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  • Php mail pulling form data from previous page

    - by Mark
    So I have a form being filled out on one php like so: <p> <label for="first_name">First Name: </label> <input type="text" size="30" name="first_name" id="first_name"/> </p> <p> <label for="last_name"> Last Name:</label> <input type="text" size="30" name="last_name" id="last_name"/> </p> <p> <label for="address_street">Street:</label> <input type="text" size="30" name="address_street" id="address_street"/> </p> <p> <label for="address_city">City:</label> <input type="text" size="30" name="address_city" id="address_city"/> </p> <p> <label for="address_state">State/Province:</label> <input type="text" size="30" name="address_state" id="address_state"/> </p> <p> <label for="email">Your e-mail: </label> <input type="text" size="30" name="email" id="email"/> </p> <p> <label for="phone">Your phone number: </label> <input type="text" size="30" name="phone" id="phone"/> </p> This is on one php page. From here, it goes to another php which part of it contains script to send a html email to recipient. Problem is, I cannot seem to get it to pull the variables even though I thought I declared them correctly and mixed them into the html correctly. <?php $first_name = $_POST['first_name']; $last_name = $_POST['last_name']; $to = "[email protected], [email protected]"; $subject = "HTML email for ALPS"; $message .= ' <html> <body> <div style="display: inline-block; width: 28%; float: left;"> <img src="http://englishintheusa.com/images/alps-logo.jpg" alt="ALPS Language School" /> </div> <div style="display: inline-block; width: 68%; float: right;"> <p style="color: #4F81BD; font-size: 20px; text-decoration: underline;">Thanks You For Your Inquiry!</p> </div> <div style="padding-left: 20px; color: #666666; font-size: 16.8px; clear: both;"> <p>Dear $first_name $last_name ,</p> </br > <p>Thank you for the following inquiry:</p> </br > </br > </br > </br > <p>****Comment goes here****</p> </br > </br > <p>We will contact you within 2 business days. Our office is open Monday-Friday, 8:30 AM - 5:00 PM Pacific Standard Time.</p> </br > <p>Thank you for your interest!</p> </br > </br > <p>Best Regards,</p> </br > </br > <p>ALPS Language School</p> </br > </br > <p>430 Broadway East</p> <p>Seattle WA 98102</p> <p>Phone: 206.720.6363</p> <p>Fax: 206. 720.1806</p> <p>Email: [email protected]</p> </div> </body> </html>'; // Always set content-type when sending HTML email $headers .= "MIME-Version: 1.0" . "\r\n"; $headers .= "Content-type:text/html;charset=UTF-8" . "\r\n"; // More headers mail($to,$subject,$message,$headers); ?> So you see where I am trying to get first_name and last_name. Well it doesn't come out correctly. Can someone help here?

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  • What version-control system is most trivial to set up and use for toy projects?

    - by Norman Ramsey
    I teach the third required intro course in a CS department. One of my homework assignments asks students to speed up code they have written for a previous assignment. Factor-of-ten speedups are routine; factors of 100 or 1000 are not unheard of. (For a factor of 1000 speedup you have to have made rookie mistakes with malloc().) Programs are improved by a sequence is small changes. I ask students to record and describe each change and the resulting improvement. While you're improving a program it is also possible to break it. Wouldn't it be nice to back out? You can see where I'm going with this: my students would benefit enormously from version control. But there are some caveats: Our computing environment is locked down. Anything that depends on a central repository is suspect. Our students are incredibly overloaded. Not just classes but jobs, sports, music, you name it. For them to use a new tool it has to be incredibly easy and have obvious benefits. Our students do most work in pairs. Getting bits back and forth between accounts is problematic. Could this problem also be solved by distributed version control? Complexity is the enemy. I know setting up a CVS repository is too baffling---I myself still have trouble because I only do it once a year. I'm told SVN is even harder. Here are my comments on existing systems: I think central version control (CVS or SVN) is ruled out because our students don't have the administrative privileges needed to make a repository that they can share with one other student. (We are stuck with Unix file permissions.) Also, setup on CVS or SVN is too hard. darcs is way easy to set up, but it's not obvious how you share things. darcs send (to send patches by email) seems promising but it's not clear how to set it up. The introductory documentation for git is not for beginners. Like CVS setup, it's something I myself have trouble with. I'm soliciting suggestions for what source-control to use with beginning students. I suspect we can find resources to put a thin veneer over an existing system and to simplify existing documentation. We probably don't have resources to write new documentation. So, what's really easy to setup, commit, revert, and share changes with a partner but does not have to be easy to merge or to work at scale? A key constraint is that programming pairs have to be able to share work with each other and only each other, and pairs change every week. Our infrastructure is Linux, Solaris, and Windows with a netapp filer. I doubt my IT staff wants to create a Unix group for each pair of students. Is there an easier solution I've overlooked? (Thanks for the accepted answer, which beats the others on account of its excellent reference to Git Magic as well as the helpful comments.)

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  • Fastest way to pad a number in Java to a certain number of digits

    - by Martin
    Am trying to create a well-optimised bit of code to create number of X-digits in length (where X is read from a runtime properties file), based on a DB-generated sequence number (Y), which is then used a folder-name when saving a file. I've come up with three ideas so far, the fastest of which is the last one, but I'd appreciate any advice people may have on this... 1) Instantiate a StringBuilder with initial capacity X. Append Y. While length < X, insert a zero at pos zero. 2) Instantiate a StringBuilder with initial capacity X. While length < X, append a zero. Create a DecimalFormat based on StringBuilder value, and then format the number when it's needed. 3) Create a new int of Math.pow( 10, X ) and add Y. Use String.valueOf() on the new number and then substring(1) it. The second one can obviously be split into outside-loop and inside-loop sections. So, any tips? Using a for-loop of 10,000 iterations, I'm getting similar timings from the first two, and the third method is approximately ten-times faster. Does this seem correct? Full test-method code below... // Setup test variables int numDigits = 9; int testNumber = 724; int numIterations = 10000; String folderHolder = null; DecimalFormat outputFormat = new DecimalFormat( "#,##0" ); // StringBuilder test long before = System.nanoTime(); for ( int i = 0; i < numIterations; i++ ) { StringBuilder sb = new StringBuilder( numDigits ); sb.append( testNumber ); while ( sb.length() < numDigits ) { sb.insert( 0, 0 ); } folderHolder = sb.toString(); } long after = System.nanoTime(); System.out.println( "01: " + outputFormat.format( after - before ) + " nanoseconds" ); System.out.println( "Sanity check: Folder = \"" + folderHolder + "\"" ); // DecimalFormat test before = System.nanoTime(); StringBuilder sb = new StringBuilder( numDigits ); while ( sb.length() < numDigits ) { sb.append( 0 ); } DecimalFormat formatter = new DecimalFormat( sb.toString() ); for ( int i = 0; i < numIterations; i++ ) { folderHolder = formatter.format( testNumber ); } after = System.nanoTime(); System.out.println( "02: " + outputFormat.format( after - before ) + " nanoseconds" ); System.out.println( "Sanity check: Folder = \"" + folderHolder + "\"" ); // Substring test before = System.nanoTime(); int baseNum = (int)Math.pow( 10, numDigits ); for ( int i = 0; i < numIterations; i++ ) { int newNum = baseNum + testNumber; folderHolder = String.valueOf( newNum ).substring( 1 ); } after = System.nanoTime(); System.out.println( "03: " + outputFormat.format( after - before ) + " nanoseconds" ); System.out.println( "Sanity check: Folder = \"" + folderHolder + "\"" );

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  • where is the error in this C code , and how to get rid of the warnings?

    - by mekasperasky
    #include<stdio.h> #include<string.h> //This program is a sorting application that reads a sequence of numbers from a file and prints them on the screen . The reading from the file here , is a call back function . typedef int (*CompFunc)(const char* , const char* ); typedef int (*ReadCheck)(char nullcheck); char array[100]; //Let this fucntion be done in the library itself . It doesnt care as to where the compare function and how is it implemented . Meaning suppose the function wants to do sort in ascending order or in descending order then the changes have to be done by the client code in the "COMPARE" function who will be implementing the lib code . void ReadFile(FILE *fp,ReadCheck rc) { char a; char d[100]; int count = 0,count1=0; a=fgetc(fp); while(1 != (*rc)(a)) { if(a=='\0') { strcpy(array[count],d); count=count+1; } else { d[count1]=a; count1=count1+1; } } } void Bubblesort(int* array , int size , int elem_size , CompFunc cf) { int i,j; int *temp; for( i=0;i < size ;i++) { for ( j=0;j < size -1 ; j++) { // make the callback to the comparision function if(1 == (*cf)(array+j*elem_size,array+ (j+1)*elem_size)) { //interchanging of elements temp = malloc(sizeof(int *) * elem_size); memcpy(temp , array+j*elem_size,elem_size); memcpy(array+j*elem_size,array+(j+1)*elem_size,elem_size); memcpy(array + (j+1)*elem_size , temp , elem_size); free(temp); } } } } //Let these functions be done at the client side int Compare(const char* el1 , const char* el2) { int element1 = *(int*)el1; int element2 = *(int*)el2; if(element1 < element2 ) return -1; if(element1 > element2) return 1 ; return 0; } int ReadChecked(char nullcheck) { if (nullcheck=='\n') return 1; else return 0; } int main() { FILE fp1; int k; fp1=fopen("readdata.txt","r"); Readfile(fp1,&ReadChecked); Bubblesort((char*)array,5,sizeof(array[0]),&Compare); printf("after sorting \n"); for (k=0;k<5;k++) printf("%d",array[k]); return 0; } The error i get is fsc1.c: In function ‘ReadFile’: fsc1.c:19: warning: passing argument 1 of ‘strcpy’ makes pointer from integer without a cast fsc1.c: In function ‘Bubblesort’: fsc1.c:40: warning: passing argument 1 of ‘cf’ from incompatible pointer type fsc1.c:40: warning: passing argument 2 of ‘cf’ from incompatible pointer type fsc1.c:43: warning: incompatible implicit declaration of built-in function ‘malloc’ fsc1.c:47: warning: incompatible implicit declaration of built-in function ‘free’ fsc1.c: In function ‘main’: fsc1.c:80: error: incompatible types in assignment fsc1.c:82: warning: passing argument 1 of ‘Bubblesort’ from incompatible pointer type

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  • Sqlite3 : "Database is locked" error

    - by Miraaj
    Hi all, In my cocoa application I am maintaining a SQLite db within resources folder and trying to do some select, delete operations in it but after some time it starts giving me 'Database is locked' error. The methods which I am using for select delete operations are as follows: // method to retrieve data if (sqlite3_open([databasePath UTF8String], &database) != SQLITE_OK) { sqlite3_close(database); NSAssert(0, @"Failed to open database"); } NSLog(@"mailBodyFor:%d andFlag:%d andFlag:%@",UId,x,Ffolder); NSMutableArray *recordsToReturn = [[NSMutableArray alloc] initWithCapacity:2]; NSString *tempMsg; const char *sqlStatementNew; NSLog(@"before switch"); switch (x) { case 9: // tempMsg=[NSString stringWithFormat:@"SELECT * FROM users_messages"]; tempMsg=[NSString stringWithFormat:@"SELECT message,AttachFileOriName as oriFileName,AttachmentFileName as fileName FROM users_messages WHERE id = (select message_id from users_messages_status where id= '%d')",UId]; NSLog(@"mail body query - %@",tempMsg); break; default: break; } sqlStatementNew = [tempMsg cStringUsingEncoding:NSUTF8StringEncoding]; sqlite3_stmt *compiledStatementNew; NSLog(@"before if statement"); if(sqlite3_prepare_v2(database, sqlStatementNew, -1, &compiledStatementNew, NULL) == SQLITE_OK) { NSLog(@"the sql is finalized"); while(sqlite3_step(compiledStatementNew) == SQLITE_ROW) { NSMutableDictionary *recordDict = [[NSMutableDictionary alloc] initWithCapacity:3]; NSString *message; if((char *)sqlite3_column_text(compiledStatementNew, 0)){ message = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatementNew, 0)]; } else{ message = @""; } NSLog(@"message - %@",message); NSString *oriFileName; if((char *)sqlite3_column_text(compiledStatementNew, 1)){ oriFileName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatementNew, 1)]; } else{ oriFileName = @""; } NSLog(@"oriFileName - %@",oriFileName); NSString *fileName; if((char *)sqlite3_column_text(compiledStatementNew, 2)){ fileName = [NSString stringWithUTF8String:(char *)sqlite3_column_text(compiledStatementNew, 2)]; } else{ fileName = @""; } NSLog(@"fileName - %@",fileName); [recordDict setObject:message forKey:@"message"]; [recordDict setObject:oriFileName forKey:@"oriFileName"]; [recordDict setObject:fileName forKey:@"fileName"]; [recordsToReturn addObject:recordDict]; [recordDict release]; } sqlite3_finalize(compiledStatementNew); sqlite3_close(database); NSLog(@"user messages return -%@",recordsToReturn); return recordsToReturn; } else{ NSLog(@"Error while creating retrieving mailBodyFor in messaging '%s'", sqlite3_errmsg(database)); sqlite3_close(database); } // method to delete data if (sqlite3_open([databasePath UTF8String], &database) != SQLITE_OK) { sqlite3_close(database); NSAssert(0, @"Failed to open database"); } NSString *deleteQuery = [[NSString alloc] initWithFormat:@"delete from users_messages_status where id IN(%@)",ids]; NSLog(@"users_messages_status msg deleteQuery - %@",deleteQuery); sqlite3_stmt *deleteStmnt; const char *sql = [deleteQuery cStringUsingEncoding:NSUTF8StringEncoding]; if(sqlite3_prepare_v2(database, sql, -1, &deleteStmnt, NULL) != SQLITE_OK){ NSLog(@"Error while creating delete statement. '%s'", sqlite3_errmsg(database)); } else{ NSLog(@"successful deletion from users_messages"); } if(SQLITE_DONE != sqlite3_step(deleteStmnt)){ NSLog(@"Error while deleting. '%s'", sqlite3_errmsg(database)); } sqlite3_close(database); Things are going wrong in this sequence Data is retrieved 'Database is locked' error arises on performing delete operation. When I retry to perform 1st step.. it now gives same error. Can anyone suggest me: If I am doing anything wrong or missing some check? Is there any way to unlock it when it gives locked error? Thanks, Miraaj

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  • How to get latitude and longitude position that stored in MySQL and use it in Android map application

    - by gunawan haruna
    I have tried to get the latitude and longitude position that was stored in MySQL. I want use the values to my Android map application. Here is my code: deskripsi.Java Button direction = (Button) findViewById (R.id.btnDir); direction.setOnClickListener(new OnClickListener(){ public void onClick(View arg0) { Intent z = getIntent(); des_lat = z.getExtras().getString("des_lat"); des_long = z.getExtras().getString("des_long"); Intent i = new Intent(android.content.Intent.ACTION_VIEW, Uri.parse("http://maps.google.com/maps?&daddr="+des_lat+","+des_long)); //("geo:37.827500,-122.481670")); startActivity(i); } }); And here is the content.Java private ListView list; int x; private String panjang[]; public void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.kontent); super.initButtonSearch(); list = (ListView) findViewById(R.id.list); JSONObject jo; try { jo = new JSONObject(JsonKontent); JSONArray ja = jo.getJSONArray("result"); System.out.println("Panjang : " + ja.length()); if (ja.length() == 0) { Toast.makeText(Content.this, "Data tidak ada!", Toast.LENGTH_LONG).show(); finish(); } content_id = new String[ja.length()]; c_title = new String[ja.length()]; c_telephone = new String[ja.length()]; c_short_description = new String[ja.length()]; c_long_description = new String[ja.length()]; c_image1 = new String[ja.length()]; c_image2 = new String[ja.length()]; l_address = new String[ja.length()]; catagory_id = new String[ja.length()]; Location myLoc = new Location("sharedPreferences"); Location restLoc = new Location("restaurantTable"); l_latitude = new String[ja.length()]; l_longitude = new String[ja.length()]; c_name = new String[ja.length()]; panjang = new String[ja.length()]; for (x = 0; x < ja.length(); x++) { JSONObject joj = ja.getJSONObject(x); content_id[x] = joj.getString("content_id"); catagory_id[x] = joj.getString("catagory_id"); c_title[x] = joj.getString("c_title"); c_telephone[x] = joj.getString("c_telephone"); c_short_description[x] = joj.getString("c_short_description"); c_long_description[x] = joj.getString("c_long_description"); c_image1[x] = HTTPConnection.urlPicture + joj.getString("c_image1"); c_image2[x] = HTTPConnection.urlPicture + joj.getString("c_image2"); l_address[x] = joj.getString("l_address"); l_latitude[x] = joj.getString("l_latitude"); l_longitude[x] = joj.getString("l_longitude"); c_name[x] = joj.getString("c_name"); myLoc.setLatitude(myLatitude); myLoc.setLongitude(myLongitude); restLoc.setLatitude(Double.parseDouble(l_latitude[x])); restLoc.setLongitude(Double.parseDouble(l_longitude[x])); float f = myLoc.distanceTo(restLoc); int f_int = Math.round(f / 100); f = Float.valueOf(f_int) / 10; String dist = new DecimalFormat("#,##0.0").format(f); System.out.println("Panjang " + dist + " km"); panjang[x] = dist + " km"; } } catch (JSONException e) { Toast.makeText(Content.this, "Data yang dicari tidak ada!", Toast.LENGTH_LONG).show(); finish(); } PFCAdapter adapter = new PFCAdapter(this, c_image1, c_title, l_address, panjang); list.setAdapter(adapter); list.setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) { // TODO Auto-generated method stub System.out.println("Content ID: " + Content.content_id[Deskripsi.id]); Deskripsi.id = arg2; waitDialog = ProgressDialog.show(Content.this, "Memuat", "Harap tunggu, sedang terhubung dengan server"); waitDialog.setIcon(R.drawable.iconnya); waitDialog.show(); new LihatRatingTask().execute(); } }); } class LihatRatingTask extends AsyncTask<Void, Void, Void> { protected Void doInBackground(Void... Arg0) { Deskripsi.jsonRating = HTTPConnection.openUrl(HTTPConnection.host + "lihat_rating.php?content_id=" + Content.content_id[Deskripsi.id]); Deskripsi.jsonSubCategory = HTTPConnection .openUrl(HTTPConnection.host + "sub_catagory_parameter.php?content_id=" + Content.content_id[Deskripsi.id]); RoutePath.place = HTTPConnection .LoadImageFromWeb(HTTPConnection.host + "Logo/" + image[Integer.valueOf(catagory_id[Deskripsi.id]) - 1]); Intent i = new Intent(Content.this, Deskripsi.class); i.putExtra("des_lat", l_latitude); i.putExtra("des_long", l_longitude); startActivity(i); waitDialog.dismiss(); return null; } protected void onPostExecute(Void result) { // TODO Auto-generated method stub super.onPostExecute(result); waitDialog.dismiss(); } } } The result is in destination EditText in maps application for Android "null,null" How to make it "destination_latitude, destination_longitude"? Help me please.

