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  • Android app hanging, sometimes until Force Close / Wait dialog appears

    - by fredley
    I'm making an app that records uncompressed (wav format) audio. I'm using this class to actually record the audio. Currently, my application records fine (I can play the file), however when I click the button to stop the recording, the app hangs for 10 seconds or so, with no log output or any signs of life. Finally it comes round, dumps a load of errors into the log, updates the UI etc. I'm using AsyncTasks to try and avoid this kind of thing but it's not working. Here's my code: //Called on clicks of the record button. rar is the instance of RehearsalAudioRecorder private OnClickListener RecordListener = new OnClickListener(){ @Override public void onClick(View v) { Log.d("Record","Click"); if (recording){ new stopRecordingTask().execute(rar,null,null); startStop.setText("Record"); statusBar.setText("Recording Finished, ready to Encode"); }else{ recording = true; new startRecordingTask().execute(rar,null,null); startStop.setText("Stop"); statusBar.setText("Recording Started"); } } }; private class startRecordingTask extends AsyncTask<RehearsalAudioRecorder,Void,Void>{ @Override protected Void doInBackground(RehearsalAudioRecorder... rs) { RehearsalAudioRecorder r = rs[0]; r.setOutputFile("/sdcard/rarOut.wav"); r.prepare(); r.start(); return null; } } private class stopRecordingTask extends AsyncTask<RehearsalAudioRecorder,Void,Void>{ @Override protected Void doInBackground(RehearsalAudioRecorder... rs) { RehearsalAudioRecorder r = rs[0]; r.stop(); r.reset(); return null; } } In Logcat, I always get output like this, which has me stumped. I have no idea what's causing it (I'm logging the RehearsalAudioRecorder class, and it's being started/stopped correctly by the button clicks. This output occurs after the log output for the button click and correct stop() method call) 12-19 11:59:11.172: ERROR/AudioRecord-JNI(22662): Unable to retrieve AudioRecord object, can't record 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): Error occured in updateListener, recording is aborted 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): stop() called on illegal state: STOPPED 12-19 11:59:11.172: ERROR/AudioRecord-JNI(22662): Unable to retrieve AudioRecord object, can't record 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): Error occured in updateListener, recording is aborted 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): stop() called on illegal state: ERROR 12-19 11:59:11.172: ERROR/AudioRecord-JNI(22662): Unable to retrieve AudioRecord object, can't record 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): Error occured in updateListener, recording is aborted 12-19 11:59:11.172: ERROR/uk.ac.cam.tfmw2.steg.RehearsalAudioRecorder(22662): stop() called on illegal state: ERROR ... 10 or more times I've been fiddling with this all day and I'm not getting anywhere, any input would be greatly appreciated. Update I've replace the AsyncTasks with Threads, still doesn't work, the app completely hangs when I click record, despite the fact the Log indicates there's nothing going on in the main thread. Still completely stumped.

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  • How to design a data model that deals with (real) contracts?

    - by Geoffrey
    I was looking for some advice on designing a data model for contract administration. The general life cycle of a contract is thus: Contract is created and in a "draft" state. It is viewable internally and changes may be made. Contract goes out to vendor, status is set to "pending" Contract is rejected by vendor. At this state, nothing can be done to the contract. No statuses may be added to the collection. Contract is accepted by vendor. At this state, nothing can be done to the contract. No statuses may be added to the collection. I obviously want to avoid a situation where the contract is accepted and, say, the amount is changed. Here are my classes: [EnforceNoChangesAfterDraftState] public class VendorContract { public virtual Vendor Vendor { get; set; } public virtual decimal Amount { get; set; } public virtual VendorContact VendorContact { get; set; } public virtual string CreatedBy { get; set; } public virtual DateTime CreatedOn { get; set; } public virtual FileStore Contract { get; set; } public virtual IList<VendorContractStatus> ContractStatus { get; set; } } [EnforceCorrectWorkflow] public class VendorContractStatus { public virtual VendorContract VendorContract { get; set; } public virtual FileStore ExecutedDocument { get; set; } public virtual string Status { get; set; } public virtual string Reason { get; set; } public virtual string CreatedBy { get; set; } public virtual DateTime CreatedOn { get; set; } } I've omitted the filestore class, which is basically a key/value lookup to find the document based on its guid. The VendorContractStatus is mapped as a many-to-one in Nhibernate. I then use a custom validator as described here. If anything but draft is returned in the VendorContractStatus collection, no changes are allowed. Furthermore the VendorContractStatus must follow the correct workflow (you can add a rejected after a pending, but you can't add anything else to the collection if a reject or accepted exists, etc.). All sounds alright? Well a colleague has argued that we should simply add an "IsDraft" bool property to VendorContract and not accept updates if IsDraft is false. Then we should setup a method inside of VendorContractStatus for updating the status, if something gets added after a draft, it sets the IsDraft property of VendorContract to false. I do not like this as it feels like I'm dirtying up the POCOs and adding logic that should persist in the validation area, that no rules should really exist in these classes and they shouldn't be aware of their states. Any thoughts on this and what is the better practice from a DDD perspective? From my view, if in the future we want more complex rules, my way will be more maintainable over the long run. Say we have contracts over a certain amount to be approved by a manager. I would think it would be better to have a one-to-one mapping with a VendorContractApproval class, rather than adding IsApproved properties, but that's just speculation. This might be splitting hairs, but this is the first real gritty enterprise software project we've done. Any advice would be appreciated!

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  • Async networking + threading problem

    - by randallmeadows
    I kick off a network request, assuming no login credentials are required to talk to the destination server. If they are required, then I get an authentication challenge, at which point I display a view requesting said credentials from the user. When they are supplied, I restart the network request, using those credentials. That's all fine and dandy, as long as I only do one request at a time. But I'm not, typically. When both requests are kicked off, I get the first challenge, and present the prompt (using -presentModalViewController:). Then the 2nd challenge comes in. And I crash when it tries to display the 2nd prompt. I have the bulk of this wrapped in an @synchronized() block, but this has no effect because these delegate methods are all being called on the same (main) thread. The docs say the delegate methods are called on the same thread in which the connection was started. OK, no problem; I'll just write a method that I run on a background thread using -performSelectorInBackground: NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:NO]; [connections addObject:connection]; [self performSelectorInBackground:@selector(startConnection:) withObject:connection]; [connection release]; - (void)startConnection:(NSURLConnection *)connection { NSAutoreleasePool *pool = [NSAutoreleasePool new]; [connection scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode]; [connection start]; [pool drain]; } which should put every network request, and its callbacks, on its own thread, and then my @synchronized() blocks will take effect. The docs for -initWithRequest:... state "Messages to the delegate will be sent on the thread that calls this method. By default, for the connection to work correctly the calling thread’s run loop must be operating in the default run loop mode." Ok, I'm doing that. They also state "If you pass NO [for startImmediately], you must schedule the connection in a run loop before starting it." OK, I'm doing that, too. Furthermore, the docs for NSRunLoop state "Each NSThread object, including the application’s main thread, has an NSRunLoop object automatically created for it as needed. If you need to access the current thread’s run loop, you do so with the class method currentRunLoop." I'm assuming this applies to the background thread created by the call -performSelectorInBackground... (which does appear to be the case, when I execute 'po [NSClassFromString(@"NSRunLoop") currentRunLoop]' in the -startConnection: method). The -startConnection: method is indeed being called. But after kicking off the connection, I now never get any callbacks on it. None of the -connectionDid… delegate methods. (I even tried explicitly starting the thread's run loop, but that made no difference; I've used threads like this before, and I've never had to start the run loop manually before--but I'm now grasping at straws...) I think I've come up with a workaround such that I only handle one request at a time, but it's kludgy and I'd like to do this the Right Way. But, what am I missing here? Thanks! randy

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  • How to refresh a GridView?

