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• what TERM to use to get rid of color escape codes?

  - by slivu

  Is there a way to get rid of escape codes in terminal output? Say even if the script are sending that codes they are ignored by terminal and text displayed as is, without colors, bolds etc. I need to display terminal output on a HTML page. For now i'm using javascript to remove escape codes, but it becomes clunky cause i receive output by chars, and have to wait until all content received then update it, leading in weird effects.

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• psloglist -w into a file

  - by user11588

  I'm trying to redirect windows event log continuously into a file. psloglist.exe has the -w feature (that listens for new events and outputs to console) so I tried combining it with redirection into a file like so: psloglist -w > out.txt It doesn't work. As new events are logged they do not show up in the file. However, if I remove > out.txt new events do shows up in the console!

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• UITableView issue when using separate delegate/dataSource

  - by Adam Alexander

  General Description: To start with what works, I have a UITableView which has been placed onto an Xcode-generated view using Interface Builder. The view's File Owner is set to an Xcode-generated subclass of UIViewController. To this subclass I have added working implementations of numberOfSectionsInTableView: tableView:numberOfRowsInSection: and tableView:cellForRowAtIndexPath: and the Table View's dataSource and delegate are connected to this class via the File Owner in Interface Builder. The above configuration works with no problems. The issue occurs when I want to move this Table View's dataSource and delegate implementations out to a separate class, most likely because there are other controls on the View besides the Table View and I'd like to move the Table View-related code out to its own class. To accomplish this, I try the following: Create a new subclass of UITableViewController in Xcode Move the known-good implementations of numberOfSectionsInTableView: tableView:numberOfRowsInSection: and tableView:cellForRowAtIndexPath: to the new subclass Drag a Table View Controller to the top level of the existing XIB in InterfaceBuilder, delete the View/TableView that are automatically created for this Table View Controller, then set the Table View Controller's class to match the new subclass Remove the previously-working Table View's existing dataSource and delegate connections and connect them to the new Table View Controller When complete, I do not have a working Table View. I end up with one of three outcomes which can seemingly happen at random: When the Table View loads, I get a runtime error indicating I am sending tableView:cellForRowAtIndexPath: to an object which does not recognize it When the Table View loads, the project breaks into the debugger without error There is no error, but the Table View does not appear With some debugging and having created a basic project just to reproduce this issue, I am usually seeing the 3rd option above (no error but no visible table view). I added some NSLog calls and found that although numberOfSectionsInTableView and numberOfRowsInSection are both getting called, cellForRowAtIndexPath is not. I am convinced I'm missing something really simple and was hoping the answer may be obvious to someone with more experience than I have. If this doesn't turn out to be an easy answer I would be happy to update with some code or a sample project. Thanks for your time! Complete steps to reproduce: Create a new iPhone OS, View-Based Application in Xcode and call it TableTest Open TableTestViewController.xib in Interface Builder and drag a Table View onto the provided view surface. Connect the Table View's dataSource and delegate outlets to File's Owner, which should already represent the TableTestViewController class. Save your changes Back in Xcode, add the following code to TableTestViewController.m: - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView { NSLog(@"Returning num sections"); return 1; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { NSLog(@"Returning num rows"); return 1; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { NSLog(@"Trying to return cell"); static NSString *CellIdentifier = @"Cell"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease]; } cell.text = @"Hello"; NSLog(@"Returning cell"); return cell; } Build and Go, and you should see the word Hello appear in the TableView Now to attempt to move this TableView's logic out to a separate class, first create a new file in Xcode, choosing UITableViewController subclass and calling the class TableTestTableViewController Remove the above code snippet from TableTestViewController.m and place it into TableTestTableViewController.m, replacing the default implementation of these three methods with ours. Back in Interface Builder within the same TableTestViewController.xib file, drag a Table View Controller into the main IB window and delete the new Table View object that automatically came with it Set the class for this new Table View Controller to TableTestTableViewController Remove the dataSource and delegate bindings from the existing, previously-working Table View and reconnect the same two bindings to the new Table Test Table View Controller we created. Save changes, Build and Go, and if you're getting the results I'm getting, note the Table View no longer functions properly Solution: With some more troubleshooting and some assistance from the iPhone Developer Forums at https://devforums.apple.com/message/5453, I've documented a solution! The main UIViewController subclass of the project needs an outlet pointing to the UITableViewController instance. To accomplish this, simply add the following to the primary view's header (TableTestViewController.h): #import "TableTestTableViewController.h" and IBOutlet TableTestTableViewController *myTableViewController; Then, in Interface Builder, connect the new outlet from File's Owner to Table Test Table View Controller in the main IB window. No changes are necessary in the UI part of the XIB. Simply having this outlet in place, even though no user code directly uses it, resolves the problem completely. Thanks to those who've helped and credit goes to BaldEagle on the iPhone Developer Forums for finding the solution.

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• NoMethodError Rails multiple file uploads

  - by Danny McClelland

  Hi Everyone, I am working on getting multiple file uploads working for an model in my application, I have included the code below: delivers_controller.rb # POST /delivers def create @deliver = Deliver.new(params[:deliver]) process_file_uploads(@deliver) if @deliver.save flash[:notice] = 'Task was successfully created.' redirect_to(@deliver) else render :action => "new" end end protected def process_file_uploads(deliver) i = 0 while params[:attachment]['file_'+i.to_s] != "" && !params[:attachment]['file_'+i.to_s].nil? deliver.assets.build(:data => params[:attachment]['file_'+i.to_s]) i += 1 end end deliver.rb has_many :assets, :as => :attachable, :dependent => :destroy validate :validate_attachments Max_Attachments = 5 Max_Attachment_Size = 5.megabyte def validate_attachments errors.add_to_base("Too many attachments - maximum is #{Max_Attachments}") if assets.length > Max_Attachments assets.each {|a| errors.add_to_base("#{a.name} is over #{Max_Attachment_Size/1.megabyte}MB") if a.file_size > Max_Attachment_Size} end assets_controller.rb class AssetsController < ApplicationController def show asset = Asset.find(params[:id]) # do security check here send_file asset.data.path, :type => asset.data_content_type end def destroy asset = Asset.find(params[:id]) @asset_id = asset.id.to_s @allowed = Deliver::Max_Attachments - asset.attachable.assets.count asset.destroy end end asset.rb class Asset < ActiveRecord::Base has_attached_file :data, belongs_to :attachable, :polymorphic => true def url(*args) data.url(*args) end def name data_file_name end def content_type data_content_type end def file_size data_file_size end end Whenever I create a new deliver item and try to attach any files I get the following error: NoMethodError in DeliversController#create You have a nil object when you didn't expect it! You might have expected an instance of ActiveRecord::Base. The error occurred while evaluating nil.[] /Users/danny/Dropbox/SVN/railsapps/macandco/surveymanager/trunk/app/controllers/delivers_controller.rb:60:in `process_file_uploads' /Users/danny/Dropbox/SVN/railsapps/macandco/surveymanager/trunk/app/controllers/delivers_controller.rb:46:in `create' new.html.erb (Deliver view) <% content_for :header do -%> Deliver Repositories <% end -%> <% form_for(@deliver, :html => { :multipart => true }) do |f| %> <%= f.error_messages %> <p> <%= f.label :caseref %><br /> <%= f.text_field :caseref %> </p> <p> <%= f.label :casesubject %><br /> <%= f.text_area :casesubject %> </p> <p> <%= f.label :description %><br /> <%= f.text_area :description %> </p> <p>Pending Attachments: (Max of <%= Deliver::Max_Attachments %> each under <%= Deliver::Max_Attachment_Size/1.megabyte%>MB) <% if @deliver.assets.count >= Deliver::Max_Attachments %> <input id="newfile_data" type="file" disabled /> <% else %> <input id="newfile_data" type="file" /> <% end %> <div id="attachment_list"><ul id="pending_files"></ul></div> </p> <p> <%= f.submit 'Create' %> </p> <% end %> <%= link_to 'Back', delivers_path %> Show.html.erb (Delivers view) <% content_for :header do -%> Deliver Repositories <% end -%> <p> <b>Title:</b> <%=h @deliver.caseref %> </p> <p> <b>Body:</b> <%=h @deliver.casesubject %> </p> <p><b>Attached Files:</b><div id="attachment_list"><%= render :partial => "attachment", :collection => @deliver.assets %></div></p> <%= link_to 'Edit', edit_deliver_path(@deliver) %> | <%= link_to 'Back', deliver_path %> <%- if logged_in? %> <%= link_to 'Edit', edit_deliver_path(@deliver) %> | <%= link_to 'Back', delivers_path %> <% end %> _attachment.html.erb (Delivers view) <% if !attachment.id.nil? %><li id='attachment_<%=attachment.id %>'><a href='<%=attachment.url %>'><%=attachment.name %></a> (<%=attachment.file_size/1.kilobyte %>KB) <%= link_to_remote "Remove", :url => asset_path(:id => attachment), :method => :delete, :html => { :title => "Remove this attachment", :id => "remove" } %></li> <% end %> I have been banging my head against the wall with the error all day, if anyone can shed some light on it, I would be eternally grateful! Thanks, Danny

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• Using WeakReference to resolve issue with .NET unregistered event handlers causing memory leaks.

  - by Eric

  The problem: Registered event handlers create a reference from the event to the event handler's instance. If that instance fails to unregister the event handler (via Dispose, presumably), then the instance memory will not be freed by the garbage collector. Example: class Foo { public event Action AnEvent; public void DoEvent() { if (AnEvent != null) AnEvent(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } If I instantiate a Foo, and pass this to a new Bar constructor, then let go of the Bar object, it will not be freed by the garbage collector because of the AnEvent registration. I consider this a memory leak, and seems just like my old C++ days. I can, of course, make Bar IDisposable, unregister the event in the Dispose() method, and make sure to call Dispose() on instances of it, but why should I have to do this? I first question why events are implemented with strong references? Why not use weak references? An event is used to abstractly notify an object of changes in another object. It seems to me that if the event handler's instance is no longer in use (i.e., there are no non-event references to the object), then any events that it is registered with should automatically be unregistered. What am I missing? I have looked at WeakEventManager. Wow, what a pain. Not only is it very difficult to use, but its documentation is inadequate (see http://msdn.microsoft.com/en-us/library/system.windows.weakeventmanager.aspx -- noticing the "Notes to Inheritors" section that has 6 vaguely described bullets). I have seen other discussions in various places, but nothing I felt I could use. I propose a simpler solution based on WeakReference, as described here. My question is: Does this not meet the requirements with significantly less complexity? To use the solution, the above code is modified as follows: class Foo { public WeakReferenceEvent AnEvent = new WeakReferenceEvent(); internal void DoEvent() { AnEvent.Invoke(); } } class Bar { public Bar(Foo l) { l.AnEvent += l_AnEvent; } void l_AnEvent() { } } Notice two things: 1. The Foo class is modified in two ways: The event is replaced with an instance of WeakReferenceEvent, shown below; and the invocation of the event is changed. 2. The Bar class is UNCHANGED. No need to subclass WeakEventManager, implement IWeakEventListener, etc. OK, so on to the implementation of WeakReferenceEvent. This is shown here. Note that it uses the generic WeakReference that I borrowed from here: http://damieng.com/blog/2006/08/01/implementingweakreferencet I had to add Equals() and GetHashCode() to his class, which I include below for reference. class WeakReferenceEvent { public static WeakReferenceEvent operator +(WeakReferenceEvent wre, Action handler) { wre._delegates.Add(new WeakReference<Action>(handler)); return wre; } public static WeakReferenceEvent operator -(WeakReferenceEvent wre, Action handler) { foreach (var del in wre._delegates) if (del.Target == handler) { wre._delegates.Remove(del); return wre; } return wre; } HashSet<WeakReference<Action>> _delegates = new HashSet<WeakReference<Action>>(); internal void Invoke() { HashSet<WeakReference<Action>> toRemove = null; foreach (var del in _delegates) { if (del.IsAlive) del.Target(); else { if (toRemove == null) toRemove = new HashSet<WeakReference<Action>>(); toRemove.Add(del); } } if (toRemove != null) foreach (var del in toRemove) _delegates.Remove(del); } } public class WeakReference<T> : IDisposable { private GCHandle handle; private bool trackResurrection; public WeakReference(T target) : this(target, false) { } public WeakReference(T target, bool trackResurrection) { this.trackResurrection = trackResurrection; this.Target = target; } ~WeakReference() { Dispose(); } public void Dispose() { handle.Free(); GC.SuppressFinalize(this); } public virtual bool IsAlive { get { return (handle.Target != null); } } public virtual bool TrackResurrection { get { return this.trackResurrection; } } public virtual T Target { get { object o = handle.Target; if ((o == null) || (!(o is T))) return default(T); else return (T)o; } set { handle = GCHandle.Alloc(value, this.trackResurrection ? GCHandleType.WeakTrackResurrection : GCHandleType.Weak); } } public override bool Equals(object obj) { var other = obj as WeakReference<T>; return other != null && Target.Equals(other.Target); } public override int GetHashCode() { return Target.GetHashCode(); } } It's functionality is trivial. I override operator + and - to get the += and -= syntactic sugar matching events. These create WeakReferences to the Action delegate. This allows the garbage collector to free the event target object (Bar in this example) when nobody else is holding on to it. In the Invoke() method, simply run through the weak references and call their Target Action. If any dead (i.e., garbage collected) references are found, remove them from the list. Of course, this only works with delegates of type Action. I tried making this generic, but ran into the missing where T : delegate in C#! As an alternative, simply modify class WeakReferenceEvent to be a WeakReferenceEvent, and replace the Action with Action. Fix the compiler errors and you have a class that can be used like so: class Foo { public WeakReferenceEvent<int> AnEvent = new WeakReferenceEvent<int>(); internal void DoEvent() { AnEvent.Invoke(5); } } Hopefully this will help someone else when they run into the mystery .NET event memory leak!

