Exporting smartgwt grid data to csv

I needed the feature to export the ListGrid Data to Excel file, but this feature is available only for smargwt PRO and EE version. I explored if there is any way can download through js, since the data is already present with client. but couldn't find because Javascript by design do not have access to local disk. and some browsers has limited support for data URI.

so I decided to send the content back to server (I feel its not correct way), and servlet write back data.

here is example for adding context menu to grid with export options.


import com.google.gwt.user.client.ui.FormPanel;
import com.google.gwt.user.client.ui.Hidden;
import com.google.gwt.user.client.ui.RootPanel;
import com.google.gwt.user.client.ui.VerticalPanel;
import com.smartgwt.client.types.Autofit;
import com.smartgwt.client.types.ListGridFieldType;
import com.smartgwt.client.types.SelectionStyle;
import com.smartgwt.client.widgets.grid.ListGrid;
import com.smartgwt.client.widgets.grid.ListGridField;
import com.smartgwt.client.widgets.grid.ListGridRecord;
import com.smartgwt.client.widgets.menu.Menu;
import com.smartgwt.client.widgets.menu.MenuItem;
import com.smartgwt.client.widgets.menu.events.ClickHandler;
import com.smartgwt.client.widgets.menu.events.MenuItemClickEvent;

public class ExportableGrid extends ListGrid{
    public ListGridRecord[] records;

    public ExportableGrid() {
        setHeight100();
        setWidth100();
       
        addContextMenu();
       
    }
   
    private StringBuilder exportCSV(boolean all) {
        StringBuilder stringBuilder = new StringBuilder(); // csv data in here
        ListGridField[] fields = getFields();
        for (int i = 0; i < fields.length; i++) {
            ListGridField listGridField = fields[i];
            if(!listGridField.getType().equals(ListGridFieldType.IMAGE) && !listGridField.getName().equalsIgnoreCase("$72V")) {
                stringBuilder.append("\"");
                stringBuilder.append(listGridField.getName().toUpperCase());
                stringBuilder.append("\",");
            }
        }
        stringBuilder.deleteCharAt(stringBuilder.length() - 1); // remove last
        stringBuilder.append("\n");

        ListGridRecord[] recs = null;
        if (all) {
            recs = getRecords();
        } else {
            recs = getSelection();
        }
        for (int i = 0; i < recs.length; i++) {
            ListGridRecord listGridRecord = recs[i];
            ListGridField[] listGridFields = getFields();
            for (int j = 0; j < listGridFields.length; j++) {
                ListGridField listGridField = listGridFields[j];
                if(!listGridField.getType().equals(ListGridFieldType.IMAGE) && !listGridField.getName().equalsIgnoreCase("$72V")) {
                    stringBuilder.append("\"");
                    String val = listGridRecord.getAttribute(listGridField.getName());
                    stringBuilder.append(val);
                    stringBuilder.append("\",");
                }
            }
            stringBuilder.deleteCharAt(stringBuilder.length() - 1); // remove last ","
            stringBuilder.append("\n");
        }
        return stringBuilder;
    }
   
    public void export(StringBuilder stringBuilder, String fileExt) {   
        final FormPanel formPanel = new FormPanel();
        formPanel.setAction(getExportFileUrl());
        formPanel.setMethod(FormPanel.METHOD_POST);
       
        VerticalPanel verticalPanel = new VerticalPanel();
   
        Hidden data = new Hidden();
        data.setName("exprtData");
        data.setValue(stringBuilder.toString());
        verticalPanel.add(data);
       
        Hidden exportType = new Hidden();
        exportType.setName("exportType");
        exportType.setValue("clientExport");
        verticalPanel.add(exportType);
       
        Hidden fileType = new Hidden();
        fileType.setName("fileType");
        fileType.setValue(fileExt);
        verticalPanel.add(fileType);
   
        formPanel.add(verticalPanel);
        formPanel.setVisible(false);
        RootPanel.get().add(formPanel);   
        formPanel.submit();
       
    }
   
    public void addContextMenu() {
        setCanDragSelect(true); 
        setSelectionType(SelectionStyle.MULTIPLE);
        setAutoFitData(Autofit.VERTICAL); 
        setShowRollOver(false);
       
        MenuItem csvAll = new MenuItem("Export all as CSV");
        csvAll.addClickHandler(new ClickHandler() {
            @Override
            public void onClick(MenuItemClickEvent event) {
                export(exportCSV(true), "csv");
            }
        });
       
        MenuItem csvSelected = new MenuItem("Export selected as CSV");
        csvSelected.addClickHandler(new ClickHandler() {
            @Override
            public void onClick(MenuItemClickEvent event) {
                export(exportCSV(false), "csv");
            }
        });
       