    - by Daniel
    Hello everyone, I have a GridView which is pretty similar to the Google tutorial, except that I want to add the ImageViews on runtime (via a subactivity). The results are okay, but the layout of the View is messed up: The GridView doesn't fill the content of its parent, what do I have to do to design it properly? Here the code of adding the children: public void initializeWorkbench(GridView gv, Vector<String> items) { Prototype.workbench.setDimension(screenWidth, divider.height()+workbenchArea.height()); Prototype.workbench.activateWorkbench(); // this measures the workbench correctly Log.d(Prototype.TAG, "workbench width: "+Prototype.workbench.getMeasuredWidth()); // 320 Log.d(Prototype.TAG, "workbench height: "+Prototype.workbench.getMeasuredHeight()); // 30 ImageAdapter imgAdapter = new ImageAdapter(this.getContext(), items); gv.setAdapter(imgAdapter); gv.measure(screenWidth, screenHeight); gv.requestLayout(); gv.forceLayout(); Log.d(Prototype.TAG, "gv width: "+gv.getMeasuredWidth()); // 22 Log.d(Prototype.TAG, "gv height: "+gv.getMeasuredHeight()); // 119 Prototype.workbench.setDimension(screenWidth, divider.height()+workbenchArea.height()); } } activateWorkbench, setDimension and measure in the workbench (LinearLayout above the GridView): public void activateWorkbench() { if(this.equals(Prototype.workbench)) { this.setOrientation(VERTICAL); show = true; measure(); } } public void setDimension(int w, int h) { width = w; height = h; this.setLayoutParams(new LinearLayout.LayoutParams(width, height)); this.invalidate(); } private void measure() { if (this.getOrientation() == LinearLayout.VERTICAL) { int h = 0; int w = 0; this.measureChildren(0, 0); for (int i = 0; i < this.getChildCount(); i++) { View v = this.getChildAt(i); h += v.getMeasuredHeight(); w = (w < v.getMeasuredWidth()) ? v.getMeasuredWidth() : w; } if (this.equals(Prototype.tagarea)) height = (h < height) ? height : h; if (this.equals(Prototype.tagarea)) width = (w < width) ? width : w; } this.setMeasuredDimension(width, height); } The ImageAdapter constructor: public ImageAdapter(Context c, Vector<String> items) { mContext = c; boolean mExternalStorageAvailable = false; boolean mExternalStorageWriteable = false; String state = Environment.getExternalStorageState(); if (Environment.MEDIA_MOUNTED.equals(state)) { // We can read and write the media mExternalStorageAvailable = mExternalStorageWriteable = true; } else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) { // We can only read the media mExternalStorageAvailable = true; mExternalStorageWriteable = false; } else { // Something else is wrong. It may be one of many other states, but // all we need // to know is we can neither read nor write mExternalStorageAvailable = mExternalStorageWriteable = false; } if (mExternalStorageAvailable && mExternalStorageWriteable) { for (String item : items) { File f = new File(item); if (f.exists()) { try { FileInputStream fis = new FileInputStream(f); Bitmap b = BitmapFactory.decodeStream(fis); bitmaps.add(b); files.add(f); } catch (FileNotFoundException e) { Log.e(Prototype.TAG, "", e); } } } } } And the xml layout: <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" android:gravity="bottom" android:paddingLeft="0px" android:paddingTop="0px" android:paddingRight="0px"> <com.unimelb.pt3.ui.TransparentPanel android:id="@+id/workbench" android:layout_width="fill_parent" android:layout_height="10px" android:paddingTop="0px" android:paddingLeft="0px" android:paddingBottom="0px" android:paddingRight="0px"> <GridView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/gridview" android:layout_width="fill_parent" android:layout_height="fill_parent" android:columnWidth="90dp" android:numColumns="auto_fit" android:verticalSpacing="10dp" android:horizontalSpacing="10dp" android:stretchMode="columnWidth" android:gravity="center" /> </com.unimelb.pt3.ui.TransparentPanel> </LinearLayout>

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  • AJAX Generated Select Won't Redirect

    - by James
    So, basically I have this select / drop down menu that I use AJAX to retrieve and create, though when an option is selected (so onChange) I want it to redirect! Though, this still isn't working, I don't get any errors thrown when trying, and tried to do alert() debug methods yet the alerts don't get called. jquery $("#schoolMenu").change(function() { option = $("#schoolMenu option:selected").text(); alert(option); if(option != "- Please Select -") { window.location = "http://www.itmustbecollege.com/pics/pics-from-"+$("#schoolMenu option:selected").val(); } }); This is what is used to call the AJAX // // Populate Schools // $("#state").change(function() { option = $("#state option:selected").text(); if($(this).attr("class") == "menu") { if(option != "- Please Select -") { $.ajax({ type: "GET", url: "/includes/functions.php", data: "f=school&p="+option+"&m=yes", success: function(msg) { $("#fSchool").html("<p style=\"margin-left: 20px;\">Select School:</p>"+ msg); $("#fSchool").show(); $("#school").focus(); } }); } else { $("#fSchool").html(""); $("#fSchool").hide(); } } else { if(option != "- Please Select -") { $.ajax({ type: "GET", url: "/includes/functions.php", data: "f=school&p="+option, success: function(msg) { $("#fSchool").html(msg); $("#fSchool").show(); $("#school").focus(); } }); } else { $("#fSchool").html(""); $("#fSchool").hide(); } } }); It loads perfectly, if you look at http://www.itmustbecollege.com/quotes/ on that bar where you can do "sort by" of Popular | Newest | Category | School if you hover over school a dropdown comes up, select any country and another one appears, though when that is changed nothing happens. here is the PHP for that second drop down // Get College List function getCollege($state, $m = "no", $l = "no") { // Displays Schools if($m == "yes") { $options = '<select id="schoolMenu" name="school"><option value="select" selected="selected">- Please Select -</option>'; } else if($l == "yes" || $l == "yes2") { $options = ''; } else { $options = '<select name="school"><option value="select" selected="selected">- Please Select -</option>'; } $listArray = split("\|\\\\", $list); for($i=0; $i < count($listArray); $i++) { if($m == "yes") { $options .= '<option value="'. trim(titleReplace($listArray[$i])) .'">'. trim($listArray[$i]) .'</option>'; } else if($l == "yes") { $options .= '<li><a href="/quotes/quotes-from-'. titleReplace($listArray[$i]) .'" title="'. trim($listArray[$i]) .' Quotes">'. trim($listArray[$i]) .'</a></li>'; } else if($l == "yes2") { $options .= '<li><a href="/pics/pics-from-'. titleReplace($listArray[$i]) .'" title="'. trim($listArray[$i]) .' Pictures">'. trim($listArray[$i]) .'</a></li>'; } else { $options .= '<option value="'. trim($listArray[$i]) .'">'. trim($listArray[$i]) .'</option>'; } } echo $options .='</select>'; return false; } any help would be great! EDIT: Also, the way I have those drop downs coming for the menus is a bit weird and when you hover over any other "sort by" link they disappear, this is a problem with the "sort by school" because the first select box shows the list up, and if you go and select a school then somehow float over another link it disappears, any help on how to delay that or fix that minor problem?

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  • Const-correctness semantics in C++

    - by thirtythreeforty
    For fun and profit™, I'm writing a trie class in C++ (using the C++11 standard.) My trie<T> has an iterator, trie<T>::iterator. (They're all actually functionally const_iterators, because you cannot modify a trie's value_type.) The iterator's class declaration looks partially like this: template<typename T> class trie<T>::iterator : public std::iterator<std::bidirectional_iterator_tag, T> { friend class trie<T>; struct state { state(const trie<T>* const node, const typename std::vector<std::pair<typename T::value_type, std::unique_ptr<trie<T>>>>::const_iterator& node_map_it ) : node{node}, node_map_it{node_map_it} {} // This pointer is to const data: const trie<T>* node; typename std::vector<std::pair<typename T::value_type, std::unique_ptr<trie<T>>>>::const_iterator node_map_it; }; public: typedef const T value_type; iterator() =default; iterator(const trie<T>* node) { parents.emplace(node, node->children.cbegin()); // ... } // ... private: std::stack<state> parents; // ... }; Notice that the node pointer is declared const. This is because (in my mind) the iterator should not be modifying the node that it points to; it is just an iterator. Now, elsewhere in my main trie<T> class, I have an erase function that has a common STL signature--it takes an iterator to data to erase (and returns an iterator to the next object). template<typename T> typename trie<T>::iterator trie<T>::erase(const_iterator it) { // ... // Cannot modify a const object! it.parents.top().node->is_leaf = false; // ... } The compiler complains because the node pointer is read-only! The erase function definitely should modify the trie that the iterator points to, even though the iterator shouldn't. So, I have two questions: Should iterator's constructors be public? trie<T> has the necessary begin() and end() members, and of course trie<T>::iterator and trie<T> are mutual friends, but I don't know what the convention is. Making them private would solve a lot of the angst I'm having about removing the const "promise" from the iterator's constructor. What are the correct const semantics/conventions regarding the iterator and its node pointer here? Nobody has ever explained this to me, and I can't find any tutorials or articles on the Web. This is probably the more important question, but it does require a good deal of planning and proper implementation. I suppose it could be circumvented by just implementing 1, but it's the principle of the thing!