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• List getting cleared every button click inside Update Panel?

  - by sah302

  No this isn't a copy of this question: http://stackoverflow.com/questions/654423/button-in-update-panel-is-doing-a-full-postback I've got a drop down inside an update panel, and I am trying to get it to allow the person using the page to add users to a list that is bound to a gridview. The list is a global variable, and on page_load I set that to the gridview's datasource and databind it. However, anytime I click the 'add a user' button, or the button to remove the user from the list. It appears like it is doing a full post back even though all these elements are inside the update Panel. Code Behind: Public accomplishmentTypeDao As New AccomplishmentTypeDao() Public accomplishmentDao As New AccomplishmentDao() Public userDao As New UserDao() Public facultyDictionary As New Dictionary(Of Guid, String) Public facultyList As New List(Of User) Public associatedFaculty As New List(Of User) Public facultyId As New Guid Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Page.Title = "Add a New Faculty Accomplishment" ddlAccomplishmentType.DataSource = accomplishmentTypeDao.getEntireTable() ddlAccomplishmentType.DataTextField = "Name" ddlAccomplishmentType.DataValueField = "Id" ddlAccomplishmentType.DataBind() facultyList = userDao.getListOfUsersByUserGroupName("Faculty") For Each faculty As User In facultyList facultyDictionary.Add(faculty.Id, faculty.LastName & ", " & faculty.FirstName) Next If Not Page.IsPostBack Then ddlFacultyList.DataSource = facultyDictionary ddlFacultyList.DataTextField = "Value" ddlFacultyList.DataValueField = "Key" ddlFacultyList.DataBind() End If gvAssociatedUsers.DataSource = associatedFaculty gvAssociatedUsers.DataBind() End Sub Protected Sub deleteUser(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs) facultyId = New Guid(e.CommandArgument.ToString()) associatedFaculty.Remove(associatedFaculty.Find(Function(user) user.Id = facultyId)) gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Protected Sub btnAddUser_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnAddUser.Click facultyId = New Guid(ddlFacultyList.SelectedValue) associatedFaculty.Add(facultyList.Find(Function(user) user.Id = facultyId)) gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Markup: <asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager> <asp:UpdatePanel ID="upAssociatedFaculty" runat="server" UpdateMode="Conditional"> <ContentTemplate> <p><b>Created By:</b> <asp:Label ID="lblCreatedBy" runat="server"></asp:Label></p> <p><b>Accomplishment Type: </b><asp:DropDownList ID="ddlAccomplishmentType" runat="server"></asp:DropDownList></p> <p><b>Accomplishment Applies To: </b><asp:DropDownList ID="ddlFacultyList" runat="server"></asp:DropDownList> &nbsp;<asp:Button ID="btnAddUser" runat="server" Text="Add Faculty" /></p> <p> <asp:GridView ID="gvAssociatedUsers" runat="server" AutoGenerateColumns="false" GridLines="None" ShowHeader="false"> <Columns> <asp:BoundField DataField="Id" HeaderText="Id" Visible="False" /> <asp:TemplateField ShowHeader="False"> <ItemTemplate> <span style="margin-left: 15px;"> <p><%#Eval("LastName")%>, <%#Eval("FirstName")%> <asp:Button ID="btnUnassignUser" runat="server" CausesValidation="false" CommandArgument='<%# Eval("Id") %>' CommandName="Delete" OnCommand="deleteUser" Text='Remove' /></p> </span> </ItemTemplate> </asp:TemplateField> </Columns> <EmptyDataTemplate> <em>There are currently no faculty associated with this accomplishment.</em> </EmptyDataTemplate> </asp:GridView> </p> </ContentTemplate> </asp:UpdatePanel> Now I thought the point of an update panel was to be able to update things inside of it without doing a full post_back and reloading the page. So if that's the case, why is it calling page_load everytime I click the buttons? I ran this code and debug and I see that even before any of the code associated with button press fires, page_load runs again. I tried putting the gvAssociatedUser.Datasource = associatedFaculty and the line below inside the Page.IsPostBack check, that prevented the page from working. I tried every combination of settings of the update panel for ChildrenAsTriggers and UpdateMode, and none of them worked. I know this is something simple, but all the combinations I've tried won't get it to work. How can I make this thing work? Edited: It wasn't causing a full postback so I was wrong as to the cause. I thought the page was doing a full post back thus resetting my associatedFaculty list global variable, but it isn't doing a full postback. The issue I am having is everytime I click btnAddUser it will add one element to the associatedFaculty list and thus bound to gvAssociatedusers. This works the first time, but the second time I click it, it overwrites the first element. So it appears like my associatedFaculty list is getting reset each time I click the button?

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• Need help on Coda slider tabs to move inside an overflow:hidden div

  - by Reden

  I'm not too good at javascript. and hope I can get a bit of help. I'm using Coda Slider 2.0, and have designed it to where the tabs are another slider to the right of the main slider, and each item. Basically like this mootools plugin http://landofcoder.com/demo/mootool/lofslidernews/index2.1.html Problem is the items will not scroll. How do I make the items (or tabs to the right) scroll down as the slider rotates? Otherwise the slider will show the 4th slide but not scroll to the 4th item on the right, but Thanks everyone. Here is the Coda-Slider plugin: // when the DOM is ready... $(document).ready(function () { var $panels = $('#slider .scrollContainer > div'); var $container = $('#slider .scrollContainer'); // if false, we'll float all the panels left and fix the width // of the container var horizontal = true; // float the panels left if we're going horizontal if (horizontal) { $panels.css({ 'float' : 'left', 'position' : 'relative' // IE fix to ensure overflow is hidden }); // calculate a new width for the container (so it holds all panels) $container.css('width', $panels[0].offsetWidth * $panels.length); } // collect the scroll object, at the same time apply the hidden overflow // to remove the default scrollbars that will appear var $scroll = $('#slider .scroll').css('overflow', 'hidden'); // apply our left + right buttons $scroll .before('<img class="scrollButtons left" src="images/scroll_left.png" />') .after('<img class="scrollButtons right" src="images/scroll_right.png" />'); // handle nav selection function selectNav() { $(this) .parents('ul:first') .find('a') .removeClass('selected') .end() .end() .addClass('selected'); } $('#slider .navigation').find('a').click(selectNav); // go find the navigation link that has this target and select the nav function trigger(data) { var el = $('#slider .navigation').find('a[href$="' + data.id + '"]').get(0); selectNav.call(el); } if (window.location.hash) { trigger({ id : window.location.hash.substr(1) }); } else { $('ul.navigation a:first').click(); } // offset is used to move to *exactly* the right place, since I'm using // padding on my example, I need to subtract the amount of padding to // the offset. Try removing this to get a good idea of the effect var offset = parseInt((horizontal ? $container.css('paddingTop') : $container.css('paddingLeft')) || 0) * -1; var scrollOptions = { target: $scroll, // the element that has the overflow // can be a selector which will be relative to the target items: $panels, navigation: '.navigation a', // selectors are NOT relative to document, i.e. make sure they're unique prev: 'img.left', next: 'img.right', // allow the scroll effect to run both directions axis: 'xy', onAfter: trigger, // our final callback offset: offset, // duration of the sliding effect duration: 500, // easing - can be used with the easing plugin: // http://gsgd.co.uk/sandbox/jquery/easing/ easing: 'swing' }; // apply serialScroll to the slider - we chose this plugin because it // supports// the indexed next and previous scroll along with hooking // in to our navigation. $('#slider').serialScroll(scrollOptions); // now apply localScroll to hook any other arbitrary links to trigger // the effect $.localScroll(scrollOptions); // finally, if the URL has a hash, move the slider in to position, // setting the duration to 1 because I don't want it to scroll in the // very first page load. We don't always need this, but it ensures // the positioning is absolutely spot on when the pages loads. scrollOptions.duration = 1; $.localScroll.hash(scrollOptions); /////////////////////////////////////////////// // autoscroll /////////////////////////////////////////////// // start to automatically cycle the tabs cycleTimer = setInterval(function () { $scroll.trigger('next'); }, 2000); // how many milliseconds, change this to whatever you like // select some trigger elements to stop the auto-cycle var $stopTriggers = $('#slider .navigation').find('a') // tab headers .add('.scroll') // panel itself .add('.stopscroll') // links to the stop class div .add('.navigation') // links to navigation id for tabs .add("a[href^='#']"); // links to a tab // this is the function that will stop the auto-cycle function stopCycle() { // remove the no longer needed stop triggers clearInterval(cycleTimer); // stop the auto-cycle itself $buttons.show(); // show the navigation buttons document.getElementById('stopscroll').style.display='none'; // hide the stop div document.getElementById('startscroll').style.display='block'; // block the start div } // bind stop cycle function to the click event using namespaces $stopTriggers.bind('click.cycle', stopCycle); /////////////////////////////////////////////// // end autoscroll /////////////////////////////////////////////// // edit to start again /////////////////////////////////////////////// // select some trigger elements to stop the auto-cycle var $startTriggers_start = $('#slider .navigation').find('a') // tab headers .add('.startscroll'); // links to the start class div // this is the function that will stop the auto-cycle function startCycle() { // remove the no longer needed stop triggers $buttons.hide(); // show the navigation buttons $scroll.trigger('next'); // directly to the next first cycleTimer = setInterval(function () { // now set timer again $scroll.trigger('next'); }, 5000); // how many milliseconds, change this to whatever you like document.getElementById('stopscroll').style.display='block'; // block the stop div document.getElementById('startscroll').style.display='none'; // hide the start div } // bind stop cycle function to the click event using namespaces $startTriggers_start.bind('click.cycle', startCycle); /////////////////////////////////////////////// // end edit to start /////////////////////////////////////////////// });

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• What statistics can be maintained for a set of numerical data without iterating?