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  • model binding of non-sequential arrays

    - by user281180
    I am having a table in which i`m dynamically creating and deleting rows. How can I change the code such that the rows be added and deleted and the model info property filled accordingly. Bearing in mind that the rows can be dynamically created and deleted, I may have Info[0], Inf0[3], info[4]... My objective is to be able to bind the array even if it`s not in sequence. Model public class Person { public int[] Size { get; set; } public string[] Name { get; set; } public Info[]info { get; set; } } public class Info { public string Address { get; set; } public string Tel { get; set; } View <script type="text/javascript" language="javascript"> $(function () { var count = 1; $('#AddSize').live('click', function () { $("#divSize").append('</br><input type="text" id="Size" name="Size" value=""/><input type = "button" id="AddSize" value="Add"/>'); }); $('#AddName').live('click', function () { $("#divName").append('</br><input type="text" id="Name" name="Name" value=""/><input type = "button" id="AddName" value="Add"/>'); }); $('#AddRow').live('click', function () { $('#details').append('<tr><td>Address</td><td> <input type="text" name="Info[' + count + '].Address"/></td><td>Tel</td><td><input type="text" name="Info[' + count++ + '].Tel"/></td> <td><input type="button" id="AddRow" value="Add"/> </td></tr>'); }); }); </script> </head> <body> <form id="closeForm" action="<%=Url.Action("Create",new{Action="Create"}) %>" method="post" enctype="multipart/form-data"> <div id="divSize"> <input type="text" name="Size" value=""/> <input type="button" value="Add" id="AddSize" /> </div> <div id="divName"> <input type="text" name="Name" value=""/> <input type="button" value="Add" id="AddName" /> </div> <div id="Tab"> <table id="details"> <tr><td>Address</td><td> <input type="text" name="Info[0].Address"/></td><td>Tel</td><td><input type="text" name="Info[0].Tel"/></td> <td><input type="button" id="AddRow" value="Add"/> </td></tr> </table> </div> <input type="submit" value="Submit" /> </form> </body> } Controller public ActionResult Create(Person person) { return new EmptyResult(); }

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  • How do would you use jQuery's .each() to apply the same script to each element with the same class?

    - by derekmx271
    I have a with multiple cart items listed. I have a "x-men logo" looking remove button that I want to fade-in next to the item when the customer hovers over a cart item. I had no issue getting this to work when there is only one item in the list. However, when there are multiple items in the cart, the jQuery operates funky. It still does the fade in, but only when I hover over the last item in the cart, and of course all of the "remove X" images become visible. Argh... So i searched around and think the .each() is my savior. I have been trying to get it to work, with no luck. My script just breaks when I attempt to implement it. Anyone have any pointers on this *.each() thing and how to implement it into my script?* I have tried putting a cartItem.each(function(){ around the mouseEnter/mouseLeave events (and used some $(this) selectors to make it "make sense") and that didn't do anything. Tried some other things as well with no luck... Here is the HTML (Sorry, there's a lot): <ul id="head-cart-items"> <!-- Item #1 --> <li> <!-- Item #1 Wrap --> <div class="head-cart-item"> <div class="head-cart-img" style='background-image:url("/viewimageresize.asp?mh=50&amp;mw=50&amp;p=AFE&amp;f=Air_Intakes_Magnum_FORCE_Stage-1_PRO_5R")'> </div> <div class="head-cart-desc"> <h3> <a href="/partdetails/AFE/Intakes/Air_Intakes/Magnum_FORCE_Stage-1_PRO_5R/19029">AFE Magnum FORCE Stage-1 PRO 5R Air Intakes</a> </h3> <span class="head-cart-qty">Qty: 1</span> <span class="head-cart-price">$195.00</span> <!-- Here is my Remove-X... --> <a class="remove-x" href='/cart//7806887'> <img src="/images/misc/remove-x.png"> </a> </div> </div> </li> <!-- Item #2 --> <li> <!-- Item #2 Wrap --> <div class="head-cart-item"> <div class="head-cart-img" style='background-image:url("/viewimageresize.asp?mh=50&amp;mw=50&amp;p=Exedy&amp;f=Clutch_Kits_Carbon-R")'> </div> <div class="head-cart-desc"> <h3> <a href="/partdetails/Exedy/Clutch/Clutch_Kits/Carbon-R/19684">Exedy Carbon-R Clutch Kits</a> </h3> <span class="head-cart-qty">Qty: 1</span> <span class="head-cart-price">$2,880.00</span> <!-- Here is my other Remove-X... --> <a class="remove-x" href='/cart//7806888'> <img src="/images/misc/remove-x.png"> </a> </div> </div> </li> </ul> And here is the jQuery... $(document).ready(function(){ var removeX = $(".remove-x"); var cartItem = $(".head-cart-item"); // Start with an invisible X removeX.fadeTo(0,0); // When hovering over Cart Item cartItem.mouseenter(function(){ // Fade the X to 100% removeX.fadeTo("normal",1); // On mouseout, fade it back to 0% $(this).mouseleave(function(){ removeX.fadeTo("fast",0); }); }); }); If you didn't see it, here is the "X" I am trying to fade... <!-- Here is my Remove-X... --> <a class="remove-x" href='/cart//7806887'> <img src="/images/misc/remove-x.png"> </a> Thanks for the help in advance. You guys always rock my world on here. I need ya (can't go home til this is live... :(

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  • Keeping video viewing statistics breakdown by video time in a database

    - by Septagram
    I need to keep a number of statistics about the videos being watched, and one of them is what parts of the video are being watched most. The design I came up with is to split the video into 256 intervals and keep the floating-point number of views for each of them. I receive the data as a number of intervals the user watched continuously. The problem is how to store them. There are two solutions I see. Row per every video segment Let's have a database table like this: CREATE TABLE `video_heatmap` ( `id` int(11) NOT NULL AUTO_INCREMENT, `video_id` int(11) NOT NULL, `position` tinyint(3) unsigned NOT NULL, `views` float NOT NULL, PRIMARY KEY (`id`), UNIQUE KEY `idx_lookup` (`video_id`,`position`) ) ENGINE=MyISAM Then, whenever we have to process a number of views, make sure there are the respective database rows and add appropriate values to the views column. I found out it's a lot faster if the existence of rows is taken care of first (SELECT COUNT(*) of rows for a given video and INSERT IGNORE if they are lacking), and then a number of update queries is used like this: UPDATE video_heatmap SET views = views + ? WHERE video_id = ? AND position >= ? AND position < ? This seems, however, a little bloated. The other solution I came up with is Row per video, update in transactions A table will look (sort of) like this: CREATE TABLE video ( id INT NOT NULL AUTO_INCREMENT, heatmap BINARY (4 * 256) NOT NULL, ... ) ENGINE=InnoDB Then, upon every time a view needs to be stored, it will be done in a transaction with consistent snapshot, in a sequence like this: If the video doesn't exist in the database, it is created. A row is retrieved, heatmap, an array of floats stored in the binary form, is converted into a form more friendly for processing (in PHP). Values in the array are increased appropriately and the array is converted back. Row is changed via UPDATE query. So far the advantages can be summed up like this: First approach Stores data as floats, not as some magical binary array. Doesn't require transaction support, so doesn't require InnoDB, and we're using MyISAM for everything at the moment, so there won't be any need to mix storage engines. (only applies in my specific situation) Doesn't require a transaction WITH CONSISTENT SNAPSHOT. I don't know what are the performance penalties of those. I already implemented it and it works. (only applies in my specific situation) Second approach Is using a lot less storage space (the first approach is storing video ID 256 times and stores position for every segment of the video, not to mention primary key). Should scale better, because of InnoDB's per-row locking as opposed to MyISAM's table locking. Might generally work faster because there are a lot less requests being made. Easier to implement in code (although the other one is already implemented). So, what should I do? If it wasn't for the rest of our system using MyISAM consistently, I'd go with the second approach, but currently I'm leaning to the first one. But maybe there are some reasons to favour one approach or another?

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  • The css is not displayed in opera mini and balckberry browsers

    - by p.karuppasamy
    Hi All, I 'm a php developer. I develope a site for mobile using php hawhaw.inc. i use the page sim for set the css for my page as $myPage->use_simulator("http://".$_SERVER["SERVER_NAME"].":".$_SERVER['SERVER_PORT'].dirname($_SERVER['PHP_SELF'])."/css/style.css") im my css file i write the css for table. it set in the windows mobile but it's not set in the opera mini and black berry browsers. The page is $myPage = new HAW_deck("Login ", HAW_ALIGN_CENTER); /*$myPage->set_bgcolor('#337fa6'); $myPage->set_background('../images/body_bg.jpg'); $myPage->set_css_class('skin');*/ $myHtmlCode = '<link href="css/style.css" rel="stylesheet" type="text/css" media="handheld" /><link rel="stylesheet" type="text/css" href="css/style.css" /><meta name="viewport" content="initial-scale=1.0"/><meta name="viewport" content="user-scalable=false" />'; $myAdblock = new HAW_raw(HAW_HTML, $myHtmlCode); $myPage->add_raw($myAdblock); /*$myPage->set_width('50%'); $myPage->set_height('50%');*/ $myPage->use_simulator("http://".$_SERVER["SERVER_NAME"].":".$_SERVER['SERVER_PORT'].dirname($_SERVER['PHP_SELF'])."/css/style.css"); $myForm = new HAW_form($_SERVER['PHP_SELF']); $text = new HAW_text("Please enter username & password:"); $text1 = new HAW_text("REMcloud", HAW_TEXTFORMAT_BOLD | HAW_TEXTFORMAT_BIG); $myImage1 = new HAW_image('','../images/logo.png','REMcloud',''); $myImage1->set_br(1); $myImage1->set_html_width(200); $myImage1->set_html_height(100); $error=new HAW_text($_REQUEST['msg'], HAW_TEXTFORMAT_BOLD); $error->set_color("#ff0000", "red"); $theID = new HAW_input("username", "", "Username", "*N"); $theID->set_size(4); $theID->set_maxlength(20); $text2 = new HAW_text(""); $thePW = new HAW_input("password", "", "Password", "*N"); $thePW->set_size(4); $thePW->set_maxlength(20); $thePW->set_type(HAW_INPUT_PASSWORD); $theSubmission = new HAW_submit("Submit", "submit"); // add the elements in the form //$myForm->add_text($text1); $myForm->add_image($myImage1); //$myForm->add_text($text2); $myForm->add_text($error); $myForm->add_text($text2); $myForm->add_text($text); $myForm->add_text($text2); $myForm->add_input($theID); $myForm->add_text($text2); $myForm->add_input($thePW); $myForm->add_text($text2); $myForm->add_submit($theSubmission); $myPage->add_form($myForm); $myPage->create_page(); the css is /* HAWHAW skin stylesheet for the hawhaw phone */ body { background-color: #FFFFFF; text-align: center; margin: 0px; padding: 0px; color: #222222; } #skin { margin: 0px auto; padding: 0px; text-align: left; width: 280px; height: 466px; background-image: url(../../images/bg.jpg); background-color:#337fa6; background-repeat:repeat-x; } #display { position: relative; top: 80px; /* left: 43px;*/ width: 100%; height: 85%; overflow: auto; } TABLE{ width:100%; padding-left:-10px; overflow:scroll; height:20px; border:none; font-family:Calibri; font-size:14px; } tr{ height:20px; } td{ color:#fff; border:none; } a { font-family:Calibri; font-size:16px; } if any one know please advice me for the same Thanks in advance

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  • Android application displays black screen after running

    - by frgnvola
    When I click "Run as an Android Application" on Eclipse, the following is displayed in the console [2014-06-05 20:07:18 - StudentConnect] Android Launch! [2014-06-05 20:07:18 - StudentConnect] adb is running normally. [2014-06-05 20:07:18 - StudentConnect] Performing sandhu.student.connect.SplashActivity activity launch [2014-06-05 20:07:18 - StudentConnect] Using default Build Tools revision 19.0.0 [2014-06-05 20:07:18 - StudentConnect] Refreshing resource folders. [2014-06-05 20:07:18 - StudentConnect] Using default Build Tools revision 19.0.0 [2014-06-05 20:07:18 - StudentConnect] Starting incremental Pre Compiler: Checking resource changes. [2014-06-05 20:07:18 - StudentConnect] Nothing to pre compile! [2014-06-05 20:07:18 - StudentConnect] Starting incremental Package build: Checking resource changes. [2014-06-05 20:07:18 - StudentConnect] Using default Build Tools revision 19.0.0 [2014-06-05 20:07:18 - StudentConnect] Skipping over Post Compiler. [2014-06-05 20:07:20 - StudentConnect] Application already deployed. No need to reinstall. [2014-06-05 20:07:20 - StudentConnect] Starting activity sandhu.student.connect.SplashActivity on device 0f0898b2 [2014-06-05 20:07:21 - StudentConnect] ActivityManager: Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=sandhu.student.connect/.SplashActivity } [2014-06-05 20:07:21 - StudentConnect] ActivityManager: Warning: Activity not started, its current task has been brought to the front After deployed to my phone, it only displays a black screen. I recently implemented a splash screen, but it was working fine before; however I think it might have something to do with the problem. Here are my java and xml files: MainActivity.java package sandhu.student.connect; import android.app.Activity; import android.os.Bundle; import android.view.KeyEvent; import android.view.View; import android.webkit.WebSettings; import android.webkit.WebView; import android.webkit.WebViewClient; public class MainActivity extends Activity { public WebView student_zangle; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); WebView student_zangle = (WebView) findViewById(R.id.student_zangle); student_zangle.loadUrl("https://zangleweb01.clovisusd.k12.ca.us/studentconnect/"); student_zangle.setWebViewClient(new WebViewClient()); student_zangle.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY); WebSettings settings = student_zangle.getSettings(); settings.setJavaScriptEnabled(true); settings.setBuiltInZoomControls(true); settings.setLoadWithOverviewMode(true); settings.setUseWideViewPort(true); } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { WebView student_zangle = (WebView) findViewById(R.id.student_zangle); if ((keyCode == KeyEvent.KEYCODE_BACK) && student_zangle.canGoBack()) { student_zangle.goBack(); return true; } else { finish(); } return super.onKeyDown(keyCode, event); } } activity_main.xml <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/blue" tools:context=".MainActivity" > <WebView android:id="@+id/student_zangle" android:layout_width="match_parent" android:layout_height="match_parent" /> </RelativeLayout> SplashActivity.java package sandhu.student.connect; import android.os.Bundle; import android.preference.PreferenceActivity; public class SplashActivity extends PreferenceActivity { @SuppressWarnings("deprecation") @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); addPreferencesFromResource(R.xml.prefs); } } splash_activity.xml <?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/blue" android:orientation="vertical" > <ImageView android:id="@+id/imageView1" android:layout_width="250dp" android:layout_height="100dp" android:layout_alignParentTop="true" android:layout_centerHorizontal="true" android:layout_marginTop="145dp" android:contentDescription="@string/zangle_logo" android:src="@drawable/logo" /> </RelativeLayout> Also, here is a full copy of the logcat error output: 06-05 20:19:46.698: E/Watchdog(817): !@Sync 1952 06-05 20:20:09.971: E/memtrack(16438): Couldn't load memtrack module (No such file or directory) 06-05 20:20:09.971: E/android.os.Debug(16438): failed to load memtrack module: -2 06-05 20:20:11.012: E/memtrack(16451): Couldn't load memtrack module (No such file or directory) 06-05 20:20:11.012: E/android.os.Debug(16451): failed to load memtrack module: -2 06-05 20:20:11.202: E/EnterpriseContainerManager(817): ContainerPolicy Service is not yet ready!!! Please help me figure out what is wrong, or at least point me in the right direction. Thanks in advance.

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  • WiX 3 Tutorial: Understanding main WXS and WXI file

