes.size() && primes.get(x)*primes.get(x) <= i; x++) {
   if( i % primes.get(x) == 0) {
     found = false
     break
   }
 }
 if(found) {
    primes << i
    //println "last prime -> $i"
    sum += i
 }
 i+=2

 while(i % (Math.sqrt(i)) == 0) {
  println "skip $i"
  i+=2
 }
}
println "sum -> ${new java.text.DecimalFormat('###########0').format(sum)}"

Project Euler - P9

2009-08-01T09:55:00.001+08:00

Problem 9

Groovy Code

def t = 1000
def max_a = 332
def s = []

def max_b, min_c

for (int a = max_a; a > 0; a--) {
    int c = min_c = (int)((t - a) / 2 + 1)
        int b = max_b = t - a - min_c
        while (c > b && b > a) {
            def a2 = Math.pow(a, 2)
            def b2 = Math.pow(b, 2)
            def c2 = Math.pow(c, 2)
            if(a2 + b2 == c2) {
              println "$a < $b < $c, and $a + $b + $c = ${a+b+c}, and $a2 + $b2 = $c2"
              s << (a * b * c)
              break
           }
           c++
           b--
        }
    if (s.size() > 0) break
}

println s

Project Euler - P7

2009-07-25T09:53:00.000+08:00

Problem 7

Groovy Code

def primes = [2, 3, 5, 7, 11, 13, 17]
def MAX = 10001
def i = primes.get(primes.size() - 1) + 1
while (primes.size() < MAX) {
 if(!primes.any { i % it == 0 }) {
    primes << i
 }
 i++
}

println "found primes size => ${primes.size()}"
println "the prime => ${primes.get(MAX > primes.size() ? primes.size() - 1 : MAX - 1)}"

Project Euler - P6

2009-07-25T09:51:00.004+08:00

Problem 6

Groovy Code

def s1 = 0l, s2 = 0l
for (int i = 1; i <= 100; i++) {
  s1 += (long)Math.pow(i, 2)
  s2 += i
}
println "s1 -> $s1, s2 -> $s2"
def x =  (long)(Math.pow(s2, 2) - s1)
println x

Project Euler - P5

2009-07-25T09:49:00.002+08:00

Problem 5

Groovy Code

def MIN = 2, MAX = 20
def primes = [2, 3, 5, 7, 11, 13, 17, 19]
def factors = []
while (MIN <= MAX) {
    println "checking $MIN"
    if (MIN in primes) {
            factors << MIN
       println "factors changed => $factors"
    } else {
            // find MIN factors
            def fn = []
            def x = MIN
            while(!(x in primes)) {
                def f = primes.find { x % it == 0 }
                    fn << f
                    x = (int) (x / f)
            }
            fn << x
            println "factors of $MIN => $fn"
            // add factors
            def i = 0
            fn.each {
                def found = false
                for (int j = i; j < factors.size(); j++) {
                        if (it == factors.get(j)) {
                                i = j + 1
                                    found = true
                                    break
                            }
                    }
                    if (!found) {
                        factors << it
                        factors.sort()
                        println "factors changed => $factors"
                    }
            }
        }
    MIN++
}

println "factors => ${factors}"
def sum = 1
factors.each { sum *= it }
println "result => ${sum}"

Project Euler - P4

2009-07-25T09:47:00.001+08:00

Problem 4

Groovy Code

def x = 999
def y = 999

def found = false
def p
while (!found) {
   p = String.valueOf(x * y)
       println "checking $x x $y = $p"
       def same = true
       for (int i = 0; i < p.length() / 2; i++) {
           if (p.charAt(i) != p.charAt(p.length() - i - 1)) {
                   same = false
                       break
               }
       }
       found = same
       if (!found) {
           if (y == 836) {
                   y = 999
                   x--
               } else {
                   y--
               }
       }
}

println "$x x $y = $p"