  - by Dan Tao

  Update Just for future reference, I'm going to list all of the statistics that I'm aware of that can be maintained in a rolling collection, recalculated as an O(1) operation on every addition/removal (this is really how I should've worded the question from the beginning): Obvious Count Sum Mean Max* Min* Median** Less Obvious Variance Standard Deviation Skewness Kurtosis Mode*** Weighted Average Weighted Moving Average**** OK, so to put it more accurately: these are not "all" of the statistics I'm aware of. They're just the ones that I can remember off the top of my head right now. *Can be recalculated in O(1) for additions only, or for additions and removals if the collection is sorted (but in this case, insertion is not O(1)). Removals potentially incur an O(n) recalculation for non-sorted collections. **Recalculated in O(1) for a sorted, indexed collection only. ***Requires a fairly complex data structure to recalculate in O(1). ****This can certainly be achieved in O(1) for additions and removals when the weights are assigned in a linearly descending fashion. In other scenarios, I'm not sure. Original Question Say I maintain a collection of numerical data -- let's say, just a bunch of numbers. For this data, there are loads of calculated values that might be of interest; one example would be the sum. To get the sum of all this data, I could... Option 1: Iterate through the collection, adding all the values: double sum = 0.0; for (int i = 0; i < values.Count; i++) sum += values[i]; Option 2: Maintain the sum, eliminating the need to ever iterate over the collection just to find the sum: void Add(double value) { values.Add(value); sum += value; } void Remove(double value) { values.Remove(value); sum -= value; } EDIT: To put this question in more relatable terms, let's compare the two options above to a (sort of) real-world situation: Suppose I start listing numbers out loud and ask you to keep them in your head. I start by saying, "11, 16, 13, 12." If you've just been remembering the numbers themselves and nothing more, and then I say, "What's the sum?", you'd have to think to yourself, "OK, what's 11 + 16 + 13 + 12?" before responding, "52." If, on the other hand, you had been keeping track of the sum yourself while I was listing the numbers (i.e., when I said, "11" you thought "11", when I said "16", you thought, "27," and so on), you could answer "52" right away. Then if I say, "OK, now forget the number 16," if you've been keeping track of the sum inside your head you can simply take 16 away from 52 and know that the new sum is 36, rather than taking 16 off the list and them summing up 11 + 13 + 12. So my question is, what other calculations, other than the obvious ones like sum and average, are like this? SECOND EDIT: As an arbitrary example of a statistic that (I'm almost certain) does require iteration -- and therefore cannot be maintained as simply as a sum or average -- consider if I asked you, "how many numbers in this collection are divisible by the min?" Let's say the numbers are 5, 15, 19, 20, 21, 25, and 30. The min of this set is 5, which divides into 5, 15, 20, 25, and 30 (but not 19 or 21), so the answer is 5. Now if I remove 5 from the collection and ask the same question, the answer is now 2, since only 15 and 30 are divisible by the new min of 15; but, as far as I can tell, you cannot know this without going through the collection again. So I think this gets to the heart of my question: if we can divide kinds of statistics into these categories, those that are maintainable (my own term, maybe there's a more official one somewhere) versus those that require iteration to compute any time a collection is changed, what are all the maintainable ones? What I am asking about is not strictly the same as an online algorithm (though I sincerely thank those of you who introduced me to that concept). An online algorithm can begin its work without having even seen all of the input data; the maintainable statistics I am seeking will certainly have seen all the data, they just don't need to reiterate through it over and over again whenever it changes.

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• How to filter Backbone.js Collection and Rerender App View?

  - by Jeremy H.

  Is is a total Backbone.js noob question. I am working off of the ToDo Backbone.js example trying to build out a fairly simple single app interface. While the todo project is more about user input, this app is more about filtering the data based on the user options (click events). I am completely new to Backbone.js and Mongoose and have been unable to find a good example of what I am trying to do. I have been able to get my api to pull the data from the MongoDB collection and drop it into the Backbone.js collection which renders it in the app. What I cannot for the life of me figure out how to do is filter that data and re-render the app view. I am trying to filter by the "type" field in the document. Here is my script: (I am totally aware of some major refactoring needed, I am just rapid prototyping a concept.) $(function() { window.Job = Backbone.Model.extend({ idAttribute: "_id", defaults: function() { return { attachments: false } } }); window.JobsList = Backbone.Collection.extend({ model: Job, url: '/api/jobs', leads: function() { return this.filter(function(job){ return job.get('type') == "Lead"; }); } }); window.Jobs = new JobsList; window.JobView = Backbone.View.extend({ tagName: "div", className: "item", template: _.template($('#item-template').html()), initialize: function() { this.model.bind('change', this.render, this); this.model.bind('destroy', this.remove, this); }, render: function() { $(this.el).html(this.template(this.model.toJSON())); this.setText(); return this; }, setText: function() { var month=new Array(); month[0]="Jan"; month[1]="Feb"; month[2]="Mar"; month[3]="Apr"; month[4]="May"; month[5]="Jun"; month[6]="Jul"; month[7]="Aug"; month[8]="Sep"; month[9]="Oct"; month[10]="Nov"; month[11]="Dec"; var title = this.model.get('title'); var description = this.model.get('description'); var datemonth = this.model.get('datem'); var dateday = this.model.get('dated'); var jobtype = this.model.get('type'); var jobstatus = this.model.get('status'); var amount = this.model.get('amount'); var paymentstatus = this.model.get('paymentstatus') var type = this.$('.status .jobtype'); var status = this.$('.status .jobstatus'); this.$('.title a').text(title); this.$('.description').text(description); this.$('.date .month').text(month[datemonth]); this.$('.date .day').text(dateday); type.text(jobtype); status.text(jobstatus); if(amount > 0) this.$('.paymentamount').text(amount) if(paymentstatus) this.$('.paymentstatus').text(paymentstatus) if(jobstatus === 'New') { status.addClass('new'); } else if (jobstatus === 'Past Due') { status.addClass('pastdue') }; if(jobtype === 'Lead') { type.addClass('lead'); } else if (jobtype === '') { type.addClass(''); }; }, remove: function() { $(this.el).remove(); }, clear: function() { this.model.destroy(); } }); window.AppView = Backbone.View.extend({ el: $("#main"), events: { "click #leads .highlight" : "filterLeads" }, initialize: function() { Jobs.bind('add', this.addOne, this); Jobs.bind('reset', this.addAll, this); Jobs.bind('all', this.render, this); Jobs.fetch(); }, addOne: function(job) { var view = new JobView({model: job}); this.$("#activitystream").append(view.render().el); }, addAll: function() { Jobs.each(this.addOne); }, filterLeads: function() { // left here, this event fires but i need to figure out how to filter the activity list. } }); window.App = new AppView; });

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• plupload variable upload path?

  - by SoulieBaby

  Hi all, I'm using plupload to upload files to my server (http://www.plupload.com/index.php), however I wanted to know if there was any way of making the upload path variable. Basically I need to select the upload path folder first, then choose the files using plupload and then upload to the initially selected folder. I've tried a few different ways but I can't seem to pass along the variable folder path to the upload.php file. I'm using the flash version of plupload. If someone could help me out, that would be fantastic!! :) Here's my plupload jquery: jQuery.noConflict(); jQuery(document).ready(function() { jQuery("#flash_uploader").pluploadQueue({ // General settings runtimes: 'flash', url: '/assets/upload/upload.php', max_file_size: '10mb', chunk_size: '1mb', unique_names: false, // Resize images on clientside if we can resize: {width: 500, height: 350, quality: 100}, // Flash settings flash_swf_url: '/assets/upload/flash/plupload.flash.swf' }); }); And here's the upload.php file: <?php /** * upload.php * * Copyright 2009, Moxiecode Systems AB * Released under GPL License. * * License: http://www.plupload.com/license * Contributing: http://www.plupload.com/contributing */ // HTTP headers for no cache etc header('Content-type: text/plain; charset=UTF-8'); header("Expires: Mon, 26 Jul 1997 05:00:00 GMT"); header("Last-Modified: ".gmdate("D, d M Y H:i:s")." GMT"); header("Cache-Control: no-store, no-cache, must-revalidate"); header("Cache-Control: post-check=0, pre-check=0", false); header("Pragma: no-cache"); // Settings $targetDir = $_SERVER['DOCUMENT_ROOT']."/tmp/uploads"; //temp directory <- need these to be variable $finalDir = $_SERVER['DOCUMENT_ROOT']."/tmp/uploads2"; //final directory <- need these to be variable $cleanupTargetDir = true; // Remove old files $maxFileAge = 60 * 60; // Temp file age in seconds // 5 minutes execution time @set_time_limit(5 * 60); // usleep(5000); // Get parameters $chunk = isset($_REQUEST["chunk"]) ? $_REQUEST["chunk"] : 0; $chunks = isset($_REQUEST["chunks"]) ? $_REQUEST["chunks"] : 0; $fileName = isset($_REQUEST["name"]) ? $_REQUEST["name"] : ''; // Clean the fileName for security reasons $fileName = preg_replace('/[^\w\._]+/', '', $fileName); // Create target dir if (!file_exists($targetDir)) @mkdir($targetDir); // Remove old temp files if (is_dir($targetDir) && ($dir = opendir($targetDir))) { while (($file = readdir($dir)) !== false) { $filePath = $targetDir . DIRECTORY_SEPARATOR . $file; // Remove temp files if they are older than the max age if (preg_match('/\\.tmp$/', $file) && (filemtime($filePath) < time() - $maxFileAge)) @unlink($filePath); } closedir($dir); } else die('{"jsonrpc" : "2.0", "error" : {"code": 100, "message": "Failed to open temp directory."}, "id" : "id"}'); // Look for the content type header if (isset($_SERVER["HTTP_CONTENT_TYPE"])) $contentType = $_SERVER["HTTP_CONTENT_TYPE"]; if (isset($_SERVER["CONTENT_TYPE"])) $contentType = $_SERVER["CONTENT_TYPE"]; if (strpos($contentType, "multipart") !== false) { if (isset($_FILES['file']['tmp_name']) && is_uploaded_file($_FILES['file']['tmp_name'])) { // Open temp file $out = fopen($targetDir . DIRECTORY_SEPARATOR . $fileName, $chunk == 0 ? "wb" : "ab"); if ($out) { // Read binary input stream and append it to temp file $in = fopen($_FILES['file']['tmp_name'], "rb"); if ($in) { while ($buff = fread($in, 4096)) fwrite($out, $buff); } else die('{"jsonrpc" : "2.0", "error" : {"code": 101, "message": "Failed to open input stream."}, "id" : "id"}'); fclose($out); unlink($_FILES['file']['tmp_name']); } else die('{"jsonrpc" : "2.0", "error" : {"code": 102, "message": "Failed to open output stream."}, "id" : "id"}'); } else die('{"jsonrpc" : "2.0", "error" : {"code": 103, "message": "Failed to move uploaded file."}, "id" : "id"}'); } else { // Open temp file $out = fopen($targetDir . DIRECTORY_SEPARATOR . $fileName, $chunk == 0 ? "wb" : "ab"); if ($out) { // Read binary input stream and append it to temp file $in = fopen("php://input", "rb"); if ($in) { while ($buff = fread($in, 4096)){ fwrite($out, $buff); } } else die('{"jsonrpc" : "2.0", "error" : {"code": 101, "message": "Failed to open input stream."}, "id" : "id"}'); fclose($out); } else die('{"jsonrpc" : "2.0", "error" : {"code": 102, "message": "Failed to open output stream."}, "id" : "id"}'); } //Moves the file from $targetDir to $finalDir after receiving the final chunk if($chunk == ($chunks-1)){ rename($targetDir . DIRECTORY_SEPARATOR . $fileName, $finalDir . DIRECTORY_SEPARATOR . $fileName); } // Return JSON-RPC response die('{"jsonrpc" : "2.0", "result" : null, "id" : "id"}'); ?>