    - by Mladen Prajdic
    In the previous post we’ve taken a look at the WiX solution/project structure and project properties. We’re still playing with our super SuperForm application and today we’ll take a look at the general parts of the main wxs file, SuperForm.wxs, and the wxi include file. For wxs file we’ll just go over the general description of what each part does in the code comments. The more detailed descriptions will be in future posts about features themselves. WXI include file Include files are exactly what their name implies. To include a wxi file into the wxs file you have to put the wxi at the beginning of each .wxs file you wish to include it in. If you’ve ever worked with C++ you can think of the include files as .h files. For example if you include SuperFormVariables.wxi into the SuperForm.wxs, the variables in the wxi won’t be seen in FilesFragment.wxs or RegistryFragment.wxs. You’d have to include it manually into those two wxs files too. For preprocessor variable $(var.VariableName) to be seen by every file in the project you have to include them in the WiX project properties->Build->“Define preprocessor variables” textbox. This is why I’ve chosen not to go this route because in multi developer teams not everyone has the same directory structure and having a single variable would mean each developer would have to checkout the wixproj file to edit the variable. This is pretty much unacceptable by my standards. This is why we’ve added a System Environment variable named SuperFormFilesDir as is shown in the previous Wix Tutorial post. Because the FilesFragment.wxs is autogenerated on every project build we don’t want to change it manually each time by adding the include wxi at the beginning of the file. This way we couldn’t recreate it in each pre-build event. <?xml version="1.0" encoding="utf-8"?><Include> <!-- Versioning. These have to be changed for upgrades. It's not enough to just include newer files. --> <?define MajorVersion="1" ?> <?define MinorVersion="0" ?> <?define BuildVersion="0" ?> <!-- Revision is NOT used by WiX in the upgrade procedure --> <?define Revision="0" ?> <!-- Full version number to display --> <?define VersionNumber="$(var.MajorVersion).$(var.MinorVersion).$(var.BuildVersion).$(var.Revision)" ?> <!-- Upgrade code HAS to be the same for all updates. Once you've chosen it don't change it. --> <?define UpgradeCode="YOUR-GUID-HERE" ?> <!-- Path to the resources directory. resources don't really need to be included in the project structure but I like to include them for for clarity --> <?define ResourcesDir="$(var.ProjectDir)\Resources" ?> <!-- The name of your application exe file. This will be used to kill the process when updating and creating the desktop shortcut --> <?define ExeProcessName="SuperForm.MainApp.exe" ?></Include> For now there’s no way to tell WiX in Visual Studio to have a wxi include file available to the whole project, so you have to include it in each file separately. Only variables set in “Define preprocessor variables” or System Environment variables are accessible to the whole project for now. The main WXS file: SuperForm.wxs We’ll only take a look at the general structure of the main SuperForm.wxs and not its the details. We’ll cover the details in future posts. The code comments should provide plenty info about what each part does in general. Basically there are 5 major parts. The update part, the conditions and actions part, the UI install sequence, the directory structure and the features we want to include. <?xml version="1.0" encoding="UTF-8"?><!-- Add xmlns:util namespace definition to be able to use stuff from WixUtilExtension dll--><Wix xmlns="http://schemas.microsoft.com/wix/2006/wi" xmlns:util="http://schemas.microsoft.com/wix/UtilExtension"> <!-- This is how we include wxi files --> <?include $(sys.CURRENTDIR)Includes\SuperFormVariables.wxi ?> <!-- Id="*" is to enable upgrading. * means that the product ID will be autogenerated on each build. Name is made of localized product name and version number. --> <Product Id="*" Name="!(loc.ProductName) $(var.VersionNumber)" Language="!(loc.LANG)" Version="$(var.VersionNumber)" Manufacturer="!(loc.ManufacturerName)" UpgradeCode="$(var.UpgradeCode)"> <!-- Define the minimum supported installer version (3.0) and that the install should be done for the whole machine not just the current user --> <Package InstallerVersion="300" Compressed="yes" InstallScope="perMachine"/> <Media Id="1" Cabinet="media1.cab" EmbedCab="yes" /> <!-- Upgrade settings. This will be explained in more detail in a future post --> <Upgrade Id="$(var.UpgradeCode)"> <UpgradeVersion OnlyDetect="yes" Minimum="$(var.VersionNumber)" IncludeMinimum="no" Property="NEWER_VERSION_FOUND" /> <UpgradeVersion Minimum="0.0.0.0" IncludeMinimum="yes" Maximum="$(var.VersionNumber)" IncludeMaximum="no" Property="OLDER_VERSION_FOUND" /> </Upgrade> <!-- Reference the global NETFRAMEWORK35 property to check if it exists --> <PropertyRef Id="NETFRAMEWORK35"/> <!-- Startup conditions that checks if .Net Framework 3.5 is installed or if we're running the OS higher than Windows XP SP2. If not the installation is aborted. By doing the (Installed OR ...) property means that this condition will only be evaluated if the app is being installed and not on uninstall or changing --> <Condition Message="!(loc.DotNetFrameworkNeeded)"> <![CDATA[Installed OR NETFRAMEWORK35]]> </Condition> <Condition Message="!(loc.AppNotSupported)"> <![CDATA[Installed OR ((VersionNT >= 501 AND ServicePackLevel >= 2) OR (VersionNT >= 502))]]> </Condition> <!-- This custom action in the InstallExecuteSequence is needed to stop silent install (passing /qb to msiexec) from going around it. --> <CustomAction Id="NewerVersionFound" Error="!(loc.SuperFormNewerVersionInstalled)" /> <InstallExecuteSequence> <!-- Check for newer versions with FindRelatedProducts and execute the custom action after it --> <Custom Action="NewerVersionFound" After="FindRelatedProducts"> <![CDATA[NEWER_VERSION_FOUND]]> </Custom> <!-- Remove the previous versions of the product --> <RemoveExistingProducts After="InstallInitialize"/> <!-- WixCloseApplications is a built in custom action that uses util:CloseApplication below --> <Custom Action="WixCloseApplications" Before="InstallInitialize" /> </InstallExecuteSequence> <!-- This will ask the user to close the SuperForm app if it's running while upgrading --> <util:CloseApplication Id="CloseSuperForm" CloseMessage="no" Description="!(loc.MustCloseSuperForm)" ElevatedCloseMessage="no" RebootPrompt="no" Target="$(var.ExeProcessName)" /> <!-- Use the built in WixUI_InstallDir GUI --> <UIRef Id="WixUI_InstallDir" /> <UI> <!-- These dialog references are needed for CloseApplication above to work correctly --> <DialogRef Id="FilesInUse" /> <DialogRef Id="MsiRMFilesInUse" /> <!-- Here we'll add the GUI logic for installation and updating in a future post--> </UI> <!-- Set the icon to show next to the program name in Add/Remove programs --> <Icon Id="SuperFormIcon.ico" SourceFile="$(var.ResourcesDir)\Exclam.ico" /> <Property Id="ARPPRODUCTICON" Value="SuperFormIcon.ico" /> <!-- Installer UI custom pictures. File names are made up. Add path to your pics. –> <!-- <WixVariable Id="WixUIDialogBmp" Value="MyAppLogo.jpg" /> <WixVariable Id="WixUIBannerBmp" Value="installBanner.jpg" /> --> <!-- the default directory structure --> <Directory Id="TARGETDIR" Name="SourceDir"> <Directory Id="ProgramFilesFolder"> <Directory Id="INSTALLLOCATION" Name="!(loc.ProductName)" /> </Directory> </Directory> <!-- Set the default install location to the value of INSTALLLOCATION (usually c:\Program Files\YourProductName) --> <Property Id="WIXUI_INSTALLDIR" Value="INSTALLLOCATION" /> <!-- Set the components defined in our fragment files that will be used for our feature --> <Feature Id="SuperFormFeature" Title="!(loc.ProductName)" Level="1"> <ComponentGroupRef Id="SuperFormFiles" /> <ComponentRef Id="cmpVersionInRegistry" /> <ComponentRef Id="cmpIsThisUpdateInRegistry" /> </Feature> </Product></Wix> For more info on what certain attributes mean you should look into the WiX Documentation.   WiX 3 tutorial by Mladen Prajdic navigation WiX 3 Tutorial: Solution/Project structure and Dev resources WiX 3 Tutorial: Understanding main wxs and wxi file WiX 3 Tutorial: Generating file/directory fragments with Heat.exe

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  • Parallelism in .NET – Part 3, Imperative Data Parallelism: Early Termination

    - by Reed
    Although simple data parallelism allows us to easily parallelize many of our iteration statements, there are cases that it does not handle well.  In my previous discussion, I focused on data parallelism with no shared state, and where every element is being processed exactly the same. Unfortunately, there are many common cases where this does not happen.  If we are dealing with a loop that requires early termination, extra care is required when parallelizing. Often, while processing in a loop, once a certain condition is met, it is no longer necessary to continue processing.  This may be a matter of finding a specific element within the collection, or reaching some error case.  The important distinction here is that, it is often impossible to know until runtime, what set of elements needs to be processed. In my initial discussion of data parallelism, I mentioned that this technique is a candidate when you can decompose the problem based on the data involved, and you wish to apply a single operation concurrently on all of the elements of a collection.  This covers many of the potential cases, but sometimes, after processing some of the elements, we need to stop processing. As an example, lets go back to our previous Parallel.ForEach example with contacting a customer.  However, this time, we’ll change the requirements slightly.  In this case, we’ll add an extra condition – if the store is unable to email the customer, we will exit gracefully.  The thinking here, of course, is that if the store is currently unable to email, the next time this operation runs, it will handle the same situation, so we can just skip our processing entirely.  The original, serial case, with this extra condition, might look something like the following: foreach(var customer in customers) { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { // Exit gracefully if we fail to email, since this // entire process can be repeated later without issue. if (theStore.EmailCustomer(customer) == false) break; customer.LastEmailContact = DateTime.Now; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, we’re processing our loop, but at any point, if we fail to send our email successfully, we just abandon this process, and assume that it will get handled correctly the next time our routine is run.  If we try to parallelize this using Parallel.ForEach, as we did previously, we’ll run into an error almost immediately: the break statement we’re using is only valid when enclosed within an iteration statement, such as foreach.  When we switch to Parallel.ForEach, we’re no longer within an iteration statement – we’re a delegate running in a method. This needs to be handled slightly differently when parallelized.  Instead of using the break statement, we need to utilize a new class in the Task Parallel Library: ParallelLoopState.  The ParallelLoopState class is intended to allow concurrently running loop bodies a way to interact with each other, and provides us with a way to break out of a loop.  In order to use this, we will use a different overload of Parallel.ForEach which takes an IEnumerable<T> and an Action<T, ParallelLoopState> instead of an Action<T>.  Using this, we can parallelize the above operation by doing: Parallel.ForEach(customers, (customer, parallelLoopState) => { // Run some process that takes some time... DateTime lastContact = theStore.GetLastContact(customer); TimeSpan timeSinceContact = DateTime.Now - lastContact; // If it's been more than two weeks, send an email, and update... if (timeSinceContact.Days > 14) { // Exit gracefully if we fail to email, since this // entire process can be repeated later without issue. if (theStore.EmailCustomer(customer) == false) parallelLoopState.Break(); else customer.LastEmailContact = DateTime.Now; } }); There are a couple of important points here.  First, we didn’t actually instantiate the ParallelLoopState instance.  It was provided directly to us via the Parallel class.  All we needed to do was change our lambda expression to reflect that we want to use the loop state, and the Parallel class creates an instance for our use.  We also needed to change our logic slightly when we call Break().  Since Break() doesn’t stop the program flow within our block, we needed to add an else case to only set the property in customer when we succeeded.  This same technique can be used to break out of a Parallel.For loop. That being said, there is a huge difference between using ParallelLoopState to cause early termination and to use break in a standard iteration statement.  When dealing with a loop serially, break will immediately terminate the processing within the closest enclosing loop statement.  Calling ParallelLoopState.Break(), however, has a very different behavior. The issue is that, now, we’re no longer processing one element at a time.  If we break in one of our threads, there are other threads that will likely still be executing.  This leads to an important observation about termination of parallel code: Early termination in parallel routines is not immediate.  Code will continue to run after you request a termination. This may seem problematic at first, but it is something you just need to keep in mind while designing your routine.  ParallelLoopState.Break() should be thought of as a request.  We are telling the runtime that no elements that were in the collection past the element we’re currently processing need to be processed, and leaving it up to the runtime to decide how to handle this as gracefully as possible.  Although this may seem problematic at first, it is a good thing.  If the runtime tried to immediately stop processing, many of our elements would be partially processed.  It would be like putting a return statement in a random location throughout our loop body – which could have horrific consequences to our code’s maintainability. In order to understand and effectively write parallel routines, we, as developers, need a subtle, but profound shift in our thinking.  We can no longer think in terms of sequential processes, but rather need to think in terms of requests to the system that may be handled differently than we’d first expect.  This is more natural to developers who have dealt with asynchronous models previously, but is an important distinction when moving to concurrent programming models. As an example, I’ll discuss the Break() method.  ParallelLoopState.Break() functions in a way that may be unexpected at first.  When you call Break() from a loop body, the runtime will continue to process all elements of the collection that were found prior to the element that was being processed when the Break() method was called.  This is done to keep the behavior of the Break() method as close to the behavior of the break statement as possible. We can see the behavior in this simple code: var collection = Enumerable.Range(0, 20); var pResult = Parallel.ForEach(collection, (element, state) => { if (element > 10) { Console.WriteLine("Breaking on {0}", element); state.Break(); } Console.WriteLine(element); }); If we run this, we get a result that may seem unexpected at first: 0 2 1 5 6 3 4 10 Breaking on 11 11 Breaking on 12 12 9 Breaking on 13 13 7 8 Breaking on 15 15 What is occurring here is that we loop until we find the first element where the element is greater than 10.  In this case, this was found, the first time, when one of our threads reached element 11.  It requested that the loop stop by calling Break() at this point.  However, the loop continued processing until all of the elements less than 11 were completed, then terminated.  This means that it will guarantee that elements 9, 7, and 8 are completed before it stops processing.  You can see our other threads that were running each tried to break as well, but since Break() was called on the element with a value of 11, it decides which elements (0-10) must be processed. If this behavior is not desirable, there is another option.  Instead of calling ParallelLoopState.Break(), you can call ParallelLoopState.Stop().  The Stop() method requests that the runtime terminate as soon as possible , without guaranteeing that any other elements are processed.  Stop() will not stop the processing within an element, so elements already being processed will continue to be processed.  It will prevent new elements, even ones found earlier in the collection, from being processed.  Also, when Stop() is called, the ParallelLoopState’s IsStopped property will return true.  This lets longer running processes poll for this value, and return after performing any necessary cleanup. The basic rule of thumb for choosing between Break() and Stop() is the following. Use ParallelLoopState.Stop() when possible, since it terminates more quickly.  This is particularly useful in situations where you are searching for an element or a condition in the collection.  Once you’ve found it, you do not need to do any other processing, so Stop() is more appropriate. Use ParallelLoopState.Break() if you need to more closely match the behavior of the C# break statement. Both methods behave differently than our C# break statement.  Unfortunately, when parallelizing a routine, more thought and care needs to be put into every aspect of your routine than you may otherwise expect.  This is due to my second observation: Parallelizing a routine will almost always change its behavior. This sounds crazy at first, but it’s a concept that’s so simple its easy to forget.  We’re purposely telling the system to process more than one thing at the same time, which means that the sequence in which things get processed is no longer deterministic.  It is easy to change the behavior of your routine in very subtle ways by introducing parallelism.  Often, the changes are not avoidable, even if they don’t have any adverse side effects.  This leads to my final observation for this post: Parallelization is something that should be handled with care and forethought, added by design, and not just introduced casually.

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  • Parallelism in .NET – Part 9, Configuration in PLINQ and TPL

    - by Reed
    Parallel LINQ and the Task Parallel Library contain many options for configuration.  Although the default configuration options are often ideal, there are times when customizing the behavior is desirable.  Both frameworks provide full configuration support. When working with Data Parallelism, there is one primary configuration option we often need to control – the number of threads we want the system to use when parallelizing our routine.  By default, PLINQ and the TPL both use the ThreadPool to schedule tasks.  Given the major improvements in the ThreadPool in CLR 4, this default behavior is often ideal.  However, there are times that the default behavior is not appropriate.  For example, if you are working on multiple threads simultaneously, and want to schedule parallel operations from within both threads, you might want to consider restricting each parallel operation to using a subset of the processing cores of the system.  Not doing this might over-parallelize your routine, which leads to inefficiencies from having too many context switches. In the Task Parallel Library, configuration is handled via the ParallelOptions class.  All of the methods of the Parallel class have an overload which accepts a ParallelOptions argument. We configure the Parallel class by setting the ParallelOptions.MaxDegreeOfParallelism property.  For example, let’s revisit one of the simple data parallel examples from Part 2: Parallel.For(0, pixelData.GetUpperBound(0), row => { for (int col=0; col < pixelData.GetUpperBound(1); ++col) { pixelData[row, col] = AdjustContrast(pixelData[row, col], minPixel, maxPixel); } }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Here, we’re looping through an image, and calling a method on each pixel in the image.  If this was being done on a separate thread, and we knew another thread within our system was going to be doing a similar operation, we likely would want to restrict this to using half of the cores on the system.  This could be accomplished easily by doing: var options = new ParallelOptions(); options.MaxDegreeOfParallelism = Math.Max(Environment.ProcessorCount / 2, 1); Parallel.For(0, pixelData.GetUpperBound(0), options, row => { for (int col=0; col < pixelData.GetUpperBound(1); ++col) { pixelData[row, col] = AdjustContrast(pixelData[row, col], minPixel, maxPixel); } }); Now, we’re restricting this routine to using no more than half the cores in our system.  Note that I included a check to prevent a single core system from supplying zero; without this check, we’d potentially cause an exception.  I also did not hard code a specific value for the MaxDegreeOfParallelism property.  One of our goals when parallelizing a routine is allowing it to scale on better hardware.  Specifying a hard-coded value would contradict that goal. Parallel LINQ also supports configuration, and in fact, has quite a few more options for configuring the system.  The main configuration option we most often need is the same as our TPL option: we need to supply the maximum number of processing threads.  In PLINQ, this is done via a new extension method on ParallelQuery<T>: ParallelEnumerable.WithDegreeOfParallelism. Let’s revisit our declarative data parallelism sample from Part 6: double min = collection.AsParallel().Min(item => item.PerformComputation()); Here, we’re performing a computation on each element in the collection, and saving the minimum value of this operation.  If we wanted to restrict this to a limited number of threads, we would add our new extension method: int maxThreads = Math.Max(Environment.ProcessorCount / 2, 1); double min = collection .AsParallel() .WithDegreeOfParallelism(maxThreads) .Min(item => item.PerformComputation()); This automatically restricts the PLINQ query to half of the threads on the system. PLINQ provides some additional configuration options.  By default, PLINQ will occasionally revert to processing a query in parallel.  This occurs because many queries, if parallelized, typically actually cause an overall slowdown compared to a serial processing equivalent.  By analyzing the “shape” of the query, PLINQ often decides to run a query serially instead of in parallel.  This can occur for (taken from MSDN): Queries that contain a Select, indexed Where, indexed SelectMany, or ElementAt clause after an ordering or filtering operator that has removed or rearranged original indices. Queries that contain a Take, TakeWhile, Skip, SkipWhile operator and where indices in the source sequence are not in the original order. Queries that contain Zip or SequenceEquals, unless one of the data sources has an originally ordered index and the other data source is indexable (i.e. an array or IList(T)). Queries that contain Concat, unless it is applied to indexable data sources. Queries that contain Reverse, unless applied to an indexable data source. If the specific query follows these rules, PLINQ will run the query on a single thread.  However, none of these rules look at the specific work being done in the delegates, only at the “shape” of the query.  There are cases where running in parallel may still be beneficial, even if the shape is one where it typically parallelizes poorly.  In these cases, you can override the default behavior by using the WithExecutionMode extension method.  This would be done like so: var reversed = collection .AsParallel() .WithExecutionMode(ParallelExecutionMode.ForceParallelism) .Select(i => i.PerformComputation()) .Reverse(); Here, the default behavior would be to not parallelize the query unless collection implemented IList<T>.  We can force this to run in parallel by adding the WithExecutionMode extension method in the method chain. Finally, PLINQ has the ability to configure how results are returned.  When a query is filtering or selecting an input collection, the results will need to be streamed back into a single IEnumerable<T> result.  For example, the method above returns a new, reversed collection.  In this case, the processing of the collection will be done in parallel, but the results need to be streamed back to the caller serially, so they can be enumerated on a single thread. This streaming introduces overhead.  IEnumerable<T> isn’t designed with thread safety in mind, so the system needs to handle merging the parallel processes back into a single stream, which introduces synchronization issues.  There are two extremes of how this could be accomplished, but both extremes have disadvantages. The system could watch each thread, and whenever a thread produces a result, take that result and send it back to the caller.  This would mean that the calling thread would have access to the data as soon as data is available, which is the benefit of this approach.  However, it also means that every item is introducing synchronization overhead, since each item needs to be merged individually. On the other extreme, the system could wait until all of the results from all of the threads were ready, then push all of the results back to the calling thread in one shot.  The advantage here is that the least amount of synchronization is added to the system, which means the query will, on a whole, run the fastest.  However, the calling thread will have to wait for all elements to be processed, so this could introduce a long delay between when a parallel query begins and when results are returned. The default behavior in PLINQ is actually between these two extremes.  By default, PLINQ maintains an internal buffer, and chooses an optimal buffer size to maintain.  Query results are accumulated into the buffer, then returned in the IEnumerable<T> result in chunks.  This provides reasonably fast access to the results, as well as good overall throughput, in most scenarios. However, if we know the nature of our algorithm, we may decide we would prefer one of the other extremes.  This can be done by using the WithMergeOptions extension method.  For example, if we know that our PerformComputation() routine is very slow, but also variable in runtime, we may want to retrieve results as they are available, with no bufferring.  This can be done by changing our above routine to: var reversed = collection .AsParallel() .WithExecutionMode(ParallelExecutionMode.ForceParallelism) .WithMergeOptions(ParallelMergeOptions.NotBuffered) .Select(i => i.PerformComputation()) .Reverse(); On the other hand, if are already on a background thread, and we want to allow the system to maximize its speed, we might want to allow the system to fully buffer the results: var reversed = collection .AsParallel() .WithExecutionMode(ParallelExecutionMode.ForceParallelism) .WithMergeOptions(ParallelMergeOptions.FullyBuffered) .Select(i => i.PerformComputation()) .Reverse(); Notice, also, that you can specify multiple configuration options in a parallel query.  By chaining these extension methods together, we generate a query that will always run in parallel, and will always complete before making the results available in our IEnumerable<T>.