        Menu menu = new Menu(); 
        menu.setWidth(150); 
        menu.addItem(csvAll); 
        menu.addItem(csvSelected); 
       
        setContextMenu(menu);
    }
   
    private String getExportFileUrl() {
        StringBuilder urlBuilder = new StringBuilder("exportFiles/exportFiles.htm?");
        return urlBuilder.toString();
    }
   
    public void updateData() {
        records = new ListGridRecord[2];
        for (int i=0; i            records[i] = new ListGridRecord();
            records[i].setAttribute("Test", "Test"+i);
        }
    }
}

My server side controller looks like below...

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;

public class Exporter extends AbstractController {

    @Override
    protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception {
        String exportType = request.getParameter("exportType");
        if(exportType != null && exportType.equalsIgnoreCase("clientExport")){
            String fileType = request.getParameter("fileType");
            String exportData = request.getParameter("exprtData");
            byte[] bytes = exportData.getBytes();
            response.setContentLength((int) bytes.length);
            response.setHeader("Content-type" ,"application/"+fileType);
            String fileNameHeader = "attachment; filename=download."+fileType ;
            response.setHeader("Content-disposition" , fileNameHeader); 
            ServletOutputStream  stream = response.getOutputStream();   
            stream.write(bytes);
        }
        return null;
    }
}

Water mark plugin for flot

recently i needed to add some marker to all graphs in my project, since many people are using our tool and taking print-screen of the graphs for mail chain, without giving any credit :P.
so we decided to add marker text to all graphs, I found there is no straight forward way or plug-in available to add water mark or text to flot graphs. then I explored the flot API, found its well designed and easy to add plug-ins.
i created jquery.flot.marker.js
(function ($) {
    var options = {
        marker: {
            mode: null, // thinking to use for image based , text base markers
            value: "My Graph", // default value
            color: "rgba(100, 100, 100, 0.80)",
            font: "14px Arial",
            position: 'top-right' //top-left, bottom-right, bottom-left
        }
    };
    function init(plot) {
        plot.hooks.draw.push(function (plot, ctx) {
            var c = plot.getOptions().marker;
            if (!c.mode)
                return;
            //alert(plot.offset().left);
            ctx.save();
            ctx.font=c.font;
            var w;
            var h;
            if((c.position=='top-right') || (c.position=='bottom-right')) {
                w = plot.getPlaceholder().width()*0.88;
            } else {
                w = plot.offset().left-40;
            }
            if((c.position=='top-left') || (c.position=='top-right')) {
                h = 45;
            } else {
                h = plot.height();
            }
            //alert(h);
            ctx.fillStyle=c.color;
            ctx.fillText(c.value, w, h);
        });
    }
    $.plot.plugins.push({
        init: init,
        options: options,
        name: marker,
        version: '1.0'
    });
})(jQuery);
Then including plug-in file helped me to get marker on all graphs.
<script language="javascript" type="text/javascript" src="../jquery.flot.marker.js"></script>
  plot = $.plot($("#placeholder"), 
                      ${data}, 
                          marker: {
                                mode: "text",
                                value:"My Graph",
                                color:"rgba(100, 100, 100, 0.60)",
                                font: "10px Lucida Sans Unicode",
                                position: 'top-right'                           
                            },
                            grid: { hoverable: true, autoHighlight: false },
                            yaxis: { min: -1.2, max: 1.2 }
                        });

Generating Unique Ids across multiple JVM and over restart using long data type only

/*
* Long.MAX_VALUE : 9 2 2 3 3 7 2 0 3 6 8 5 4 7 7 5 8 0 7  Total 19 digits
*
* lets use fist 2 digit for peer id
* now we are left with 17 digits
* if we restrict peer id between 10 - 91
*
* then rest all 17 could be all 9's to hold in long
*
* lets create 10 UIDGenerator Objects each with unique id [0-9]
*
* so now we are left with 16 digits
*
* so if we start at some time
* System.currentTimeMillis() : 1360443174566 (13 digit)
*
* ID : XXY1360443174566TTT
*                         XX : peer id
*                          Y : object instance ID
*     1360443174566 : System.currentMillis(); //seed will change on every restart
*                       TTT : 000     Allowing to generate 999 message max per millisecond
* 
* so we can generate max 999 unique ids per millisecond
* means safe to generate approx: 1000 per millisecond, to overcome uniqueness over jvm restart
*
* we can generate 9999999999999999-1360443174566000 = 863955682543999 * 10 unique ids
* (Aprox:8000 Trillion )before getting duplicate if we start on 1360443174566
*
* Possible Failure
* 1. system time is reset
* 2. generating more than 10000 per millisecond then does not gives guarantee over jvm restart.
*/

