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  • Bulk inserting best way to about it? + Helping me understand fully what I found so far

    - by chobo2
    Hi So I saw this post here and read it and it seems like bulk copy might be the way to go. http://stackoverflow.com/questions/682015/whats-the-best-way-to-bulk-database-inserts-from-c I still have some questions and want to know how things actually work. So I found 2 tutorials. http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx First way uses 2 ado.net 2.0 features. BulkInsert and BulkCopy. the second one uses linq to sql and OpenXML. This sort of appeals to me as I am using linq to sql already and prefer it over ado.net. However as one person pointed out in the posts what he just going around the issue at the cost of performance( nothing wrong with that in my opinion) First I will talk about the 2 ways in the first tutorial I am using VS2010 Express, .net 4.0, MVC 2.0, SQl Server 2005 Is ado.net 2.0 the most current version? Based on the technology I am using, is there some updates to what I am going to show that would improve it somehow? Is there any thing that these tutorial left out that I should know about? BulkInsert I am using this table for all the examples. CREATE TABLE [dbo].[TBL_TEST_TEST] ( ID INT IDENTITY(1,1) PRIMARY KEY, [NAME] [varchar](50) ) SP Code USE [Test] GO /****** Object: StoredProcedure [dbo].[sp_BatchInsert] Script Date: 05/19/2010 15:12:47 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[sp_BatchInsert] (@Name VARCHAR(50) ) AS BEGIN INSERT INTO TBL_TEST_TEST VALUES (@Name); END C# Code /// <summary> /// Another ado.net 2.0 way that uses a stored procedure to do a bulk insert. /// Seems slower then "BatchBulkCopy" way and it crashes when you try to insert 500,000 records in one go. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchInsert() { // Get the DataTable with Rows State as RowState.Added DataTable dtInsertRows = GetDataTable(); SqlConnection connection = new SqlConnection(connectionString); SqlCommand command = new SqlCommand("sp_BatchInsert", connection); command.CommandType = CommandType.StoredProcedure; command.UpdatedRowSource = UpdateRowSource.None; // Set the Parameter with appropriate Source Column Name command.Parameters.Add("@Name", SqlDbType.VarChar, 50, dtInsertRows.Columns[0].ColumnName); SqlDataAdapter adpt = new SqlDataAdapter(); adpt.InsertCommand = command; // Specify the number of records to be Inserted/Updated in one go. Default is 1. adpt.UpdateBatchSize = 1000; connection.Open(); int recordsInserted = adpt.Update(dtInsertRows); connection.Close(); } So first thing is the batch size. Why would you set a batch size to anything but the number of records you are sending? Like I am sending 500,000 records so I did a Batch size of 500,000. Next why does it crash when I do this? If I set it to 1000 for batch size it works just fine. System.Data.SqlClient.SqlException was unhandled Message="A transport-level error has occurred when sending the request to the server. (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe.)" Source=".Net SqlClient Data Provider" ErrorCode=-2146232060 Class=20 LineNumber=0 Number=233 Server="" State=0 StackTrace: at System.Data.Common.DbDataAdapter.UpdatedRowStatusErrors(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount) at System.Data.Common.DbDataAdapter.UpdatedRowStatus(RowUpdatedEventArgs rowUpdatedEvent, BatchCommandInfo[] batchCommands, Int32 commandCount) at System.Data.Common.DbDataAdapter.Update(DataRow[] dataRows, DataTableMapping tableMapping) at System.Data.Common.DbDataAdapter.UpdateFromDataTable(DataTable dataTable, DataTableMapping tableMapping) at System.Data.Common.DbDataAdapter.Update(DataTable dataTable) at TestIQueryable.Program.BatchInsert() in C:\Users\a\Downloads\TestIQueryable\TestIQueryable\TestIQueryable\Program.cs:line 124 at TestIQueryable.Program.Main(String[] args) in C:\Users\a\Downloads\TestIQueryable\TestIQueryable\TestIQueryable\Program.cs:line 16 InnerException: Time it took to insert 500,000 records with insert batch size of 1000 took "2 mins and 54 seconds" Of course this is no official time I sat there with a stop watch( I am sure there are better ways but was too lazy to look what they where) So I find that kinda slow compared to all my other ones(expect the linq to sql insert one) and I am not really sure why. Next I looked at bulkcopy /// <summary> /// An ado.net 2.0 way to mass insert records. This seems to be the fastest. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchBulkCopy() { // Get the DataTable DataTable dtInsertRows = GetDataTable(); using (SqlBulkCopy sbc = new SqlBulkCopy(connectionString, SqlBulkCopyOptions.KeepIdentity)) { sbc.DestinationTableName = "TBL_TEST_TEST"; // Number of records to be processed in one go sbc.BatchSize = 500000; // Map the Source Column from DataTabel to the Destination Columns in SQL Server 2005 Person Table // sbc.ColumnMappings.Add("ID", "ID"); sbc.ColumnMappings.Add("NAME", "NAME"); // Number of records after which client has to be notified about its status sbc.NotifyAfter = dtInsertRows.Rows.Count; // Event that gets fired when NotifyAfter number of records are processed. sbc.SqlRowsCopied += new SqlRowsCopiedEventHandler(sbc_SqlRowsCopied); // Finally write to server sbc.WriteToServer(dtInsertRows); sbc.Close(); } } This one seemed to go really fast and did not even need a SP( can you use SP with bulk copy? If you can would it be better?) BatchCopy had no problem with a 500,000 batch size.So again why make it smaller then the number of records you want to send? I found that with BatchCopy and 500,000 batch size it took only 5 seconds to complete. I then tried with a batch size of 1,000 and it only took 8 seconds. So much faster then the bulkinsert one above. Now I tried the other tutorial. USE [Test] GO /****** Object: StoredProcedure [dbo].[spTEST_InsertXMLTEST_TEST] Script Date: 05/19/2010 15:39:03 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO ALTER PROCEDURE [dbo].