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  • Using Durandal to Create Single Page Apps

    - by Stephen.Walther
    A few days ago, I gave a talk on building Single Page Apps on the Microsoft Stack. In that talk, I recommended that people use Knockout, Sammy, and RequireJS to build their presentation layer and use the ASP.NET Web API to expose data from their server. After I gave the talk, several people contacted me and suggested that I investigate a new open-source JavaScript library named Durandal. Durandal stitches together Knockout, Sammy, and RequireJS to make it easier to use these technologies together. In this blog entry, I want to provide a brief walkthrough of using Durandal to create a simple Single Page App. I am going to demonstrate how you can create a simple Movies App which contains (virtual) pages for viewing a list of movies, adding new movies, and viewing movie details. The goal of this blog entry is to give you a sense of what it is like to build apps with Durandal. Installing Durandal First things first. How do you get Durandal? The GitHub project for Durandal is located here: https://github.com/BlueSpire/Durandal The Wiki — located at the GitHub project — contains all of the current documentation for Durandal. Currently, the documentation is a little sparse, but it is enough to get you started. Instead of downloading the Durandal source from GitHub, a better option for getting started with Durandal is to install one of the Durandal NuGet packages. I built the Movies App described in this blog entry by first creating a new ASP.NET MVC 4 Web Application with the Basic Template. Next, I executed the following command from the Package Manager Console: Install-Package Durandal.StarterKit As you can see from the screenshot of the Package Manager Console above, the Durandal Starter Kit package has several dependencies including: · jQuery · Knockout · Sammy · Twitter Bootstrap The Durandal Starter Kit package includes a sample Durandal application. You can get to the Starter Kit app by navigating to the Durandal controller. Unfortunately, when I first tried to run the Starter Kit app, I got an error because the Starter Kit is hard-coded to use a particular version of jQuery which is already out of date. You can fix this issue by modifying the App_Start\DurandalBundleConfig.cs file so it is jQuery version agnostic like this: bundles.Add( new ScriptBundle("~/scripts/vendor") .Include("~/Scripts/jquery-{version}.js") .Include("~/Scripts/knockout-{version}.js") .Include("~/Scripts/sammy-{version}.js") // .Include("~/Scripts/jquery-1.9.0.min.js") // .Include("~/Scripts/knockout-2.2.1.js") // .Include("~/Scripts/sammy-0.7.4.min.js") .Include("~/Scripts/bootstrap.min.js") ); The recommendation is that you create a Durandal app in a folder off your project root named App. The App folder in the Starter Kit contains the following subfolders and files: · durandal – This folder contains the actual durandal JavaScript library. · viewmodels – This folder contains all of your application’s view models. · views – This folder contains all of your application’s views. · main.js — This file contains all of the JavaScript startup code for your app including the client-side routing configuration. · main-built.js – This file contains an optimized version of your application. You need to build this file by using the RequireJS optimizer (unfortunately, before you can run the optimizer, you must first install NodeJS). For the purpose of this blog entry, I wanted to start from scratch when building the Movies app, so I deleted all of these files and folders except for the durandal folder which contains the durandal library. Creating the ASP.NET MVC Controller and View A Durandal app is built using a single server-side ASP.NET MVC controller and ASP.NET MVC view. A Durandal app is a Single Page App. When you navigate between pages, you are not navigating to new pages on the server. Instead, you are loading new virtual pages into the one-and-only-one server-side view. For the Movies app, I created the following ASP.NET MVC Home controller: public class HomeController : Controller { public ActionResult Index() { return View(); } } There is nothing special about the Home controller – it is as basic as it gets. Next, I created the following server-side ASP.NET view. This is the one-and-only server-side view used by the Movies app: @{ Layout = null; } <!DOCTYPE html> <html> <head> <title>Index</title> </head> <body> <div id="applicationHost"> Loading app.... </div> @Scripts.Render("~/scripts/vendor") <script type="text/javascript" src="~/App/durandal/amd/require.js" data-main="/App/main"></script> </body> </html> Notice that I set the Layout property for the view to the value null. If you neglect to do this, then the default ASP.NET MVC layout will be applied to the view and you will get the <!DOCTYPE> and opening and closing <html> tags twice. Next, notice that the view contains a DIV element with the Id applicationHost. This marks the area where virtual pages are loaded. When you navigate from page to page in a Durandal app, HTML page fragments are retrieved from the server and stuck in the applicationHost DIV element. Inside the applicationHost element, you can place any content which you want to display when a Durandal app is starting up. For example, you can create a fancy splash screen. I opted for simply displaying the text “Loading app…”: Next, notice the view above includes a call to the Scripts.Render() helper. This helper renders out all of the JavaScript files required by the Durandal library such as jQuery and Knockout. Remember to fix the App_Start\DurandalBundleConfig.cs as described above or Durandal will attempt to load an old version of jQuery and throw a JavaScript exception and stop working. Your application JavaScript code is not included in the scripts rendered by the Scripts.Render helper. Your application code is loaded dynamically by RequireJS with the help of the following SCRIPT element located at the bottom of the view: <script type="text/javascript" src="~/App/durandal/amd/require.js" data-main="/App/main"></script> The data-main attribute on the SCRIPT element causes RequireJS to load your /app/main.js JavaScript file to kick-off your Durandal app. Creating the Durandal Main.js File The Durandal Main.js JavaScript file, located in your App folder, contains all of the code required to configure the behavior of Durandal. Here’s what the Main.js file looks like in the case of the Movies app: require.config({ paths: { 'text': 'durandal/amd/text' } }); define(function (require) { var app = require('durandal/app'), viewLocator = require('durandal/viewLocator'), system = require('durandal/system'), router = require('durandal/plugins/router'); //>>excludeStart("build", true); system.debug(true); //>>excludeEnd("build"); app.start().then(function () { //Replace 'viewmodels' in the moduleId with 'views' to locate the view. //Look for partial views in a 'views' folder in the root. viewLocator.useConvention(); //configure routing router.useConvention(); router.mapNav("movies/show"); router.mapNav("movies/add"); router.mapNav("movies/details/:id"); app.adaptToDevice(); //Show the app by setting the root view model for our application with a transition. app.setRoot('viewmodels/shell', 'entrance'); }); }); There are three important things to notice about the main.js file above. First, notice that it contains a section which enables debugging which looks like this: //>>excludeStart(“build”, true); system.debug(true); //>>excludeEnd(“build”); This code enables debugging for your Durandal app which is very useful when things go wrong. When you call system.debug(true), Durandal writes out debugging information to your browser JavaScript console. For example, you can use the debugging information to diagnose issues with your client-side routes: (The funny looking //> symbols around the system.debug() call are RequireJS optimizer pragmas). The main.js file is also the place where you configure your client-side routes. In the case of the Movies app, the main.js file is used to configure routes for three page: the movies show, add, and details pages. //configure routing router.useConvention(); router.mapNav("movies/show"); router.mapNav("movies/add"); router.mapNav("movies/details/:id");   The route for movie details includes a route parameter named id. Later, we will use the id parameter to lookup and display the details for the right movie. Finally, the main.js file above contains the following line of code: //Show the app by setting the root view model for our application with a transition. app.setRoot('viewmodels/shell', 'entrance'); This line of code causes Durandal to load up a JavaScript file named shell.js and an HTML fragment named shell.html. I’ll discuss the shell in the next section. Creating the Durandal Shell You can think of the Durandal shell as the layout or master page for a Durandal app. The shell is where you put all of the content which you want to remain constant as a user navigates from virtual page to virtual page. For example, the shell is a great place to put your website logo and navigation links. The Durandal shell is composed from two parts: a JavaScript file and an HTML file. Here’s what the HTML file looks like for the Movies app: <h1>Movies App</h1> <div class="container-fluid page-host"> <!--ko compose: { model: router.activeItem, //wiring the router afterCompose: router.afterCompose, //wiring the router transition:'entrance', //use the 'entrance' transition when switching views cacheViews:true //telling composition to keep views in the dom, and reuse them (only a good idea with singleton view models) }--><!--/ko--> </div> And here is what the JavaScript file looks like: define(function (require) { var router = require('durandal/plugins/router'); return { router: router, activate: function () { return router.activate('movies/show'); } }; }); The JavaScript file contains the view model for the shell. This view model returns the Durandal router so you can access the list of configured routes from your shell. Notice that the JavaScript file includes a function named activate(). This function loads the movies/show page as the first page in the Movies app. If you want to create a different default Durandal page, then pass the name of a different age to the router.activate() method. Creating the Movies Show Page Durandal pages are created out of a view model and a view. The view model contains all of the data and view logic required for the view. The view contains all of the HTML markup for rendering the view model. Let’s start with the movies show page. The movies show page displays a list of movies. The view model for the show page looks like this: define(function (require) { var moviesRepository = require("repositories/moviesRepository"); return { movies: ko.observable(), activate: function() { this.movies(moviesRepository.listMovies()); } }; }); You create a view model by defining a new RequireJS module (see http://requirejs.org). You create a RequireJS module by placing all of your JavaScript code into an anonymous function passed to the RequireJS define() method. A RequireJS module has two parts. You retrieve all of the modules which your module requires at the top of your module. The code above depends on another RequireJS module named repositories/moviesRepository. Next, you return the implementation of your module. The code above returns a JavaScript object which contains a property named movies and a method named activate. The activate() method is a magic method which Durandal calls whenever it activates your view model. Your view model is activated whenever you navigate to a page which uses it. In the code above, the activate() method is used to get the list of movies from the movies repository and assign the list to the view model movies property. The HTML for the movies show page looks like this: <table> <thead> <tr> <th>Title</th><th>Director</th> </tr> </thead> <tbody data-bind="foreach:movies"> <tr> <td data-bind="text:title"></td> <td data-bind="text:director"></td> <td><a data-bind="attr:{href:'#/movies/details/'+id}">Details</a></td> </tr> </tbody> </table> <a href="#/movies/add">Add Movie</a> Notice that this is an HTML fragment. This fragment will be stuffed into the page-host DIV element in the shell.html file which is stuffed, in turn, into the applicationHost DIV element in the server-side MVC view. The HTML markup above contains data-bind attributes used by Knockout to display the list of movies (To learn more about Knockout, visit http://knockoutjs.com). The list of movies from the view model is displayed in an HTML table. Notice that the page includes a link to a page for adding a new movie. The link uses the following URL which starts with a hash: #/movies/add. Because the link starts with a hash, clicking the link does not cause a request back to the server. Instead, you navigate to the movies/add page virtually. Creating the Movies Add Page The movies add page also consists of a view model and view. The add page enables you to add a new movie to the movie database. Here’s the view model for the add page: define(function (require) { var app = require('durandal/app'); var router = require('durandal/plugins/router'); var moviesRepository = require("repositories/moviesRepository"); return { movieToAdd: { title: ko.observable(), director: ko.observable() }, activate: function () { this.movieToAdd.title(""); this.movieToAdd.director(""); this._movieAdded = false; }, canDeactivate: function () { if (this._movieAdded == false) { return app.showMessage('Are you sure you want to leave this page?', 'Navigate', ['Yes', 'No']); } else { return true; } }, addMovie: function () { // Add movie to db moviesRepository.addMovie(ko.toJS(this.movieToAdd)); // flag new movie this._movieAdded = true; // return to list of movies router.navigateTo("#/movies/show"); } }; }); The view model contains one property named movieToAdd which is bound to the add movie form. The view model also has the following three methods: 1. activate() – This method is called by Durandal when you navigate to the add movie page. The activate() method resets the add movie form by clearing out the movie title and director properties. 2. canDeactivate() – This method is called by Durandal when you attempt to navigate away from the add movie page. If you return false then navigation is cancelled. 3. addMovie() – This method executes when the add movie form is submitted. This code adds the new movie to the movie repository. I really like the Durandal canDeactivate() method. In the code above, I use the canDeactivate() method to show a warning to a user if they navigate away from the add movie page – either by clicking the Cancel button or by hitting the browser back button – before submitting the add movie form: The view for the add movie page looks like this: <form data-bind="submit:addMovie"> <fieldset> <legend>Add Movie</legend> <div> <label> Title: <input data-bind="value:movieToAdd.title" required /> </label> </div> <div> <label> Director: <input data-bind="value:movieToAdd.director" required /> </label> </div> <div> <input type="submit" value="Add" /> <a href="#/movies/show">Cancel</a> </div> </fieldset> </form> I am using Knockout to bind the movieToAdd property from the view model to the INPUT elements of the HTML form. Notice that the FORM element includes a data-bind attribute which invokes the addMovie() method from the view model when the HTML form is submitted. Creating the Movies Details Page You navigate to the movies details Page by clicking the Details link which appears next to each movie in the movies show page: The Details links pass the movie ids to the details page: #/movies/details/0 #/movies/details/1 #/movies/details/2 Here’s what the view model for the movies details page looks like: define(function (require) { var router = require('durandal/plugins/router'); var moviesRepository = require("repositories/moviesRepository"); return { movieToShow: { title: ko.observable(), director: ko.observable() }, activate: function (context) { // Grab movie from repository var movie = moviesRepository.getMovie(context.id); // Add to view model this.movieToShow.title(movie.title); this.movieToShow.director(movie.director); } }; }); Notice that the view model activate() method accepts a parameter named context. You can take advantage of the context parameter to retrieve route parameters such as the movie Id. In the code above, the context.id property is used to retrieve the correct movie from the movie repository and the movie is assigned to a property named movieToShow exposed by the view model. The movie details view displays the movieToShow property by taking advantage of Knockout bindings: <div> <h2 data-bind="text:movieToShow.title"></h2> directed by <span data-bind="text:movieToShow.director"></span> </div> Summary The goal of this blog entry was to walkthrough building a simple Single Page App using Durandal and to get a feel for what it is like to use this library. I really like how Durandal stitches together Knockout, Sammy, and RequireJS and establishes patterns for using these libraries to build Single Page Apps. Having a standard pattern which developers on a team can use to build new pages is super valuable. Once you get the hang of it, using Durandal to create new virtual pages is dead simple. Just define a new route, view model, and view and you are done. I also appreciate the fact that Durandal did not attempt to re-invent the wheel and that Durandal leverages existing JavaScript libraries such as Knockout, RequireJS, and Sammy. These existing libraries are powerful libraries and I have already invested a considerable amount of time in learning how to use them. Durandal makes it easier to use these libraries together without losing any of their power. Durandal has some additional interesting features which I have not had a chance to play with yet. For example, you can use the RequireJS optimizer to combine and minify all of a Durandal app’s code. Also, Durandal supports a way to create custom widgets (client-side controls) by composing widgets from a controller and view. You can download the code for the Movies app by clicking the following link (this is a Visual Studio 2012 project): Durandal Movie App

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  • CodePlex Daily Summary for Saturday, February 27, 2010

    CodePlex Daily Summary for Saturday, February 27, 2010New ProjectsASP.NET MVC ScriptBehind: Dynamic, developer & designer friendly script inclusion, compression and optimization for ASP.NET MVCCSLib.Net: CSLib.Net (Common Solutions Library) is yet another library with commonly used utilities, helpers, extensions and etc.DNN Module - Google Analytic Dashboard: Here is a Google Analytic Dashboard DNN Module which contain following sub modules. * Visitors Overview * World Map Overlay * Traf...dotUML: dotUML is a toolkit that enables developers to create and visualize UML diagrams like sequence, use case or component diagrams. EventRegistration: Event Registration ProgramGameStore League Manager: GameStore League Manager makes it easier for gaming store managers to run local leagues for card games, board games and any game where there is a h...GibberIM: GibberIM (Gibberish IM) is yet another Jabber instant messanger implementation.HTTP Compression Library for Heavy Load Web Server: Deflater is a HTTP Compression Library, supporting Deflate (RFC 1950, RFC 1951) and GZip (RFC 1952). It is designed to encode and compress HTML con...HydroLiDAR: This is a research project intended to explore algorithms and techniques for extracting Hydrographic features (rivers, watersheds, ponds, pits, etc...Lan Party Manager: Lan Party ManagerMAPS SQL Analysis Project: This solution demonstrates how to build a Business Intelligence solution on top of the MAPS databaseMMDB Parallax ALM: An open source Application Lifecycle Management (ALM) system, being built by Mike Mooney of MMDB Solutions, as a learning/teaching exercise. MyColorSprite: This Silverlight app is a color selection tool especially great for creating gredient color brushes for the xaml code. It allows a user create/pic...PDF Form Bubble Up: Bubble Up takes PDF Forms stored in SharePoint document libraries and "bubbles up" the data in the PDF Form to the library. This means the data tha...PostBack Blog Engine: A modified Oxite open-source blog engine on top of the DB4O object database engine.Project Otto: A Silverlight Isometric Rendering Engine and Demo GameQFrac: Fraktalų generatorius parašytas naudojant Qt karkasą.RapidIoC: RapidIoC provides lightning fast IoC capabilities including Dependency Injection & AOP. The modular framework will allow for constructor, property,...Shatranj: A WPF / Silverlight based frontend to Huo Chess. This project was conceived as a way to learn key WPF / Silverlight concepts. At the release, it...WHS SkyDrive Backup Add In: This project allows for Windows Home Server to backup selected folders to your free 25GB Live SkyDrive. Simply dump the Home Server Add In, into y...Workflow Type Browser for WF4: This Workflow Type Browser displays type information for all arguments and variables in a WF4 workflow. It is designed for use in a rehosted desig...ZoomBarPlus: Windows Mobile Service designed for the HTC Touch Pro 2. Adds additional functionality to the zoom bar at the bottom of the screen. You can map key...New ReleasesBCryptTool: BCryptTool v0.2: The Microsoft .NET Framework 3.5 (SP1) is needed to run this program.Braintree Client Library: Braintree-1.1.1: Braintree-1.1.1CC.Utilities: CC.Utilities 1.0.10.226: Minor bug fixes. A few new functions in the Interop namespace. DoubleBufferedGraphics now exposes the underlying memory Image through the Mem...CC.Votd: CC.Votd 1.0.10.227: This release includes several bug fixes and enchancements. The most notable enhancement is the RssItemCache which will allow the screensaver to f...DNN Module - Google Analytic Dashboard: DNN Module - Google Analytic Dashboard: Here is a Google Analytic Dashboard DNN Module which contain following sub modules. * Visitors Overview * World Map Overlay * Traffic ...Extend SmallBasic: Teaching Extensions v.008: Fixed Message Box to appear in front as expected. Added ColorWheel.getRandomColor() Including Recipes and Concept slides as part of releaseFolderSize: FolderSize.Win32.1.0.5.0: FolderSize.Win32.1.0.5.0 A simple utility intended to be used to scan harddrives for the folders that take most place and display this to the user...Free Silverlight & WPF Chart Control - Visifire: Visifire SL and WPF Charts 3.0.4 beta Released: Hi, Today we are releasing the much awaited Zooming feature. In this version of Zooming you will be able to zoom/scale the PlotArea of the chart. ...GameStore League Manager: League Manager 1.0: Rough and ready first version. You will need to have SQL Server Express 2005 or 2008 installed on your machine to use this software. Unzip to a l...Google Maps API 3 Visual Studio Intellisense: google-maps-3-vs-1-0-vsdoc: google-maps-3-vs-1-0 provides Visual Studio intellisense in-line api documentation and code completion for Google Maps API V3. Updated 02/25/10 A...HaoRan_WebCam: HaoRan.WebCam.Web beta2: 在年前发布的那一版基于silverlight4(beta)版的摄像头应用之后。经过最近一段时间的完善。目前已推出了beta2版,在修改了原有程序bug的基础上,做了如下变化: 1.将图片载入修改成为按原图宽高比进行缩放,所以以前沿X,Y轴变化就变成了一个缩放条同比例变化了。 ...IQToolkit Contrib: IQToolkitContrib.zip (v1.0.17.1): Update to DataServiceClientRepository - added ExecuteNonEntity to deal with calling Wcf Data Service methods for Dto classes (opposed to Entity cla...kdar: KDAR 0.0.15: KDAR - Kernel Debugger Anti Rootkit - new module cheks added - bugs fixedLogJoint - Log Viewer: logjoint 1.5: - Added support for more formats - Timeline improvement - Unicode logs and encodings supportMyColorSprite: MyColorSprite: MyColorSprite This Silverlight app is a color selection tool especially great for creating gredient color brushes for the xaml code. It allows a ...OAuthLib: OAuthLib (1.6.0.1): Difference between 1.6.0.0 is just version number.Picasa Downloader: PicasaDownloader Setup (41085): Changelog: Fixed workitem 10296 (Saving at resolutions above 1600px), Added experimental support for a modifier of the image download url (inse...Prolog.NET: Prolog.NET 1.0 Beta 1.1: Installer includes: primary Prolog.NET assembly Prolog.NET Workbench PrologTest console application all required dependencies Beta 1.1 in...QFrac: QFrac 1.0: Pirmoji stabili QFrac versija.SharepointApplicationFramework: SAF QuickPoll: Release Notes: This web part is written in VS2010 beta2 and uses Microsoft Chart Controls. Packaged into a single WSP. This wsp creates a quick po...Star System Simulator: Star System Simulator 2.2: An minor update to Version 2.1. Changes in this release: User interface enhancements/fixes with toolbar and icons. Features in this release: Mod...ToDoListReminder: Version 1.0.1.0: Bugs fixed: 10316, 10317 Handler for "Window Closing" event was added Error handling for XML parsing was addedVCC: Latest build, v2.1.30226.0: Automatic drop of latest buildWindows Remote Assistance For Skype: Beta 1.0.1: Major changes: 1) Now using Skype4COM to interact with Skype 2) InvitationXML is compressed 3) Showing warning on first run to Allow Access to SkypeWorkflow Type Browser for WF4: Release 1.0: There has been much surprise and disappointment expressed by the WF4 developer community since Microsoft made it clear that Intellisense woould not...Most Popular ProjectsData Dictionary CreatorOutlook 2007 Messaging API (MAPI) Code SamplesCommon Data Parameters ModuleTeam System - Work Item Spell Checker (All Languages)Tyrannt Online (Client/Server RPG)Ray Tracer StarterMeeting DemoNick BerardiScreenslayerRawrMost Active ProjectsDinnerNow.netRawrBlogEngine.NETMapWindow GISSLARToolkit - Silverlight Augmented Reality ToolkitInfoServiceSharpMap - Geospatial Application Framework for the CLRCommon Context Adapterspatterns & practices – Enterprise LibraryNB_Store - Free DotNetNuke Ecommerce Catalog Module