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• Repopulating a collection of Backbone forms with previously submitted data

  - by Brian Wheat

  I am able to post my forms to my database and I have stepped through my back end function to check and see that my Get function is returning the same data I submitted. However I am having trouble understanding how to have this data rendered upon visiting the page again. What am I missing? The intention is to be able to create, read, update, or delete (CRUD) some personal contact data for a variable collection of individuals. //Model var PersonItem = Backbone.Model.extend({ url: "/Application/PersonList", idAttribute: "PersonId", schema: { Title: { type: 'Select', options: function (callback) { $.getJSON("/Application/GetTitles/").done(callback); } }, Salutation: { type: 'Select', options: ['Mr.', 'Mrs.', 'Ms.', 'Dr.'] }, FirstName: 'Text', LastName: 'Text', MiddleName: 'Text', NameSuffix: 'Text', StreetAddress: 'Text', City: 'Text', State: { type: 'Select', options: function (callback) { $.getJSON("/Application/GetStates/").done(callback); } }, ZipCode: 'Text', PhoneNumber: 'Text', DateOfBirth: 'Date', } }); Backbone.Form.setTemplates(template, PersonItem); //Collection var PersonList = Backbone.Collection.extend({ model: PersonItem , url: "/Application/PersonList" }); //Views var PersonItemView = Backbone.Form.extend({ tagName: "li", events: { 'click button.delete': 'remove', 'change input': 'change' }, initialize: function (options) { console.log("ItemView init"); PersonItemView.__super__.initialize.call(this, options); _.bindAll(this, 'render', 'remove'); console.log("ItemView set attr = " + options); }, render: function () { PersonItemView.__super__.render.call(this); $('fieldset', this.el).append("<button class=\"delete\" style=\"float: right;\">Delete</button>"); return this; }, change: function (event) { var target = event.target; console.log('changing ' + target.id + ' from: ' + target.defaultValue + ' to: ' + target.value); }, remove: function () { console.log("delete button pressed"); this.model.destroy({ success: function () { alert('person deleted successfully'); } }); return false; } }); var PersonListView = Backbone.View.extend({ el: $("#application_fieldset"), events: { 'click button#add': 'addPerson', 'click button#save': 'save2db' }, initialize: function () { console.log("PersonListView Constructor"); _.bindAll(this, 'render', 'addPerson', 'appendItem', 'save'); this.collection = new PersonList(); this.collection.bind('add', this.appendItem); //this.collection.fetch(); this.collection.add([new PersonItem()]); console.log("collection length = " + this.collection.length); }, render: function () { var self = this; console.log(this.collection.models); $(this.el).append("<button id='add'>Add Person</button>"); $(this.el).append("<button id='save'>Save</button>"); $(this.el).append("<fieldset><legend>Contact</legend><ul id=\"anchor_list\"></ul>"); _(this.collection.models).each(function (item) { self.appendItem(item); }, this); $(this.el).append("</fieldset>"); }, addPerson: function () { console.log("addPerson clicked"); var item = new PersonItem(); this.collection.add(item); }, appendItem: function (item) { var itemView = new PersonItemView({ model: item }); $('#anchor_list', this.el).append(itemView.render().el); }, save2db: function () { var self = this; console.log("PersonListView save"); _(this.collection.models).each(function (item) { console.log("item = " + item.toJSON()); var cid = item.cid; console.log("item.set"); item.set({ Title: $('#' + cid + '_Title').val(), Salutation: $('#' + cid + '_Salutation').val(), FirstName: $('#' + cid + '_FirstName').val(), LastName: $('#' + cid + '_LastName').val(), MiddleName: $('#' + cid + '_MiddleName').val(), NameSuffix: $('#' + cid + '_NameSuffix').val(), StreetAddress: $('#' + cid + '_StreetAddress').val(), City: $('#' + cid + '_City').val(), State: $('#' + cid + '_State').val(), ZipCode: $('#' + cid + '_ZipCode').val(), PhoneNumber: $('#' + cid + '_PhoneNumber').val(), DateOfBirth: $('#' + cid + '_DateOfBirth').find('input').val() }); if (item.isNew()) { console.log("item.isNew"); self.collection.create(item); } else { console.log("!item.isNew"); item.save(); } }); return false; } }); var personList = new PersonList(); var view = new PersonListView({ collection: personList }); personList.fetch({ success: function () { $("#application_fieldset").append(view.render()); } });

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• Lua metatable Objects cannot be purge from memory?

  - by Prometheus3k

  Hi there, I'm using a proprietary platform that reported memory usage in realtime on screen. I decided to use a Class.lua I found on http://lua-users.org/wiki/SimpleLuaClasses However, I noticed memory issues when purging object created by this using a simple Account class. Specifically, I would start with say 146k of memory used, create 1000 objects of a class that just holds an integer instance variable and store each object into a table. The memory used is now 300k I would then exit, iterating through the table and setting each element in the table to nil. But would never get back the 146k, usually after this I am left using 210k or something similar. If I run the load sequence again during the same session, it does not exceed 300k so it is not a memory leak. I have tried creating 1000 integers in a table and setting these to nil, which does give me back 146k. In addition I've tried a simpler class file (Account2.lua) that doesn't rely on a class.lua. This still incurs memory fragmentation but not as much as the one that uses Class.lua Can anybody explain what is going on here? How can I purge these objects and get back the memory? here is the code --------Class.lua------ -- class.lua -- Compatible with Lua 5.1 (not 5.0). --http://lua-users.org/wiki/SimpleLuaClasses function class(base,ctor) local c = {} -- a new class instance if not ctor and type(base) == 'function' then ctor = base base = nil elseif type(base) == 'table' then -- our new class is a shallow copy of the base class! for i,v in pairs(base) do c[i] = v end c._base = base end -- the class will be the metatable for all its objects, -- and they will look up their methods in it. c.__index = c -- expose a ctor which can be called by () local mt = {} mt.__call = function(class_tbl,...) local obj = {} setmetatable(obj,c) if ctor then ctor(obj,...) else -- make sure that any stuff from the base class is initialized! if base and base.init then base.init(obj,...) end end return obj end c.init = ctor c.instanceOf = function(self,klass) local m = getmetatable(self) while m do if m == klass then return true end m = m._base end return false end setmetatable(c,mt) return c end --------Account.lua------ --Import Class template require 'class' local classname = "Account" --Declare class Constructor Account = class(function(acc,balance) --Instance variables declared here. if(balance ~= nil)then acc.balance = balance else --default value acc.balance = 2097 end acc.classname = classname end) --------Account2.lua------ local account2 = {} account2.classname = "unnamed" account2.balance = 2097 -----------Constructor 1 do local metatable = { __index = account2; } function Account2() return setmetatable({}, metatable); end end --------Main.lua------ require 'Account' require 'Account2' MAX_OBJ = 5000; test_value = 1000; Obj_Table = {}; MODE_ACC0 = 0 --integers MODE_ACC1 = 1 --Account MODE_ACC2 = 2 --Account2 TEST_MODE = MODE_ACC0; Lua_mem = ""; print("##1) collectgarbage('count'): " .. collectgarbage('count')); function Load() for i=1, MAX_OBJ do if(TEST_MODE == MODE_ACC0 )then table.insert(Obj_Table, test_value); elseif(TEST_MODE == MODE_ACC1 )then table.insert(Obj_Table, Account(test_value)); --Account.lua elseif(TEST_MODE == MODE_ACC2 )then table.insert(Obj_Table, Account2()); --Account2.lua Obj_Table[i].balance = test_value; end end print("##2) collectgarbage('count'): " .. collectgarbage('count')); end function Purge() --metatable purge if(TEST_MODE ~= MODE_ACC0)then --purge stage 0: print("set each elements metatable to nil") for i=1, MAX_OBJ do setmetatable(Obj_Table[i], nil); end end --purge stage 1: print("set table element to nil") for i=1, MAX_OBJ do Obj_Table[i] = nil; end --purge stage 2: print("start table.remove..."); for i=1, MAX_OBJ do table.remove(Obj_Table, i); end print("...end table.remove"); --purge stage 3: print("create new object_table {}"); Obj_Table= {}; --purge stage 4: print("collectgarbage('collect')"); collectgarbage('collect'); print("##3) collectgarbage('count'): " .. collectgarbage('count')); end --Loop callback function OnUpdate() collectgarbage('collect'); Lua_mem = collectgarbage('count'); end ------------------- --NOTE: --On start of game runs Load(), another runs Purge() --Update I've updated the code with suggestions from comments below, and will post my findings later today.

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• Button in Update Panel doing full postback?

  - by sah302

  No this isn't a copy of this question: http://stackoverflow.com/questions/654423/button-in-update-panel-is-doing-a-full-postback I've got a drop down inside an update panel, and I am trying to get it to allow the person using the page to add users to a list that is bound to a gridview. The list is a global variable, and on page_load I set that to the gridview's datasource and databind it. However, anytime I click the 'add a user' button, or the button to remove the user from the list. It appears like it is doing a full post back even though all these elements are inside the update Panel. Code Behind: Public accomplishmentTypeDao As New AccomplishmentTypeDao() Public accomplishmentDao As New AccomplishmentDao() Public userDao As New UserDao() Public facultyDictionary As New Dictionary(Of Guid, String) Public facultyList As New List(Of User) Public associatedFaculty As New List(Of User) Public facultyId As New Guid Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Page.Title = "Add a New Faculty Accomplishment" ddlAccomplishmentType.DataSource = accomplishmentTypeDao.getEntireTable() ddlAccomplishmentType.DataTextField = "Name" ddlAccomplishmentType.DataValueField = "Id" ddlAccomplishmentType.DataBind() facultyList = userDao.getListOfUsersByUserGroupName("Faculty") For Each faculty As User In facultyList facultyDictionary.Add(faculty.Id, faculty.LastName & ", " & faculty.FirstName) Next If Not Page.IsPostBack Then ddlFacultyList.DataSource = facultyDictionary ddlFacultyList.DataTextField = "Value" ddlFacultyList.DataValueField = "Key" ddlFacultyList.DataBind() End If gvAssociatedUsers.DataSource = associatedFaculty gvAssociatedUsers.DataBind() End Sub Protected Sub deleteUser(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.CommandEventArgs) facultyId = New Guid(e.CommandArgument.ToString()) associatedFaculty.Remove(associatedFaculty.Find(Function(user) user.Id = facultyId)) gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Protected Sub btnAddUser_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnAddUser.Click facultyId = New Guid(ddlFacultyList.SelectedValue) associatedFaculty.Add(facultyList.Find(Function(user) user.Id = facultyId)) gvAssociatedUsers.DataBind() upAssociatedFaculty.Update() End Sub Markup: <asp:ScriptManager ID="ScriptManager1" runat="server"> </asp:ScriptManager> <asp:UpdatePanel ID="upAssociatedFaculty" runat="server" UpdateMode="Conditional"> <ContentTemplate> <p><b>Created By:</b> <asp:Label ID="lblCreatedBy" runat="server"></asp:Label></p> <p><b>Accomplishment Type: </b><asp:DropDownList ID="ddlAccomplishmentType" runat="server"></asp:DropDownList></p> <p><b>Accomplishment Applies To: </b><asp:DropDownList ID="ddlFacultyList" runat="server"></asp:DropDownList> &nbsp;<asp:Button ID="btnAddUser" runat="server" Text="Add Faculty" /></p> <p> <asp:GridView ID="gvAssociatedUsers" runat="server" AutoGenerateColumns="false" GridLines="None" ShowHeader="false"> <Columns> <asp:BoundField DataField="Id" HeaderText="Id" Visible="False" /> <asp:TemplateField ShowHeader="False"> <ItemTemplate> <span style="margin-left: 15px;"> <p><%#Eval("LastName")%>, <%#Eval("FirstName")%> <asp:Button ID="btnUnassignUser" runat="server" CausesValidation="false" CommandArgument='<%# Eval("Id") %>' CommandName="Delete" OnCommand="deleteUser" Text='Remove' /></p> </span> </ItemTemplate> </asp:TemplateField> </Columns> <EmptyDataTemplate> <em>There are currently no faculty associated with this accomplishment.</em> </EmptyDataTemplate> </asp:GridView> </p> </ContentTemplate> </asp:UpdatePanel> Now I thought the point of an update panel was to be able to update things inside of it without doing a full post_back and reloading the page. So if that's the case, why is it calling page_load everytime I click the buttons? I ran this code and debug and I see that even before any of the code associated with button press fires, page_load runs again. I tried putting the gvAssociatedUser.Datasource = associatedFaculty and the line below inside the Page.IsPostBack check, that prevented the page from working. I tried every combination of settings of the update panel for ChildrenAsTriggers and UpdateMode, and none of them worked. I know this is something simple, but all the combinations I've tried won't get it to work. How can I make this thing work?

