How to Create an RPM Package

In this blog, I'm going to teach you how to create an RPM package.

1. Create a simple hello.cpp

#include <iostream>
using namespace std;

int main() {
    cout << "Hello World" << endl;
    return 0;
}

2. Create a Makefile

CC = g++ 
CCFLAGS = -g -Wall
SRC = hello.cpp
TARGET = hello

.PHONY: clean install

all: hello

install: $(TARGET)
    if [ -d ${DESTDIR} ]; then rm -rf ${DESTDIR}; fi
    mkdir -p ${DESTDIR}
    cp $(TARGET) ${DESTDIR} 

hello: 
    $(CC) $(CCFLAGS) -o $(TARGET) $(SRC)

clean:
    rm -rf $(TARGET)

3. Put hello.cpp and the Makefile in a directory structure like this

/home/foobar/hello/Makefile
                  /hello.cpp

4. Create a tarball of hello project

cd /home/foobar
tar czvf hello-0.1.tar.gz hello/

5. Create an rpmbuild directory

mkdir -p /home/foobar/rpmbuild

6. Create BUILD  BUILDROOT  RPMS  SOURCES  SPECS  SRPMS directories inside the /home/foobar/rpmbuild directory
BUILD --> the source files are unpacked and compiled here
BUILDROOT --> files are installed here
RPMS --> binary RPMs are created here
SOURCES --> source tarballs
SPECS --> spec files
SRPMS --> source RPMs
7. Create a spec file in the /hom/foobar/rpmbuild/SPECS/hello.spec

Summary             : Hello World program
Name                : hello
Version             : 0.1 
Release             : 1%{?dist}
License             : GPLv3+
Source              : %{name}-%{version}.tar.gz

%description
A simple Hello World program

%prep
%setup -q -n %{name}

%build
make

%install
make install DESTDIR="%{buildroot}%{_bindir}"

%files
%{_bindir}/hello

%prep --> this stage calls %setup to unpack hello-0.1.tar.gz to /home/foobar/rpmbuild/BUILD/hello. %{name} is a macro variable that substitutes to hello

%build --> this stage calls "make" in the /home/foobar/rpmbuild/BUILD/hello to create a hello executable

%install --> this stage calls "make install" to install the files into /home/foobar/rpmbuild/BUILDROOT/usr/bin. %{buildroot} is a macro variable that substitutes to /home/foobar/rpmbuild/BUILDROOT. Make sure the Makefile supports DESTDIR argument

%files --> lists all the files to be installed. %{_bindir} is a macro variablesubstitutes to /usr/bin. In this example, only hello executable needs to be installed into /usr/bin

8. Build the source and binary RPMs

rpmbuild -ba /home/foobar/SPECS/hello.spec

-ba option means build all (prep, build, install)
The binary RPM will be created in /home/foobar/rpmbuild/RPMS
The source RPM will be created in /home/foobar/rpmbuild/SRPMS
9. Install the newly created binary RPM

sudo rpm -ivh hello-0.1-1.fc16.i686.rpm

10. Test if hello program was successfully installed

hello

You should see "Hello World" output
11. Remove the hello package

sudo rpm -e hello

Building Boost with Visual C++ 2010 Express

Following my last blog about Building Boost with MinGW, here I'm going to show you step-by-step how to build Boost with Visual C++ 2010 Express. The latest Boost as of this writing is 1.48.0, so I'm going to use that version.

1. Download Visual C++ 2010 Express from Microsoft website and install it.
2. Download Windows SDK. This is optional, but it can be pretty useful if you plan to call any Windows API.
3. Download Boost from Boost website.
4. Extract Boost to any location of you preference.
5. Modify the C:\Program Files\Microsoft Visual Studio 10.0\VC\bin\vcvars32.bat as shown below. You need to edit this file as an Administrator. Visual C++ 2010 Express seems to have a bug for not setting all these variables automatically. You need to uncomment the first 3 lines. Setting WindowsSdkDir is optional if you skipped step 2.