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  • Building a Windows Phone 7 Twitter Application using Silverlight

    - by ScottGu
    On Monday I had the opportunity to present the MIX 2010 Day 1 Keynote in Las Vegas (you can watch a video of it here).  In the keynote I announced the release of the Silverlight 4 Release Candidate (we’ll ship the final release of it next month) and the VS 2010 RC tools for Silverlight 4.  I also had the chance to talk for the first time about how Silverlight and XNA can now be used to build Windows Phone 7 applications. During my talk I did two quick Windows Phone 7 coding demos using Silverlight – a quick “Hello World” application and a “Twitter” data-snacking application.  Both applications were easy to build and only took a few minutes to create on stage.  Below are the steps you can follow yourself to build them on your own machines as well. [Note: In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] Building a “Hello World” Windows Phone 7 Application First make sure you’ve installed the Windows Phone Developer Tools CTP – this includes the Visual Studio 2010 Express for Windows Phone development tool (which will be free forever and is the only thing you need to develop and build Windows Phone 7 applications) as well as an add-on to the VS 2010 RC that enables phone development within the full VS 2010 as well. After you’ve downloaded and installed the Windows Phone Developer Tools CTP, launch the Visual Studio 2010 Express for Windows Phone that it installs or launch the VS 2010 RC (if you have it already installed), and then choose “File”->”New Project.”  Here, you’ll find the usual list of project template types along with a new category: “Silverlight for Windows Phone”. The first CTP offers two application project templates. The first is the “Windows Phone Application” template - this is what we’ll use for this example. The second is the “Windows Phone List Application” template - which provides the basic layout for a master-details phone application: After creating a new project, you’ll get a view of the design surface and markup. Notice that the design surface shows the phone UI, letting you easily see how your application will look while you develop. For those familiar with Visual Studio, you’ll also find the familiar ToolBox, Solution Explorer and Properties pane. For our HelloWorld application, we’ll start out by adding a TextBox and a Button from the Toolbox. Notice that you get the same design experience as you do for Silverlight on the web or desktop. You can easily resize, position and align your controls on the design surface. Changing properties is easy with the Properties pane. We’ll change the name of the TextBox that we added to username and change the page title text to “Hello world.” We’ll then write some code by double-clicking on the button and create an event handler in the code-behind file (MainPage.xaml.cs). We’ll start out by changing the title text of the application. The project template included this title as a TextBlock with the name textBlockListTitle (note that the current name incorrectly includes the word “list”; that will be fixed for the final release.)  As we write code against it we get intellisense showing the members available.  Below we’ll set the Text property of the title TextBlock to “Hello “ + the Text property of the TextBox username: We now have all the code necessary for a Hello World application.  We have two choices when it comes to deploying and running the application. We can either deploy to an actual device itself or use the built-in phone emulator: Because the phone emulator is actually the phone operating system running in a virtual machine, we’ll get the same experience developing in the emulator as on the device. For this sample, we’ll just press F5 to start the application with debugging using the emulator.  Once the phone operating system loads, the emulator will run the new “Hello world” application exactly as it would on the device: Notice that we can change several settings of the emulator experience with the emulator toolbar – which is a floating toolbar on the top right.  This includes the ability to re-size/zoom the emulator and two rotate buttons.  Zoom lets us zoom into even the smallest detail of the application: The orientation buttons allow us easily see what the application looks like in landscape mode (orientation change support is just built into the default template): Note that the emulator can be reused across F5 debug sessions - that means that we don’t have to start the emulator for every deployment. We’ve added a dialog that will help you from accidentally shutting down the emulator if you want to reuse it.  Launching an application on an already running emulator should only take ~3 seconds to deploy and run. Within our Hello World application we’ll click the “username” textbox to give it focus.  This will cause the software input panel (SIP) to open up automatically.  We can either type a message or – since we are using the emulator – just type in text.  Note that the emulator works with Windows 7 multi-touch so, if you have a touchscreen, you can see how interaction will feel on a device just by pressing the screen. We’ll enter “MIX 10” in the textbox and then click the button – this will cause the title to update to be “Hello MIX 10”: We provide the same Visual Studio experience when developing for the phone as other .NET applications. This means that we can set a breakpoint within the button event handler, press the button again and have it break within the debugger: Building a “Twitter” Windows Phone 7 Application using Silverlight Rather than just stop with “Hello World” let’s keep going and evolve it to be a basic Twitter client application. We’ll return to the design surface and add a ListBox, using the snaplines within the designer to fit it to the device screen and make the best use of phone screen real estate.  We’ll also rename the Button “Lookup”: We’ll then return to the Button event handler in Main.xaml.cs, and remove the original “Hello World” line of code and take advantage of the WebClient networking class to asynchronously download a Twitter feed. This takes three lines of code in total: (1) declaring and creating the WebClient, (2) attaching an event handler and then (3) calling the asynchronous DownloadStringAsync method. In the DownloadStringAsync call, we’ll pass a Twitter Uri plus a query string which pulls the text from the “username” TextBox. This feed will pull down the respective user’s most frequent posts in an XML format. When the call completes, the DownloadStringCompleted event is fired and our generated event handler twitter_DownloadStringCompleted will be called: The result returned from the Twitter call will come back in an XML based format.  To parse this we’ll use LINQ to XML. LINQ to XML lets us create simple queries for accessing data in an xml feed. To use this library, we’ll first need to add a reference to the assembly (right click on the References folder in the solution explorer and choose “Add Reference): We’ll then add a “using System.Xml.Linq” namespace reference at the top of the code-behind file at the top of Main.xaml.cs file: We’ll then add a simple helper class called TwitterItem to our project. TwitterItem has three string members – UserName, Message and ImageSource: We’ll then implement the twitter_DownloadStringCompleted event handler and use LINQ to XML to parse the returned XML string from Twitter.  What the query is doing is pulling out the three key pieces of information for each Twitter post from the username we passed as the query string. These are the ImageSource for their profile image, the Message of their tweet and their UserName. For each Tweet in the XML, we are creating a new TwitterItem in the IEnumerable<XElement> returned by the Linq query.  We then assign the generated TwitterItem sequence to the ListBox’s ItemsSource property: We’ll then do one more step to complete the application. In the Main.xaml file, we’ll add an ItemTemplate to the ListBox. For the demo, I used a simple template that uses databinding to show the user’s profile image, their tweet and their username. <ListBox Height="521" HorizonalAlignment="Left" Margin="0,131,0,0" Name="listBox1" VerticalAlignment="Top" Width="476"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel Orientation="Horizontal" Height="132"> <Image Source="{Binding ImageSource}" Height="73" Width="73" VerticalAlignment="Top" Margin="0,10,8,0"/> <StackPanel Width="370"> <TextBlock Text="{Binding UserName}" Foreground="#FFC8AB14" FontSize="28" /> <TextBlock Text="{Binding Message}" TextWrapping="Wrap" FontSize="24" /> </StackPanel> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> Now, pressing F5 again, we are able to reuse the emulator and re-run the application. Once the application has launched, we can type in a Twitter username and press the  Button to see the results. Try my Twitter user name (scottgu) and you’ll get back a result of TwitterItems in the Listbox: Try using the mouse (or if you have a touchscreen device your finger) to scroll the items in the Listbox – you should find that they move very fast within the emulator.  This is because the emulator is hardware accelerated – and so gives you the same fast performance that you get on the actual phone hardware. Summary Silverlight and the VS 2010 Tools for Windows Phone (and the corresponding Expression Blend Tools for Windows Phone) make building Windows Phone applications both really easy and fun.  At MIX this week a number of great partners (including Netflix, FourSquare, Seesmic, Shazaam, Major League Soccer, Graphic.ly, Associated Press, Jackson Fish and more) showed off some killer application prototypes they’ve built over the last few weeks.  You can watch my full day 1 keynote to see them in action. I think they start to show some of the promise and potential of using Silverlight with Windows Phone 7.  I’ll be doing more blog posts in the weeks and months ahead that cover that more. Hope this helps, Scott

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  • CodePlex Daily Summary for Friday, December 17, 2010

    CodePlex Daily Summary for Friday, December 17, 2010Popular ReleasesVCC: Latest build, v2.1.31217.1: Automatic drop of latest buildBCrypt.Net: BCrypt.Net R4: Fixed a integer overflow at workFactor = 31LiveChat Starter Kit: LCSK v1.0: This is a working version of the LCSK for Visual Studio 2010, ASP.NET MVC 3 (using Razor View Engine). this is still provider based (with 1 provider Sql) and this is still using WebService and Windows Forms operator console. The solution is cleaner, with an installer to create tables etc. Let me know your feedbackOrchard Project: Orchard 0.9: Orchard Release Notes Build: 0.9.253 Published: 12/16/2010 How to Install OrchardTo install the Orchard tech preview using Web PI, follow these instructions: http://www.orchardproject.net/docs/Installing-Orchard-Using-Web-PI.ashx Web PI will detect your hardware environment and install the application. --OR-- Alternatively, to install the release manually, download the Orchard.Web.0.9.253.zip file. The zip contents are pre-built and ready-to-run. Simply extract the contents of the Orch...SharpDropBox Client for .NET: WP7 SharpDropBox Client - 0.1 Technology Preview: I decided to go ahead and release this. It works well for simple browsing folder structure/downloading files (and login works). See samples for an example of how to use it. I am in progress with a couple other methods which aren't currently working.SQL Monitor: SQL Monitor 2.9: 1. automatically set sql for new query if a object is selected(table/sp/function/view)SplendidCRM: SplendidCRM 5.0 Community Edition: SplendidCRM Software has adopted the GNU Affero General Public License Version 3 (AGPLv3) for its Community Edition. This release includes the full set of SQL source code in the Community Edition, something that was previously only available in the Professional and Enterprise Editions. An article on the subject of Commercial Open-Source licensing has been posted at http://www.codeproject.com/KB/architecture/splendid-guide-article6.aspx.DotSpatial: DotSpatial 12-15-2010: This release contains a few minor bug fixes and hopefully the GDAL libraries for the 3.5 x86 build actually built to the correct directory this time.DotNetNuke® Community Edition: 05.06.01 Beta: This is the initial Beta of DotNetNuke 5.6.1. See the DotNetNuke Roadmap a full list of changes in this release.MSBuild Extension Pack: December 2010: Release Blog Post The MSBuild Extension Pack December 2010 release provides a collection of over 380 MSBuild tasks. A high level summary of what the tasks currently cover includes the following: System Items: Active Directory, Certificates, COM+, Console, Date and Time, Drives, Environment Variables, Event Logs, Files and Folders, FTP, GAC, Network, Performance Counters, Registry, Services, Sound Code: Assemblies, AsyncExec, CAB Files, Code Signing, DynamicExecute, File Detokenisation, GU...Access Control Service Samples and Documentation (Labs): Samples-R3: Contains latest ACS samples (corresponding to R3 release) that show how to integrate ACS with web services, ASP.NET websites (Web Forms and MVC) and on how to interact with the ACS Management Service. The Readmes for these samples are available here.TweetSharp: TweetSharp v2.0.0.0 - Preview 5: Documentation for this release may be found at http://tweetsharp.codeplex.com/wikipage?title=UserGuide&referringTitle=Documentation. Note: This code is currently preview quality. Preview 5 ChangesMaintenance release with user reported fixes Preview 4 ChangesReintroduced fluent interface support via satellite assembly Added entities support, entity segmentation, and ITweetable/ITweeter interfaces for client development Numerous fixes reported by preview users Preview 3 ChangesNumerous ...EnhSim: EnhSim 2.2.2 ALPHA: 2.2.2 ALPHAThis release adds in the changes for 4.03a at level 85 To use this release, you must have the Microsoft Visual C++ 2010 Redistributable Package installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=A7B7A05E-6DE6-4D3A-A423-37BF0912DB84 To use the GUI you must have the .NET 4.0 Framework installed. This can be downloaded from http://www.microsoft.com/downloads/en/details.aspx?FamilyID=9cfb2d51-5ff4-4491-b0e5-b386f32c0992 - The spirit ...Silverlight Contrib: Silverlight Contrib 2010.1.0: 2010.1.0 New FeaturesCompatibility Release for Silverlight 4 and Visual Studio 2010FlickrNet API Library: 3.1.4000: Newest release. Now contains dedicated Windows Phone 7 DLL as well as all previous DLLs. Also contains Windows Help file documentation now as standard.mojoPortal: 2.3.5.8: see release notes on mojoportal.com http://www.mojoportal.com/mojoportal-2358-released.aspx Note that we have separate deployment packages for .NET 3.5 and .NET 4.0 The deployment package downloads on this page are pre-compiled and ready for production deployment, they contain no C# source code. To download the source code see the Source Code Tab I recommend getting the latest source code using TortoiseHG, you can get the source code corresponding to this release here.Microsoft All-In-One Code Framework: Visual Studio 2010 Code Samples 2010-12-13: Code samples for Visual Studio 2010SuperWebSocket: SuperWebSocket Drop 2: Changes: based on SuperSocket 1.3 supported sub protocol supported SSL/TLS encryption (wss) in Sync socket mode fixed some data communication bugsWii Backup Fusion: Wii Backup Fusion 0.9 Beta: - Aqua or brushed metal style for Mac OS X - Shows selection count beside ID - Game list selection mode via settings - Compare Files <-> WBFS game lists - Verify game images/DVD/WBFS - WIT command line for log (via settings) - Cancel possibility for loading games process - Progress infos while loading games - Localization for dates - UTF-8 support - Shortcuts added - View game infos in browser - Transfer infos for log - All transfer routines rewritten - Extract image from image/WBFS - Support....NETTER Code Starter Pack: v1.0.beta: '.NETTER Code Starter Pack ' contains a gallery of Visual Studio 2010 solutions leveraging latest and new technologies and frameworks based on Microsoft .NET Framework. Each Visual Studio solution included here is focused to provide a very simple starting point for cutting edge development technologies and framework, using well known Northwind database (for database driven scenarios). The current release of this project includes starter samples for the following technologies: ASP.NET Dynamic...New ProjectsaoleFilter: This is a Filter by MagicshuiChocottone: Simple to-do listData Access Engine (DAE): Data Access Engine (DAE) is an open source and free .NET component to access all popular DBMSs such as Microsoft SQL Server, MySQL, Oracle, Microsoft Access, SQLite and databases that connected by ODBC. DAE helps to connect different DBMSs at the same time. DependencyEvaluation: Programmatically sort your objects based on dependencies. Would work as a compiler framework, project planning, data binding, etc.Doc2Text Converter: A converter that can convert document files(like .doc,.ppt,and .pdf) to plain text.Dynamics AX Test Runner for Visual Studio 2010: Invoke Dynamics AX Test cases from within Visual Studio 2010 and retrieve the results.ExtensibleExtensions: Pack of extensions, firstly text utilities like pluralize, capitalize will be included.FluentHttp: .NET fluent api wrapper for creating restful web requests.K:L:O:N:K Updater Service: The K:L:O:N:K Updater Service is a deployment tool which can be used to deploy Microsoft Installer (msi ), zip or other file formats. A directory is setup to be the deployment directory. Put files into this directory and the packages are distributed and installed at clients.Keyki: my code repositoryLED Editor: Simple project for editing a LED sequence ...Maui: SchedulerMcAfee Vulnerability Manager - Delta Report: Processes two .CSV files generated by McAfee Vulnerability Manager to highlight which vulnerabilities were patched or are still outstanding.milkway Project: A java web project under Spring. Galaxy is an enterprise wiki system.Minecraft Save Wizard: Do you like minecraft ? Do you like it so much that you wish there were more worlds ? Well now you can have as many worlds as you desire. Simply move them to and from your saves folder to a backup folder using this software. It couldn't be simpler ;)Minis Manager: A manager for miniature figures to use for rpgs etc.Model2Form: An ASP.NET Control similar to GridView but it auto builds a Web From in run-time by binding a Model. OBD C# Wrapper: OBD C# Wrapper I want to help peaople to get data from an OBD system. The idea is to create a C# class with preconfigured methods for load values and for use them in a GUI. With this class people have to focalized on the GUI design and not on the interface with OBD.Opalis Extension Local Group and User Management: A Opalis Integration pack allowing for management of local computer groups and users.Opalis Integration Pack: VMWare VSphere: An integration Pack for Opalis. Extending Opalis to integrate fully with VMWare. Built using the Vmware Powershell CMDLets wrapped in C#.Opalis Utilities: An integration pack for Opalis. Extending Opalis to provide some addition UtilitiesOrchard Maps: A Maps module for OrchardOur ICProject: IC 2011 projectpatterns & practices: Project Silk: Project Silk provides guidance and sample implementations that describe and illustrate recommended practices for building next generation web applications using web technologies like HTML5, jQuery, CSS3 and IE9. pianduan: ????pob: xna game in developmentpscommand Firefox Extension: A Firefox extension which allows user to invoke PowerShell commands on links.R.NET: R.NET enables .NET Framework to collaborate with R statistical computing. R.NET requires .NET Framework 4 and R.dll. You already have the DLL in the `bin' folder if you installed R environment, and you need no other extra installations. R.NET is developed in C#.Rough Set tool set: Rough Set Tool SetSerial Port Terminal (SPTerm): Serial Port Terminal (SPTerm) is used for basic communication using serial port (com). Sending bytes and ASCII from PC can be done using SPTerm. It is useful for micro controller projects for UART and simple transmission. Hex data can be sent out directly from text box in SPTermSLGame: NullThe Jumping Point: TJP is a 2 player sidescroller based on SFML. TJP is developed in C++ and will be available for both linux and windows.UIT CRM: Ð? án môn h?c Qu?n lý d? án CNTT c?a nhóm. (tru?ng ÐH CNTT - ÐHQG TpHCM)