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  • Updating nested attributes causes duplicate entries

    - by params_noob
    I have a has_many and belongs_to relationship between Job and Address. When I try to update Job and Address in the same form, it updates job but creates a duplicate entry for Address. Am I missing something here? The Edit and Update Actions from Jobs: def edit @job = Job.find(params[:id]) end def update @job = Job.find(params[:id]) if @job.update_attributes(job_params) flash[:success] = "Job Updated" redirect_to current_user else render 'edit' end end The edit form: <h1>Edit Job Information</h1> <div class="row"> <div class="span6 offset3"> <%= form_for(@job) do |f| %> <%= render 'shared/error_messages' %> <%= f.label :recipient %> <%= f.text_field :recipient %> <%= f.label :age %> <%= f.text_field :age %> <%= f.label :gender %> <%= f.text_field :gender %> <%= f.label :ethnicity %> <%= f.text_field :ethnicity %> <%= f.label :height %> <%= f.text_field :height %> <%= f.label :weight %> <%= f.text_field :weight %> <%= f.label :hair %> <%= f.text_field :hair %> <%= f.label :eyes %> <%= f.text_field :eyes %> <%= f.label :other_info %> <%= f.text_field :other_info %> <h3> Address Information </h3> <%= f.fields_for :addresses do |address| %> <%= address.label :label, "Label" %> <%= address.text_field :label %> <%= address.label :addy, "Address" %> <%= address.text_field :addy %> <%= address.label :apt, "Apt/Suite/etc" %> <%= address.text_field :apt %> <%= address.label :city, "City" %> <%= address.text_field :city %> <%= address.label :state, "State" %> <%= address.text_field :state %> <%= address.label :zip, "Zip code" %> <%= address.text_field :zip %> <% end %> <%= f.label :instructions, "Service Instructions" %> <%= f.text_field :instructions %> <%= check_box_tag(:rush) %> <%= label_tag(:rush, "Rush?") %> <%= f.submit "Update Job", class: "btn btn-large btn-primary" %> <% end %> </div> </div>

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  • jquery drag and drop script and problem in reading json array

    - by Mac Taylor
    i made a script , exactly like wordpress widgets page and u can drag and drop objects this is my jquery script : <script type="text/javascript" >$(function(){ $('.widget') .each(function(){ $(this).hover(function(){ $(this).find('h4').addClass('collapse'); }, function(){ $(this).find('h4').removeClass('collapse'); }) .find('h4').hover(function(){ $(this).find('.in-widget-title').css('visibility', 'visible'); }, function(){ $(this).find('.in-widget-title').css('visibility', 'hidden'); }) .click(function(){ $(this).siblings('.widget-inside').toggle(); //Save state on change of collapse state of panel updateWidgetData(); }) .end() .find('.in-widget-title').css('visibility', 'hidden'); }); $('.column').sortable({ connectWith: '.column', handle: 'h4', cursor: 'move', placeholder: 'placeholder', forcePlaceholderSize: true, opacity: 0.4, start: function(event, ui){ //Firefox, Safari/Chrome fire click event after drag is complete, fix for that if($.browser.mozilla || $.browser.safari) $(ui.item).find('.widget-inside').toggle(); }, stop: function(event, ui){ ui.item.css({'top':'0','left':'0'}); //Opera fix if(!$.browser.mozilla && !$.browser.safari) updateWidgetData(); } }) .disableSelection(); }); function updateWidgetData(){ var items=[]; $('.column').each(function(){ var columnId=$(this).attr('id'); $('.widget', this).each(function(i){ var collapsed=0; if($(this).find('.widget-inside').css('display')=="none") collapsed=1; //Create Item object for current panel var item={ id: $(this).attr('id'), collapsed: collapsed, order : i, column: columnId }; //Push item object into items array items.push(item); }); }); //Assign items array to sortorder JSON variable var sortorder={ items: items }; //Pass sortorder variable to server using ajax to save state $.post("blocks.php"+"&order="+$.toJSON(sortorder), function(data){ $('#console').html(data).fadeIn("slow"); }); } </script> main part is saving object orders in table and this is my php part : function stripslashes_deep($value) { $value = is_array($value) ? array_map('stripslashes_deep', $value) : stripslashes($value); return $value; } $order = $_GET['order']; $order = sql_quote($order); if(empty($order)){ echo "Invalid data"; exit; } global $db,$prefix; if (get_magic_quotes_gpc()) { $_POST = array_map('stripslashes_deep', $_POST); $_GET = array_map('stripslashes_deep', $_GET); $_COOKIE = array_map('stripslashes_deep', $_COOKIE); $_REQUEST = array_map('stripslashes_deep', $_REQUEST); } $data=json_decode($order); foreach($newdata->items as $item) { //Extract column number for panel $col_id=preg_replace('/[^\d\s]/', '', $item->column); //Extract id of the panel $widget_id=preg_replace('/[^\d\s]/', '', $item->id); $sql="UPDATE blocks_tbl SET bposition='$col_id', weight='".$item->order."' WHERE id='".$widget_id."'"; mysql_query($sql) or die('Error updating widget DB'); } print_r($order); now forexample the output is this : items\":[{\"id\":\"item26\",\"collapsed\":1,\"order\":0,\"column\":\"c\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":0,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":1,\"column\":\"i\"},{\"id\":\"item1\",\"collapsed\":1,\"order\":2,\"column\":\"i\"},{\"id\":\"item3\",\"collapsed\":1,\"order\":3,\"column\":\"i\"},{\"id\":\"item16\",\"collapsed\":1,\"order\":4,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":5,\"column\":\"i\"},{\"id\":\"item6\",\"collapsed\":1,\"order\":6,\"column\":\"i\"},{\"id\":\"item17\",\"collapsed\":1,\"order\":7,\"column\":\"i\"},{\"id\":\"item19\",\"collapsed\":1,\"order\":8,\"column\":\"i\"},{\"id\":\"item10\",\"collapsed\":1,\"order\":9,\"column\":\"i\"},{\"id\":\"item11\",\"collapsed\":1,\"order\":10,\"column\":\"i\"},{\"id\":\"item0\",\"collapsed\":1,\"order\":0,\"column\":\"l\"},{\"id\":\"item5\",\"collapsed\":1,\"order\":1,\"column\":\"l\"},{\"id\":\"item8\",\"collapsed\":1,\"order\":2,\"column\":\"l\"},{\"id\":\"item13\",\"collapsed\":1,\"order\":3,\"column\":\"l\"},{\"id\":\"item21\",\"collapsed\":1,\"order\":4,\"column\":\"l\"},{\"id\":\"item28\",\"collapsed\":1,\"order\":5,\"column\":\"l\"},{\"id\":\"item7\",\"collapsed\":1,\"order\":0,\"column\":\"r\"},{\"id\":\"item20\",\"collapsed\":1,\"order\":1,\"column\":\"r\"},{\"id\":\"item15\",\"collapsed\":1,\"order\":2,\"column\":\"r\"},{\"id\":\"item18\",\"collapsed\":1,\"order\":3,\"column\":\"r\"},{\"id\":\"item14\",\"collapsed\":1,\"order\":4,\"column\":\"r\"}]} question is how can i find out column_id or order im a little bit confused

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  • Data Warehouse ETL slow - change primary key in dimension?