public class UIDUtil {
    private static UIDUtil instance;
    private UIDGenerator[] uidGenerators;
    private static short MAX_ALLOWED_PEER_ID = 91;
    private static short MIN_ALLOWED_PEER_ID = 10;
    private long totalIdsGenerated;
    private long startTime;
    private UIDUtil() {
        short peerId = loadPeerId();
        uidGenerators = new UIDGenerator[10];
        for(byte i=0; i<10; i++) {
            uidGenerators[i] = new UIDGenerator(peerId, i);
        }
        startTime = System.currentTimeMillis();
    }
    public static UIDUtil getInstance() {
        if(instance == null)
            instance = new UIDUtil();
        return instance;
    }
    public long getNextId() {
        return uidGenerators[(int) ((totalIdsGenerated++)%10)].getNextID();
    }
    private short loadPeerId() {
        //TODO:    load peerId from properties, db, remote etc
        short peerId = 90;
        if(peerId > MAX_ALLOWED_PEER_ID || peerId < MIN_ALLOWED_PEER_ID) {
            peerId = (short) (MIN_ALLOWED_PEER_ID + (short)(Math.random() * ((MAX_ALLOWED_PEER_ID - MIN_ALLOWED_PEER_ID) + 1)));
            try {
                throw new Exception("Peer ID must be in the range : "+MIN_ALLOWED_PEER_ID+"-"+MAX_ALLOWED_PEER_ID+" inclusive");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        return peerId;
    }
    public long getTotalIdsGenerated() {
        return totalIdsGenerated;
    }
    public double getIdProducingRate() {
        long elapsedTime = System.currentTimeMillis()-startTime;
        if(elapsedTime == 0)
            elapsedTime = 1;
        return (double) (totalIdsGenerated/elapsedTime)*1000;
    }
}

 

public class UIDGenerator {
    private long variableId ;
    private long fixedId;

    private static long MAX_ALLOWED_VARIABLE_ID = 9999999999999999l;
    public UIDGenerator(short peerId, byte index) {
        //place peer on proper decimal location
        fixedId = (long) (peerId*Math.pow(10, 17));//exp : 9100000000000000000
        fixedId += (long) (index*Math.pow(10, 16));//exp : 9130000000000000000
        //initialise with 16 digit seed
        variableId = loadVariableId();
    }

    public synchronized long getNextID() {
        long newId = variableId++;
        if(newId == MAX_ALLOWED_VARIABLE_ID) {
            variableId = loadVariableId();
        }
        return (fixedId + newId);
    }

    private long loadVariableId() {
        long currentTime = System.currentTimeMillis();
        long temp = currentTime;
        byte digits = 0;
        while(temp > 0) {
            temp /= 10;
            digits++;
        }
        return (long) (currentTime*Math.pow(10, 16-digits));
    }
}

Smart Gwt TreeGrid filter Example ..

import java.util.ArrayList;
import java.util.List;

import com.smartgwt.client.widgets.grid.events.FilterEditorSubmitEvent;
import com.smartgwt.client.widgets.grid.events.FilterEditorSubmitHandler;
import com.smartgwt.client.widgets.tree.Tree;
import com.smartgwt.client.widgets.tree.TreeGrid;
import com.smartgwt.client.widgets.tree.TreeGridField;
import com.smartgwt.client.widgets.tree.TreeNode;

public class TreeGridExperiment extends TreeGrid{
    private Tree tree;
    private TreeNodeRecord[] records;
   
    public TreeGridExperiment() {
        tree = new Tree();
        updateData();
        setShowFilterEditor(true);
        setFilterOnKeypress(false);

        enableFiltering();
        TreeGridField field = new TreeGridField(TreeNodeRecord.NODE_NAME);
        field.setCanFilter(true);
        setFields(field);
    }
   
    private void enableFiltering() {
        addFilterEditorSubmitHandler(new FilterEditorSubmitHandler() {
            @Override
            public void onFilterEditorSubmit(FilterEditorSubmitEvent event) {
                String inputValue = event.getCriteria().getAttribute(TreeNodeRecord.NODE_NAME);
                if(inputValue == null){
                    setData(tree);
                    return;
                }
                setData(new Tree());
                List matchingNodes = new ArrayList();
                for (TreeNodeRecord record : records) {
                    if(record.contains(inputValue.toLowerCase(), tree)){
                        matchingNodes.add(record);
                    }
                }
                Tree newTree = new Tree();
                newTree.setData(matchingNodes.toArray(new TreeNodeRecord[0]));
                setData(newTree);
                for (TreeNodeRecord treeNodeRecord : matchingNodes) {
                    newTree.openAll(treeNodeRecord);
                }
            }
        });
    }