[spTEST_InsertXMLTEST_TEST](@UpdatedProdData nText) AS DECLARE @hDoc int exec sp_xml_preparedocument @hDoc OUTPUT,@UpdatedProdData INSERT INTO TBL_TEST_TEST(NAME) SELECT XMLProdTable.NAME FROM OPENXML(@hDoc, 'ArrayOfTBL_TEST_TEST/TBL_TEST_TEST', 2) WITH ( ID Int, NAME varchar(100) ) XMLProdTable EXEC sp_xml_removedocument @hDoc C# code. /// <summary> /// This is using linq to sql to make the table objects. /// It is then serailzed to to an xml document and sent to a stored proedure /// that then does a bulk insert(I think with OpenXML) /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertXMLBatch() { using (TestDataContext db = new TestDataContext()) { TBL_TEST_TEST[] testRecords = new TBL_TEST_TEST[500000]; for (int count = 0; count < 500000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; testRecords[count] = testRecord; } StringBuilder sBuilder = new StringBuilder(); System.IO.StringWriter sWriter = new System.IO.StringWriter(sBuilder); XmlSerializer serializer = new XmlSerializer(typeof(TBL_TEST_TEST[])); serializer.Serialize(sWriter, testRecords); db.insertTestData(sBuilder.ToString()); } } So I like this because I get to use objects even though it is kinda redundant. I don't get how the SP works. Like I don't get the whole thing. I don't know if OPENXML has some batch insert under the hood but I do not even know how to take this example SP and change it to fit my tables since like I said I don't know what is going on. I also don't know what would happen if the object you have more tables in it. Like say I have a ProductName table what has a relationship to a Product table or something like that. In linq to sql you could get the product name object and make changes to the Product table in that same object. So I am not sure how to take that into account. I am not sure if I would have to do separate inserts or what. The time was pretty good for 500,000 records it took 52 seconds The last way of course was just using linq to do it all and it was pretty bad. /// <summary> /// This is using linq to sql to to insert lots of records. /// This way is slow as it uses no mass insert. /// Only tried to insert 50,000 records as I did not want to sit around till it did 500,000 records. /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertAll() { using (TestDataContext db = new TestDataContext()) { db.CommandTimeout = 600; for (int count = 0; count < 50000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; db.TBL_TEST_TESTs.InsertOnSubmit(testRecord); } db.SubmitChanges(); } } I did only 50,000 records and that took over a minute to do. So I really narrowed it done to the linq to sql bulk insert way or bulk copy. I am just not sure how to do it when you have relationship for either way. I am not sure how they both stand up when doing updates instead of inserts as I have not gotten around to try it yet. I don't think I will ever need to insert/update more than 50,000 records at one type but at the same time I know I will have to do validation on records before inserting so that will slow it down and that sort of makes linq to sql nicer as your got objects especially if your first parsing data from a xml file before you insert into the database. Full C# code using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Xml.Serialization; using System.Data; using System.Data.SqlClient; namespace TestIQueryable { class Program { private static string connectionString = ""; static void Main(string[] args) { BatchInsert(); Console.WriteLine("done"); } /// <summary> /// This is using linq to sql to to insert lots of records. /// This way is slow as it uses no mass insert. /// Only tried to insert 50,000 records as I did not want to sit around till it did 500,000 records. /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertAll() { using (TestDataContext db = new TestDataContext()) { db.CommandTimeout = 600; for (int count = 0; count < 50000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; db.TBL_TEST_TESTs.InsertOnSubmit(testRecord); } db.SubmitChanges(); } } /// <summary> /// This is using linq to sql to make the table objects. /// It is then serailzed to to an xml document and sent to a stored proedure /// that then does a bulk insert(I think with OpenXML) /// http://www.codeproject.com/KB/linq/BulkOperations_LinqToSQL.aspx /// </summary> private static void LinqInsertXMLBatch() { using (TestDataContext db = new TestDataContext()) { TBL_TEST_TEST[] testRecords = new TBL_TEST_TEST[500000]; for (int count = 0; count < 500000; count++) { TBL_TEST_TEST testRecord = new TBL_TEST_TEST(); testRecord.NAME = "Name : " + count; testRecords[count] = testRecord; } StringBuilder sBuilder = new StringBuilder(); System.IO.StringWriter sWriter = new System.IO.StringWriter(sBuilder); XmlSerializer serializer = new XmlSerializer(typeof(TBL_TEST_TEST[])); serializer.Serialize(sWriter, testRecords); db.insertTestData(sBuilder.ToString()); } } /// <summary> /// An ado.net 2.0 way to mass insert records. This seems to be the fastest. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchBulkCopy() { // Get the DataTable DataTable dtInsertRows = GetDataTable(); using (SqlBulkCopy sbc = new SqlBulkCopy(connectionString, SqlBulkCopyOptions.KeepIdentity)) { sbc.DestinationTableName = "TBL_TEST_TEST"; // Number of records to be processed in one go sbc.BatchSize = 500000; // Map the Source Column from DataTabel to the Destination Columns in SQL Server 2005 Person Table // sbc.ColumnMappings.Add("ID", "ID"); sbc.ColumnMappings.Add("NAME", "NAME"); // Number of records after which client has to be notified about its status sbc.NotifyAfter = dtInsertRows.Rows.Count; // Event that gets fired when NotifyAfter number of records are processed. sbc.SqlRowsCopied += new SqlRowsCopiedEventHandler(sbc_SqlRowsCopied); // Finally write to server sbc.WriteToServer(dtInsertRows); sbc.Close(); } } /// <summary> /// Another ado.net 2.0 way that uses a stored procedure to do a bulk insert. /// Seems slower then "BatchBulkCopy" way and it crashes when you try to insert 500,000 records in one go. /// http://www.codeproject.com/KB/cs/MultipleInsertsIn1dbTrip.aspx#_Toc196622241 /// </summary> private static void BatchInsert() { // Get the DataTable with Rows State as RowState.Added DataTable dtInsertRows = GetDataTable(); SqlConnection connection = new SqlConnection(connectionString); SqlCommand command = new SqlCommand("sp_BatchInsert", connection); command.CommandType = CommandType.StoredProcedure; command.UpdatedRowSource = UpdateRowSource.None; // Set the Parameter with appropriate Source Column Name command.Parameters.Add("@Name", SqlDbType.VarChar, 50, dtInsertRows.Columns[0].ColumnName); SqlDataAdapter adpt = new SqlDataAdapter(); adpt.InsertCommand = command; // Specify the number of records to be Inserted/Updated in one go. Default is 1. adpt.UpdateBatchSize = 500000; connection.Open(); int recordsInserted = adpt.Update(dtInsertRows); connection.Close(); } private static DataTable GetDataTable() { // You First need a DataTable and have all the insert values in it DataTable dtInsertRows = new DataTable(); dtInsertRows.Columns.Add("NAME"); for (int i = 0; i < 500000; i++) { DataRow drInsertRow = dtInsertRows.NewRow(); string name = "Name : " + i; drInsertRow["NAME"] = name; dtInsertRows.Rows.Add(drInsertRow); } return dtInsertRows; } static void sbc_SqlRowsCopied(object sender, SqlRowsCopiedEventArgs e) { Console.WriteLine("Number of records affected : " + e.RowsCopied.ToString()); } } }