    - by Jubbles
    I have a working MySQL data warehouse that is organized as a star schema and I am using Talend Open Studio for Data Integration 5.1 to create the ETL process. I would like this process to run once per day. I have estimated that one of the dimension tables (dimUser) will have approximately 2 million records and 23 columns. I created a small test ETL process in Talend that worked, but given the amount of data that may need to be updated daily, the current performance will not cut it. It takes the ETL process four minutes to UPDATE or INSERT 100 records to dimUser. If I assumed a linear relationship between the count of records and the amount of time to UPDATE or INSERT, then there is no way the ETL can finish in 3-4 hours (my hope), let alone one day. Since I'm unfamiliar with Java, I wrote the ETL as a Python script and ran into the same problem. Although, I did discover that if I did only INSERT, the process went much faster. I am pretty sure that the bottleneck is caused by the UPDATE statements. The primary key in dimUser is an auto-increment integer. My friend suggested that I scrap this primary key and replace it with a multi-field primary key (in my case, 2-3 fields). Before I rip the test data out of my warehouse and change the schema, can anyone provide suggestions or guidelines related to the design of the data warehouse the ETL process how realistic it is to have an ETL process INSERT or UPDATE a few million records each day will my friend's suggestion significantly help If you need any further information, just let me know and I'll post it. UPDATE - additional information: mysql> describe dimUser; Field Type Null Key Default Extra user_key int(10) unsigned NO PRI NULL auto_increment id_A int(10) unsigned NO NULL id_B int(10) unsigned NO NULL field_4 tinyint(4) unsigned NO 0 field_5 varchar(50) YES NULL city varchar(50) YES NULL state varchar(2) YES NULL country varchar(50) YES NULL zip_code varchar(10) NO 99999 field_10 tinyint(1) NO 0 field_11 tinyint(1) NO 0 field_12 tinyint(1) NO 0 field_13 tinyint(1) NO 1 field_14 tinyint(1) NO 0 field_15 tinyint(1) NO 0 field_16 tinyint(1) NO 0 field_17 tinyint(1) NO 1 field_18 tinyint(1) NO 0 field_19 tinyint(1) NO 0 field_20 tinyint(1) NO 0 create_date datetime NO 2012-01-01 00:00:00 last_update datetime NO 2012-01-01 00:00:00 run_id int(10) unsigned NO 999 I used a surrogate key because I had read that it was good practice. Since, from a business perspective, I want to keep aware of potential fraudulent activity (say for 200 days a user is associated with state X and then the next day they are associated with state Y - they could have moved or their account could have been compromised), so that is why geographic data is kept. The field id_B may have a few distinct values of id_A associated with it, but I am interested in knowing distinct (id_A, id_B) tuples. In the context of this information, my friend suggested that something like (id_A, id_B, zip_code) be the primary key. For the large majority of daily ETL processes (80%), I only expect the following fields to be updated for existing records: field_10 - field_14, last_update, and run_id (this field is a foreign key to my etlLog table and is used for ETL auditing purposes).

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  • Normalizing a table

    - by Alex
    I have a legacy table, which I can't change. The values in it can be modified from legacy application (application also can't be changed). Due to a lot of access to the table from new application (new requirement), I'd like to create a temporary table, which would hopefully speed up the queries. The actual requirement, is to calculate number of business days from X to Y. For example, give me all business days from Jan 1'st 2001 until Dec 24'th 2004. The table is used to mark which days are off, as different companies may have different days off - it isn't just Saturday + Sunday) The temporary table would be created from a .NET program, each time user enters the screen for this query (user may run query multiple times, with different values, table is created once), so I'd like it to be as fast as possible. Approach below runs in under a second, but I only tested it with a small dataset, and still it takes probably close to half a second, which isn't great for UI - even though it's just the overhead for first query. The legacy table looks like this: CREATE TABLE [business_days]( [country_code] [char](3) , [state_code] [varchar](4) , [calendar_year] [int] , [calendar_month] [varchar](31) , [calendar_month2] [varchar](31) , [calendar_month3] [varchar](31) , [calendar_month4] [varchar](31) , [calendar_month5] [varchar](31) , [calendar_month6] [varchar](31) , [calendar_month7] [varchar](31) , [calendar_month8] [varchar](31) , [calendar_month9] [varchar](31) , [calendar_month10] [varchar](31) , [calendar_month11] [varchar](31) , [calendar_month12] [varchar](31) , misc. ) Each month has 31 characters, and any day off (Saturday + Sunday + holiday) is marked with X. Each half day is marked with an 'H'. For example, if a month starts on a Thursday, than it will look like (Thursday+Friday workdays, Saturday+Sunday marked with X): ' XX XX ..' I'd like the new table to look like so: create table #Temp (country varchar(3), state varchar(4), date datetime, hours int) And I'd like to only have rows for days which are off (marked with X or H from previous query) What I ended up doing, so far is this: Create a temporary-intermediate table, that looks like this: create table #Temp_2 (country_code varchar(3), state_code varchar(4), calendar_year int, calendar_month varchar(31), month_code int) To populate it, I have a union which basically unions calendar_month, calendar_month2, calendar_month3, etc. Than I have a loop which loops through all the rows in #Temp_2, after each row is processed, it is removed from #Temp_2. To process the row there is a loop from 1 to 31, and substring(calendar_month, counter, 1) is checked for either X or H, in which case there is an insert into #Temp table. [edit added code] Declare @country_code char(3) Declare @state_code varchar(4) Declare @calendar_year int Declare @calendar_month varchar(31) Declare @month_code int Declare @calendar_date datetime Declare @day_code int WHILE EXISTS(SELECT * From #Temp_2) -- where processed = 0) BEGIN Select Top 1 @country_code = t2.country_code, @state_code = t2.state_code, @calendar_year = t2.calendar_year, @calendar_month = t2.calendar_month, @month_code = t2.month_code From #Temp_2 t2 -- where processed = 0 set @day_code = 1 while @day_code <= 31 begin if substring(@calendar_month, @day_code, 1) = 'X' begin set @calendar_date = convert(datetime, (cast(@month_code as varchar) + '/' + cast(@day_code as varchar) + '/' + cast(@calendar_year as varchar))) insert into #Temp (country, state, date, hours) values (@country_code, @state_code, @calendar_date, 8) end if substring(@calendar_month, @day_code, 1) = 'H' begin set @calendar_date = convert(datetime, (cast(@month_code as varchar) + '/' + cast(@day_code as varchar) + '/' + cast(@calendar_year as varchar))) insert into #Temp (country, state, date, hours) values (@country_code, @state_code, @calendar_date, 4) end set @day_code = @day_code + 1 end delete from #Temp_2 where @country_code = country_code AND @state_code = state_code AND @calendar_year = calendar_year AND @calendar_month = calendar_month AND @month_code = month_code --update #Temp_2 set processed = 1 where @country_code = country_code AND @state_code = state_code AND @calendar_year = calendar_year AND @calendar_month = calendar_month AND @month_code = month_code END I am not an expert in SQL, so I'd like to get some input on my approach, and maybe even a much better approach suggestion. After having the temp table, I'm planning to do (dates would be coming from a table): select cast(convert(datetime, ('01/31/2012'), 101) -convert(datetime, ('01/17/2012'), 101) as int) - ((select sum(hours) from #Temp where date between convert(datetime, ('01/17/2012'), 101) and convert(datetime, ('01/31/2012'), 101)) / 8) Besides the solution of normalizing the table, the other solution I implemented for now, is a function which does all this logic of getting the business days by scanning the current table. It runs pretty fast, but I'm hesitant to call a function, if I can instead add a simpler query to get result. (I'm currently trying this on MSSQL, but I would need to do same for Sybase ASE and Oracle)

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  • Table Name is null in the sqlite database in android device