   :: @call :GetVSCommonToolsDir
   :: @if "%VS100COMNTOOLS%"=="" goto error_no_VS100COMNTOOLSDIR
   :: @call "%VS100COMNTOOLS%VCVarsQueryRegistry.bat" 32bit No64bit
   
   @SET WindowsSdkDir=C:\Program Files\Microsoft SDKs\Windows\v7.1\
   @SET VSINSTALLDIR=C:\Program Files\Microsoft Visual Studio 10.0\
   @SET VCINSTALLDIR=C:\Program Files\Microsoft Visual Studio 10.0\VC\
   @SET VS100COMNTOOLS=%VSINSTALLDIR%\Common7\IDE\
   @SET PATH=%PATH%;%VCINSTALLDIR%\bin;%VS100COMNTOOLS%
   @SET FrameworkDir32=C:\Windows\Microsoft.NET\Framework
   @SET FrameworkVersion32=v4.0.30319
   @SET Framework35Version=v3.5

6. Open Visual Studio Command Prompt (2010) and go to your boost installation directory. 
7. Build Boost build tool (b2).

   [boost_dir]\bootstrap.bat

8. Build Boost (you can start making your coffee or do whatever you like since this process is gonna take a while). All the libraries will be created in the stage\lib folder.

[boost_dir]\b2.exe toolset=msvc --build-type complete stage

9. Open your Visual C++ 2010 Express and create a new Win32 Console project.

10. Right click on the project --> Properties--> Configuration Properties --> C/C++ --> General and add [boost_dir] in the Additional Include Directories.
11. In the same Properties window Configuration Properties --> Linker -->  General, add [boost_dir]\stage\lib in the Additional Library Directories.
12. Let's now test our Boost libraries.

#include "stdafx.h"
#include <string>
#include <iostream>
#include <boost/shared_ptr.hpp>
#include <boost/regex.hpp>
using namespace std;

int _tmain(int argc, _TCHAR* argv[])
{
    boost::shared_ptr<string> ptr(new string("Hello World, Boost"));
    boost::smatch matches;
    boost::regex pattern("Hello World,\\s*(.*)");
    boost::regex_match(*ptr, matches, pattern);
    cout << matches[1] << endl;

    system("pause");

 return 0;
}

Understanding serialVersionUID

If we ever wonder why we need to declare a serialversionUID when we implement java.util.Serializable, this article can provide a good idea why not declaring a serialVersionUID can cause a problem.

import java.io.Serializable;

public class Hello implements Serializable {
//    private static final long serialVersionUID = 1L;
    private String message;

//    public String getTheSameMessage() {
//        return message;
//    }
    
    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("Hello [message=").append(message).append("]");
        return builder.toString();
    }
}

package org.fredy;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class Main {
    public static void main(String[] args) throws Exception {
        Hello h = new Hello();
        h.setMessage("Hello World");
        
        ObjectOutputStream oos = null;
        try {
            oos = new ObjectOutputStream(
                new FileOutputStream(new File("out.obj")));
            oos.writeObject(h);
        } finally{
            if (oos != null) {
                oos.close();
            }
        }
        
//        ObjectInputStream ois = null;
//        try {
//            ois = new ObjectInputStream(
//                new FileInputStream(new File("out.obj")));
//            Hello h1 = (Hello) ois.readObject();
//            System.out.println(h1.getMessage());
//        }
//        finally {
//            if (ois != null) {
//                ois.close();
//            }
//        }
    }
}

Now execute the Main class. This will create a file named out.obj.

Let's now uncomment some lines in Hello class and comment out some lines in Main class as depicted below.

import java.io.Serializable;

public class Hello implements Serializable {
//    private static final long serialVersionUID = 1L;
    private String message;

    public String getTheSameMessage() {
        return message;
    }
    
    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("Hello [message=").append(message).append("]");
        return builder.toString();
    }
}

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class Main {
    public static void main(String[] args) throws Exception {
//        Hello h = new Hello();
//        h.setMessage("Hello World");
//        
//        ObjectOutputStream oos = null;
//        try {
//            oos = new ObjectOutputStream(
//                new FileOutputStream(new File("out.obj")));
//            oos.writeObject(h);
//        } finally{
//            if (oos != null) {
//                oos.close();
//            }
//        }
        
        ObjectInputStream ois = null;
        try {
            ois = new ObjectInputStream(
                new FileInputStream(new File("out.obj")));
            Hello h1 = (Hello) ois.readObject();
            System.out.println(h1.getMessage());
        }
        finally {
            if (ois != null) {
                ois.close();
            }
        }
    }
}

Execute the Main class again. A java.io.InvalidClassException will be thrown because the Hello class that was serialized is no longer compatible with updated Hello class. To fix this problem, we need to declare serialVersionUID in the Hello class.