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• Hiding Options of a Select with JQuery

  - by Syed Abdul Rahman

  Okay, let's start with an example. Keep in mind, this is only an example. <select id = "selection1">     <option value = "1" id = "1">Number 1</option>     <option value = "2" id = "2">Number 2</option>     <option value = "3" id = "3">Number 3</option> </select> Now from here, we have a dropdown with 3 options. What I want to do now is to hide an option. Adding style = "display:none" will not help. The option would not appear in the dropdownlist, but using the arrow keys, you can still select it. Essentially, it does exactly what the code says. It isn't displayed, and it stops there. A JQuery function of $("#1").hide() will not work. Plus, I don't only want to hide the option, I want to completely remove it. Any possibility on doing so? Do I have to use parent/sibling/child elements? If so, I'm still not sure how. Any help on this would be greatly appreciated. Thanks.           Another question - It's related Ok, so I found out that there is a .remove() available in JQuery. Works well. But what if I want to bring it back? if(condition)     {     $(this).remove();     } I can loops this. Shouldn't be complicated. But the thing of which I am trying to do is this: Maximum Capacity of Class: (Input field here) Select Room: (Dropdown here) What I'd like for it to do is to update is Dropdown using a function such as .change() or .keyup. I could create the dropdown only after something is typed. At a change or a keyup, execute the dropdown accordingly. But what I am doing is this: $roomarray = mysql_query("SELECT *     FROM         (         SELECT *,         CASE         WHEN type = 'Classroom' THEN 1         WHEN type = 'Computer laboratory' THEN 2         WHEN type = 'Lecture Hall' THEN 3         WHEN type = 'Auditorium' THEN 4         END AS ClassTypeValue         FROM rooms         ) t     ORDER BY ClassTypeValue, maxppl, roomID"); echo "<select id = \"room\">"; while ($rooms = mysql_fetch_array($roomarray)) { ?> <option value=<?php echo $rooms['roomID']; ?> id=<?php echo $rooms['roomID']; ?>><?php echo $rooms['type']; echo "&nbsp;"; echo $rooms['roomID']; echo "&nbsp;("; echo $rooms['maxppl']; echo ")"; ?></option> <?php } echo "</select>"; Yes, I know it is very messy. I plan to change it later on. But the issue now is this: Can I toggle the removal of the options according to what has been typed? Is it possible to do so with a dropdown made from a loop? Because I sure as hell can't keep executing SQL Queries. Or is that even an option? Because if it's possible, I still think it's a bad one.

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• files get uploaded just before they get cancelled

  - by user1763986

  Got a little situation here where I am trying to cancel a file's upload. What I have done is stated that if the user clicks on the "Cancel" button, then it will simply remove the iframe so that it does not go to the page where it uploads the files into the server and inserts data into the database. Now this works fine if the user clicks on the "Cancel" button in quickish time the problem I have realised though is that if the user clicks on the "Cancel" button very late, it sometimes doesn't remove the iframe in time meaning that the file has just been uploaded just before the user has clicked on the "Cancel" button. So my question is that is there a way that if the file does somehow get uploaded before the user clicks on the "Cancel" button, that it deletes the data in the database and removes the file from the server? Below is the image upload form: <form action="imageupload.php" method="post" enctype="multipart/form-data" target="upload_target_image" onsubmit="return imageClickHandler(this);" class="imageuploadform" > <p class="imagef1_upload_process" align="center"> Loading...<br/> <img src="Images/loader.gif" /> </p> <p class="imagef1_upload_form" align="center"> <br/> <span class="imagemsg"></span> <label>Image File: <input name="fileImage" type="file" class="fileImage" /></label><br/> <br/> <label class="imagelbl"><input type="submit" name="submitImageBtn" class="sbtnimage" value="Upload" /></label> </p> <p class="imagef1_cancel" align="center"> <input type="reset" name="imageCancel" class="imageCancel" value="Cancel" /> </p> <iframe class="upload_target_image" name="upload_target_image" src="#" style="width:0px;height:0px;border:0px;solid;#fff;"></iframe> </form> Below is the jquery function which controls the "Cancel" button: $(imageuploadform).find(".imageCancel").on("click", function(event) { $('.upload_target_image').get(0).contentwindow $("iframe[name='upload_target_image']").attr("src", "javascript:'<html></html>'"); return stopImageUpload(2); }); Below is the php code where it uploads the files and inserts the data into the database. The form above posts to this php page "imageupload.php": <body> <?php include('connect.php'); session_start(); $result = 0; //uploads file move_uploaded_file($_FILES["fileImage"]["tmp_name"], "ImageFiles/" . $_FILES["fileImage"]["name"]); $result = 1; //set up the INSERT SQL query command to insert the name of the image file into the "Image" Table $imagesql = "INSERT INTO Image (ImageFile) VALUES (?)"; //prepare the above SQL statement if (!$insert = $mysqli->prepare($imagesql)) { // Handle errors with prepare operation here } //bind the parameters (these are the values that will be inserted) $insert->bind_param("s",$img); //Assign the variable of the name of the file uploaded $img = 'ImageFiles/'.$_FILES['fileImage']['name']; //execute INSERT query $insert->execute(); if ($insert->errno) { // Handle query error here } //close INSERT query $insert->close(); //Retrieve the ImageId of the last uploded file $lastID = $mysqli->insert_id; //Insert into Image_Question Table (be using last retrieved Image id in order to do this) $imagequestionsql = "INSERT INTO Image_Question (ImageId, SessionId, QuestionId) VALUES (?, ?, ?)"; //prepare the above SQL statement if (!$insertimagequestion = $mysqli->prepare($imagequestionsql)) { // Handle errors with prepare operation here echo "Prepare statement err imagequestion"; } //Retrieve the question number $qnum = (int)$_POST['numimage']; //bind the parameters (these are the values that will be inserted) $insertimagequestion->bind_param("isi",$lastID, 'Exam', $qnum); //execute INSERT query $insertimagequestion->execute(); if ($insertimagequestion->errno) { // Handle query error here } //close INSERT query $insertimagequestion->close(); ?> <!--Javascript which will output the message depending on the status of the upload (successful, failed or cancelled)--> <script> window.top.stopImageUpload(<?php echo $result; ?>, '<?php echo $_FILES['fileImage']['name'] ?>'); </script> </body> UPDATE: Below is the php code "cancelimage.php" where I want to delete the cancelled file from the server and delete the record from the database. It is set up but not finished, can somebody finish it off so I can retrieve the name of the file and it's id using $_SESSION? <?php // connect to the database include('connect.php'); /* check connection */ if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); die(); } //remove file from server unlink("ImageFiles/...."); //need to retrieve file name here where the ... line is //DELETE query statement where it will delete cancelled file from both Image and Image Question Table $imagedeletesql = " DELETE img, img_q FROM Image AS img LEFT JOIN Image_Question AS img_q ON img_q.ImageId = img.ImageId WHERE img.ImageFile = ?"; //prepare delete query if (!$delete = $mysqli->prepare($imagedeletesql)) { // Handle errors with prepare operation here } //Dont pass data directly to bind_param store it in a variable $delete->bind_param("s",$img); //execute DELETE query $delete->execute(); if ($delete->errno) { // Handle query error here } //close query $delete->close(); ?> Can you please provide an sample code in your answer to make it easier for me. Thank you

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• Dynamic Type to do away with Reflection

  The dynamic type in C# 4.0 is a welcome addition to the language. One thing Ive been doing a lot with it is to remove explicit Reflection code thats often necessary when you dynamically need to walk and object hierarchy. In the past Ive had a number of ReflectionUtils that used string based expressions to walk an object hierarchy. With the introduction of dynamic much of the ReflectionUtils code can be removed for cleaner code that runs considerably faster to boot. The old Way - Reflection Heres...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Cannot find winemenubuilder.exe when trying to run StarCraft 2

  - by Gernot

  Recently I've installed StarCraft 2 via playonlinux. The installation was absolutly no problem, everything was fine. But if I want to start the game now, it crashes. If I start it on the Terminal I get following error: optirun /usr/share/playonlinux/playonlinux --run "StarCraft II Wings of Liberty" [POL_Wine_SetVersionEnv] Message: Setting wine version path: 1.3.27, amd64 [POL_Wine_SetVersionEnv] Message: "/home/gernot/.PlayOnLinux//wine/linux-amd64/1.3.27" exists [POL_Wine] Message: Running wine-1.3.27 StarCraft II.exe wine: cannot find L"C:\\windows\\system32\\winemenubuilder.exe" rm: Cannot remove »*“ : Can't find directory or file. Has anybody an idea what to do?