    - by Mahe
    I am building a simple app which stores some contacts and retrieves contacts in android phone device. I have created my own database and a table and inserting the values to the table in phone. My phone is not rooted. So I cannot access the files, but I see that values are stored in the table. And tested on a emulator also. Till here it is fine. Display all the contacts in a list by fetching data from table. This is also fine. But the problem is When I am trying to delete the record, it shows the table name is null in the logcat(not an exception), and the data is not deleted. But in emulator the data is getting deleted from table. I am not able to achieve this through phone. This is my code for deleting, public boolean onContextItemSelected(MenuItem item) { super.onContextItemSelected(item); AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item .getMenuInfo(); int menuItemIndex = item.getItemId(); String[] menuItems = getResources().getStringArray(R.array.menu); String menuItemName = menuItems[menuItemIndex]; String listItemName = Customers[info.position]; if (item.getTitle().toString().equalsIgnoreCase("Delete")) { Toast.makeText( context, "Selected List item is: " + listItemName + "MenuItem is: " + menuItemName, Toast.LENGTH_LONG).show(); DB = context.openOrCreateDatabase("CustomerDetails.db", MODE_PRIVATE, null); try { int pos = info.position; pos = pos + 1; Log.d("", "customers[pos]: " + Customers[info.position]); Cursor c = DB .rawQuery( "Select customer_id,first_name,last_name from CustomerInfo", null); int rowCount = c.getCount(); DB.delete(Table_name, "customer_id" + "=" + String.valueOf(pos), null); DB.close(); Log.d("", "" + String.valueOf(pos)); Toast.makeText(context, "Deleted Customer", Toast.LENGTH_LONG) .show(); // Customers[info.position]=null; getCustomers(); } catch (Exception e) { Toast.makeText(context, "Delete unsuccessfull", Toast.LENGTH_LONG).show(); } } this is my logcat, 07-02 10:12:42.976: D/Cursor(1560): Database path: CustomerDetails.db 07-02 10:12:42.976: D/Cursor(1560): Table name : null 07-02 10:12:42.984: D/Cursor(1560): Database path: CustomerDetails.db 07-02 10:12:42.984: D/Cursor(1560): Table name : null Don't know the reason why data is not being deleted. Data exists in the table. This is the specification I have given for creating the table public static String customer_id="customer_id"; public static String site_id="site_id"; public static String last_name="last_name"; public static String first_name="first_name"; public static String phone_number="phone_number"; public static String address="address"; public static String city="city"; public static String state="state"; public static String zip="zip"; public static String email_address="email_address"; public static String custlat="custlat"; public static String custlng="custlng"; public static String Table_name="CustomerInfo"; final SQLiteDatabase DB = context.openOrCreateDatabase( "CustomerDetails.db", MODE_PRIVATE, null); final String CREATE_TABLE = "create table if not exists " + Table_name + " (" + customer_id + " integer primary key autoincrement, " + first_name + " text not null, " + last_name + " text not null, " + phone_number+ " integer not null, " + address+ " text not null, " + city+ " text not null, " + state+ " text not null, " + zip+ " integer not null, " + email_address+ " text not null, " + custlat+ " double, " + custlng+ " double " +" );"; DB.execSQL(CREATE_TABLE); DB.close(); Please correct my code. I am struggling from two days. Any help is appreciated!!

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  • Help With Proxy Username & Pass with GeckoFX??!!

    - by John
    Hello, I am trying to set the proxy username and password. I saw this posting (http://geckofx.org/viewtopic.php?id=832) and I thought it might be a similar setting for the username/password, such as : Skybound.Gecko.GeckoPreferences.User["network.proxy.user"] = (user); Skybound.Gecko.GeckoPreferences.User["network.proxy.password"] = (password); But, nothing has worked so far. Can anyone help? I would really appreciate it!!! I am using VB.net if that helps. Thanks!!

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  • Setting collation property in the connection string to SQL Server 2005

    - by user369745
    I have a ASP.Net web application with connection string for SQL Server 2005 in the web.config. Data Source=ABCSERVER;Network Library=DBMSSOCN;Initial Catalog=myDataBase; User ID=myUsername;Password=myPassword; I want to specify the collation property in the web.config for different languages like French like Data Source=ABCSERVER;Network Library=DBMSSOCN;Initial Catalog=myDataBase; User ID=myUsername;Password=myPassword;Collation=French_CS_AS But the Collation word is not valid in the connection string. What is the correct keyword that we need to use to specify the collation in SQL Server 2005 connection string?

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  • Using DefaultCredentials and DefaultNetworkCredentials

    - by Fred
    Hi, We're having a hard time figuring how these credentials objects work. In fact, they may not work how we expected them to work. Here's an explanation of the current issue. We got 2 servers that needs to talk with each other through webservices. The first one (let's call it Server01) has a Windows Service running as the NetworkService account. The other one (Server02) has ReportingServices running with IIS 6.0. The Windows Service on Server01 is trying to use the Server02's ReportingServices' WebService to generate reports and send them by email. So, here's what we tried so far. Setting the credentials at runtime (This works perfectly fine): rs.Credentials = new NetworkCredentials("user", "pass", "domain"); Now, if we could use a generic user all would be fine, however... we are not allowed to. So, we are trying to use the DefaultCredetials or DefaultNetworkCredentials and pass it to the RS Webservice: `rs.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials OR `rs.Credentials = System.Net.CredentialCache.DefaultCredentials Either way won't work. We're always getting 401 Unauthrorized from IIS. Now, what we know is that if we want to give access to a resource logged as NetworkService, we need to grant it to "DOMAIN\MachineName$" (http://msdn.microsoft.com/en-us/library/ms998320.aspx): Granting Access to a Remote SQL Server If you are accessing a database on another server in the same domain (or in a trusted domain), the Network Service account's network credentials are used to authenticate to the database. The Network Service account's credentials are of the form DomainName\AspNetServer$, where DomainName is the domain of the ASP.NET server and AspNetServer is your Web server name. For example, if your ASP.NET application runs on a server named SVR1 in the domain CONTOSO, the SQL Server sees a database access request from CONTOSO\SVR1$. We assumed that granting access the same way with IIS would work. However, it does not. Or at least, something is not set properly for it to authenticate correctly. So, here are some questions: We've read about "Impersonating Users" somewhere, do we need to set this somewhere in the Windows Service ? Is it possible to grant access to the NetworkService built-in account to a remote IIS server ? Thanks for reading!

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  • Gone With the Wind?

    - by antony.reynolds
    Where Have All the Composites Gone? I was just asked to help out with an interesting problem at a customer.  All their composites had disappeared from the EM console, none of them showed as loading in the log files and there was an ominous error message in the logs. Symptoms After a server restart the customer noticed that none of his composites were available, they didn’t show in the EM console and in the log files they saw this error message: SEVERE: WLSFabricKernelInitializer.getCompositeList Error during parsing and processing of deployed-composites.xml file This indicates some sort of problem when parsing the deployed-composites.xml file.  This is very bad because the deployed-composites.xml file is basically the table of contents that tells SOA Infrastructure what composites to load and where to find them in MDS.  If you can’t read this file you can’t load any composites and your SOA Server now has all the utility of a chocolate teapot. Verification We can look at the deployed-composites.xml file from MDS either by connecting JDeveloper to MDS, exporting the file using WLST or exporting the whole soa-infra MDS partition by using EM->SOA->soa-infra->Administration->MDS Configuration.  Exporting via EM is probably the easiest because it then prepares you to fix the problem later.  After exporting the partition to local storage on the SOA Server I then ran an XSLT transform across the file deployed-composites/deployed-composites.xml. <?xml version="1.0" encoding="utf-8"?> <xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/1999/xhtml">     <xsl:output indent="yes"/>     <xsl:template match="/">         <testResult>             <composite-series>                 <xsl:attribute name="elementCount"><xsl:value-of select="count(deployed-composites/composite-series)"/></xsl:attribute>                 <xsl:attribute name="nameAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series[@name])"/></xsl:attribute>                 <xsl:attribute name="defaultAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series[@default])"/></xsl:attribute>                 <composite-revision>                     <xsl:attribute name="elementCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision)"/></xsl:attribute>                     <xsl:attribute name="dnAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@dn])"/></xsl:attribute>                     <xsl:attribute name="stateAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@state])"/></xsl:attribute>                     <xsl:attribute name="modeAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@mode])"/></xsl:attribute>                     <xsl:attribute name="locationAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision[@location])"/></xsl:attribute>                     <composite>                         <xsl:attribute name="elementCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision/composite)"/></xsl:attribute>                         <xsl:attribute name="dnAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision/composite[@dn])"/></xsl:attribute>                         <xsl:attribute name="deployedTimeAttributeCount"><xsl:value-of select="count(deployed-composites/composite-series/composite-revision/composite[@deployedTime])"/></xsl:attribute>                     </composite>                 </composite-revision>                 <xsl:apply-templates select="deployed-composites/composite-series"/>             </composite-series>         </testResult>     </xsl:template>     <xsl:template match="composite-series">             <xsl:if test="not(@name) or not(@default) or composite-revision[not(@dn) or not(@state) or not(@mode) or not(@location)]">                 <ErrorNode>                     <xsl:attribute name="elementPos"><xsl:value-of select="position()"/></xsl:attribute>                     <xsl:copy-of select="."/>                 </ErrorNode>             </xsl:if>     </xsl:template> </xsl:stylesheet> The output from this is not pretty but it shows any <composite-series> tags that are missing expected attributes (name and default).  It also shows how many composites are in the file (111) and how many revisions of those composites (115). <?xml version="1.0" encoding="UTF-8"?> <testResult xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.w3.org/1999/xhtml">    <composite-series elementCount="111" nameAttributeCount="110" defaultAttributeCount="110">       <composite-revision elementCount="115" dnAttributeCount="114" stateAttributeCount="115"                           modeAttributeCount="115"                           locationAttributeCount="114">          <composite elementCount="115" dnAttributeCount="114" deployedTimeAttributeCount="115"/>       </composite-revision>       <ErrorNode elementPos="82">          <composite-series xmlns="">             <composite-revision state="on" mode="active">                <composite deployedTime="2010-12-15T11:50:16.067+01:00"/>             </composite-revision>          </composite-series>       </ErrorNode>    </composite-series> </testResult> From this I could see that one of the <composite-series> elements (number 82 of 111) seemed to be corrupt. Having found the problem I now needed to fix it. Fixing the Problem The solution was really quite easy.  First for safeties sake I took a backup of the exported MDS partition.  I then edited the deployed-composites/deployed-composites.xml file to remove the offending <composite-series> tag. Finally I restarted the SOA domain and was rewarded by seeing that the deployed composites were now visible. Summary One possible cause of not being able to see deployed composites after a SOA 11g system restart is a corrupt deployed-composites.xml file.  Retrieving this file from MDS, repairing it, and replacing it back into MDS can solve the problem.  This still leaves the problem of how did this file become corrupt!