Project Euler - P3

2009-07-24T10:44:00.003+08:00

Problem 3

Groovy Code

def primes = [2, 3, 5, 7, 11, 13, 17]
def MAX = 600851475143
def factor = 0
def i = primes.get(primes.size() - 1) + 1
while (MAX > 1) {
    if(!primes.any { i % it == 0 }) {
        primes << i
        if (MAX % i == 0) {
            factor = i
            MAX = (long)(MAX/i)
            println "current factor => $factor"
        }
    }
    i++
}
println factor

Project Euler - P2

2009-07-24T10:24:00.004+08:00

Problem 2

Groovy Code

def MAX = 4000000
def fibonacci = [1,2]

def num = 3
while(num < MAX) {
    fibonacci << num
    num = fibonacci.get(fibonacci.size() - 2) + fibonacci.get(fibonacci.size() - 1)
}

def evens = fibonacci.grep { it % 2 == 0 }

println "sum of evens => ${evens.sum()}"

Project Euler - P1

2009-07-24T10:16:00.006+08:00

Problem 1

Groovy Code:

final def MAX = 1000
def sum = 0
(3..MAX-1).each {
    if (it % 3 == 0 || it % 5 == 0) {
        //println it
        sum += it
    }
}
println "sum => $sum"

OpenGL ES - Some References

2009-07-06T22:06:00.002+08:00

Just see here.

Python - Spring in Python

2009-07-06T10:28:00.003+08:00

Interesting, Spring in Python now...

Android - Activity & Task

2009-07-01T08:34:00.006+08:00

Here are something relative to Android Activity & Task:

Introduction AsyncTask
Reference doc of AsyncTask
Shelves Sample

Activity and Task Guidelines

Grails - Upgrading to Version 1.1

2009-05-12T09:48:00.006+08:00

Seems like that it would be better to wait for 1.1.1 release. :P See Robert Fletcher's notes.

Grails - The Bug of Version 1.0.4 File Uploading

2009-02-16T13:03:00.004+08:00

While using Grails 1.0.4 and deploy to Tomcat, there might be a strange NPE thrown out. Please check out these discussions for more details:

Grails - Changes in Version 1.1 Part One : Plugins

2008-12-29T09:47:00.004+08:00

In the release of Grails 1.1, all plugins would no longer be installed in project folder. Instantly, plugins would be installed in plugins repository (default location: USER_HOME\.grails\GRAILS_VERSION\projects\APP_NAME\plugins, or could be specified in grails-app\conf\BuildConfig.groovy). On the other hand, installed plugins would also be registered in application's meta data (application.properties), Grails would check plugins registration before compiling project.

MySQL - Restore Database Dump File

2008-11-14T15:19:00.004+08:00

Following is the example:

mysql - u user_name -p your_password database_name < file_name.sql

Groovy - Socket Programming Example

2008-11-13T14:56:00.007+08:00

Following is the example:

def remote = new Socket('HOST', PORT, true)
remote.withStreams { i, o ->
    def w = new PrintWriter(o, true)
    w.println 'QUERY_STRING'
    def r = new BufferedReader(new InputStreamReader(i))
    result = r.readLine().trim()
    r.close()
    w.close()
}                
remote.close()

References:
here & here

jQuery.js - Adding Class to SELECT Objects Problem in IE6

2008-11-10T15:08:00.007+08:00

Occurred while adding css class to select objects, the drop-down layer wouldn't be displayed properly.

$("select[name='componentName']").addClass('someClass');

Grails - Multiple Datasource Plugin

2008-11-07T11:04:00.005+08:00

Here is the unofficial plugin which enables Grails to support multiple datasources.

Grails - HTTP Status Page & URL Rewriting for Tomcat

2008-11-04T13:44:00.014+08:00

To use Tomcat as the servlet container of Grails applications, the default URL mapping of http status codes would not work well. Instead of that, error page declarations in the web.xml is a workarounds, such like:

<error-page>
<error-code>403</error-code>
<location>/403.jsp</location>
</error-page>
<error-page>
<error-code>404</error-code>
<location>/404.jsp</location>
</error-page>
<error-page>
<error-code>500</error-code>
<location>/500.jsp</location>
</error-page>

And, if there are already relative Grails controllers or GSPs handling HTTP status codes, we could just simply use the JSPs for redirect:

<%response.sendRedirect(request.getContextPath() + "/errors/notFound");%>

UPDATE:
1. Here is the issue ticket and also a better workaround.
2. And here is another blog reference posted by the issue reporter.
3. Another relative issue which is worth keeping trace.