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  • Get data from MySQL to Android application

    - by Mona
    I want to get data from MySQL database using PHP and display it in Android activity. I code it and pass JSON Array but there is a problem i dont know how to connect to server and my all database is on local server. I code it Kindly tell me where i go wrong so I can get exact results. I'll be very thankful to you. My PHP code is: <?php $response = array(); require_once __DIR__ . '/db_connect.php'; $db = new DB_CONNECT(); if (isset($_GET["cid"])) { $cid = $_GET['cid']; // get a product from products table $result = mysql_query("SELECT *FROM my_task WHERE cid = $cid"); if (!empty($result)) { // check for empty result if (mysql_num_rows($result) > 0) { $result = mysql_fetch_array($result); $task = array(); $task["cid"] = $result["cid"]; $task["cus_name"] = $result["cus_name"]; $task["contact_number"] = $result["contact_number"]; $task["ticket_no"] = $result["ticket_no"]; $task["task_detail"] = $result["task_detail"]; // success $response["success"] = 1; // user node $response["task"] = array(); array_push($response["my_task"], $task); // echoing JSON response echo json_encode($response); } else { // no task found $response["success"] = 0; $response["message"] = "No product found"; // echo no users JSON echo json_encode($response); } } else { // no task found $response["success"] = 0; $response["message"] = "No product found"; echo json_encode($response); } } else { $response["success"] = 0; $response["message"] = "Required field(s) is missing"; // echoing JSON response echo json_encode($response);} ?> My Android code is: public class My_Task extends Activity { TextView cus_name_txt, contact_no_txt, ticket_no_txt, task_detail_txt; EditText attend_by_txtbx, cus_name_txtbx, contact_no_txtbx, ticket_no_txtbx, task_detail_txtbx; Button btnSave; Button btnDelete; String cid; // Progress Dialog private ProgressDialog tDialog; // Creating JSON Parser object JSONParser jParser = new JSONParser(); ArrayList<HashMap<String, String>> my_taskList; // single task url private static final String url_read_mytask = "http://198.168.0.29/mobile/read_My_Task.php"; // url to update product private static final String url_update_mytask = "http://198.168.0.29/mobile/update_mytask.php"; // url to delete product private static final String url_delete_mytask = "http://198.168.0.29/mobile/delete_mytask.php"; // JSON Node names private static String TAG_SUCCESS = "success"; private static String TAG_MYTASK = "my_task"; private static String TAG_CID = "cid"; private static String TAG_NAME = "cus_name"; private static String TAG_CONTACT = "contact_number"; private static String TAG_TICKET = "ticket_no"; private static String TAG_TASKDETAIL = "task_detail"; private static String attend_by_txt; // task JSONArray JSONArray my_task = null; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.my_task); cus_name_txt = (TextView) findViewById(R.id.cus_name_txt); contact_no_txt = (TextView)findViewById(R.id.contact_no_txt); ticket_no_txt = (TextView)findViewById(R.id.ticket_no_txt); task_detail_txt = (TextView)findViewById(R.id.task_detail_txt); attend_by_txtbx = (EditText)findViewById(R.id.attend_by_txt); attend_by_txtbx.setText(My_Task.attend_by_txt); Spinner severity = (Spinner) findViewById(R.id.severity_spinner); // Create an ArrayAdapter using the string array and a default spinner layout ArrayAdapter<CharSequence> adapter3 = ArrayAdapter.createFromResource(this, R.array.Severity_array, android.R.layout.simple_dropdown_item_1line); // Specify the layout to use when the list of choices appears adapter3.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // Apply the adapter to the spinner severity.setAdapter(adapter3); // save button btnSave = (Button) findViewById(R.id.btnSave); btnDelete = (Button) findViewById(R.id.btnDelete); // getting product details from intent Intent i = getIntent(); // getting product id (pid) from intent cid = i.getStringExtra(TAG_CID); // Getting complete product details in background thread new GetProductDetails().execute(); // save button click event btnSave.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View arg0) { // starting background task to update product new SaveProductDetails().execute(); } }); // Delete button click event btnDelete.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View arg0) { // deleting product in background thread new DeleteProduct().execute(); } }); } /** * Background Async Task to Get complete product details * */ class GetProductDetails extends AsyncTask<String, String, String> { /** * Before starting background thread Show Progress Dialog * */ @Override protected void onPreExecute() { super.onPreExecute(); tDialog = new ProgressDialog(My_Task.this); tDialog.setMessage("Loading task details. Please wait..."); tDialog.setIndeterminate(false); tDialog.setCancelable(true); tDialog.show(); } /** * Getting product details in background thread * */ protected String doInBackground(String... params) { // updating UI from Background Thread runOnUiThread(new Runnable() { public void run() { // Check for success tag int success; try { // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("cid", cid)); // getting product details by making HTTP request // Note that product details url will use GET request JSONObject json = JSONParser.makeHttpRequest( url_read_mytask, "GET", params); // check your log for json response Log.d("Single Task Details", json.toString()); // json success tag success = json.getInt(TAG_SUCCESS); if (success == 1) { // successfully received product details JSONArray my_taskObj = json .getJSONArray(TAG_MYTASK); // JSON Array // get first product object from JSON Array JSONObject my_task = my_taskObj.getJSONObject(0); // task with this cid found // Edit Text // display task data in EditText cus_name_txtbx = (EditText) findViewById(R.id.cus_name_txt); cus_name_txtbx.setText(my_task.getString(TAG_NAME)); contact_no_txtbx = (EditText) findViewById(R.id.contact_no_txt); contact_no_txtbx.setText(my_task.getString(TAG_CONTACT)); ticket_no_txtbx = (EditText) findViewById(R.id.ticket_no_txt); ticket_no_txtbx.setText(my_task.getString(TAG_TICKET)); task_detail_txtbx = (EditText) findViewById(R.id.task_detail_txt); task_detail_txtbx.setText(my_task.getString(TAG_TASKDETAIL)); } else { // task with cid not found } } catch (JSONException e) { e.printStackTrace(); } } }); return null; } /** * After completing background task Dismiss the progress dialog * **/ protected void onPostExecute(String file_url) { // dismiss the dialog once got all details tDialog.dismiss(); } } /** * Background Async Task to Save product Details * */ class SaveProductDetails extends AsyncTask<String, String, String> { /** * Before starting background thread Show Progress Dialog * */ @Override protected void onPreExecute() { super.onPreExecute(); tDialog = new ProgressDialog(My_Task.this); tDialog.setMessage("Saving task ..."); tDialog.setIndeterminate(false); tDialog.setCancelable(true); tDialog.show(); } /** * Saving product * */ protected String doInBackground(String... args) { // getting updated data from EditTexts String cus_name = cus_name_txt.getText().toString(); String contact_no = contact_no_txt.getText().toString(); String ticket_no = ticket_no_txt.getText().toString(); String task_detail = task_detail_txt.getText().toString(); // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair(TAG_CID, cid)); params.add(new BasicNameValuePair(TAG_NAME, cus_name)); params.add(new BasicNameValuePair(TAG_CONTACT, contact_no)); params.add(new BasicNameValuePair(TAG_TICKET, ticket_no)); params.add(new BasicNameValuePair(TAG_TASKDETAIL, task_detail)); // sending modified data through http request // Notice that update product url accepts POST method JSONObject json = JSONParser.makeHttpRequest(url_update_mytask, "POST", params); // check json success tag try { int success = json.getInt(TAG_SUCCESS); if (success == 1) { // successfully updated Intent i = getIntent(); // send result code 100 to notify about product update setResult(100, i); finish(); } else { // failed to update product } } catch (JSONException e) { e.printStackTrace(); } return null; } /** * After completing background task Dismiss the progress dialog * **/ protected void onPostExecute(String file_url) { // dismiss the dialog once product uupdated tDialog.dismiss(); } } /***************************************************************** * Background Async Task to Delete Product * */ class DeleteProduct extends AsyncTask<String, String, String> { /** * Before starting background thread Show Progress Dialog * */ @Override protected void onPreExecute() { super.onPreExecute(); tDialog = new ProgressDialog(My_Task.this); tDialog.setMessage("Deleting Product..."); tDialog.setIndeterminate(false); tDialog.setCancelable(true); tDialog.show(); } /** * Deleting product * */ protected String doInBackground(String... args) { // Check for success tag int success; try { // Building Parameters List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("cid", cid)); // getting product details by making HTTP request JSONObject json = JSONParser.makeHttpRequest( url_delete_mytask, "POST", params); // check your log for json response Log.d("Delete Task", json.toString()); // json success tag success = json.getInt(TAG_SUCCESS); if (success == 1) { // product successfully deleted // notify previous activity by sending code 100 Intent i = getIntent(); // send result code 100 to notify about product deletion setResult(100, i); finish(); } } catch (JSONException e) { e.printStackTrace(); } return null; } /** * After completing background task Dismiss the progress dialog * **/ protected void onPostExecute(String file_url) { // dismiss the dialog once product deleted tDialog.dismiss(); } } public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) { // An item was selected. You can retrieve the selected item using // parent.getItemAtPosition(pos) } public void onNothingSelected(AdapterView<?> parent) { // Another interface callback } } My JSONParser code is: public class JSONParser { static InputStream is = null; static JSONObject jObj = null; static String json = ""; // constructor public JSONParser() { } // function get json from url // by making HTTP POST or GET mehtod public static JSONObject makeHttpRequest(String url, String method, List<NameValuePair> params) { // Making HTTP request try { // check for request method if(method == "POST"){ // request method is POST // defaultHttpClient DefaultHttpClient httpClient = new DefaultHttpClient(); HttpPost httpPost = new HttpPost(url); httpPost.setEntity(new UrlEncodedFormEntity(params)); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); }else if(method == "GET"){ // request method is GET DefaultHttpClient httpClient = new DefaultHttpClient(); String paramString = URLEncodedUtils.format(params, "utf-8"); url += "?" + paramString; HttpGet httpGet = new HttpGet(url); HttpResponse httpResponse = httpClient.execute(httpGet); HttpEntity httpEntity = httpResponse.getEntity(); is = httpEntity.getContent(); } } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { BufferedReader reader = new BufferedReader(new InputStreamReader( is, "iso-8859-1"), 8); StringBuilder sb = new StringBuilder(); String line = null; while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); json = sb.toString(); } catch (Exception e) { Log.e("Buffer Error", "Error converting result " + e.toString()); } // try parse the string to a JSON object try { jObj = new JSONObject(json); } catch (JSONException e) { Log.e("JSON Parser", "Error parsing data " + e.toString()); } // return JSON String return jObj; my all database is in localhost and it is not opening an activity. displays an error "Stopped unexpectedly":( How can i get exact results. Kindly guide me