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  • HTML5 cache manifest: whitelisting ALL remote resources?

    - by Alex Ford
    I'm doing an iPhone version of a desktop site that includes a blog. The blog often embeds images from other domains (the image URLs always start with http:// in this case, obviously), but because I'm using cache-manifest, these images don't load because they aren't declared in the manifest file. I have a NETWORK: whitelist section that has all of my AJAX request files, etc. I've even whitelisted the flickr farm domains because a lot of the images we add to the blog come from our flickr page. The flickr images show up just fine, but any other "random" image hotlinks from another domain show broken. I tried adding a line like this: http:// to the NETWORK: section, but it doesn't seem to like http:// as a whitelist. Does anyone have any thoughts on this? Thanks! Alex

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  • Delphi: Get MAC of Router

    - by Daniel Marschall
    Hello, I am using Delphi and I want to determinate the physical MAC address of a network device in my network, in this case the Router itself. My code: var idsnmp: tidsnmp; val:string; begin idsnmp := tidsnmp.create; try idsnmp.QuickSend('.1.3.6.1.2.1.4.22.1.2', 'public', '10.0.0.1', val); showmessage(val); finally idsnmp.free; end; end; where 10.0.0.1 is my router. Alas, QuickSend does always send "Connection reset by peer #10054". I tried to modify the MIB-OID and I also tried the IP 127.0.0.1 which connection should never fail. I did not find any useable Tutorials about TIdSNMP at Google. :-( Regards Daniel Marschall

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  • XCOPY to remote server

    - by Max
    In order to improve the deployment / build process of my ASP.NET app, I would like to make a .bat that builds the current solution in release mode xcopy the files to a remote server Creating a release build via command line is easy. But how can I xcopy the files to the remote server? I think I have to map the remote destination to a network drive (?). However I could not connect to the remote server, although I have enabled file sharing for the folder on the server. Maybe the firewall is blocking the request? Which port should I open? Or is there another solution? EDIT Thanks for all the answers so far, but I probably need a step by step guide on how to set up the folder sharing on the server. I shared the folder, I opened up port 445 so that I can connect to the server but still, I cant connect from my local machine to the server in order to map the network path to a system drive.

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  • Login failed for user 'DOMAIN\MACHINENAME$'

    - by sah302
    I know this is almost duplicate of : http://stackoverflow.com/questions/1269706/the-error-login-failed-for-user-nt-authority-iusr-in-asp-net-and-sql-server-2 and http://stackoverflow.com/questions/97594/login-failed-for-user-username-system-data-sqlclient-sqlexception-with-linq-i but some things don't add up compared to other appliations on my server and I am not sure why. Boxes being used: Web Box SQL Box SQL Test Box My Application: I've got aASP.NET Web Application, which references a class library that uses LINQ-to-SQL. Connection string set up properly in the class library. As per http://stackoverflow.com/questions/97594/login-failed-for-user-username-system-data-sqlclient-sqlexception-with-linq-i I also added this connection string to the Web Application. The connection string uses SQL credentials as so (in both web app and class library): <add name="Namespace.My.MySettings.ConnectionStringProduction" connectionString="Data Source=(SQL Test Box);Initial Catalog=(db name);Persist Security Info=True;User ID=ID;Password=Password" providerName="System.Data.SqlClient" /> This connection confirmed as working via adding it to server explorer. This is the connection string my .dbml file is using. The problem: I get the following error: System.Data.SqlClient.SqlException: Login failed for user 'DOMAIN\MACHINENAME$'. Now referencing this http://stackoverflow.com/questions/1269706/the-error-login-failed-for-user-nt-authority-iusr-in-asp-net-and-sql-server-2 it says that's really the local network service and using any other non-domain name will not work. But I am confused because I've checked both SQL Box and SQL Test Box SQL Management Studio and both have NT AUTHORITY/NETWORK SERVICE under Security - Logins, at the database level, that isn't listed under Security - Users, but at the database level Security - Users I have the user displayed in the connection string. At NTFS level on web server, the permissions have NETWORK SERVICE has full control. The reason why I am confused is because I have many other web applications on my Web Server, that reference databases on both SQL Box and SQL Test Box, and they all work. But I cannot find a difference between them and my current application, other than I am using a class library. Will that matter? Checking NTFS permissions, setup of Security Logins at the server and databases levels, connection string and method of connecting (SQL Server credentials), and IIS application pool and other folder options, are all the same. Why do these applications work without adding the machinename$ to the permissions of either of my SQL boxes? But that is what the one link is telling me to do to fix this problem.

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  • Adventures in MVVM &ndash; My ViewModel Base