Scala - Learning Note Part One

2008-02-18T09:45:00.003+08:00

Reference:
Code Commit's Articles
AlBlue's Articles

Scala has a type inference mechanism to determine object types in runtime
No semicolon only if multi statements in a single line
The file extension is : .scala, and it is not a necessary to keep the saving file name to be the same as class name.
Compiler: scalac; Executor: scala or using java but have to indicate the classpath to properly place
All methods are implicitly public
Unit is the type which is similar to void
Keyword: val to declare a constant, similar to Java's final
_ character is a wildcard
Class constructor is the statements of the class body. To overloading a constructor just simply declare this(args) methods

Grails - Fine Gained Transaction Configuration Idea

2008-01-23T10:52:00.001+08:00

Here is an article talking about how to manually configuration transaction behaviors in Grails. Furthermore, there might be a more groovy-style approach after 1.0 release.

Grails - Transaction in Version 0.6

2007-12-08T10:59:00.001+08:00

There are two kinds of transaction control in Grails 0.6. One is domain class dynamic method: withTransaction, the other is auto injected by SpringFramework to all service classes.
The transaction control within the closure of withTransaction is handled manually by programmers, that means that programmers have to commit or rollback the transaction by certain logic. On the other hand, the auto injected transaction control is handled by the SpringFramework's Transaction Manager which would commit the transaction automatically if there is no any RuntimeException occurred.

prototype.js - The Problem of Element.update in IE 6

2007-11-14T07:36:00.002+08:00

The implementation of Element.update is to update the innerHTML of the element. But it just doesn't work well if you want to update a Select object in IE 6 due to the famous bug (please refer to here and here).
A workaround of this problem is to replace the whole Select element instead of to assign the innerHTML property.

Before :

element.innerHTML = html.stripScripts();

After:

element.replace('<select id=\'' + element.id + '\' name=\'' + element.name + '\'>' + html.scripScripts() + '</select>');

And don't forget to set CSS styles and listening javascript events back!

Such like:

var className = element.className;
element.replace('...');
$(element.id).className = className;

Grails - Multi-DataSource Plugin

2007-11-12T17:51:00.001+08:00

General idea is using Spring, just set up additional datasources, Hibernate SessionFactory and mapping classes in grails/conf/spring/resource.xml.

Step 1.
Create POJOs in src/ folder

Step 2.
Set up target datasource in grails/conf/spring/resouce.xml

Step 3.
Set up relative Hibernate SessionFactory in grails/conf/spring/resouce.xml with the datasource bean and POJO classes.

Step 4.
Create DAO classes extend from Spring HibernateDaoSupport class and declare those DAO classes in grails/conf/spring/resouce.xml and inject the SessionFactory defined at Step 3.

Step 5.
Now the DAO classes are ready to inject to grails services and controllers.

Future study : Multi-Phase Transaction

Grails - LiquiBase Plugin

2007-10-16T13:29:00.001+08:00

LiguiBase is a database refactorying tool and also a plugin for Grails.

General commands :

diff - only available in command line mode

Display the schema differentiations between the two databases.

Usage Example :
java -jar liquibase.jar
--classpath=DRIVER_JAR
--changeLogFile=CHANGELOG.XML
--driver=DRIVER_CLASS
--url=DB_CONNECTION_URL
--username=USER_NAME
--password=PASSWORD
diffChangeLog or diff
--baseUrl=TARGET_DB_CONNECTION_URL
--baseUsername=TARGET_DB_USER_NAME
--basePassword=TARGET_DB_PASSWORD

generate-changelong

Display schema changes between actual database and domain classes.

migrate

Apply the changes of domain classes to actual database schema.

tag

Tag presenting database schema.

rollback

Roll back to specific time or tagged database schema.

db-doc

Generate database schema doc files which are similar to JavaDoc.

drop-all

Drop the schema of target database.