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  • Ada and 'The Book'

    - by Phil Factor
    The long friendship between Charles Babbage and Ada Lovelace created one of the most exciting and mysterious of collaborations ever to have resulted in a technological breakthrough. The fireworks that created by the collision of two prodigious mathematical and creative talents resulted in an invention, the Analytical Engine, which went on to change society fundamentally. However, beyond that, we just don't know what the bulk of their collaborative work was about:;  it was done in strictest secrecy. Even the known outcome of their friendship, the first programmable computer, was shrouded in mystery. At the time, nobody, except close friends and family, had any idea of Ada Byron's contribution to the invention of the ‘Engine’, and how to program it. Her great insight was published in August 1843, under the initials AAL, standing for Ada Augusta Lovelace, her title then being the Countess of Lovelace. It was contained in a lengthy ‘note’ to her translation of a publication that remains the best description of Babbage's amazing Analytical Engine. The secret identity of the person behind those enigmatic initials was finally revealed by Prince de Polignac who, seventy years later, wrote to Ada's daughter to seek confirmation that her mother had, indeed, been the author of the brilliant sentences that described so accurately how Babbage's mechanical computer could be programmed with punch-cards. L.F. Menabrea's paper on the Analytical Engine first appeared in the 'Bibliotheque Universelle de Geneve' in October 1842, and Ada translated it anonymously for Taylor's 'Scientific Memoirs'. Charles Babbage was surprised that she had not written an original paper as she already knew a surprising amount about the way the machine worked. He persuaded her to at least write some explanatory notes. These notes ended up extending to four times the length of the original article and represented the first published account of how a machine could be programmed to perform any calculation. Her example of programming the Bernoulli sequence would have worked on the Analytical engine had the device’s construction been completed, and gave Ada an unassailable claim to have invented the art of programming. What was the reason for Ada's secrecy? She was the only legitimate child of Lord Byron, who was probably the best known celebrity of the age, so she was already famous. She was a senior aristocrat, with titles, a fortune in money and vast estates in the Midlands. She had political influence, and was the cousin of Lord Melbourne, who was the Prime Minister at that time. She was friendly with the young Queen Victoria. Her mathematical activities were a pastime, and not one that would be considered by others to be in keeping with her roles and responsibilities. You wouldn't dare to dream up a fictional heroine like Ada. She was dazzlingly beautiful and talented. She could speak several languages fluently, and play some musical instruments with professional skill. Contemporary accounts refer to her being 'accomplished in science, art and literature'. On top of that, she was a brilliant mathematician, a talent inherited from her mother, Annabella Milbanke. In her mother's circle of literary and scientific friends was Charles Babbage, and Ada's friendship with him dates from her teenage zest for Mathematics. She was one of the first people he'd ever met who understood what he had attempted to achieve with the 'Difference Engine', and with whom he could converse as intellectual equals. He arranged for her to have an education from the most talented academics in the country. Ada melted the heart of the cantankerous genius to the point that he became a faithful and loyal father-figure to her. She was one of the very few who could grasp the principles of the later, and very different, ‘Analytical Engine’ which was designed from the start to tackle a variety of tasks. Sadly, Ada Byron's life ended less than a decade after completing the work that assured her long-term fame, in November 1852. She was dying of cancer, her gambling habits had caused her to run up huge debts, she'd had more than one affairs, and she was being blackmailed. Her brilliant but unempathic mother was nursing her in her final illness, destroying her personal letters and records, and repaying her debts. Her husband was distraught but helpless. Charles Babbage, however, maintained his steadfast paternalistic friendship to the end. She appointed her loyal friend to be her executor. For years, she and Babbage had been working together on a secret project, known only as 'The Book'. We have a clue to what it was in a letter written by her nine years earlier, on 11th August 1843. It was a joint project by herself and Lord Lovelace, her husband, and was intended to involve Babbage's 'undivided energies'. It involved 'consulting your Engine' (it required Babbage’s computer). The letter gives no hint about the project except for the high-minded nature of its purpose, and its highly mathematical nature.  From then on, the surviving correspondence between the two gives only veiled references to 'The Book'. There isn't much, since Babbage later destroyed any letters that could have damaged her reputation within the Establishment. 'I cannot spare the book today, which I am very sorry for. At the moment I want it for constant reference, but I think you can have it tomorrow' (Oct 1844)  And 'I will send you the book directly, and you can say, when you receive it, how long you will want to keep it'. (Nov 1844)  The two of them were obviously intent on the work: She writes, four years later, 'I have an engagement for Wednesday which will prevent me from attending to your wishes about the book' (Dec 1848). This was something that they both needed to work on, but could not do in parallel: 'I will send the book on Tuesday, and it can be left with you till Friday' (11 Feb 1849). After six years work, it had been so well-handled that it was beginning to fall apart: 'Don't forget the new cover you promised for the book. The poor book is very shabby and wants one' (20 Sept 1849). So what was going on? The word 'book' was not a code-word: it was a real book, probably a 'printer's blank', plain paper, but properly bound so printers and publishers could show off how the published work might look. The hints from the correspondence are of advanced mathematics. It is obvious that the book was travelling between them, back and forth, each one working on it for less than a week before passing it back. Ada and her husband were certainly involved in gambling large sums of money on the horses, and so most biographers have concluded that the three of them were trying to calculate the mathematical odds on the horses. This theory has three large problems. Firstly, Ada's original letter proposing the project refers to its high-minded nature. Babbage was temperamentally opposed to gambling and would scarcely have given so much time to the project, even though he was devoted to Ada. Secondly, Babbage would have very soon have realized the hopelessness of trying to beat the bookies. This sort of betting never attracts his type of intellectual background. The third problem is that any work on calculating the odds on horses would not need a well-thumbed book to pass back and forth between them; they would have not had to work in series. The original project was instigated by Ada, along with her husband, William King-Noel, 1st Earl of Lovelace. Charles Babbage was invited to join the project after the couple had come up with the idea. What could William have contributed? One might assume that William was a Bertie Wooster character, addicted only to the joys of the turf, but this was far from the truth. He was a scientist, a Cambridge graduate who was later elected to be a Fellow of the Royal Society. After Eton, he went to Trinity College, Cambridge. On graduation, he entered the diplomatic service and acted as secretary under Lord Nugent, who was Lord Commissioner of the Ionian Islands. William was very friendly with Babbage too, able to discuss scientific matters on equal terms. He was a capable engineer who invented a process for bending large timbers by the application of steam heat. He delivered a paper to the Institution of Civil Engineers in 1849, and received praise from the great engineer, Isambard Kingdom Brunel. As well as being Lord Lieutenant of the County of Surrey for most of Victoria's reign, he had time for a string of scientific and engineering achievements. Whatever the project was, it is unlikely that William was a junior partner. After Ada's death, the project disappeared. Then, two years later, Babbage, through one of his occasional outbursts of temper, demonstrated that he was able to decrypt one of the most powerful of secret codes, Vigenère's autokey cipher.  All contemporary diplomatic and military messages used a variant of this cipher. Babbage had made three important discoveries, namely, the mathematical law of this cipher, the principle of the key periodicity, and the technique of the symmetry of position. The technique is now known as the Kasiski examination, also called the Kasiski test, but Babbage got there first. At one time, he listed amongst his future projects, the writing of a book 'The Philosophy of Decyphering', but it never came to anything. This discovery was going to change the course of history, since it was used to decipher the Russians’ military dispatches in the Crimean war. Babbage himself played a role during the Crimean War as a cryptographical adviser to his friend, Rear-Admiral Sir Francis Beaufort of the Admiralty. This is as much as we can be certain about in trying to make sense of the bulk of the time that Charles Babbage and Ada Lovelace worked together. Nine years of intensive work, involving the 'Engine' and a great deal of mathematics and research seems to have been lost: or has it? I've argued in the past http://www.simple-talk.com/community/blogs/philfactor/archive/2008/06/13/59614.aspx that the cracking of the Vigenère autokey cipher, was a fundamental motive behind the British Government's support and funding of the 'Difference Engine'. The Duke of Wellington, whose understanding of the military significance of being able to read enemy dispatches, was the most steadfast advocate of the project. If the three friends were actually doing the work of cracking codes by mathematical techniques that used the techniques of key periodicity, and symmetry of position (the use of a book being passed quickly to and fro is very suggestive), intending to then use the 'Engine' to do the routine cracking of each dispatch, then this is a rather different story. The project was Ada and William's idea. (William had served in the diplomatic service and would be familiar with the use of codes). This makes Ada Lovelace the initiator of a project which, by giving both Britain, and probably the USA, a diplomatic and military advantage in the second part of the Nineteenth century, changed world history. Ada would never have wanted any credit for cracking the cipher, and developing the method that rendered all contemporary military and diplomatic ciphering techniques nugatory; quite the reverse. And it is clear from the gaps in the record of the letters between the collaborators that the evidence was destroyed, probably on her request by her irascible but intensely honorable executor, Charles Babbage. Charles Babbage toyed with the idea of going public, but the Crimean war put an end to that. The British Government had a valuable secret, and intended to keep it that way. Ada and Charles had quite often discussed possible moneymaking projects that would fund the development of the Analytic Engine, the first programmable computer, but their secret work was never in the running as a potential cash cow. I suspect that the British Government was, even then, working on the concealment of a discovery whose value to the nation depended on it remaining so. The success of code-breaking in the Crimean war, and the American Civil war, led to the British and Americans  subsequently giving much more weight and funding to the science of decryption. Paradoxically, this makes Ada's contribution even closer to the creation of Colossus, the first digital computer, at Bletchley Park, specifically to crack the Nazi’s secret codes.

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  • [GEEK SCHOOL] Network Security 1: Securing User Accounts and Passwords in Windows

    - by Matt Klein
    This How-To Geek School class is intended for people who want to learn more about security when using Windows operating systems. You will learn many principles that will help you have a more secure computing experience and will get the chance to use all the important security tools and features that are bundled with Windows. Obviously, we will share everything you need to know about using them effectively. In this first lesson, we will talk about password security; the different ways of logging into Windows and how secure they are. In the proceeding lesson, we will explain where Windows stores all the user names and passwords you enter while working in this operating systems, how safe they are, and how to manage this data. Moving on in the series, we will talk about User Account Control, its role in improving the security of your system, and how to use Windows Defender in order to protect your system from malware. Then, we will talk about the Windows Firewall, how to use it in order to manage the apps that get access to the network and the Internet, and how to create your own filtering rules. After that, we will discuss the SmartScreen Filter – a security feature that gets more and more attention from Microsoft and is now widely used in its Windows 8.x operating systems. Moving on, we will discuss ways to keep your software and apps up-to-date, why this is important and which tools you can use to automate this process as much as possible. Last but not least, we will discuss the Action Center and its role in keeping you informed about what’s going on with your system and share several tips and tricks about how to stay safe when using your computer and the Internet. Let’s get started by discussing everyone’s favorite subject: passwords. The Types of Passwords Found in Windows In Windows 7, you have only local user accounts, which may or may not have a password. For example, you can easily set a blank password for any user account, even if that one is an administrator. The only exception to this rule are business networks where domain policies force all user accounts to use a non-blank password. In Windows 8.x, you have both local accounts and Microsoft accounts. If you would like to learn more about them, don’t hesitate to read the lesson on User Accounts, Groups, Permissions & Their Role in Sharing, in our Windows Networking series. Microsoft accounts are obliged to use a non-blank password due to the fact that a Microsoft account gives you access to Microsoft services. Using a blank password would mean exposing yourself to lots of problems. Local accounts in Windows 8.1 however, can use a blank password. On top of traditional passwords, any user account can create and use a 4-digit PIN or a picture password. These concepts were introduced by Microsoft to speed up the sign in process for the Windows 8.x operating system. However, they do not replace the use of a traditional password and can be used only in conjunction with a traditional user account password. Another type of password that you encounter in Windows operating systems is the Homegroup password. In a typical home network, users can use the Homegroup to easily share resources. A Homegroup can be joined by a Windows device only by using the Homegroup password. If you would like to learn more about the Homegroup and how to use it for network sharing, don’t hesitate to read our Windows Networking series. What to Keep in Mind When Creating Passwords, PINs and Picture Passwords When creating passwords, a PIN, or a picture password for your user account, we would like you keep in mind the following recommendations: Do not use blank passwords, even on the desktop computers in your home. You never know who may gain unwanted access to them. Also, malware can run more easily as administrator because you do not have a password. Trading your security for convenience when logging in is never a good idea. When creating a password, make it at least eight characters long. Make sure that it includes a random mix of upper and lowercase letters, numbers, and symbols. Ideally, it should not be related in any way to your name, username, or company name. Make sure that your passwords do not include complete words from any dictionary. Dictionaries are the first thing crackers use to hack passwords. Do not use the same password for more than one account. All of your passwords should be unique and you should use a system like LastPass, KeePass, Roboform or something similar to keep track of them. When creating a PIN use four different digits to make things slightly harder to crack. When creating a picture password, pick a photo that has at least 10 “points of interests”. Points of interests are areas that serve as a landmark for your gestures. Use a random mixture of gesture types and sequence and make sure that you do not repeat the same gesture twice. Be aware that smudges on the screen could potentially reveal your gestures to others. The Security of Your Password vs. the PIN and the Picture Password Any kind of password can be cracked with enough effort and the appropriate tools. There is no such thing as a completely secure password. However, passwords created using only a few security principles are much harder to crack than others. If you respect the recommendations shared in the previous section of this lesson, you will end up having reasonably secure passwords. Out of all the log in methods in Windows 8.x, the PIN is the easiest to brute force because PINs are restricted to four digits and there are only 10,000 possible unique combinations available. The picture password is more secure than the PIN because it provides many more opportunities for creating unique combinations of gestures. Microsoft have compared the two login options from a security perspective in this post: Signing in with a picture password. In order to discourage brute force attacks against picture passwords and PINs, Windows defaults to your traditional text password after five failed attempts. The PIN and the picture password function only as alternative login methods to Windows 8.x. Therefore, if someone cracks them, he or she doesn’t have access to your user account password. However, that person can use all the apps installed on your Windows 8.x device, access your files, data, and so on. How to Create a PIN in Windows 8.x If you log in to a Windows 8.x device with a user account that has a non-blank password, then you can create a 4-digit PIN for it, to use it as a complementary login method. In order to create one, you need to go to “PC Settings”. If you don’t know how, then press Windows + C on your keyboard or flick from the right edge of the screen, on a touch-enabled device, then press “Settings”. The Settings charm is now open. Click or tap the link that says “Change PC settings”, on the bottom of the charm. In PC settings, go to Accounts and then to “Sign-in options”. Here you will find all the necessary options for changing your existing password, creating a PIN, or a picture password. To create a PIN, press the “Add” button in the PIN section. The “Create a PIN” wizard is started and you are asked to enter the password of your user account. Type it and press “OK”. Now you are asked to enter a 4-digit pin in the “Enter PIN” and “Confirm PIN” fields. The PIN has been created and you can now use it to log in to Windows. How to Create a Picture Password in Windows 8.x If you log in to a Windows 8.x device with a user account that has a non-blank password, then you can also create a picture password and use it as a complementary login method. In order to create one, you need to go to “PC settings”. In PC Settings, go to Accounts and then to “Sign-in options”. Here you will find all the necessary options for changing your existing password, creating a PIN, or a picture password. To create a picture password, press the “Add” button in the “Picture password” section. The “Create a picture password” wizard is started and you are asked to enter the password of your user account. You are shown a guide on how the picture password works. Take a few seconds to watch it and learn the gestures that can be used for your picture password. You will learn that you can create a combination of circles, straight lines, and taps. When ready, press “Choose picture”. Browse your Windows 8.x device and select the picture you want to use for your password and press “Open”. Now you can drag the picture to position it the way you want. When you like how the picture is positioned, press “Use this picture” on the left. If you are not happy with the picture, press “Choose new picture” and select a new one, as shown during the previous step. After you have confirmed that you want to use this picture, you are asked to set up your gestures for the picture password. Draw three gestures on the picture, any combination you wish. Please remember that you can use only three gestures: circles, straight lines, and taps. Once you have drawn those three gestures, you are asked to confirm. Draw the same gestures one more time. If everything goes well, you are informed that you have created your picture password and that you can use it the next time you sign in to Windows. If you don’t confirm the gestures correctly, you will be asked to try again, until you draw the same gestures twice. To close the picture password wizard, press “Finish”. Where Does Windows Store Your Passwords? Are They Safe? All the passwords that you enter in Windows and save for future use are stored in the Credential Manager. This tool is a vault with the usernames and passwords that you use to log on to your computer, to other computers on the network, to apps from the Windows Store, or to websites using Internet Explorer. By storing these credentials, Windows can automatically log you the next time you access the same app, network share, or website. Everything that is stored in the Credential Manager is encrypted for your protection.