    - by Brian Genisio's House Of Bilz
    More Adventures in MVVM First, I’d like to say: THIS IS NOT A NEW MVVM FRAMEWORK. I tend to believe that MVVM support code should be specific to the system you are building and the developers working on it.  I have yet to find an MVVM framework that does everything I want it to without doing too much.  Don’t get me wrong… there are some good frameworks out there.  I just like to pick and choose things that make sense for me.  I’d also like to add that some of these features only work in WPF.  As of Silveright 4, they don’t support binding to dynamic properties, so some of the capabilities are lost. That being said, I want to share my ViewModel base class with the world.  I have had several conversations with people about the problems I have solved using this ViewModel base.  A while back, I posted an article about some experiments with a “Rails Inspired ViewModel”.  What followed from those ideas was a ViewModel base class that I take with me and use in my projects.  It has a lot of features, all designed to reduce the friction in writing view models. I have put the code out on Codeplex under the project: ViewModelSupport. Finally, this article focuses on the ViewModel and only glosses over the View and the Model.  Without all three, you don’t have MVVM.  But this base class is for the ViewModel, so that is what I am focusing on. Features: Automatic Command Plumbing Property Change Notification Strongly Typed Property Getter/Setters Dynamic Properties Default Property values Derived Properties Automatic Method Execution Command CanExecute Change Notification Design-Time Detection What about Silverlight? Automatic Command Plumbing This feature takes the plumbing out of creating commands.  The common pattern for commands in a ViewModel is to have an Execute method as well as an optional CanExecute method.  To plumb that together, you create an ICommand Property, and set it in the constructor like so: Before public class AutomaticCommandViewModel { public AutomaticCommandViewModel() { MyCommand = new DelegateCommand(Execute_MyCommand, CanExecute_MyCommand); } public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } public DelegateCommand MyCommand { get; private set; } } With the base class, this plumbing is automatic and the property (MyCommand of type ICommand) is created for you.  The base class uses the convention that methods be prefixed with Execute_ and CanExecute_ in order to be plumbed into commands with the property name after the prefix.  You are left to be expressive with your behavior without the plumbing.  If you are wondering how CanExecuteChanged is raised, see the later section “Command CanExecute Change Notification”. After public class AutomaticCommandViewModel : ViewModelBase { public void Execute_MyCommand() { // Do something } public bool CanExecute_MyCommand() { // Are we in a state to do something? return true; } }   Property Change Notification One thing that always kills me when implementing ViewModels is how to make properties that notify when they change (via the INotifyPropertyChanged interface).  There have been many attempts to make this more automatic.  My base class includes one option.  There are others, but I feel like this works best for me. The common pattern (without my base class) is to create a private backing store for the variable and specify a getter that returns the private field.  The setter will set the private field and fire an event that notifies the change, only if the value has changed. Before public class PropertyHelpersViewModel : INotifyPropertyChanged { private string text; public string Text { get { return text; } set { if(text != value) { text = value; RaisePropertyChanged("Text"); } } } protected void RaisePropertyChanged(string propertyName) { var handlers = PropertyChanged; if(handlers != null) handlers(this, new PropertyChangedEventArgs(propertyName)); } public event PropertyChangedEventHandler PropertyChanged; } This way of defining properties is error-prone and tedious.  Too much plumbing.  My base class eliminates much of that plumbing with the same functionality: After public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get<string>("Text"); } set { Set("Text", value);} } }   Strongly Typed Property Getters/Setters It turns out that we can do better than that.  We are using a strongly typed language where the use of “Magic Strings” is often frowned upon.  Lets make the names in the getters and setters strongly typed: A refinement public class PropertyHelpersViewModel : ViewModelBase { public string Text { get { return Get(() => Text); } set { Set(() => Text, value); } } }   Dynamic Properties In C# 4.0, we have the ability to program statically OR dynamically.  This base class lets us leverage the powerful dynamic capabilities in our ecosystem. (This is how the automatic commands are implemented, BTW)  By calling Set(“Foo”, 1), you have now created a dynamic property called Foo.  It can be bound against like any static property.  The opportunities are endless.  One great way to exploit this behavior is if you have a customizable view engine with templates that bind to properties defined by the user.  The base class just needs to create the dynamic properties at runtime from information in the model, and the custom template can bind even though the static properties do not exist. All dynamic properties still benefit from the notifiable capabilities that static properties do. For any nay-sayers out there that don’t like using the dynamic features of C#, just remember this: the act of binding the View to a ViewModel is dynamic already.  Why not exploit it?  Get over it :) Just declare the property dynamically public class DynamicPropertyViewModel : ViewModelBase { public DynamicPropertyViewModel() { Set("Foo", "Bar"); } } Then reference it normally <TextBlock Text="{Binding Foo}" />   Default Property Values The Get() method also allows for default properties to be set.  Don’t set them in the constructor.  Set them in the property and keep the related code together: public string Text { get { return Get(() => Text, "This is the default value"); } set { Set(() => Text, value);} }   Derived Properties This is something I blogged about a while back in more detail.  This feature came from the chaining of property notifications when one property affects the results of another, like this: Before public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); RaisePropertyChanged("Percentage"); RaisePropertyChanged("Output"); } } public int Percentage { get { return (int)(100 * Score); } } public string Output { get { return "You scored " + Percentage + "%."; } } } The problem is: The setter for Score has to be responsible for notifying the world that Percentage and Output have also changed.  This, to me, is backwards.    It certainly violates the “Single Responsibility Principle.” I have been bitten in the rear more than once by problems created from code like this.  What we really want to do is invert the dependency.  Let the Percentage property declare that it changes when the Score Property changes. After public class DependantPropertiesViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public int Percentage { get { return (int)(100 * Score); } } [DependsUpon("Percentage")] public string Output { get { return "You scored " + Percentage + "%."; } } }   Automatic Method Execution This one is extremely similar to the previous, but it deals with method execution as opposed to property.  When you want to execute a method triggered by property changes, let the method declare the dependency instead of the other way around. Before public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); WhenScoreChanges(); } } public void WhenScoreChanges() { // Handle this case } } After public class DependantMethodsViewModel : ViewModelBase { public double Score { get { return Get(() => Score); } set { Set(() => Score, value); } } [DependsUpon("Score")] public void WhenScoreChanges() { // Handle this case } }   Command CanExecute Change Notification Back to Commands.  One of the responsibilities of commands that implement ICommand – it must fire an event declaring that CanExecute() needs to be re-evaluated.  I wanted to wait until we got past a few concepts before explaining this behavior.  You can use the same mechanism here to fire off the change.  In the CanExecute_ method, declare the property that it depends upon.  When that property changes, the command will fire a CanExecuteChanged event, telling the View to re-evaluate the state of the command.  The View will make appropriate adjustments, like disabling the button. DependsUpon works on CanExecute methods as well public class CanExecuteViewModel : ViewModelBase { public void Execute_MakeLower() { Output = Input.ToLower(); } [DependsUpon("Input")] public bool CanExecute_MakeLower() { return !string.IsNullOrWhiteSpace(Input); } public string Input { get { return Get(() => Input); } set { Set(() => Input, value);} } public string Output { get { return Get(() => Output); } set { Set(() => Output, value); } } }   Design-Time Detection If you want to add design-time data to your ViewModel, the base class has a property that lets you ask if you are in the designer.  You can then set some default values that let your designer see what things might look like in runtime. Use the IsInDesignMode property public DependantPropertiesViewModel() { if(IsInDesignMode) { Score = .5; } }   What About Silverlight? Some of the features in this base class only work in WPF.  As of version 4, Silverlight does not support binding to dynamic properties.  This, in my opinion, is a HUGE limitation.  Not only does it keep you from using many of the features in this ViewModel, it also keeps you from binding to ViewModels designed in IronRuby.  Does this mean that the base class will not work in Silverlight?  No.  Many of the features outlined in this article WILL work.  All of the property abstractions are functional, as long as you refer to them statically in the View.  This, of course, means that the automatic command hook-up doesn’t work in Silverlight.  You need to plumb it to a static property in order for the Silverlight View to bind to it.  Can I has a dynamic property in SL5?     Good to go? So, that concludes the feature explanation of my ViewModel base class.  Feel free to take it, fork it, whatever.  It is hosted on CodePlex.  When I find other useful additions, I will add them to the public repository.  I use this base class every day.  It is mature, and well tested.  If, however, you find any problems with it, please let me know!  Also, feel free to suggest patches to me via the CodePlex site.  :)

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  • Design for a machine learning artificial intelligence framework

    - by Lirik
    This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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  • RPC Runtime exception

    - by viswanathan
    Hi I am having an application which requires inter process communication between different processes in different machines. Assume i have 2 processes in different machines which communicate usnig RPC. Everything works fine in the normal case. Now if i remove network and reconnect the same my processes still work however what happens is sometimes an RPC call(which sends a message from one process on one machine to another process on another machine) fails with an error code value of 3765269347, which may not really make any sense. This failure occurs only sometimes and i have no clue as to why this occurs. Anybody knows any reason why this may occur or general network related RPC issues. Thanks in advance.