    public void updateData() {
        records = new TreeNodeRecord[2];

        for (int i = 0; i < 2; i++) {
            records[i] = new TreeNodeRecord("Display " + i);
            TreeNodeRecord[] leafs = new TreeNodeRecord[2];
            for (int j = 0; j < 1; j++) {
                leafs[j] = new TreeNodeRecord("Leaf" + j+i);
            }
            records[i].setChildren(leafs);
        }
        tree.setData(records);
        this.setData(tree);
    }
}

class TreeNodeRecord extends TreeNode {
    public static String NODE_NAME = "nodeName";
   
    public TreeNodeRecord(String attribute) {
        setAttribute(NODE_NAME, attribute);
    }

    public boolean contains(String inputValue, Tree tree) {
        if(getAttributeAsString(NODE_NAME).toLowerCase().contains(inputValue)) {
            return true;
        } else {
            TreeNode[] childes = tree.getChildren(this);
            for (TreeNode treeNode : childes) {
                TreeNodeRecord record = (TreeNodeRecord)treeNode;
                if(record.contains(inputValue, tree)){
                    return true;
                }
            }
        }
        return false;
    }
}

    

Extending OpenNMS

The OpenNMS installation directory contains etc/ directory which contains all kind of configuration files which require to run openNMS, it has various configuration files for each daemon module, for example for capability daemon there is capsd.xml for collector daemon it has capsd.xml and for dataCollection definition it has jmx-dataCollection.xml for Mbeans definition, similarity for snmp there is dataCollection.xml for defining what OID’s need to be collected for SNMP services.

Now this etc directory also contains service-configuration.xml which has all module definition plus which method to be invoked for loading the module. These modules can be daemon or non daemon depending upon the requirement. all module follows standard MBean criteria. These modules are started in the sequence they are mention in the file. I mean top most will be executed first and the bottom most ( which is embedded jetty-web server) will be the last.

 

<service-configuration>
  <service>
    <name>:Name=XSLTProcessor</name>
    <class-name>mx4j.tools.adaptor.http.XSLTProcessor</class-name>
  </service>
  <service>
    <name>:Name=HttpAdaptor</name>
    <class-name>mx4j.tools.adaptor.http.HttpAdaptor</class-name>
    <attribute>
      <name>Port</name>
      <value type="java.lang.Integer">8180</value>
    </attribute>
    <attribute>
      <name>Host</name>
…………………………………….

If we add new service definition here, the OpenNMS will load our service ..

for example let say we want to delete all logs or previous data collected on starting up openNMS, we have to add our service in this xml then only openNMS could start our service.

<service-configuration>

<service>
  <name>OurService:Name=CleanupService</name>
  <class-name>org.ourservice.Clean</class-name>
  <invoke at="start" pass="0" method="start"/>

</service>
  <service>
    <name>:Name=XSLTProcessor</name>
    <class-name>mx4j.tools.adaptor.http.XSLTProcessor</class-name>
  </service>
  <service>
    <name>:Name=HttpAdaptor</name>
    <class-name>mx4j.tools.adaptor.http.HttpAdaptor</class-name>
    <attribute>
      <name>Port</name>
      <value type="java.lang.Integer">8180</value>
    </attribute>
    <attribute>
      <name>Host</name>

now CleanupService will be triggered first. for starting this service start method will be invoked of Clean class. The clean Class must implement MBean.
create CleanMBean interface and declare start method signature.

package org.ourservice;

public interface CleanMBean {
    public void start();
}

now create Clean class and implement CleanMBean interface, also implement logic to clean the data.

package org.ourservice;

public class Clean implements CleanMBean {
    public void start(){
       System.out.println(“Cleaned all”);

     }

}

 

 

After compiling the Clean class and other dependant classes. create classes directory inside openNMS installation directory and put all our classes inside. then start openNMS.

Java5 Instumentation API

The instrumentation API is for run time byte manupulation, or you can say bytecode engineering. 

we have to define our instrumentation agent which consist starting point same as main method of any java application with different arguments.

String : arguments to this agent..