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  • Creating a JSONP Formatter for ASP.NET Web API

    - by Rick Strahl
    Out of the box ASP.NET WebAPI does not include a JSONP formatter, but it's actually very easy to create a custom formatter that implements this functionality. JSONP is one way to allow Browser based JavaScript client applications to bypass cross-site scripting limitations and serve data from the non-current Web server. AJAX in Web Applications uses the XmlHttp object which by default doesn't allow access to remote domains. There are number of ways around this limitation <script> tag loading and JSONP is one of the easiest and semi-official ways that you can do this. JSONP works by combining JSON data and wrapping it into a function call that is executed when the JSONP data is returned. If you use a tool like jQUery it's extremely easy to access JSONP content. Imagine that you have a URL like this: http://RemoteDomain/aspnetWebApi/albums which on an HTTP GET serves some data - in this case an array of record albums. This URL is always directly accessible from an AJAX request if the URL is on the same domain as the parent request. However, if that URL lives on a separate server it won't be easily accessible to an AJAX request. Now, if  the server can serve up JSONP this data can be accessed cross domain from a browser client. Using jQuery it's really easy to retrieve the same data with JSONP:function getAlbums() { $.getJSON("http://remotedomain/aspnetWebApi/albums?callback=?",null, function (albums) { alert(albums.length); }); } The resulting callback the same as if the call was to a local server when the data is returned. jQuery deserializes the data and feeds it into the method. Here the array is received and I simply echo back the number of items returned. From here your app is ready to use the data as needed. This all works fine - as long as the server can serve the data with JSONP. What does JSONP look like? JSONP is a pretty simple 'protocol'. All it does is wrap a JSON response with a JavaScript function call. The above result from the JSONP call looks like this:Query17103401925975181569_1333408916499( [{"Id":"34043957","AlbumName":"Dirty Deeds Done Dirt Cheap",…},{…}] ) The way JSONP works is that the client (jQuery in this case) sends of the request, receives the response and evals it. The eval basically executes the function and deserializes the JSON inside of the function. It's actually a little more complex for the framework that does this, but that's the gist of what happens. JSONP works by executing the code that gets returned from the JSONP call. JSONP and ASP.NET Web API As mentioned previously, JSONP support is not natively in the box with ASP.NET Web API. But it's pretty easy to create and plug-in a custom formatter that provides this functionality. The following code is based on Christian Weyers example but has been updated to the latest Web API CodePlex bits, which changes the implementation a bit due to the way dependent objects are exposed differently in the latest builds. Here's the code:  using System; using System.IO; using System.Net; using System.Net.Http.Formatting; using System.Net.Http.Headers; using System.Threading.Tasks; using System.Web; using System.Net.Http; namespace Westwind.Web.WebApi { /// <summary> /// Handles JsonP requests when requests are fired with /// text/javascript or application/json and contain /// a callback= (configurable) query string parameter /// /// Based on Christian Weyers implementation /// https://github.com/thinktecture/Thinktecture.Web.Http/blob/master/Thinktecture.Web.Http/Formatters/JsonpFormatter.cs /// </summary> public class JsonpFormatter : JsonMediaTypeFormatter { public JsonpFormatter() { SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/json")); SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/javascript")); //MediaTypeMappings.Add(new UriPathExtensionMapping("jsonp", "application/json")); JsonpParameterName = "callback"; } /// <summary> /// Name of the query string parameter to look for /// the jsonp function name /// </summary> public string JsonpParameterName {get; set; } /// <summary> /// Captured name of the Jsonp function that the JSON call /// is wrapped in. Set in GetPerRequestFormatter Instance /// </summary> private string JsonpCallbackFunction; public override bool CanWriteType(Type type) { return true; } /// <summary> /// Override this method to capture the Request object /// and look for the query string parameter and /// create a new instance of this formatter. /// /// This is the only place in a formatter where the /// Request object is available. /// </summary> /// <param name="type"></param> /// <param name="request"></param> /// <param name="mediaType"></param> /// <returns></returns> public override MediaTypeFormatter GetPerRequestFormatterInstance(Type type, HttpRequestMessage request, MediaTypeHeaderValue mediaType) { var formatter = new JsonpFormatter() { JsonpCallbackFunction = GetJsonCallbackFunction(request) }; return formatter; } /// <summary> /// Override to wrap existing JSON result with the /// JSONP function call /// </summary> /// <param name="type"></param> /// <param name="value"></param> /// <param name="stream"></param> /// <param name="contentHeaders"></param> /// <param name="transportContext"></param> /// <returns></returns> public override Task WriteToStreamAsync(Type type, object value, Stream stream, HttpContentHeaders contentHeaders, TransportContext transportContext) { if (!string.IsNullOrEmpty(JsonpCallbackFunction)) { return Task.Factory.StartNew(() => { var writer = new StreamWriter(stream); writer.Write( JsonpCallbackFunction + "("); writer.Flush(); base.WriteToStreamAsync(type, value, stream, contentHeaders, transportContext).Wait(); writer.Write(")"); writer.Flush(); }); } else { return base.WriteToStreamAsync(type, value, stream, contentHeaders, transportContext); } } /// <summary> /// Retrieves the Jsonp Callback function /// from the query string /// </summary> /// <returns></returns> private string GetJsonCallbackFunction(HttpRequestMessage request) { if (request.Method != HttpMethod.Get) return null; var query = HttpUtility.ParseQueryString(request.RequestUri.Query); var queryVal = query[this.JsonpParameterName]; if (string.IsNullOrEmpty(queryVal)) return null; return queryVal; } } } Note again that this code will not work with the Beta bits of Web API - it works only with post beta bits from CodePlex and hopefully this will continue to work until RTM :-) This code is a bit different from Christians original code as the API has changed. The biggest change is that the Read/Write functions no longer receive a global context object that gives access to the Request and Response objects as the older bits did. Instead you now have to override the GetPerRequestFormatterInstance() method, which receives the Request as a parameter. You can capture the Request there, or use the request to pick up the values you need and store them on the formatter. Note that I also have to create a new instance of the formatter since I'm storing request specific state on the instance (information whether the callback= querystring is present) so I return a new instance of this formatter. Other than that the code should be straight forward: The code basically writes out the function pre- and post-amble and the defers to the base stream to retrieve the JSON to wrap the function call into. The code uses the Async APIs to write this data out (this will take some getting used to seeing all over the place for me). Hooking up the JsonpFormatter Once you've created a formatter, it has to be added to the request processing sequence by adding it to the formatter collection. Web API is configured via the static GlobalConfiguration object.  protected void Application_Start(object sender, EventArgs e) { // Verb Routing RouteTable.Routes.MapHttpRoute( name: "AlbumsVerbs", routeTemplate: "albums/{title}", defaults: new { title = RouteParameter.Optional, controller = "AlbumApi" } ); GlobalConfiguration .Configuration .Formatters .Insert(0, new Westwind.Web.WebApi.JsonpFormatter()); }   That's all it takes. Note that I added the formatter at the top of the list of formatters, rather than adding it to the end which is required. The JSONP formatter needs to fire before any other JSON formatter since it relies on the JSON formatter to encode the actual JSON data. If you reverse the order the JSONP output never shows up. So, in general when adding new formatters also try to be aware of the order of the formatters as they are added. Resources JsonpFormatter Code on GitHub© Rick Strahl, West Wind Technologies, 2005-2012Posted in Web Api   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • SQL SERVER – Weekly Series – Memory Lane – #033

    - by Pinal Dave
    Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Spatial Database Definition and Research Documents Here is the definition from Wikipedia about spatial database : A spatial database is a database that is optimized to store and query data related to objects in space, including points, lines and polygons. While typical databases can understand various numeric and character types of data, additional functionality needs to be added for databases to process spatial data types. Select Only Date Part From DateTime – Best Practice A very common question which I receive is how to only get Date or Time part from datetime value. In this blog post I explain the same in very simple words. T-SQL Paging Query Technique Comparison (OVER and ROW_NUMBER()) – CTE vs. Derived Table I have received few emails and comments about my post SQL SERVER – T-SQL Paging Query Technique Comparison – SQL 2000 vs SQL 2005. The main question was is this can be done using CTE? Absolutely! What about Performance? It is identical! Please refer above mentioned article for the history of paging. SQL SERVER – Cannot resolve collation conflict for equal to operation One of the very first error I ever encountered in my career was to resolve this conflict. I have blogged about it and I have realized that many others like me who are facing this error. LEN and DATALENGTH of NULL Simple Example Here is the question for you what is the LEN of NULL value? Well it is very easy – just read the blog. Recovery Models and Selection Very simple and easy explanation of the Database Backup Recovery Model and how to select the best option for you. Explanation SQL SERVER Hash Join Hash join gives best performance when two more join tables are joined and at-least one of them have no index or is not sorted. It is also expected that smaller of the either of table can be read in memory completely (though not necessary). Easy Sequence of SELECT FROM JOIN WHERE GROUP BY HAVING ORDER BY SELECT yourcolumns FROM tablenames JOIN tablenames WHERE condition GROUP BY yourcolumns HAVING aggregatecolumn condition ORDER BY yourcolumns NorthWind Database or AdventureWorks Database – Samples Databases In this blog post we learn how to install Northwind database. I also shared the source where one can download this database as that is used in many examples on MSDN help files. sp_HelpText for sp_HelpText – Puzzle A simple quick puzzle – do you know the answer of it? If not, go ahead and read the blog. 2008 SQL SERVER – 2008 – Step By Step Installation Guide With Images When SQL Server 2008 was newly introduced lots of people had no clue how to install SQL Server 2008 and the amount of the question which I used to receive were so much. I wrote this blog post with the spirit that this will help all the newbies to install SQL Server 2008 with the help of images. Still today this blog post has been bible for all of the people who are confused with SQL Server installation. Inline Variable Assignment I loved this feature. I have always wanted this feature to be present in SQL Server. The last time when I met developers from Microsoft SQL Server, I had talked about this feature. I think this feature saves some time but make the code more readable. Introduction to Policy Management – Enforcing Rules on SQL Server If our company policy is to create all the Stored Procedure with prefix ‘usp’ that developers should be just prevented to create Stored Procedure with any other prefix. Let us see a small tutorial how to create conditions and policy which will prevent any future SP to be created with any other prefix. 2009 Performance Counters from System Views – By Kevin Mckenna Many of you are not aware of this fact that access to performance information is readily available in SQL Server and that too without querying performance counters using a custom application or via perfmon. Till now, this fact has remained undisclosed but through this post I would like to explain you can easily access SQL Server performance counter information. Without putting much effort you will come across the system viewsys.dm_os_performance_counters. As the name suggests, this provides you easy access to the SQL Server performance counter information that is passed on to perfmon, but you can get at it via tsql. Customize Toolbar – Remove Debug Button from Toolbar I was fond of SQL Server Debugger feature in SQL Server 2000. To my utter disappointment, this feature was withdrawn from SQL Server 2005. The button of the debugger is similar to a play button and is used to run debugging commands of Visual Studio. Because of this reason, it gets very much infuriating for developers when they are developing on both – Visual Studio and SSMS. Let us now see how we can remove debugging button from SQL Server Management Studio. Effect of Normalization on Index and Performance A very interesting conversation which started from twitter. If you want to read one link this is the link I encourage you to read it. SSMS Feature – Multi-server Queries Using SQL Server Management Studio (SSMS) DBAs can now query multiple servers from one window. It is quite common for DBAs with large amount of servers to maintain and gather information from multiple SQL Servers and create report. This feature is a blessing for the DBAs, as they can now assemble all the information instantaneously without going anywhere. Query Optimizer Hint ROBUST PLAN – Question to You “ROBUST PLAN” is a kind of query hint which works quite differently than other hints. It does not improve join or force any indexes to use; it just makes sure that a query does not crash due to over the limit size of row. Let me elaborate upon it in the blog post. 2010 Do you really know the difference between various date functions available in SQL Server 2012? Here is a three part story where we explored the same with examples: Fastest Way to Restore the Database Difference Between DATETIME and DATETIME2 Difference Between DATETIME and DATETIME2 – WITH GETDATE Shrinking NDF and MDF Files – Readers’ Opinion Shrinking Database always creates performance degradation and increases fragmentation in the database. I suggest that you keep that in mind before you start reading the following comment. If you are going to say Shrinking Database is bad and evil, here I am saying it first and loud. Now, the comment of Imran is written while keeping in mind only the process showing how the Shrinking Database Operation works. Imran has already explained his understanding and requests further explanation. I have removed the Best Practices section from Imran’s comments, as there are a few corrections. 2011 Solution – Puzzle – SELECT * vs SELECT COUNT(*) This is very interesting question and I am very confident that not every one knows the answer to this question. Let me ask you again – Which will be faster SELECT* or SELECT COUNT (*) or do you think this is apples and oranges comparison. 2012 Service Broker and CAP_CPU_PERCENT – Limiting SQL Server Instances to CPU Usage In SQL Server 2012 there are a few enhancements with regards to SQL Server Resource Governor. One of the enhancement is how the resources are allocated. Let me explain you with examples. Let us understand the entire discussion with the help of three different examples. Finding Size of a Columnstore Index Using DMVs One of the very common question I often see is need of the list of columnstore index along with their size and corresponding table name. I quickly re-wrote a script using DMVs sys.indexes and sys.dm_db_partition_stats. This script gives the size of the columnstore index on disk only. I am sure there will be advanced script to retrieve details related to components associated with the columnstore index. However, I believe following script is sufficient to start getting an idea of columnstore index size. Developer Training Resources and Summary Roundup Developer Training - Importance and Significance - Part 1 In this part we discussed the importance of training in the real world. The most important and valuable resource any company is its employee. Employees who have been well-trained will be better at their jobs and produce a better product.  An employee who is well trained obviously knows more about their job and all the technical aspects. I have a very high opinion about training employees and it is the most important task. Developer Training – Employee Morals and Ethics – Part 2 In this part we discussed the most crucial components of training. Often employees are expecting the company to pay for their training and the company expresses no interest in training the employee. Quite often training expenses are the real issue for both the employee and employer. Developer Training – Difficult Questions and Alternative Perspective - Part 3 This part was the most difficult to write as I tried to address a few difficult questions and answers. Training is such a sensitive issue that many developers when not receiving chance for training think about leaving the organization. Developer Training – Various Options for Developer Training – Part 4 In this part I tried to explore a few methods and options for training. The generic feedback I received on this blog post was short and I should have explored each of the subject of the training in details. I believe there are two big buckets of training 1) Instructor Lead Training and 2) Self Lead Training. Developer Training – A Conclusive Summary- Part 5 There is no better motivation than a personal desire to learn new technology. Honestly there is nothing more personal learning. That “change is the only constant” and “adapt & overcome” are the essential lessons of life. One cannot stop the learning and resist the change. In the IT industry “ego of knowing all” and the “resistance to change” are the most challenging issues. A Quick Look at Logging and Ideas around Logging Question: What is the first thing comes to your mind when you hear the word “Logging”? Strange enough I got a different answer every single time. Let me just list what answer I got from my friends. Let us go over them one by one. Beginning Performance Tuning with SQL Server Execution Plan Solution of Puzzle – Swap Value of Column Without Case Statement Earlier this week I asked a question where I asked how to Swap Values of the column without using CASE Statement. Read here: SQL SERVER – A Puzzle – Swap Value of Column Without Case Statement. I have proposed 3 different solutions in the blog posts itself. I had requested the help of the community to come up with alternate solutions and honestly I am stunned and amazed by the qualified entries. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Hello Operator, My Switch Is Bored