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  • SQL SERVER – Concurrency Basics – Guest Post by Vinod Kumar

    - by pinaldave
    This guest post is by Vinod Kumar. Vinod Kumar has worked with SQL Server extensively since joining the industry over a decade ago. Working on various versions from SQL Server 7.0, Oracle 7.3 and other database technologies – he now works with the Microsoft Technology Center (MTC) as a Technology Architect. Let us read the blog post in Vinod’s own voice. Learning is always fun when it comes to SQL Server and learning the basics again can be more fun. I did write about Transaction Logs and recovery over my blogs and the concept of simplifying the basics is a challenge. In the real world we always see checks and queues for a process – say railway reservation, banks, customer supports etc there is a process of line and queue to facilitate everyone. Shorter the queue higher is the efficiency of system (a.k.a higher is the concurrency). Every database does implement this using checks like locking, blocking mechanisms and they implement the standards in a way to facilitate higher concurrency. In this post, let us talk about the topic of Concurrency and what are the various aspects that one needs to know about concurrency inside SQL Server. Let us learn the concepts as one-liners: Concurrency can be defined as the ability of multiple processes to access or change shared data at the same time. The greater the number of concurrent user processes that can be active without interfering with each other, the greater the concurrency of the database system. Concurrency is reduced when a process that is changing data prevents other processes from reading that data or when a process that is reading data prevents other processes from changing that data. Concurrency is also affected when multiple processes are attempting to change the same data simultaneously. Two approaches to managing concurrent data access: Optimistic Concurrency Model Pessimistic Concurrency Model Concurrency Models Pessimistic Concurrency Default behavior: acquire locks to block access to data that another process is using. Assumes that enough data modification operations are in the system that any given read operation is likely affected by a data modification made by another user (assumes conflicts will occur). Avoids conflicts by acquiring a lock on data being read so no other processes can modify that data. Also acquires locks on data being modified so no other processes can access the data for either reading or modifying. Readers block writer, writers block readers and writers. Optimistic Concurrency Assumes that there are sufficiently few conflicting data modification operations in the system that any single transaction is unlikely to modify data that another transaction is modifying. Default behavior of optimistic concurrency is to use row versioning to allow data readers to see the state of the data before the modification occurs. Older versions of the data are saved so a process reading data can see the data as it was when the process started reading and not affected by any changes being made to that data. Processes modifying the data is unaffected by processes reading the data because the reader is accessing a saved version of the data rows. Readers do not block writers and writers do not block readers, but, writers can and will block writers. Transaction Processing A transaction is the basic unit of work in SQL Server. Transaction consists of SQL commands that read and update the database but the update is not considered final until a COMMIT command is issued (at least for an explicit transaction: marked with a BEGIN TRAN and the end is marked by a COMMIT TRAN or ROLLBACK TRAN). Transactions must exhibit all the ACID properties of a transaction. ACID Properties Transaction processing must guarantee the consistency and recoverability of SQL Server databases. Ensures all transactions are performed as a single unit of work regardless of hardware or system failure. A – Atomicity C – Consistency I – Isolation D- Durability Atomicity: Each transaction is treated as all or nothing – it either commits or aborts. Consistency: ensures that a transaction won’t allow the system to arrive at an incorrect logical state – the data must always be logically correct.  Consistency is honored even in the event of a system failure. Isolation: separates concurrent transactions from the updates of other incomplete transactions. SQL Server accomplishes isolation among transactions by locking data or creating row versions. Durability: After a transaction commits, the durability property ensures that the effects of the transaction persist even if a system failure occurs. If a system failure occurs while a transaction is in progress, the transaction is completely undone, leaving no partial effects on data. Transaction Dependencies In addition to supporting all four ACID properties, a transaction might exhibit few other behaviors (known as dependency problems or consistency problems). Lost Updates: Occur when two processes read the same data and both manipulate the data, changing its value and then both try to update the original data to the new value. The second process might overwrite the first update completely. Dirty Reads: Occurs when a process reads uncommitted data. If one process has changed data but not yet committed the change, another process reading the data will read it in an inconsistent state. Non-repeatable Reads: A read is non-repeatable if a process might get different values when reading the same data in two reads within the same transaction. This can happen when another process changes the data in between the reads that the first process is doing. Phantoms: Occurs when membership in a set changes. It occurs if two SELECT operations using the same predicate in the same transaction return a different number of rows. Isolation Levels SQL Server supports 5 isolation levels that control the behavior of read operations. Read Uncommitted All behaviors except for lost updates are possible. Implemented by allowing the read operations to not take any locks, and because of this, it won’t be blocked by conflicting locks acquired by other processes. The process can read data that another process has modified but not yet committed. When using the read uncommitted isolation level and scanning an entire table, SQL Server can decide to do an allocation order scan (in page-number order) instead of a logical order scan (following page pointers). If another process doing concurrent operations changes data and move rows to a new location in the table, the allocation order scan can end up reading the same row twice. Also can happen if you have read a row before it is updated and then an update moves the row to a higher page number than your scan encounters later. Performing an allocation order scan under Read Uncommitted can cause you to miss a row completely – can happen when a row on a high page number that hasn’t been read yet is updated and moved to a lower page number that has already been read. Read Committed Two varieties of read committed isolation: optimistic and pessimistic (default). Ensures that a read never reads data that another application hasn’t committed. If another transaction is updating data and has exclusive locks on data, your transaction will have to wait for the locks to be released. Your transaction must put share locks on data that are visited, which means that data might be unavailable for others to use. A share lock doesn’t prevent others from reading but prevents them from updating. Read committed (snapshot) ensures that an operation never reads uncommitted data, but not by forcing other processes to wait. SQL Server generates a version of the changed row with its previous committed values. Data being changed is still locked but other processes can see the previous versions of the data as it was before the update operation began. Repeatable Read This is a Pessimistic isolation level. Ensures that if a transaction revisits data or a query is reissued the data doesn’t change. That is, issuing the same query twice within a transaction cannot pickup any changes to data values made by another user’s transaction because no changes can be made by other transactions. However, this does allow phantom rows to appear. Preventing non-repeatable read is a desirable safeguard but cost is that all shared locks in a transaction must be held until the completion of the transaction. Snapshot Snapshot Isolation (SI) is an optimistic isolation level. Allows for processes to read older versions of committed data if the current version is locked. Difference between snapshot and read committed has to do with how old the older versions have to be. It’s possible to have two transactions executing simultaneously that give us a result that is not possible in any serial execution. Serializable This is the strongest of the pessimistic isolation level. Adds to repeatable read isolation level by ensuring that if a query is reissued rows were not added in the interim, i.e, phantoms do not appear. Preventing phantoms is another desirable safeguard, but cost of this extra safeguard is similar to that of repeatable read – all shared locks in a transaction must be held until the transaction completes. In addition serializable isolation level requires that you lock data that has been read but also data that doesn’t exist. Ex: if a SELECT returned no rows, you want it to return no. rows when the query is reissued. This is implemented in SQL Server by a special kind of lock called the key-range lock. Key-range locks require that there be an index on the column that defines the range of values. If there is no index on the column, serializable isolation requires a table lock. Gets its name from the fact that running multiple serializable transactions at the same time is equivalent of running them one at a time. Now that we understand the basics of what concurrency is, the subsequent blog posts will try to bring out the basics around locking, blocking, deadlocks because they are the fundamental blocks that make concurrency possible. Now if you are with me – let us continue learning for SQL Server Locking Basics. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: Concurrency

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  • Design for a machine learning artificial intelligence framework (community wiki)

    - by Lirik
    This is a community wiki which aims to provide a good design for a machine learning/artificial intelligence framework (ML/AI framework). Please contribute to the design of a language-agnostic framework which would allow multiple ML/AI algorithms to be plugged into a single framework which: runs the algorithms with a user-specified data set. facilitates learning, qualification, and classification. allows users to easily plug in new algorithms. can aggregate or create an ensemble of the existing algorithms. can save/load the progress of the algorithm (i.e. save the network and weights of a neural network, save the tree of a decision tree, etc.). What is a good design for this sort of ML/AI framework?

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  • publish XML using WCF

    - by khalil
    Hi, I want to publish some data as XML from a SQL Server database using a WCF service to a location on our content delivery network. (www.somelocation-on-cdn/myxml.xml) This data which is published as XML will have to be updated at an interval of time. I was thinking of writing a WCF service to return the data required, create a RSS reader to update / write the XML file to a location on the content delivery network. Is this approach correct? Can I use WCF REST instead of WCF SOAP As a further enhancement I want to be to use this WCF Service to make cross domain calls using JSONP from our website Thanks

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