Instrumentation object, instrumentation agent is a class with a special method, with a predefined signature, that the JVM will invoke before the rest of the application for you to set up any instrumentation code. Generally, instrumentation is the act of transforming classes for profiling purposes: for example, an interesting feature provided by the instrumentation framework is the ability to measure the memory usage of an object. 
 

import java.lang.instrument.Instrumentation;

public class MyAgent {
    public static void premain(String agentArguments,
            Instrumentation instrumentation) {

        MyTransFormer transformer = new MyTransFormer();
        instrumentation.addTransformer(transformer);
        Node node = new Node();
        long size = instrumentation.getObjectSize(node);
        System.out.println("size of "+ node.getClass().getSimpleName() + size);
    }
}

we have compiled the agent class and  we need to package it into a jar , we also need to create a manifest file

Premain-Class: MyAgent 

java -javaagent:myagent.jar TestMain

creating transformer

import java.lang.instrument.ClassFileTransformer; 
import java.security.ProtectionDomain; 

public class MyTransFormer implements ClassFileTransformer {

    public MyTransFormer() {
        super();
    }

public byte[] transform(ClassLoader loader, String className,
            Class redefiningClass, ProtectionDomain domain, byte[] bytes) {
        // some changes in byte code // there are some standard API for byte
        // code modification exp: BCEL, ASM etc…
        return bytes;
    }
}

There are some links i went while reading .

1. http://www.javalobby.org/java/forums/t19309.html#92037417


2. http://www.cs.nuim.ie/~jpower/Research/instrument/#examples


3. http://www.javamex.com/tutorials/memory/instrumentation.shtml

Handling more than one exception, Java SE 7 new feature.

In Java SE 7 and later, a single catch block can handle 
more than one type of exception. This feature can reduce code 
duplication and lessen the temptation to catch an overly broad 
exception. 

consider the following example... 

try{
.............

}

catch (IOException ex) {
     logger.log(ex);
     throw ex;
catch (SQLException ex) {
     logger.log(ex);
     throw ex;
}

The following example, which is valid in Java SE 7 and later, 

eliminates the duplicated code:

catch (IOException|SQLException ex) {
    logger.log(ex);
    throw ex;
} 

Installing openNMS on RedHat using rpm.

I am assuming postgres database is already installed.

download the following rpm.

• openNMS core :
  opennms-core-1.8.5-1.noarch.rpm
•  jetty for opennms :
  opennms-webapp-jetty-1.8.5-1.noarch.rpm 
• Jicmp  from here depending upon the the architecture. for example :
  (jicmp-1.0.6-1.fc8.i386.rpm)
  http://rpmfind.net/linux/rpm2html/search.php?query=jicmp&submit=Search+...&system=&arch=

 now installing process...
rpm -ivh opennms-core-1.8.5-1.noarch.rpm
rpm -ivh  jicmp-1.0.6-1.fc8.i386.rpm
rpm -ivh opennms-webapp-jetty-1.8.5-1.noarch.rpm


stop postgres database if it is running
/etc/init.d/postgresql stop

To allow OpenNMS to connect to the database, you will need to edit your database's  
pg_hba.conf file. On many default installations it can be found in the directory
/var/lib/pgsql/data/

local   all   all                      ident sameuser
host    all   all    127.0.0.1/32      ident sameuser
host    all   all    ::1/128           ident sameuser

You will need to change these entries to resemble the following: 

local   all   all                      trust

host    all   all    127.0.0.1/32      trust

host    all   all    ::1/128           trust

Next, you will need to edit postgresql.conf to accept TCP/IP 

connections. As with pg_hba.conf, check the defaults or your 

distribution's PostgreSQL documentation for the location of 

this file. As before, on many default installations it can 

be found in the directory /var/lib/pgsql/data/ Both 

postgresql.conf and pg_hba.conf by default should be 

in the same location.

....

#listen_addresses = 'localhost'

 ....

uncomment this line to resemble

....

listen_addresses = 'localhost'

 ....

start the postgres db..
/etc/init.d/postgresql start


go to /opt/opennms/bin/ (default installation dir for opennms)

run the install script...
#>install



after that start opennms

#>opennms start

open http://localhost:8980/opennms/index.jsp

and enjoy...:)

IIT-BHU-Anamika

Simulating queue using stack...

Problem statement: we are given one stack and we have to implement the queue using this stack means enqueue(insert into stack) and dequeue ( pop from stack) should behave as queue. No additional stack should be used.

This can be done using Operating system stack by using recursion.

public class SimulatedQueue < E > {
    private java.util.Stack < E > stack = 
                     new java.util.Stack < E >();

    public void insert(E elem) {
        if (!stack.empty()) {
            E topElem = stack.pop();
            insert(elem);
            stack.push(topElem);
        }
        else
            stack.push(elem);
    }

    public E remove() {
        return stack.pop();
    }
}