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• How to Create Auto Playlists in Windows Media Player 12

  - by DigitalGeekery

  Are you getting tired of the same old playlists in Windows Media Player? Today we’ll show you how to create dynamic auto playlists based on criteria you choose in WMP 12 in Windows 7. Auto Playlists In Library view, click on Create playlist dropdown arrow and select Create auto playlist. On the New Auto Playlist window type in a name for the playlist in the text box. Now we need to choose our criteria by which to filter your playlist. Select Click here to add criteria. For our example, we will create a playlist of songs that were added to the library in the last week from the Alternative genre. So, we will first select Date Added from the dropdown list. Many criteria will have addition options to configure. In the example below you will see that we have a few options to fine tune.   We will filter all the songs added to the library in the last 7 days. We will select Is After from the first dropdown list. Then select Last 7 Days from the second dropdown list. You can add multiple criteria to further filter your playlist. If you can’t find the criteria you are looking for, select “More” at the bottom of the dropdown list.   This will pull up a filter window with all the criteria. Select a filter and then click OK when finished.   From the Genre dropdown, we will select Alternative. If you’d like to add Pictures, Videos, or TV Shows to your auto playlists you can do so by selecting them from the dropdown list under And also include. You will then be able to select criteria for your pictures, videos, or TV shows from the dropdown list.   Finally, you can also add restrictions to your music such as the number of items, duration, or total size. We will limit the duration of our playlist to one hour by selecting Limit Total Duration To… Then type in 1 hour…Click OK.   Our library is automatically filtered and a playlist is created based on the criteria we selected. When additional songs are added to the Windows Media Player library, any of new songs that fit the criteria will automatically be added to the New Songs playlist. You can also save a copy of an auto playlist as a regular playlist. Switch to Playlists view by clicking Playlists from either the top menu or the navigation bar. Select the Play tab and then click Clear list to remove any tracks from the list pane.   Right-click on the playlist you want to save, select Add to, and then Play list. The songs from your auto playlist will appear as an Unsaved list on the list pane. Click Save list. Type in a name for your playlist. Your auto playlist will continue to change as you add or remove items from your Media Player library that meet the criteria you established. The new saved playlist we just created will stay as it is currently. Editing a Auto playlist is easy. Right-click on the playlist and select Edit. Now you are ready to enjoy your playlist. Conclusion Auto playlists are great way to keep your playlists fresh in Windows Media Player 12. Users can get creative and experiment with the wide variety of criteria to customize their listening experience. If you are new to playlists in Windows Media Player, you may want to check our our previous post on how to create custom playlists in Windows Media Player 12. Are you looking to get better sound from WMP 12? Take a look at how to improve playback using enhancements in Windows Media Player 12. Similar Articles Productive Geek Tips Create Custom Playlists in Windows Media Player 12Fixing When Windows Media Player Library Won’t Let You Add FilesInstall and Use the VLC Media Player on Ubuntu LinuxMake Windows Media Player Automatically Open in Mini Player ModeMake VLC Player Look like Windows Media Player 10 TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips VMware Workstation 7 Acronis Online Backup DVDFab 6 Revo Uninstaller Pro Error Goblin Explains Windows Error Codes Twelve must-have Google Chrome plugins Cool Looking Skins for Windows Media Player 12 Move the Mouse Pointer With Your Face Movement Using eViacam Boot Windows Faster With Boot Performance Diagnostics Create Ringtones For Your Android Phone With RingDroid

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• Error: cluster_port_ready: could not find psql binary

  - by Christoffer D. Brammer

  When I use apt-get install i get the error: Error: cluster_port_ready: could not find psql binary What do I do here? I have tried to remove PostgreSQL 8.2 but it gives this error: The following packages have unmet dependencies: postgresql-8.2: Depends: libkrb53 (>= 1.6.dfsg.1) but it is not installable Depends: postgresql-client-8.2 but it is not installable E: Unmet dependencies. Try 'apt-get -f install' with no packages (or specify a solution). And then I end up at the start, with the error when trying apt-get -f install. /Christoffer

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• Cloning A Database On The Same Server Using Rman Duplicate From Active Database

  - by alejandro.vargas

  To clone a database using Rman we used to require an existing Rman backup, on 11g we can clone databases using the "from active" database option. In this case we do not require an existing backup, the active datafiles will be used as the source for the clone. In order to clone with the source database open it must be on archivelog mode. Otherwise we can make the clone mounting the source database, as shown in this example. These are the steps required to complete the clone: Configure The Network Create A Password File For The New Database Create An Init.Ora For The New Database Create The Admin Directory For The New Database Shutdown And Startup Mount The Source Database Startup Nomount The New Database Connect To The Target (Source) And Auxiliary (New Clone) Databases Using Rman Execute The Duplicate Command Remove The Old Pfile Check The New Database A step by step example is provided on this file: rman-duplicate-from-active-database.pdf

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• SQL03070: This statement is not recognized in this context

  - by prash

  Recently I have started working with VS2010 and Fx4. There have been various challenges. We also introduced a new Database Project in our solution. And found this error. The reason for this error is: the project system expects the stored procedure as a create statement only.  The additional statements to drop if existing are not necessary within the project system.  Project deployment takes care of detecting if the sproc already exists and if it needs to be updated. To resolve this error you can simply remove the additional statements other then your create SP, Function etc. OR Exclude the file from build. Right Click on your file in Solution Explorer, Click Properties > Build Action > Not in Build

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• Oracle Coherence, Split-Brain and Recovery Protocols In Detail

  - by Ricardo Ferreira

  This article provides a high level conceptual overview of Split-Brain scenarios in distributed systems. It will focus on a specific example of cluster communication failure and recovery in Oracle Coherence. This includes a discussion on the witness protocol (used to remove failed cluster members) and the panic protocol (used to resolve Split-Brain scenarios). Note that the removal of cluster members does not necessarily indicate a Split-Brain condition. Oracle Coherence does not (and cannot) detect a Split-Brain as it occurs, the condition is only detected when cluster members that previously lost contact with each other regain contact. Cluster Topology and Configuration In order to create an good didactic for the article, let's assume a cluster topology and configuration. In this example we have a six member cluster, consisting of one JVM on each physical machine. The member IDs are as follows: Member ID  IP Address  1  10.149.155.76  2  10.149.155.77  3  10.149.155.236  4  10.149.155.75  5  10.149.155.79  6  10.149.155.78 Members 1, 2, and 3 are connected to a switch, and members 4, 5, and 6 are connected to a second switch. There is a link between the two switches, which provides network connectivity between all of the machines. Member 1 is the first member to join this cluster, thus making it the senior member. Member 6 is the last member to join this cluster. Here is a log snippet from Member 6 showing the complete member set: 2010-02-26 15:27:57.390/3.062 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=6): Started DefaultCacheServer... SafeCluster: Name=cluster:0xDDEB Group{Address=224.3.5.3, Port=35465, TTL=4} MasterMemberSet ( ThisMember=Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) OldestMember=Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ActualMemberSet=MemberSet(Size=6, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) RecycleMillis=120000 RecycleSet=MemberSet(Size=0, BitSetCount=0 ) ) At approximately 15:30, the connection between the two switches is severed: Thirty seconds later (the default packet timeout in development mode) the logs indicate communication failures across the cluster. In this example, the communication failure was caused by a network failure. In a production setting, this type of communication failure can have many root causes, including (but not limited to) network failures, excessive GC, high CPU utilization, swapping/virtual memory, and exceeding maximum network bandwidth. In addition, this type of failure is not necessarily indicative of a split brain. Any communication failure will be logged in this fashion. Member 2 logs a communication failure with Member 5: 2010-02-26 15:30:32.638/196.928 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=5, Timestamp=2010-02-26 15:27:49.095, Address=10.149.155.79:8088, MachineId=1103, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:3229, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) ) The Coherence clustering protocol (TCMP) is a reliable transport mechanism built on UDP. In order for the protocol to be reliable, it requires an acknowledgement (ACK) for each packet delivered. If a packet fails to be acknowledged within the configured timeout period, the Coherence cluster member will log a packet timeout (as seen in the log message above). When this occurs, the cluster member will consult with other members to determine who is at fault for the communication failure. If the witness members agree that the suspect member is at fault, the suspect is removed from the cluster. If the witnesses unanimously disagree, the accuser is removed. This process is known as the witness protocol. Since Member 2 cannot communicate with Member 5, it selects two witnesses (Members 1 and 4) to determine if the communication issue is with Member 5 or with itself (Member 2). However, Member 4 is on the switch that is no longer accessible by Members 1, 2 and 3; thus a packet timeout for member 4 is recorded as well: 2010-02-26 15:30:35.648/199.938 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=2): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) Member 1 has the ability to confirm the departure of member 4, however Member 6 cannot as it is also inaccessible. At the same time, Member 3 sends a request to remove Member 6, which is followed by a report from Member 3 indicating that Member 6 has departed the cluster: 2010-02-26 15:30:35.706/199.996 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft request for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) 2010-02-26 15:30:35.709/199.999 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=2): MemberLeft notification for Member 6 received from Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) The log for Member 3 determines how Member 6 departed the cluster: 2010-02-26 15:30:35.161/191.694 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=3): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ) 2010-02-26 15:30:35.165/191.698 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=3): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) Member(Id=2, Timestamp=2010-02-26 15:27:17.847, Address=10.149.155.77:8088, MachineId=1101, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:296, Role=CoherenceServer) ); removing Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) In this case, Member 3 happened to select two witnesses that it still had connectivity with (Members 1 and 2) thus resulting in a simple decision to remove Member 6. Given the departure of Member 6, Member 2 is left with a single witness to confirm the departure of Member 4: 2010-02-26 15:30:35.713/200.003 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=2): Member departure confirmed by MemberSet(Size=1, BitSetCount=2 Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) ); removing Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) In the meantime, Member 4 logs a missing heartbeat from the senior member. This message is also logged on Members 5 and 6. 2010-02-26 15:30:07.906/150.453 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=PacketListenerN, member=4): Scheduled senior member heartbeat is overdue; rejoining multicast group. Next, Member 4 logs a TcpRing failure with Member 2, thus resulting in the termination of Member 2: 2010-02-26 15:30:21.421/163.968 Oracle Coherence GE 3.5.3/465p2 <D4> (thread=Cluster, member=4): TcpRing: Number of socket exceptions exceeded maximum; last was "java.net.SocketTimeoutException: connect timed out"; removing the member: 2 For quick process termination detection, Oracle Coherence utilizes a feature called TcpRing which is a sparse collection of TCP/IP-based connections between different members in the cluster. Each member in the cluster is connected to at least one other member, which (if at all possible) is running on a different physical box. This connection is not used for any data transfer, only heartbeat communications are sent once a second per each link. If a certain number of exceptions are thrown while trying to re-establish a connection, the member throwing the exceptions is removed from the cluster. Member 5 logs a packet timeout with Member 3 and cites witnesses Members 4 and 6: 2010-02-26 15:30:29.791/165.037 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=PacketPublisher, member=5): Timeout while delivering a packet; requesting the departure confirmation for Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ) 2010-02-26 15:30:29.798/165.044 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=5): Member departure confirmed by MemberSet(Size=2, BitSetCount=2 Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member(Id=6, Timestamp=2010-02-26 15:27:58.635, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) ); removing Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer) Eventually we are left with two distinct clusters consisting of Members 1, 2, 3 and Members 4, 5, 6, respectively. In the latter cluster, Member 4 is promoted to senior member. The connection between the two switches is restored at 15:33. Upon the restoration of the connection, the cluster members immediately receive cluster heartbeats from the two senior members. In the case of Members 1, 2, and 3, the following is logged: 2010-02-26 15:33:14.970/369.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): The member formerly known as Member(Id=4, Timestamp=2010-02-26 15:30:35.341, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. Likewise for Members 4, 5, and 6: 2010-02-26 15:33:14.343/336.890 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=4): The member formerly known as Member(Id=1, Timestamp=2010-02-26 15:30:31.64, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) has been forcefully evicted from the cluster, but continues to emit a cluster heartbeat; henceforth, the member will be shunned and its messages will be ignored. This message indicates that a senior heartbeat is being received from members that were previously removed from the cluster, in other words, something that should not be possible. For this reason, the recipients of these messages will initially ignore them. After several iterations of these messages, the existence of multiple clusters is acknowledged, thus triggering the panic protocol to reconcile this situation. When the presence of more than one cluster (i.e. Split-Brain) is detected by a Coherence member, the panic protocol is invoked in order to resolve the conflicting clusters and consolidate into a single cluster. The protocol consists of the removal of smaller clusters until there is one cluster remaining. In the case of equal size clusters, the one with the older Senior Member will survive. Member 1, being the oldest member, initiates the protocol: 2010-02-26 15:33:45.970/400.066 Oracle Coherence GE 3.5.3/465p2 <Warning> (thread=Cluster, member=1): An existence of a cluster island with senior Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) containing 3 nodes have been detected. Since this Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) is the senior of an older cluster island, the panic protocol is being activated to stop the other island's senior and all junior nodes that belong to it. Member 3 receives the panic: 2010-02-26 15:33:45.803/382.336 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=3): Received panic from senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer) caused by Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer) Member 4, the senior member of the younger cluster, receives the kill message from Member 3: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. In turn, Member 4 requests the departure of its junior members 5 and 6: 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:43.343/349.015 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=6): Received a Kill message from a valid Member(Id=4, Timestamp=2010-02-26 15:27:39.574, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer); stopping cluster service. Once Members 4, 5, and 6 restart, they rejoin the original cluster with senior member 1. The log below is from Member 4. Note that it receives a different member id when it rejoins the cluster. 2010-02-26 15:33:44.921/367.468 Oracle Coherence GE 3.5.3/465p2 <Error> (thread=Cluster, member=4): Received a Kill message from a valid Member(Id=3, Timestamp=2010-02-26 15:27:24.892, Address=10.149.155.236:8088, MachineId=1260, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:32459, Role=CoherenceServer); stopping cluster service. 2010-02-26 15:33:46.921/369.468 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Service Cluster left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:InvocationService, member=4): Service InvocationService left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=OptimisticCache, member=4): Service OptimisticCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=ReplicatedCache, member=4): Service ReplicatedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=DistributedCache, member=4): Service DistributedCache left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Invocation:Management, member=4): Service Management left the cluster 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service Management with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service DistributedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service ReplicatedCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service OptimisticCache with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member 6 left service InvocationService with senior member 5 2010-02-26 15:33:47.046/369.593 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=4): Member(Id=6, Timestamp=2010-02-26 15:33:47.046, Address=10.149.155.78:8088, MachineId=1102, Location=process:228, Role=CoherenceServer) left Cluster with senior member 4 2010-02-26 15:33:49.218/371.765 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=main, member=n/a): Restarting cluster 2010-02-26 15:33:49.421/371.968 Oracle Coherence GE 3.5.3/465p2 <D5> (thread=Cluster, member=n/a): Service Cluster joined the cluster with senior service member n/a 2010-02-26 15:33:49.625/372.172 Oracle Coherence GE 3.5.3/465p2 <Info> (thread=Cluster, member=n/a): This Member(Id=5, Timestamp=2010-02-26 15:33:50.499, Address=10.149.155.75:8088, MachineId=1099, Location=process:800, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=1) joined cluster "cluster:0xDDEB" with senior Member(Id=1, Timestamp=2010-02-26 15:27:06.931, Address=10.149.155.76:8088, MachineId=1100, Location=site:usdhcp.oraclecorp.com,machine:dhcp-burlington6-4fl-east-10-149,process:511, Role=CoherenceServer, Edition=Grid Edition, Mode=Development, CpuCount=2, SocketCount=2) Cool isn't it?