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  • Implementing Scrolling Background in LibGDX game

    - by Vishal Kumar
    I am making a game in LibGDX. After working for whole a day..I could not come out with a solution on Scrolling background. My Screen width n height is 960 x 540. I have a png image of 1024 x 540. I want to scroll the background in such a way that it contuosly goes back with camera x-- as per camera I tried many alternatives... drawing the image twice ..did a lot of calculations and many others.... but finally end up with this dirty code if(bg_x2 >= - Assets.bg.getRegionWidth()) { //calculated it to position bg .. camera was initially at 15 bg_x2 = (16 -4*camera.position.x); bg_x1=bg_x2+Assets.bg.getRegionWidth(); } else{ bg_x1 = (16 -4*camera.position.x)%224; // this 16 is not proper //I think there can be other ways bg_x2=bg_x1+Assets.bg.getRegionWidth(); } //drawing twice batch.draw(Assets.bg, bg_x2, bg_y); batch.draw(Assets.bg, bg_x1, bg_y); The Simple idea is SCROLLING BACKGROUND WITH SIZE SOMEWHAT MORE THAN SCREEN SIZE SO THAT IT LOOK SMOOTH. Even after a lot of search, i didn't find an online solution. Please help.

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  • Technical Article: Oracle Magazine Java Developer of the Year Adam Bien on Java EE 6 Simplicity by Design

    - by janice.heiss(at)oracle.com
    Java Champion and Oracle Magazine Java Developer of the Year, Adam Bien, offers his unique perspective on how to leverage new Java EE 6 features to build simple and maintainable applications in a new article in Oracle Magazine. Bien examines different Java EE 6 architectures and design approaches in an effort to help developers build efficient, simple, and maintainable applications.From the article: "Java EE 6 consists of a set of independent APIs released together under the Java EE name. Although these APIs are independent, they fit together surprisingly well. For a given application, you could use only JavaServer Faces (JSF) 2.0, you could use Enterprise JavaBeans (EJB) 3.1 for transactional services, or you could use Contexts and Dependency Injection (CDI) with Java Persistence API (JPA) 2.0 and the Bean Validation model to implement transactions.""With a pragmatic mix of available Java EE 6 APIs, you can entirely eliminate the need to implement infrastructure services such as transactions, threading, throttling, or monitoring in your application. The real challenge is in selecting the right subset of APIs that minimizes overhead and complexity while making sure you don't have to reinvent the wheel with custom code. As a general rule, you should strive to use existing Java SE and Java EE services before expanding your search to find alternatives." Read the entire article here.

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  • It&rsquo;s All About Expectation Management

    - by D'Arcy Lussier
    I saw this tweet from Gerald Weinberg today: I’d expand on this – its not just managers, its our clients as well. With so much focus on “agile” and reducing the amount of wasteful documentation created, those that typically consume traditional deliverables haven’t caught up. For many, there still is a correlation between seeing a mountain of paper, or a 30 page Word document, or a 40 slide PowerPoint, and feeling like some “work” was done. The “Value Driven Development” movement is still in its infancy, even with the adoption and success stories. So, we have two options – we can complain about it, or we can learn how to live with it while continuing to evangelize about the benefits of value over bloat. The reality is that perceived value is still value, so what’s important – especially in a situation as Gerald mentions where management or clients don’t understand the work – is to find out what the manager/client values and deliver to that. That doesn’t mean you don’t discuss it. That doesn’t mean that if you see risks being represented in what a manager/client is asking you don’t question it and provide alternatives. But it does mean that you don’t slam the door on it – you don’t just toss it aside and ignore what their perceived value is. The world isn’t perfect, primarily because its filled with imperfect people. The only way to get better is to engage and not dismiss each other, even if we disagree on value.