Getting Started with OrientDB

OrientDB is a NoSQL document database (http://code.google.com/p/orient/). Here I'm gonna show you how to get started with OrientDB.

apply plugin: 'java'
apply plugin: 'eclipse'

repositories {
    mavenCentral()
    maven { url 'http://www.orientechnologies.com/listing/m2' }
}

dependencies {
    compile 'com.orientechnologies:orient-commons:1.0rc7'
    compile 'com.orientechnologies:orientdb-core:1.0rc7'
}

The sample code below shows some basic create, retrieve, update, delete operations

package test;

import java.io.IOException;
import java.io.Serializable;
import java.util.List;

import com.orientechnologies.orient.core.db.document.ODatabaseDocumentTx;
import com.orientechnologies.orient.core.db.object.ODatabaseObjectTx;
import com.orientechnologies.orient.core.metadata.schema.OClass;
import com.orientechnologies.orient.core.metadata.schema.OType;
import com.orientechnologies.orient.core.record.impl.ODocument;
import com.orientechnologies.orient.core.serialization.OBase64Utils;
import com.orientechnologies.orient.core.sql.query.OSQLSynchQuery;

public class Main {
    static class Message implements Serializable {
        private static final long serialVersionUID = 1L;
        private String msg;
        
        public Message(String msg) {
            this.msg = msg;
        }
        
        public String getMessage() {
            return msg;
        }
    }
    
    public static void main(String[] args) throws Exception {
        ODatabaseDocumentTx db = new ODatabaseDocumentTx("local:testdb");
        if (!db.exists()) {
            db.create();
            
            // creating a schema is optional, but can be useful
            OClass personClass = db.getMetadata().getSchema().createClass("person");
            personClass.createProperty("id", OType.INTEGER);
            personClass.createProperty("name", OType.STRING);
            personClass.createProperty("msg", OType.STRING);
            db.getMetadata().getSchema().save(); // don't forget to save it
            
            // creating some records
            for (int i = 0; i < 10; i++) {
                ODocument doc = new ODocument(db, "person");
                doc.field("id", i + 1);
                doc.field("name", "foo" + i);
                Message msg = new Message("Hello" + i);
                doc.field("msg", OBase64Utils.encodeObject(msg));
                doc.save();
            }
        }
        else {
            // default username/password
            db.open("admin", "admin");
        }
        
        try {
            // query all records
            for (ODocument doc : db.browseClass("person")) {
                printPersonRecord(doc);
            }

            // query some records
            List<ODocument> results = db.query(new OSQLSynchQuery<ODocument>(
                "select * from person where name like 'foo%' order by id desc"));
            for (ODocument doc : results) {
                printPersonRecord(doc);
            }

            // create a new record
            ODocument doc = new ODocument(db, "person");
            doc.field("id", "11");
            doc.field("name", "foo11");
            Message msg = new Message("Hello" + 11);
            doc.field("msg", OBase64Utils.encodeObject(msg));
            doc.save();
            // verify it
            printPersonRecord(doc);
            // update it
            doc.field("name", "bar");
            doc.save();
            // verify it again
            printPersonRecord(doc);
            // delete it
            doc.delete();
            // count the number of records
            System.out.println(db.countClass("person"));
        }
        finally {
            db.close();
        }
    }
    
    private static void printPersonRecord(ODocument doc) 
        throws ClassNotFoundException, IOException {
        Message msg = (Message) OBase64Utils.decodeToObject(
            doc.field("msg").toString());
        System.out.println("id=" + doc.field("id") + ";" + 
            "name=" + doc.field("name") + ";" +
            "message=" + msg.getMessage());
    }
}

Creating a schema is useful to indicate the type of a field. If we omitted the creation of the schema, the query "order by id desc" would be sorted based on string rather than integer since by default all the fields are considered as a string in OrientDB.

OrientDB has a pretty useful utility to serialize/deserialize Java object and encode/decode it using base64 as shown in the example above.

If we look at the content of the testdb, there are two files created ls person.och and person.0.ocl for the "person" class. There is a limit of the number of classes/clusters that OrientDB can have. The default max number of classes/clusters is 32,768 (thanks Luca Garulli for the correction!).