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• Creating STA COM compatible ASP.NET Applications

  - by Rick Strahl

  When building ASP.NET applications that interface with old school COM objects like those created with VB6 or Visual FoxPro (MTDLL), it's extremely important that the threads that are serving requests use Single Threaded Apartment Threading. STA is a COM built-in technology that allows essentially single threaded components to operate reliably in a multi-threaded environment. STA's guarantee that COM objects instantiated on a specific thread stay on that specific thread and any access to a COM object from another thread automatically marshals that thread to the STA thread. The end effect is that you can have multiple threads, but a COM object instance lives on a fixed never changing thread. ASP.NET by default uses MTA (multi-threaded apartment) threads which are truly free spinning threads that pay no heed to COM object marshaling. This is vastly more efficient than STA threading which has a bit of overhead in determining whether it's OK to run code on a given thread or whether some sort of thread/COM marshaling needs to occur. MTA COM components can be very efficient, but STA COM components in a multi-threaded environment always tend to have a fair amount of overhead. It's amazing how much COM Interop I still see today so while it seems really old school to be talking about this topic, it's actually quite apropos for me as I have many customers using legacy COM systems that need to interface with other .NET applications. In this post I'm consolidating some of the hacks I've used to integrate with various ASP.NET technologies when using STA COM Components. STA in ASP.NET Support for STA threading in the ASP.NET framework is fairly limited. Specifically only the original ASP.NET WebForms technology supports STA threading directly via its STA Page Handler implementation or what you might know as ASPCOMPAT mode. For WebForms running STA components is as easy as specifying the ASPCOMPAT attribute in the @Page tag:<%@ Page Language="C#" AspCompat="true" %> which runs the page in STA mode. Removing it runs in MTA mode. Simple. Unfortunately all other ASP.NET technologies built on top of the core ASP.NET engine do not support STA natively. So if you want to use STA COM components in MVC or with class ASMX Web Services, there's no automatic way like the ASPCOMPAT keyword available. So what happens when you run an STA COM component in an MTA application? In low volume environments - nothing much will happen. The COM objects will appear to work just fine as there are no simultaneous thread interactions and the COM component will happily run on a single thread or multiple single threads one at a time. So for testing running components in MTA environments may appear to work just fine. However as load increases and threads get re-used by ASP.NET COM objects will end up getting created on multiple different threads. This can result in crashes or hangs, or data corruption in the STA components which store their state in thread local storage on the STA thread. If threads overlap this global store can easily get corrupted which in turn causes problems. STA ensures that any COM object instance loaded always stays on the same thread it was instantiated on. What about COM+? COM+ is supposed to address the problem of STA in MTA applications by providing an abstraction with it's own thread pool manager for COM objects. It steps in to the COM instantiation pipeline and hands out COM instances from its own internally maintained STA Thread pool. This guarantees that the COM instantiation threads are STA threads if using STA components. COM+ works, but in my experience the technology is very, very slow for STA components. It adds a ton of overhead and reduces COM performance noticably in load tests in IIS. COM+ can make sense in some situations but for Web apps with STA components it falls short. In addition there's also the need to ensure that COM+ is set up and configured on the target machine and the fact that components have to be registered in COM+. COM+ also keeps components up at all times, so if a component needs to be replaced the COM+ package needs to be unloaded (same is true for IIS hosted components but it's more common to manage that). COM+ is an option for well established components, but native STA support tends to provide better performance and more consistent usability, IMHO. STA for non supporting ASP.NET Technologies As mentioned above only WebForms supports STA natively. However, by utilizing the WebForms ASP.NET Page handler internally it's actually possible to trick various other ASP.NET technologies and let them work with STA components. This is ugly but I've used each of these in various applications and I've had minimal problems making them work with FoxPro STA COM components which is about as dififcult as it gets for COM Interop in .NET. In this post I summarize several STA workarounds that enable you to use STA threading with these ASP.NET Technologies: ASMX Web Services ASP.NET MVC WCF Web Services ASP.NET Web API ASMX Web Services I start with classic ASP.NET ASMX Web Services because it's the easiest mechanism that allows for STA modification. It also clearly demonstrates how the WebForms STA Page Handler is the key technology to enable the various other solutions to create STA components. Essentially the way this works is to override the WebForms Page class and hijack it's init functionality for processing requests. Here's what this looks like for Web Services:namespace FoxProAspNet { public class WebServiceStaHandler : System.Web.UI.Page, IHttpAsyncHandler { protected override void OnInit(EventArgs e) { IHttpHandler handler = new WebServiceHandlerFactory().GetHandler( this.Context, this.Context.Request.HttpMethod, this.Context.Request.FilePath, this.Context.Request.PhysicalPath); handler.ProcessRequest(this.Context); this.Context.ApplicationInstance.CompleteRequest(); } public IAsyncResult BeginProcessRequest( HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } } public class AspCompatWebServiceStaHandlerWithSessionState : WebServiceStaHandler, IRequiresSessionState { } } This class overrides the ASP.NET WebForms Page class which has a little known AspCompatBeginProcessRequest() and AspCompatEndProcessRequest() method that is responsible for providing the WebForms ASPCOMPAT functionality. These methods handle routing requests to STA threads. Note there are two classes - one that includes session state and one that does not. If you plan on using ASP.NET Session state use the latter class, otherwise stick to the former. This maps to the EnableSessionState page setting in WebForms. This class simply hooks into this functionality by overriding the BeginProcessRequest and EndProcessRequest methods and always forcing it into the AspCompat methods. The way this works is that BeginProcessRequest() fires first to set up the threads and starts intializing the handler. As part of that process the OnInit() method is fired which is now already running on an STA thread. The code then creates an instance of the actual WebService handler factory and calls its ProcessRequest method to start executing which generates the Web Service result. Immediately after ProcessRequest the request is stopped with Application.CompletRequest() which ensures that the rest of the Page handler logic doesn't fire. This means that even though the fairly heavy Page class is overridden here, it doesn't end up executing any of its internal processing which makes this code fairly efficient. In a nutshell, we're highjacking the Page HttpHandler and forcing it to process the WebService process handler in the context of the AspCompat handler behavior. Hooking up the Handler Because the above is an HttpHandler implementation you need to hook up the custom handler and replace the standard ASMX handler. To do this you need to modify the web.config file (here for IIS 7 and IIS Express): <configuration> <system.webServer> <handlers> <remove name="WebServiceHandlerFactory-Integrated-4.0" /> <add name="Asmx STA Web Service Handler" path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" precondition="integrated"/> </handlers> </system.webServer> </configuration> (Note: The name for the WebServiceHandlerFactory-Integrated-4.0 might be slightly different depending on your server version. Check the IIS Handler configuration in the IIS Management Console for the exact name or simply remove the handler from the list there which will propagate to your web.config). For IIS 5 & 6 (Windows XP/2003) or the Visual Studio Web Server use:<configuration> <system.web> <httpHandlers> <remove path="*.asmx" verb="*" /> <add path="*.asmx" verb="*" type="FoxProAspNet.WebServiceStaHandler" /> </httpHandlers> </system.web></configuration> To test, create a new ASMX Web Service and create a method like this: [WebService(Namespace = "http://foxaspnet.org/")] [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)] public class FoxWebService : System.Web.Services.WebService { [WebMethod] public string HelloWorld() { return "Hello World. Threading mode is: " + System.Threading.Thread.CurrentThread.GetApartmentState(); } } Run this before you put in the web.config configuration changes and you should get: Hello World. Threading mode is: MTA Then put the handler mapping into Web.config and you should see: Hello World. Threading mode is: STA And you're on your way to using STA COM components. It's a hack but it works well! I've used this with several high volume Web Service installations with various customers and it's been fast and reliable. ASP.NET MVC ASP.NET MVC has quickly become the most popular ASP.NET technology, replacing WebForms for creating HTML output. MVC is more complex to get started with, but once you understand the basic structure of how requests flow through the MVC pipeline it's easy to use and amazingly flexible in manipulating HTML requests. In addition, MVC has great support for non-HTML output sources like JSON and XML, making it an excellent choice for AJAX requests without any additional tools. Unlike WebForms ASP.NET MVC doesn't support STA threads natively and so some trickery is needed to make it work with STA threads as well. MVC gets its handler implementation through custom route handlers using ASP.NET's built in routing semantics. To work in an STA handler requires working in the Page Handler as part of the Route Handler implementation. As with the Web Service handler the first step is to create a custom HttpHandler that can instantiate an MVC request pipeline properly:public class MvcStaThreadHttpAsyncHandler : Page, IHttpAsyncHandler, IRequiresSessionState { private RequestContext _requestContext; public MvcStaThreadHttpAsyncHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); _requestContext = requestContext; } public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, object extraData) { return this.AspCompatBeginProcessRequest(context, cb, extraData); } protected override void OnInit(EventArgs e) { var controllerName = _requestContext.RouteData.GetRequiredString("controller"); var controllerFactory = ControllerBuilder.Current.GetControllerFactory(); var controller = controllerFactory.CreateController(_requestContext, controllerName); if (controller == null) throw new InvalidOperationException("Could not find controller: " + controllerName); try { controller.Execute(_requestContext); } finally { controllerFactory.ReleaseController(controller); } this.Context.ApplicationInstance.CompleteRequest(); } public void EndProcessRequest(IAsyncResult result) { this.AspCompatEndProcessRequest(result); } public override void ProcessRequest(HttpContext httpContext) { throw new NotSupportedException("STAThreadRouteHandler does not support ProcessRequest called (only BeginProcessRequest)"); } } This handler code figures out which controller to load and then executes the controller. MVC internally provides the information needed to route to the appropriate method and pass the right parameters. Like the Web Service handler the logic occurs in the OnInit() and performs all the processing in that part of the request. Next, we need a RouteHandler that can actually pick up this handler. Unlike the Web Service handler where we simply registered the handler, MVC requires a RouteHandler to pick up the handler. RouteHandlers look at the URL's path and based on that decide on what handler to invoke. The route handler is pretty simple - all it does is load our custom handler: public class MvcStaThreadRouteHandler : IRouteHandler { public IHttpHandler GetHttpHandler(RequestContext requestContext) { if (requestContext == null) throw new ArgumentNullException("requestContext"); return new MvcStaThreadHttpAsyncHandler(requestContext); } } At this point you can instantiate this route handler and force STA requests to MVC by specifying a route. The following sets up the ASP.NET Default Route:Route mvcRoute = new Route("{controller}/{action}/{id}", new RouteValueDictionary( new { controller = "Home", action = "Index", id = UrlParameter.Optional }), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute);   To make this code a little easier to work with and mimic the behavior of the routes.MapRoute() functionality extension method that MVC provides, here is an extension method for MapMvcStaRoute(): public static class RouteCollectionExtensions { public static void MapMvcStaRoute(this RouteCollection routeTable, string name, string url, object defaults = null) { Route mvcRoute = new Route(url, new RouteValueDictionary(defaults), new MvcStaThreadRouteHandler()); RouteTable.Routes.Add(mvcRoute); } } With this the syntax to add  route becomes a little easier and matches the MapRoute() method:RouteTable.Routes.MapMvcStaRoute( name: "Default", url: "{controller}/{action}/{id}", defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional } ); The nice thing about this route handler, STA Handler and extension method is that it's fully self contained. You can put all three into a single class file and stick it into your Web app, and then simply call MapMvcStaRoute() and it just works. Easy! To see whether this works create an MVC controller like this: public class ThreadTestController : Controller { public string ThreadingMode() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Try this test both with only the MapRoute() hookup in the RouteConfiguration in which case you should get MTA as the value. Then change the MapRoute() call to MapMvcStaRoute() leaving all the parameters the same and re-run the request. You now should see STA as the result. You're on your way using STA COM components reliably in ASP.NET MVC. WCF Web Services running through IIS WCF Web Services provide a more robust and wider range of services for Web Services. You can use WCF over HTTP, TCP, and Pipes, and WCF services support WS* secure services. There are many features in WCF that go way beyond what ASMX can do. But it's also a bit more complex than ASMX. As a basic rule if you need to serve straight SOAP Services over HTTP I 'd recommend sticking with the simpler ASMX services especially if COM is involved. If you need WS* support or want to serve data over non-HTTP protocols then WCF makes more sense. WCF is not my forte but I found a solution from Scott Seely on his blog that describes the progress and that seems to work well. I'm copying his code below so this STA information is all in one place and quickly explain. Scott's code basically works by creating a custom OperationBehavior which can be specified via an [STAOperation] attribute on every method. Using his attribute you end up with a class (or Interface if you separate the contract and class) that looks like this: [ServiceContract] public class WcfService { [OperationContract] public string HelloWorldMta() { return Thread.CurrentThread.GetApartmentState().ToString(); } // Make sure you use this custom STAOperationBehavior // attribute to force STA operation of service methods [STAOperationBehavior] [OperationContract] public string HelloWorldSta() { return Thread.CurrentThread.GetApartmentState().ToString(); } } Pretty straight forward. The latter method returns STA while the former returns MTA. To make STA work every method needs to be marked up. The implementation consists of the attribute and OperationInvoker implementation. Here are the two classes required to make this work from Scott's post:public class STAOperationBehaviorAttribute : Attribute, IOperationBehavior { public void AddBindingParameters(OperationDescription operationDescription, System.ServiceModel.Channels.BindingParameterCollection bindingParameters) { } public void ApplyClientBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.ClientOperation clientOperation) { // If this is applied on the client, well, it just doesn’t make sense. // Don’t throw in case this attribute was applied on the contract // instead of the implementation. } public void ApplyDispatchBehavior(OperationDescription operationDescription, System.ServiceModel.Dispatcher.DispatchOperation dispatchOperation) { // Change the IOperationInvoker for this operation. dispatchOperation.Invoker = new STAOperationInvoker(dispatchOperation.Invoker); } public void Validate(OperationDescription operationDescription) { if (operationDescription.SyncMethod == null) { throw new InvalidOperationException("The STAOperationBehaviorAttribute " + "only works for synchronous method invocations."); } } } public class STAOperationInvoker : IOperationInvoker { IOperationInvoker _innerInvoker; public STAOperationInvoker(IOperationInvoker invoker) { _innerInvoker = invoker; } public object[] AllocateInputs() { return _innerInvoker.AllocateInputs(); } public object Invoke(object instance, object[] inputs, out object[] outputs) { // Create a new, STA thread object[] staOutputs = null; object retval = null; Thread thread = new Thread( delegate() { retval = _innerInvoker.Invoke(instance, inputs, out staOutputs); }); thread.SetApartmentState(ApartmentState.STA); thread.Start(); thread.Join(); outputs = staOutputs; return retval; } public IAsyncResult InvokeBegin(object instance, object[] inputs, AsyncCallback callback, object state) { // We don’t handle async… throw new NotImplementedException(); } public object InvokeEnd(object instance, out object[] outputs, IAsyncResult result) { // We don’t handle async… throw new NotImplementedException(); } public bool IsSynchronous { get { return true; } } } The key in this setup is the Invoker and the Invoke method which creates a new thread and then fires the request on this new thread. Because this approach creates a new thread for every request it's not super efficient. There's a bunch of overhead involved in creating the thread and throwing it away after each thread, but it'll work for low volume requests and insure each thread runs in STA mode. If better performance is required it would be useful to create a custom thread manager that can pool a number of STA threads and hand off threads as needed rather than creating new threads on every request. If your Web Service needs are simple and you need only to serve standard SOAP 1.x requests, I would recommend sticking with ASMX services. It's easier to set up and work with and for STA component use it'll be significantly better performing since ASP.NET manages the STA thread pool for you rather than firing new threads for each request. One nice thing about Scotts code is though that it works in any WCF environment including self hosting. It has no dependency on ASP.NET or WebForms for that matter. STA - If you must STA components are a  pain in the ass and thankfully there isn't too much stuff out there anymore that requires it. But when you need it and you need to access STA functionality from .NET at least there are a few options available to make it happen. Each of these solutions is a bit hacky, but they work - I've used all of them in production with good results with FoxPro components. I hope compiling all of these in one place here makes it STA consumption a little bit easier. I feel your pain :-) Resources Download STA Handler Code Examples Scott Seely's original STA WCF OperationBehavior Article© Rick Strahl, West Wind Technologies, 2005-2012Posted in FoxPro   ASP.NET  .NET  COM   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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• Enable Automatic Code First Migrations On SQL Database in Azure Web Sites