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  • Bump the Bill

    - by David Dorf
    I'm writing this from 3,400 feet in the air somewhere between Chicago and Austin. GoGo In-flight strikes again. Is there anywhere I can't get a WiFi connection? While listening to Deacon Blues by Steely Dan and skimming the news, I just came across an interesting article on mobile payments. Remember when I wrote about the iPhone Bump application and its possible use in retail? Well it looks like PayPal updated their mobile payments application to include the bump technology. Now its possible to transfer money between individuals by bumping iPhones. According to the WSJ, Paypal did 24 million transactions in 2008 and 140 million in 2009 on mobile phones. As the technology gets easier to use, that number is bound to increase. Alternatives to Paypal include Google Checkout, Amazon Payments, wireless carriers ("put it on my phone bill"), smart cards (using your phone's SIM card), and iTunes. That last one comes courtesy of a story Joe Skorupa wrote on mobile payments. It looks like Apple allows iPhone apps to take micro-payments via iTunes accounts, so there may come a time when its possible to use your iPhone to make a purchase in a retail store and have your credit card charged via your iTunes account. There are still some improvements in usability to be made before using a phone will be easier than swiping a credit card, but its already better than fussing with cash.

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  • Implementing fog of war in opengl es 2.0 game

    - by joxnas
    Hi game development community, this is my first question here! ;) I'm developing a tactics/strategy real time android game and I've been wondering for some time what's the best way to implement an efficient and somewhat nice looking fog of war to incorporate in it. My experience with OpenGL or Android is not vast by any means, but I think it is sufficient for what I'm asking here. So far I have thought in some solutions: Draw white circles to a dark background, corresponding to the units visibility, then render to a texture, and then drawing a quad with that texture with blend mode set to multiply. Will this approach be efficient? Will it take too much memory? (I don't know how to render to texture and then use the texture. Is it too messy?) Have a grid object with a vertex shader which has an array of uniforms having the coordinates of all units, and another array which has their visibility range. The number of units will very probably never be bigger then 100. The vertex shader needs to test for each considered vertex, if there is some unit which can see it. In order to do this it, will have to loop the array with the coordinates and do some calculations based on distance. The efficiency of this is inversely proportional to the looks of it. A more dense grid will result in a more beautiful fog of war... but will require a greater amount of vertexes to be checked. Is it possible to find a nice compromise or is this a bad solution from the start? Which solution is the best? Are there better alternatives? Which ones? Thank you for your time.

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  • What are the best ways to cope with «one of those days»? [closed]

    - by Júlio Santos
    I work in a fast-paced startup and am absolutely in love with what I do. Still, I wake up to a bad mood as often as the next guy. I find that forcing myself to play out my day as usual doesn't help — in fact, it only makes it worse, possibly ruining my productivity for the rest of the week. There are several ways I can cope with this, for instance: dropping the current task for the day and getting that awesome but low-priority feature in place; doing some pending research for future development (i.e. digging up ruby gems); spending the day reading and educating myself; just taking the day off. The first three items are productive in themselves, and taking the day off recharges my coding mana for the rest of the week. Being a young developer, I'm pretty sure there's a multitude of alternatives that I haven't come across yet. How can programmers cope with off days? Edit: I am looking for answers related specifically to this profession. I therefore believe that coping with off days in our field is fundamentally different that doing so in other areas. Programmers (especially in a start-up) are a unique breed in this context in the sense that they tend to have a multitude of tasks at hand on any given moment, so they can easily switch between these without wreaking too much havoc. Programmers also tend to work based on clear, concise objectives — provided they are well managed either by themselves or a third party — and hence have a great deal of flexibility when it comes to managing their time. Finally, our line of work creates the opportunity — necessity, if you will — to fit a plethora of tasks not directly related to the current one, such as research and staying on top of new releases and software updates.

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  • Ask the Readers: Which Web Browser Do You Use?

    - by Mysticgeek
    Yesterday we looked at the Browser Ballot Screen, which offers 12 different browsers as alternatives to IE for European Windows users. This got us thinking about this weeks question. What browser do you use for your daily web navigation?   Yesterday we showed you the Browser Ballot Screen which was introduced in March to Windows users in Europe. While it offers the choice of the most well known browsers on the market, there are some obscure choices as well. This got us thinking about what web browser(s) you use at home, in the office, or even on your mobile devices. Some people might have a favorite browser they use at home but are required to use IE at work due to proprietary applications the company uses. Also, if you use an operating system other than Windows, you might favor Safari, Firefox, Konqueror..etc. What web browser do you use? Leave a comment and join in the discussion! Similar Articles Productive Geek Tips Mysticgeek Blog: A Look at Internet Explorer 8 Beta 1 on Windows XPSet the Default Browser on Ubuntu From the Command LineAnnouncing the How-To Geek ForumsHow-To Geek Bounty: $103.24(Paid!) for Active Desktop for VistaA Few Things I’ve Learned from Writing at How-To Geek TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 PCmover Professional Explore Google Public Data Visually The Ultimate Excel Cheatsheet Convert the Quick Launch Bar into a Super Application Launcher Automate Tasks in Linux with Crontab Discover New Bundled Feeds in Google Reader Play Music in Chrome by Simply Dragging a File

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  • Formating Columns in Excel created by af:exportCollectionActionListener

    - by Duncan Mills
    The af:exportCollectionActionListener behavior in ADF Faces Rich client provides a very simple way of quickly dumping out the contents or selected rows in a table or treeTable to Excel. However, that simplicity comes at a price as it pretty much left up to Excel how to format the data. A common use case where you have a problem is that of ID columns which are often long numerics. You probably want to represent this data as a string, Excel however will probably have other ideas and render it as an exponent  - not what you intended. In earlier releases of the framework you could sort of work around this by taking advantage of a bug which would allow you to surround the outputText in question with invisible outputText components which provided formatting hints to Excel. Something like this: <af:column headertext="Some wide label">  <af:panelgrouplayout layout="horizontal">     <af:outputtext value="=TEXT(" visible="false">     <af:outputtext value="#{row.bigNumberValue}" rendered="true"/>    <af:outputtext value=",0)" visible="false">   </af:panelgrouplayout> </af:column> However, this bug was fixed and so it can no longer be used as a trick, the export now ignores invisible columns. So, if you really need control over the formatting there are several alternatives: First the more powerful ADF Desktop Integration (ADFdi) package which allows you to build fully transactional spreadsheets that "pull" the data and can update it. This gives you all the control that might need on formatting but it does need specific Excel Add-ins on the client to work. For more information about ADFdi have a look at this tutorial on OTN. Or you can of course look at BI Publisher or Apache POI if you're happy with output only spreadsheets

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  • What free Remote Desktop (server) solutions are there?