    - by Paul White
    This is a post for T-SQL Tuesday #43 hosted by my good friend Rob Farley. The topic this month is Plan Operators. I haven’t taken part in T-SQL Tuesday before, but I do like to write about execution plans, so this seemed like a good time to start. This post is in two parts. The first part is primarily an excuse to use a pretty bad play on words in the title of this blog post (if you’re too young to know what a telephone operator or a switchboard is, I hate you). The second part of the post looks at an invisible query plan operator (so to speak). 1. My Switch Is Bored Allow me to present the rare and interesting execution plan operator, Switch: Books Online has this to say about Switch: Following that description, I had a go at producing a Fast Forward Cursor plan that used the TOP operator, but had no luck. That may be due to my lack of skill with cursors, I’m not too sure. The only application of Switch in SQL Server 2012 that I am familiar with requires a local partitioned view: CREATE TABLE dbo.T1 (c1 int NOT NULL CHECK (c1 BETWEEN 00 AND 24)); CREATE TABLE dbo.T2 (c1 int NOT NULL CHECK (c1 BETWEEN 25 AND 49)); CREATE TABLE dbo.T3 (c1 int NOT NULL CHECK (c1 BETWEEN 50 AND 74)); CREATE TABLE dbo.T4 (c1 int NOT NULL CHECK (c1 BETWEEN 75 AND 99)); GO CREATE VIEW V1 AS SELECT c1 FROM dbo.T1 UNION ALL SELECT c1 FROM dbo.T2 UNION ALL SELECT c1 FROM dbo.T3 UNION ALL SELECT c1 FROM dbo.T4; Not only that, but it needs an updatable local partitioned view. We’ll need some primary keys to meet that requirement: ALTER TABLE dbo.T1 ADD CONSTRAINT PK_T1 PRIMARY KEY (c1);   ALTER TABLE dbo.T2 ADD CONSTRAINT PK_T2 PRIMARY KEY (c1);   ALTER TABLE dbo.T3 ADD CONSTRAINT PK_T3 PRIMARY KEY (c1);   ALTER TABLE dbo.T4 ADD CONSTRAINT PK_T4 PRIMARY KEY (c1); We also need an INSERT statement that references the view. Even more specifically, to see a Switch operator, we need to perform a single-row insert (multi-row inserts use a different plan shape): INSERT dbo.V1 (c1) VALUES (1); And now…the execution plan: The Constant Scan manufactures a single row with no columns. The Compute Scalar works out which partition of the view the new value should go in. The Assert checks that the computed partition number is not null (if it is, an error is returned). The Nested Loops Join executes exactly once, with the partition id as an outer reference (correlated parameter). The Switch operator checks the value of the parameter and executes the corresponding input only. If the partition id is 0, the uppermost Clustered Index Insert is executed, adding a row to table T1. If the partition id is 1, the next lower Clustered Index Insert is executed, adding a row to table T2…and so on. In case you were wondering, here’s a query and execution plan for a multi-row insert to the view: INSERT dbo.V1 (c1) VALUES (1), (2); Yuck! An Eager Table Spool and four Filters! I prefer the Switch plan. My guess is that almost all the old strategies that used a Switch operator have been replaced over time, using things like a regular Concatenation Union All combined with Start-Up Filters on its inputs. Other new (relative to the Switch operator) features like table partitioning have specific execution plan support that doesn’t need the Switch operator either. This feels like a bit of a shame, but perhaps it is just nostalgia on my part, it’s hard to know. Please do let me know if you encounter a query that can still use the Switch operator in 2012 – it must be very bored if this is the only possible modern usage! 2. Invisible Plan Operators The second part of this post uses an example based on a question Dave Ballantyne asked using the SQL Sentry Plan Explorer plan upload facility. If you haven’t tried that yet, make sure you’re on the latest version of the (free) Plan Explorer software, and then click the Post to SQLPerformance.com button. That will create a site question with the query plan attached (which can be anonymized if the plan contains sensitive information). Aaron Bertrand and I keep a close eye on questions there, so if you have ever wanted to ask a query plan question of either of us, that’s a good way to do it. The problem The issue I want to talk about revolves around a query issued against a calendar table. The script below creates a simplified version and adds 100 years of per-day information to it: USE tempdb; GO CREATE TABLE dbo.Calendar ( dt date NOT NULL, isWeekday bit NOT NULL, theYear smallint NOT NULL,   CONSTRAINT PK__dbo_Calendar_dt PRIMARY KEY CLUSTERED (dt) ); GO -- Monday is the first day of the week for me SET DATEFIRST 1;   -- Add 100 years of data INSERT dbo.Calendar WITH (TABLOCKX) (dt, isWeekday, theYear) SELECT CA.dt, isWeekday = CASE WHEN DATEPART(WEEKDAY, CA.dt) IN (6, 7) THEN 0 ELSE 1 END, theYear = YEAR(CA.dt) FROM Sandpit.dbo.Numbers AS N CROSS APPLY ( VALUES (DATEADD(DAY, N.n - 1, CONVERT(date, '01 Jan 2000', 113))) ) AS CA (dt) WHERE N.n BETWEEN 1 AND 36525; The following query counts the number of weekend days in 2013: SELECT Days = COUNT_BIG(*) FROM dbo.Calendar AS C WHERE theYear = 2013 AND isWeekday = 0; It returns the correct result (104) using the following execution plan: The query optimizer has managed to estimate the number of rows returned from the table exactly, based purely on the default statistics created separately on the two columns referenced in the query’s WHERE clause. (Well, almost exactly, the unrounded estimate is 104.289 rows.) There is already an invisible operator in this query plan – a Filter operator used to apply the WHERE clause predicates. We can see it by re-running the query with the enormously useful (but undocumented) trace flag 9130 enabled: Now we can see the full picture. The whole table is scanned, returning all 36,525 rows, before the Filter narrows that down to just the 104 we want. Without the trace flag, the Filter is incorporated in the Clustered Index Scan as a residual predicate. It is a little bit more efficient than using a separate operator, but residual predicates are still something you will want to avoid where possible. The estimates are still spot on though: Anyway, looking to improve the performance of this query, Dave added the following filtered index to the Calendar table: CREATE NONCLUSTERED INDEX Weekends ON dbo.Calendar(theYear) WHERE isWeekday = 0; The original query now produces a much more efficient plan: Unfortunately, the estimated number of rows produced by the seek is now wrong (365 instead of 104): What’s going on? The estimate was spot on before we added the index! Explanation You might want to grab a coffee for this bit. Using another trace flag or two (8606 and 8612) we can see that the cardinality estimates were exactly right initially: The highlighted information shows the initial cardinality estimates for the base table (36,525 rows), the result of applying the two relational selects in our WHERE clause (104 rows), and after performing the COUNT_BIG(*) group by aggregate (1 row). All of these are correct, but that was before cost-based optimization got involved :) Cost-based optimization When cost-based optimization starts up, the logical tree above is copied into a structure (the ‘memo’) that has one group per logical operation (roughly speaking). The logical read of the base table (LogOp_Get) ends up in group 7; the two predicates (LogOp_Select) end up in group 8 (with the details of the selections in subgroups 0-6). These two groups still have the correct cardinalities as trace flag 8608 output (initial memo contents) shows: During cost-based optimization, a rule called SelToIdxStrategy runs on group 8. It’s job is to match logical selections to indexable expressions (SARGs). It successfully matches the selections (theYear = 2013, is Weekday = 0) to the filtered index, and writes a new alternative into the memo structure. The new alternative is entered into group 8 as option 1 (option 0 was the original LogOp_Select): The new alternative is to do nothing (PhyOp_NOP = no operation), but to instead follow the new logical instructions listed below the NOP. The LogOp_GetIdx (full read of an index) goes into group 21, and the LogOp_SelectIdx (selection on an index) is placed in group 22, operating on the result of group 21. The definition of the comparison ‘the Year = 2013’ (ScaOp_Comp downwards) was already present in the memo starting at group 2, so no new memo groups are created for that. New Cardinality Estimates The new memo groups require two new cardinality estimates to be derived. First, LogOp_Idx (full read of the index) gets a predicted cardinality of 10,436. This number comes from the filtered index statistics: DBCC SHOW_STATISTICS (Calendar, Weekends) WITH STAT_HEADER; The second new cardinality derivation is for the LogOp_SelectIdx applying the predicate (theYear = 2013). To get a number for this, the cardinality estimator uses statistics for the column ‘theYear’, producing an estimate of 365 rows (there are 365 days in 2013!): DBCC SHOW_STATISTICS (Calendar, theYear) WITH HISTOGRAM; This is where the mistake happens. Cardinality estimation should have used the filtered index statistics here, to get an estimate of 104 rows: DBCC SHOW_STATISTICS (Calendar, Weekends) WITH HISTOGRAM; Unfortunately, the logic has lost sight of the link between the read of the filtered index (LogOp_GetIdx) in group 22, and the selection on that index (LogOp_SelectIdx) that it is deriving a cardinality estimate for, in group 21. The correct cardinality estimate (104 rows) is still present in the memo, attached to group 8, but that group now has a PhyOp_NOP implementation. Skipping over the rest of cost-based optimization (in a belated attempt at brevity) we can see the optimizer’s final output using trace flag 8607: This output shows the (incorrect, but understandable) 365 row estimate for the index range operation, and the correct 104 estimate still attached to its PhyOp_NOP. This tree still has to go through a few post-optimizer rewrites and ‘copy out’ from the memo structure into a tree suitable for the execution engine. One step in this process removes PhyOp_NOP, discarding its 104-row cardinality estimate as it does so. To finish this section on a more positive note, consider what happens if we add an OVER clause to the query aggregate. This isn’t intended to be a ‘fix’ of any sort, I just want to show you that the 104 estimate can survive and be used if later cardinality estimation needs it: SELECT Days = COUNT_BIG(*) OVER () FROM dbo.Calendar AS C WHERE theYear = 2013 AND isWeekday = 0; The estimated execution plan is: Note the 365 estimate at the Index Seek, but the 104 lives again at the Segment! We can imagine the lost predicate ‘isWeekday = 0’ as sitting between the seek and the segment in an invisible Filter operator that drops the estimate from 365 to 104. Even though the NOP group is removed after optimization (so we don’t see it in the execution plan) bear in mind that all cost-based choices were made with the 104-row memo group present, so although things look a bit odd, it shouldn’t affect the optimizer’s plan selection. I should also mention that we can work around the estimation issue by including the index’s filtering columns in the index key: CREATE NONCLUSTERED INDEX Weekends ON dbo.Calendar(theYear, isWeekday) WHERE isWeekday = 0 WITH (DROP_EXISTING = ON); There are some downsides to doing this, including that changes to the isWeekday column may now require Halloween Protection, but that is unlikely to be a big problem for a static calendar table ;)  With the updated index in place, the original query produces an execution plan with the correct cardinality estimation showing at the Index Seek: That’s all for today, remember to let me know about any Switch plans you come across on a modern instance of SQL Server! Finally, here are some other posts of mine that cover other plan operators: Segment and Sequence Project Common Subexpression Spools Why Plan Operators Run Backwards Row Goals and the Top Operator Hash Match Flow Distinct Top N Sort Index Spools and Page Splits Singleton and Range Seeks Bitmaps Hash Join Performance Compute Scalar © 2013 Paul White – All Rights Reserved Twitter: @SQL_Kiwi

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  • Metro: Understanding Observables

    - by Stephen.Walther
    The goal of this blog entry is to describe how the Observer Pattern is implemented in the WinJS library. You learn how to create observable objects which trigger notifications automatically when their properties are changed. Observables enable you to keep your user interface and your application data in sync. For example, by taking advantage of observables, you can update your user interface automatically whenever the properties of a product change. Observables are the foundation of declarative binding in the WinJS library. The WinJS library is not the first JavaScript library to include support for observables. For example, both the KnockoutJS library and the Microsoft Ajax Library (now part of the Ajax Control Toolkit) support observables. Creating an Observable Imagine that I have created a product object like this: var product = { name: "Milk", description: "Something to drink", price: 12.33 }; Nothing very exciting about this product. It has three properties named name, description, and price. Now, imagine that I want to be notified automatically whenever any of these properties are changed. In that case, I can create an observable product from my product object like this: var observableProduct = WinJS.Binding.as(product); This line of code creates a new JavaScript object named observableProduct from the existing JavaScript object named product. This new object also has a name, description, and price property. However, unlike the properties of the original product object, the properties of the observable product object trigger notifications when the properties are changed. Each of the properties of the new observable product object has been changed into accessor properties which have both a getter and a setter. For example, the observable product price property looks something like this: price: { get: function () { return this.getProperty(“price”); } set: function (value) { this.setProperty(“price”, value); } } When you read the price property then the getProperty() method is called and when you set the price property then the setProperty() method is called. The getProperty() and setProperty() methods are methods of the observable product object. The observable product object supports the following methods and properties: · addProperty(name, value) – Adds a new property to an observable and notifies any listeners. · backingData – An object which represents the value of each property. · bind(name, action) – Enables you to execute a function when a property changes. · getProperty(name) – Returns the value of a property using the string name of the property. · notify(name, newValue, oldValue) – A private method which executes each function in the _listeners array. · removeProperty(name) – Removes a property and notifies any listeners. · setProperty(name, value) – Updates a property and notifies any listeners. · unbind(name, action) – Enables you to stop executing a function in response to a property change. · updateProperty(name, value) – Updates a property and notifies any listeners. So when you create an observable, you get a new object with the same properties as an existing object. However, when you modify the properties of an observable object, then you can notify any listeners of the observable that the value of a particular property has changed automatically. Imagine that you change the value of the price property like this: observableProduct.price = 2.99; In that case, the following sequence of events is triggered: 1. The price setter calls the setProperty(“price”, 2.99) method 2. The setProperty() method updates the value of the backingData.price property and calls the notify() method 3. The notify() method executes each function in the collection of listeners associated with the price property Creating Observable Listeners If you want to be notified when a property of an observable object is changed, then you need to register a listener. You register a listener by using the bind() method like this: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 2.99; } }; app.start(); })(); In the code above, the bind() method is used to associate the price property with a function. When the price property is changed, the function logs the new value of the price property to the Visual Studio JavaScript console. The price property is associated with the function using the following line of code: // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); Coalescing Notifications If you make multiple changes to a property – one change immediately following another – then separate notifications won’t be sent. Instead, any listeners are notified only once. The notifications are coalesced into a single notification. For example, in the following code, the product price property is updated three times. However, only one message is written to the JavaScript console. Only the last value assigned to the price property is written to the JavaScript Console window: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 3.99; observableProduct.price = 2.99; observableProduct.price = 1.99; Only the last value assigned to price, the value 1.99, appears in the console: If there is a time delay between changes to a property then changes result in different notifications. For example, the following code updates the price property every second: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Add 1 to price every second window.setInterval(function () { observableProduct.price += 1; }, 1000); In this case, separate notification messages are logged to the JavaScript Console window: If you need to prevent multiple notifications from being coalesced into one then you can take advantage of promises. I discussed WinJS promises in a previous blog entry: http://stephenwalther.com/blog/archive/2012/02/22/windows-web-applications-promises.aspx Because the updateProperty() method returns a promise, you can create different notifications for each change in a property by using the following code: // Change the price observableProduct.updateProperty("price", 3.99) .then(function () { observableProduct.updateProperty("price", 2.99) .then(function () { observableProduct.updateProperty("price", 1.99); }); }); In this case, even though the price is immediately changed from 3.99 to 2.99 to 1.99, separate notifications for each new value of the price property are sent. Bypassing Notifications Normally, if a property of an observable object has listeners and you change the property then the listeners are notified. However, there are certain situations in which you might want to bypass notification. In other words, you might need to change a property value silently without triggering any functions registered for notification. If you want to change a property without triggering notifications then you should change the property by using the backingData property. The following code illustrates how you can change the price property silently: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price silently observableProduct.backingData.price = 5.99; console.log(observableProduct.price); // Writes 5.99 The price is changed to the value 5.99 by changing the value of backingData.price. Because the observableProduct.price property is not set directly, any listeners associated with the price property are not notified. When you change the value of a property by using the backingData property, the change in the property happens synchronously. However, when you change the value of an observable property directly, the change is always made asynchronously. Summary The goal of this blog entry was to describe observables. In particular, we discussed how to create observables from existing JavaScript objects and bind functions to observable properties. You also learned how notifications are coalesced (and ways to prevent this coalescing). Finally, we discussed how you can use the backingData property to update an observable property without triggering notifications. In the next blog entry, we’ll see how observables are used with declarative binding to display the values of properties in an HTML document.

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  • Commit in SQL

    - by PRajkumar
    SQL Transaction Control Language Commands (TCL)                                           (COMMIT) Commit Transaction As a SQL language we use transaction control language very frequently. Committing a transaction means making permanent the changes performed by the SQL statements within the transaction. A transaction is a sequence of SQL statements that Oracle Database treats as a single unit. This statement also erases all save points in the transaction and releases transaction locks. Oracle Database issues an implicit COMMIT before and after any data definition language (DDL) statement. Oracle recommends that you explicitly end every transaction in your application programs with a COMMIT or ROLLBACK statement, including the last transaction, before disconnecting from Oracle Database. If you do not explicitly commit the transaction and the program terminates abnormally, then the last uncommitted transaction is automatically rolled back.   Until you commit a transaction: ·         You can see any changes you have made during the transaction by querying the modified tables, but other users cannot see the changes. After you commit the transaction, the changes are visible to other users' statements that execute after the commit ·         You can roll back (undo) any changes made during the transaction with the ROLLBACK statement   Note: Most of the people think that when we type commit data or changes of what you have made has been written to data files, but this is wrong when you type commit it means that you are saying that your job has been completed and respective verification will be done by oracle engine that means it checks whether your transaction achieved consistency when it finds ok it sends a commit message to the user from log buffer but not from data buffer, so after writing data in log buffer it insists data buffer to write data in to data files, this is how it works.   Before a transaction that modifies data is committed, the following has occurred: ·         Oracle has generated undo information. The undo information contains the old data values changed by the SQL statements of the transaction ·         Oracle has generated redo log entries in the redo log buffer of the System Global Area (SGA). The redo log record contains the change to the data block and the change to the rollback block. These changes may go to disk before a transaction is committed ·         The changes have been made to the database buffers of the SGA. These changes may go to disk before a transaction is committed   Note:   The data changes for a committed transaction, stored in the database buffers of the SGA, are not necessarily written immediately to the data files by the database writer (DBWn) background process. This writing takes place when it is most efficient for the database to do so. It can happen before the transaction commits or, alternatively, it can happen some times after the transaction commits.   When a transaction is committed, the following occurs: 1.      The internal transaction table for the associated undo table space records that the transaction has committed, and the corresponding unique system change number (SCN) of the transaction is assigned and recorded in the table 2.      The log writer process (LGWR) writes redo log entries in the SGA's redo log buffers to the redo log file. It also writes the transaction's SCN to the redo log file. This atomic event constitutes the commit of the transaction 3.      Oracle releases locks held on rows and tables 4.      Oracle marks the transaction complete   Note:   The default behavior is for LGWR to write redo to the online redo log files synchronously and for transactions to wait for the redo to go to disk before returning a commit to the user. However, for lower transaction commit latency application developers can specify that redo be written asynchronously and that transaction do not need to wait for the redo to be on disk.   The syntax of Commit Statement is   COMMIT [WORK] [COMMENT ‘your comment’]; ·         WORK is optional. The WORK keyword is supported for compliance with standard SQL. The statements COMMIT and COMMIT WORK are equivalent. Examples Committing an Insert INSERT INTO table_name VALUES (val1, val2); COMMIT WORK; ·         COMMENT Comment is also optional. This clause is supported for backward compatibility. Oracle recommends that you used named transactions instead of commit comments. Specify a comment to be associated with the current transaction. The 'text' is a quoted literal of up to 255 bytes that Oracle Database stores in the data dictionary view DBA_2PC_PENDING along with the transaction ID if a distributed transaction becomes in doubt. This comment can help you diagnose the failure of a distributed transaction. Examples The following statement commits the current transaction and associates a comment with it: COMMIT     COMMENT 'In-doubt transaction Code 36, Call (415) 555-2637'; ·         WRITE Clause Use this clause to specify the priority with which the redo information generated by the commit operation is written to the redo log. This clause can improve performance by reducing latency, thus eliminating the wait for an I/O to the redo log. Use this clause to improve response time in environments with stringent response time requirements where the following conditions apply: The volume of update transactions is large, requiring that the redo log be written to disk frequently. The application can tolerate the loss of an asynchronously committed transaction. The latency contributed by waiting for the redo log write to occur contributes significantly to overall response time. You can specify the WAIT | NOWAIT and IMMEDIATE | BATCH clauses in any order. Examples To commit the same insert operation and instruct the database to buffer the change to the redo log, without initiating disk I/O, use the following COMMIT statement: COMMIT WRITE BATCH; Note: If you omit this clause, then the behavior of the commit operation is controlled by the COMMIT_WRITE initialization parameter, if it has been set. The default value of the parameter is the same as the default for this clause. Therefore, if the parameter has not been set and you omit this clause, then commit records are written to disk before control is returned to the user. WAIT | NOWAIT Use these clauses to specify when control returns to the user. The WAIT parameter ensures that the commit will return only after the corresponding redo is persistent in the online redo log. Whether in BATCH or IMMEDIATE mode, when the client receives a successful return from this COMMIT statement, the transaction has been committed to durable media. A crash occurring after a successful write to the log can prevent the success message from returning to the client. In this case the client cannot tell whether or not the transaction committed. The NOWAIT parameter causes the commit to return to the client whether or not the write to the redo log has completed. This behavior can increase transaction throughput. With the WAIT parameter, if the commit message is received, then you can be sure that no data has been lost. Caution: With NOWAIT, a crash occurring after the commit message is received, but before the redo log record(s) are written, can falsely indicate to a transaction that its changes are persistent. If you omit this clause, then the transaction commits with the WAIT behavior. IMMEDIATE | BATCH Use these clauses to specify when the redo is written to the log. The IMMEDIATE parameter causes the log writer process (LGWR) to write the transaction's redo information to the log. This operation option forces a disk I/O, so it can reduce transaction throughput. The BATCH parameter causes the redo to be buffered to the redo log, along with other concurrently executing transactions. When sufficient redo information is collected, a disk write of the redo log is initiated. This behavior is called "group commit", as redo for multiple transactions is written to the log in a single I/O operation. If you omit this clause, then the transaction commits with the IMMEDIATE behavior. ·         FORCE Clause Use this clause to manually commit an in-doubt distributed transaction or a corrupt transaction. ·         In a distributed database system, the FORCE string [, integer] clause lets you manually commit an in-doubt distributed transaction. The transaction is identified by the 'string' containing its local or global transaction ID. To find the IDs of such transactions, query the data dictionary view DBA_2PC_PENDING. You can use integer to specifically assign the transaction a system change number (SCN). If you omit integer, then the transaction is committed using the current SCN. ·         The FORCE CORRUPT_XID 'string' clause lets you manually commit a single corrupt transaction, where string is the ID of the corrupt transaction. Query the V$CORRUPT_XID_LIST data dictionary view to find the transaction IDs of corrupt transactions. You must have DBA privileges to view the V$CORRUPT_XID_LIST and to specify this clause. ·         Specify FORCE CORRUPT_XID_ALL to manually commit all corrupt transactions. You must have DBA privileges to specify this clause. Examples Forcing an in doubt transaction. Example The following statement manually commits a hypothetical in-doubt distributed transaction. Query the V$CORRUPT_XID_LIST data dictionary view to find the transaction IDs of corrupt transactions. You must have DBA privileges to view the V$CORRUPT_XID_LIST and to issue this statement. COMMIT FORCE '22.57.53';

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