    - by Tao
    I know Ubuntu comes with a "Remote Desktop" option that appears to be a straightforward VNC server, and I'm trying to understand the alternatives. Here are the possibilities I've heard about so far: VNC VNC + SSH Tunnelling NX Server, free edition FreeNX NeatX X2Go X11 Forwarding over SSH xrdp I'm coming at this from a Windows user's perspective: To the best of my experience, RDP (aka Terminal Services) is a reasonably secure (barring mitm/server spoofing), efficient desktop sharing protocol with well-supported clients, that can be exposed to the internet when necessary without major fears of intrusion. To the best of my knowledge straight VNC is none of those things, which is where I get confused - why wouldn't a better desktop sharing technology be developed or used in the open-source world? I know VNC can be wrapped with SSH, but that seems beyond the reach of a casual user. X11 forwarding over SSH may be more or less efficient, I have no idea, but is definitely even more complicated, and doesn't (as far as I know) give you access to already-running stuff (no desktop sharing as such, just remote application running). So, I'd like any feedback/preferences amongst these or any other "Free" desktop sharing options, using these criteria and/or any others: Security (esp. for access across internet) Efficiency (bandwidth usage, responsiveness, etc) Free-ness, as in Speech (not sure where RDP or FreeNX lie for this) Free-ness, as in Beer (are there any commercial solutions with usable dependable free offerings?) Ease of use (server and client side) Cross-OS Client availability Cross-OS Server availability Support for independent sessions and shared (and/or "Console") sessions Ongoing support/maintenance/development Thanks!

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  • Should interfaces inherit interfaces

    - by dreza
    Although this is a general question it is also specific to a problem I am currently experiencing. I currently have an interface specified in my solution called public interface IContextProvider { IDataContext { get; set; } IAreaContext { get; set; } } This interface is often used throughout the program and hence I have easy access to the objects I need. However at a fairly low level of a part of my program I need access to another class that will use IAreaContext and perform some operations off it. So I have created another factory interface to do this creation called: public interface IEventContextFactory { IEventContext CreateEventContext(int eventId); } I have a class that implements the IContextProvider and is injected using NinJect. The problem I have is that the area where I need to use this IEventContextFactory has access to the IContextProvider only and itself uses another class which will need this new interface. I don't want to have to instantiate this implementation of IEventContextFactory at the low level and would rather work with the IEventContextFactory interface throughout. However I also don't want to have to inject another parameter through the constructors just to have it passed through to the class that needs it i.e. // example of problem public class MyClass { public MyClass(IContextProvider context, IEventContextFactory event) { _context = context; _event = event; } public void DoSomething() { // the only place _event is used in the class is to pass it through var myClass = new MyChildClass(_event); myClass.PerformCalculation(); } } So my main question is, would this be acceptable or is it even common or good practice to do something like this (interface inherit another an interface): public interface IContextProvider : IEventContextFactory or should I consider better alternatives to achieving what I need. If I have not provided enough information to give suggestions let me know and I can provide more.

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  • WebLogic Weekly for June 20th, 2011

    - by james.bayer
    Welcome the first the first edition of the WebLogic Weekly.  The WebLogic Server team has been trying to extend our community outreach to new mediums like an Oracle WebLogic Youtube Channel (how-to videos and feature showcases), Twitter (sharing WebLogic links, typically blogs), and a Facebook page to do a better job sharing information, providing learning alternatives to product documentation and perhaps most importantly collecting feedback from all of our users using the tools they prefer.  This is our attempt to provide a round-up what has been going on in WebLogic over the past week.  If you would like to have something shared here, use the #weblogic tag on tweets, post on the Oracle WebLogic facebook page, or comment on these blog entries. Blogs WebLogic Server: Listing Groups of an Authenticated User by Steve Button Weblogic, QBrowser And Topics by Eric Elzinga Weblogic, Topics And (Non)-Durable Subscribers by Eric Elzinga Database Web Service using Toplink DB Provider by Vishal Jain WebLogic Server – Use the Execution Context ID in Applications – Lessons From Hansel and Gretel by James Bayer Getting All Server’s Lifecycle State in a Domain by Jay SenSharma Steps to Move Messages From One Queue To Another Queue Using WLST (Updated Version) by Ravish Mody Events If you want to share a story of something innovative you or your organization has done with WebLogic Server or other Fusion Middleware, you could win a pass to Oracle Open World 2011 and share the story there.  See Ruma Sanyal's posting on the Application Grid blog for details.  The deadline for submissions is July 22nd, 2011.

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  • make-like build tools for data?

    - by miku
    Make is a standard tools for building software. But make decides whether a target needs to be regenerated by comparing file modification times. Are there any proven, preferably small tools that handle builds not for software but for data? Something that regenerates targets not only on mod times but on certain other properties (e.g. completeness). (Or alternatively some paper that describes such a tool.) As illustration: I'd like to automate the following process: get data (e.g. a tarball) from some regularly updated source copy somewhere if it's not there (based e.g. on some filename-scheme) convert the files to different format (but only if there aren't successfully converted ones there - e.g. from a previous attempt - custom comparison routine) for each file find a certain data element and fetch some additional file from say an URL, but only if that hasn't been downloaded yet (decide on existence of file and file "freshness") finally compute something (e.g. word count for something identifiable and store it in the database, but only if the DB does not have an entry for that exact ID yet) Observations: there are different stages each stage is usually simple to compute or implement in isolation each stage may be simple, but the data volume may be large each stage may produce a few errors each stage may have different signals, on when (re)processing is needed Requirements: builds should be interruptable and idempotent (== robust) when interrupted, already processed objects should be reused to speedup the next run data paths should be easy to adjust (simple syntax, nothing new to learn, internal dsl would be ok) some form of dependency graph, that describes the process would be nice for later visualizations should leverage existing programs, if possible I've done some research on make alternatives like rake and have worked a lot with ant and maven in the past. All these tools naturally focus on code and software build, not on data builds. A system we have in place now for a task similar to the above is pretty much just shell scripts, which are compact (and are a ok glue for a variety of other programs written in other languages), so I wonder if worse is better?

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  • How do I set up live audio streams to a DLNA compliant device?

    - by Takkat
    Is there a way to stream the live output of the soundcard from our 12.04.1 LTS amd64 desktop to a DLNA-compliant external device in our network? Selecting media content in shared directories using Rygel, miniDLNA, and uShare is always fine - but so far we completely failed to get a live audio stream to a client via DLNA. Pulseaudio claims to have a DLNA/UPnP media server that together with Rygel is supposed to do just this. But we were unable to get it running. We followed the steps outlined in live.gnome.org, this answer here, and also in another similar guide. As soon as we select the local audio device, or our GST-Launch stream in the DLNA client Rygel displays the following message and the client states it reached the end of the playlist: (rygel:7380): Rygel-WARNING **: rygel-http-request.vala:97: Invalid seek request This is how we configured GST-Launch in rygel.conf: [GstLaunch] enabled=true launch-items=mypulseaudiosink mypulseaudiosink-title=Audio on @HOSTNAME@ mypulseaudiosink-mime=audio/x-wav mypulseaudiosink-launch=pulsesrc device=<device> ! wavpackenc For <device> we tried with the default sink name, this name appended with .monitor, and in addition with upnp-sink and upnp.monitor that was created when we selected DLNA media server from paprefs. We also tried to encode using lamemp3enc with no luck. These are our pulseaudio modules: http://paste.ubuntu.com/1202913/ These are our sinks: http://paste.ubuntu.com/1202916/ Did we miss any other additional configuration needed to get this running? Are there any other alternatives for sending the audio of our soundcard as live stream to a DLNA client?

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  • PHP Browser Game Question - Pretty General Language Suitability and Approach Question

    - by JimBadger
    I'm developing a browser game, using PHP, but I'm unsure if the way I'm going about doing it is to be encouraged anymore. It's basically one of those MMOs where you level up various buildings and what have you, but, you then commit some abstract fighting entity that the game gives you, to an automated battle with another player (producing a textual, but hopefully amusing and varied combat report). Basically, as soon as two players agree to fight, PHP functions on the "fight.php" page run queries against a huge MySQL database, looking up all sorts of complicated fight moves and outcomes. There are about three hundred thousand combinations of combat stance, attack, move and defensive stances, so obviously this is quite a resource hungry process, and, on the super cheapo hosted server I'm using for development, it rapidly runs out of memory. The PHP script for the fight logic currently has about a thousand lines of code in it, and I'd say it's about half-finished as I try to add a bit of AI into the fight script. Is there a better way to do something this massive than simply having some functions in a PHP file calling the MySQL Database? I taught myself a modicum of PHP a while ago, and most of the stuff I read online (ages ago) about similar games was all PHP-based. but a) am I right to be using PHP at all, and b) am I missing some clever way of doing things that will somehow reduce server resource requirements? I'd consider non PHP alternatives but, if PHP is suitable, I'd rather stick to that, so there's no overhead of learning something new. I think I'd bite that bullet if it's the best option for a better game, though.

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  • Java - System design with distributed Queues and Locks

    - by sunny
    Looking for inputs to evaluate a design for a system (java) which would have a distributed queue serving several (but not too many) nodes. These nodes would process objects present in the distributed queue and on occasion require a distributed lock across the cluster on an arbitrary (distributed) data structures. These (distributed) data structures could potentially lie in a distributed cache. Eliminating Terracotta (DSO),Hazelcast and Akka what could be alternative choices. Currently considering zookeeper as a distributed locking mechanism. Since the recommendation of a znode is not to exceed the 1M size , the understanding is that zookeeper should not be used a distributed queue. And also from Netflix curator tech note 4. So should a distributed cache, say like memcached, or redis be used to emulate a distributed queue ? i.e. The distributed queue will be stored in the caches and will be locked cluster-wide via zookeeper. Are there potential pitfalls with this high-level approach. The objects don't need to be taken off the queue. The object will pass through a lifecycle which will determine its removal from the queue. There would be about 10k+ objects in a queue at a given time changing states and any node could service one stage of the object's lifecycle. (Although not strictly necessary .. i.e. one node could serve the entire lifecycle if that is more efficient.) Any suggestions/alternatives ? sidenote: new to zookeeper ; redis etc.

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  • iPhone 4S Costs 50k In India. Heck! Rather I Buy Tata Nano Car For Twice The Money

    - by Gopinath
    Are you waiting to buy iPhone 4S in India? Stop waiting and start looking for alternatives as its going to be released in India with mind blowing price tags. A 16 GB iPhone 4S costs Rs. 44,500 + tax, 32 GB at 50,900 and the 64 GB..wait! Are you really interested to know the price? I’m not at all. Its ridiculous to spend 50,000 for a mobile phone in India. I hope majority of Indians agree with me. The Tata Nano, the world’s cheapest car, costs close to the double the price of iPhone 4S. Instead of buying an iPhone 4S for around 50K, it’s a wiser decision to buy a Tata Nano. Will the super rich of India afford to pay around 50,000 to own an iPhone 4S? I think they love to own it to show off their status but I guess they prefer to get it from US through their friends and relatives. In USA an unlocked iPhone 4S available through Apple Online Store costs just 33,500(~ 650 USD IN INR) and that is a straight away Rs. 11,000 discount. Why would the rich burn money? Airtel and Aircel has announced that the iPhone 4S is going to be available in their networks from November 25 onwards and both the operators started accepting the pre-orders. If you are really willing to burn your cash go ahead and book an iPhone 4S. This article titled,iPhone 4S Costs 50k In India. Heck! Rather I Buy Tata Nano Car For Twice The Money, was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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  • Lucene and .NET Part I

    - by javarg
    I’ve playing around with Lucene.NET and trying to get a feeling of what was required to develop and implement a full business application using it. As you would imagine, many things are required for you to implement a robust solution for indexing content and searching it afterwards. Lucene is a great and robust solution for indexing content. It offers fast and performance enhanced search engine library available in Java and .NET. You will want to use this library in many particular scenarios: In Windows Azure, to support Full Text Search (a functionality not currently supported by SQL Azure) When storing files outside or not managed by your database (like in large document storage solutions that uses File System) When Full Text Search is not really what you need Lucene is more than a Full Text Search solution. It has several analyzers that let you process and search content in different ways (decomposing sentences, deriving words, removing articles, etc.). When deciding to implement indexing using Lucene, you will need to take into account the following: How content is to be indexed by Lucene and when. Using a service that runs after a specific interval Immediately when content changes When content is to available for searching / Availability of indexed content (as in real time content search) Immediately when content changes = near real time searching After a few minutes.. Ease of maintainability and development Some Technical Concerns.. When indexing content, indexes are locked for writing operations by the Index Writer. This means that Lucene is best designed to index content using single writer approach. When searching, Index Readers take a snapshot of indexes. This has the following implications: Setting up an index reader is a costly task. Your are not supposed to create one for each query or search. A good practice is to create readers and reuse them for several searches. The latter means that even when the content gets updated, you wont be able to see the changes. You will need to recycle the reader. In the second part of this post we will review some alternatives and design considerations.

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  • Should interfaces extend (and in doing so inherit methods of) other interfaces

    - by dreza
    Although this is a general question it is also specific to a problem I am currently experiencing. I currently have an interface specified in my solution called public interface IContextProvider { IDataContext { get; set; } IAreaContext { get; set; } } This interface is often used throughout the program and hence I have easy access to the objects I need. However at a fairly low level of a part of my program I need access to another class that will use IAreaContext and perform some operations off it. So I have created another factory interface to do this creation called: public interface IEventContextFactory { IEventContext CreateEventContext(int eventId); } I have a class that implements the IContextProvider and is injected using NinJect. The problem I have is that the area where I need to use this IEventContextFactory has access to the IContextProvider only and itself uses another class which will need this new interface. I don't want to have to instantiate this implementation of IEventContextFactory at the low level and would rather work with the IEventContextFactory interface throughout. However I also don't want to have to inject another parameter through the constructors just to have it passed through to the class that needs it i.e. // example of problem public class MyClass { public MyClass(IContextProvider context, IEventContextFactory event) { _context = context; _event = event; } public void DoSomething() { // the only place _event is used in the class is to pass it through var myClass = new MyChildClass(_event); myClass.PerformCalculation(); } } So my main question is, would this be acceptable or is it even common or good practice to do something like this (interface extend another an interface): public interface IContextProvider : IEventContextFactory or should I consider better alternatives to achieving what I need. If I have not provided enough information to give suggestions let me know and I can provide more.

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  • Do I need path finding to make AI avoid obstacles?

    - by yannicuLar
    How do you know when a path-finding algorithm is really needed? There are contexts, where you just want to improve AI navigation to avoid an object, like a space -ship that won't crash on a planet or a car that already knows where to steer, but needs small corrections to avoid a road bump. As I've seen on similar posts, the obvious solution is to implement some path-finding algorithm, most likely like A*, and let your AI-controlled object to navigate through the path. Now, I have the necessary skills to implement a path-finding algorithm, and I'm not being lazy here, but I'm still a bit skeptical on if this is really needed. I have the impression that path-finding is appropriate to navigate through a maze, or picking a path when there are many alternatives. But in obstacle avoidance, when you do know the path, but need to make slight corrections, is path finding really necessary? Even when the obstacles are too sparse or small ? I mean, in real life, when you're driving and notice a bump on the road, you will just have to pick between steering a bit on the left (and have the bump on your right side) or the other way around. You will not consider stopping, or going backwards. A path finding would be appropriate when you need to pick a route through the city, right ? So, are there any other methods to help AI navigation, except path-finding? And if there are, how do you know when path-fining is the appropriate algorithm ? Thanks for any thoughts

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  • How to create a Semantic Network like wordnet based on Wikipedia?

    - by Forbidden Overseer
    I am an undergraduate student and I have to create a Semantic Network based on Wikipedia. This Semantic Network would be similar to Wordnet(except for it is based on Wikipedia and is concerned with "streams of text/topics" rather than simple words etc.) and I am thinking of using the Wikipedia XML dumps for the purpose. I guess I need to learn parsing an XML and "some other things" related to NLP and probably Machine Learning, but I am no way sure about anything involved herein after the XML parsing. Is the starting step: XML dump parsing into text a good idea/step? Any alternatives? What would be the steps involved after parsing XML into text to create a functional Semantic Network? What are the things/concepts I should learn in order to do them? I am not directly asking for book recommendations, but if you have read a book/article that teaches any thing related/helpful, please mention them. This may include a refernce to already existing implementations regarding the subject. Please correct me if I was wrong somewhere. Thanks!

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  • Browser-based GUI for a python application

    - by ack__
    I want to create a web/browser-based GUI for a command-line python application. The goal is to make use of HTML/JS technologies to create this GUI. As the application itself, it needs to run on Linux and Windows, and the interface will be accessible only from localhost (not exposed to internet). The GUI will contain 5 to 10 pages. I don't want a traditional desktop GUI that includes HTML/JS, but just a bunch of html files and some kind of controller between those and the application. I also want to make use of asynchronous programming (ajax like) so I can load and print data in the GUI without refreshing the whole page. I'd probably use jQuery for that and a couple other things. How would you recommend to design this? Performance is not the key here, I'm rather looking at reliability, portability and simplicity. I'm thinking of using a lightweight python HTTP server / framework (like CherryPy) and maybe later a Python templating system (at the begining it will just be a couple pages). EDIT: I'm looking for ideas/recommendations how to build this, not for alternatives to browser/web-based GUI.

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  • How to set Guake as preferred terminal emulator for "Run in Terminal"?

    - by d3vid
    I've recently installed Guake and like it a lot. I'd like to set it as my preferred terminal application. That is, when I right-click on a bash script file, click "Open", and choose "Run in Terminal", I want it to open in a new Guake tab. I'm not sure where to set Guake as the preferred app for "Run in Terminal". And I'm guessing that I might need the command to be something like guake --new-tab=new --execute-command="COMMANDHERE", so how do I pass that parameter? Ideally, I'd like a terminal invocation to open a new Guake tab, unless there is already one available. (Difficult to tell, what id there's already a command running in the existing tab?) Failing that, just opening a new Guake tab is ok. Also, is there an option to keep Guake hidden when this happens? Already tried: Based on How can I set default terminal used? I have already tried: gconftool --type string --set /desktop/gnome/applications/terminal/exec guake - this made Guake appear when I type Ctrl-Alt-T. setting x-terminal-emulator to \usr\bin\guake in Alternatives Configurator - this made no difference (having already made the previous change).

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  • Thoughts on web development architecture through integrating C++ in the future to a web application

    - by Holland
    I'm looking to build a website (it's actually going to be a commercial startup) I saw this question and it really shed some light on a few things that I was hoping to understand (kudos to the op). After seeing that, it would make sense that, unless the website were required to actually have millions of hits per day, it wouldn't be a viable solution to write a C++ backend on the server side. But this got me thinking. what if it in the (unlikely) events of the future, it does go that route? The problem is that, while I'm thinking of starting this all using .Net (in the beginning) just to get something quick and easy up without a lot of hassle (in terms of learning), and then moving towards something more Open Source (such as Python/Django or RoR) later to save money and to support OSS, I'm wondering IFF the website actually becomes big, will it be a good idea to integrate a C++ backend, and use Python ontop of C++ for a strong foundation, and then mitigate HTML/CSS/AJAX/etc ontop of the backend's foundation? I guess, what I'd like to know is that, given the circumstance, if this were to happen, would it be a proper approach in terms of architecture? I'd definitely be supporting MVC as that seems to be a great way to implement a website. All in all, would one consider this rational, or are there other alternatives? I like .Net, and I'd like to use it in the beginning, because I have much more experience with that than, say, Python or PHP, and I prefer it in general, but I really do want to support OSS in the future. I suppose the sentence I'm looking for is, "is this pragmatic?"

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