  - by Steve Michelotti

  Now that Azure supports .NET Framework 4.5, you can use all the latest and greatest available features. A common scenario is to be able to use Entity Framework Code First Migrations with a SQL Database in Azure. Prior to Code First Migrations, Entity Framework provided database initializers. While convenient for demos and prototypes, database initializers weren’t useful for much beyond that because, if you delete and re-create your entire database when the schema changes, you lose all of your operational data. This is the void that Migrations are meant to fill. For example, if you add a column to your model, Migrations will alter the database to add the column rather than blowing away the entire database and re-creating it from scratch. Azure is becoming increasingly easier to use – especially with features like Azure Web Sites. Being able to use Entity Framework Migrations in Azure makes deployment easier than ever. In this blog post, I’ll walk through enabling Automatic Code First Migrations on Azure. I’ll use the Simple Membership provider for my example. First, we’ll create a new Azure Web site called “migrationstest” including creating a new SQL Database along with it:   Next we’ll go to the web site and download the publish profile:   In the meantime, we’ve created a new MVC 4 website in Visual Studio 2012 using the “Internet Application” template. This template is automatically configured to use the Simple Membership provider. We’ll do our initial Publish to Azure by right-clicking our project and selecting “Publish…”. From the “Publish Web” dialog, we’ll import the publish profile that we downloaded in the previous step:   Once the site is published, we’ll just click the “Register” link from the default site. Since the AccountController is decorated with the [InitializeSimpleMembership] attribute, the initializer will be called and the initial database is created.   We can verify this by connecting to our SQL Database on Azure with SQL Management Studio (after making sure that our local IP address is added to the list of Allowed IP Addresses in Azure): One interesting note is that these tables got created with the default Entity Framework initializer – which is to create the database if it doesn’t already exist. However, our database did already exist! This is because there is a new feature of Entity Framework 5 where Code First will add tables to an existing database as long as the target database doesn’t contain any of the tables from the model. At this point, it’s time to enable Migrations. We’ll open the Package Manger Console and execute the command: PM> Enable-Migrations -EnableAutomaticMigrations This will enable automatic migrations for our project. Because we used the "-EnableAutomaticMigrations” switch, it will create our Configuration class with a constructor that sets the AutomaticMigrationsEnabled property set to true: 1: public Configuration() 2: { 3: AutomaticMigrationsEnabled = true; 4: } We’ll now add our initial migration: PM> Add-Migration Initial This will create a migration class call “Initial” that contains the entire model. But we need to remove all of this code because our database already exists so we are just left with empty Up() and Down() methods. 1: public partial class Initial : DbMigration 2: { 3: public override void Up() 4: { 5: } 6: 7: public override void Down() 8: { 9: } 10: } If we don’t remove this code, we’ll get an exception the first time we attempt to run migrations that tells us: “There is already an object named 'UserProfile' in the database”. This blog post by Julie Lerman fully describes this scenario (i.e., enabling migrations on an existing database). Our next step is to add the Entity Framework initializer that will automatically use Migrations to update the database to the latest version. We will add these 2 lines of code to the Application_Start of the Global.asax: 1: Database.SetInitializer(new MigrateDatabaseToLatestVersion<UsersContext, Configuration>()); 2: new UsersContext().Database.Initialize(false); Note the Initialize() call will force the initializer to run if it has not been run before. At this point, we can publish again to make sure everything is still working as we are expecting. This time we’re going to specify in our publish profile that Code First Migrations should be executed:   Once we have re-published we can once again navigate to the Register page. At this point the database has not been changed but Migrations is now enabled on our SQL Database in Azure. We can now customize our model. Let’s add 2 new properties to the UserProfile class – Email and DateOfBirth: 1: [Table("UserProfile")] 2: public class UserProfile 3: { 4: [Key] 5: [DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)] 6: public int UserId { get; set; } 7: public string UserName { get; set; } 8: public string Email { get; set; } 9: public DateTime DateOfBirth { get; set; } 10: } At this point all we need to do is simply re-publish. We’ll once again navigate to the Registration page and, because we had Automatic Migrations enabled, the database has been altered (*not* recreated) to add our 2 new columns. We can verify this by once again looking at SQL Management Studio:   Automatic Migrations provide a quick and easy way to keep your database in sync with your model without the worry of having to re-create your entire database and lose data. With Azure Web Sites you can set up automatic deployment with Git or TFS and automate the entire process to make it dead simple.

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• 8 Mac System Features You Can Access in Recovery Mode

  - by Chris Hoffman

  A Mac’s Recovery Mode is for more than just reinstalling Mac OS X. You’ll find many other useful troubleshooting utilities here — you can use these even if your Mac can’t boot normally. To access Recovery Mode, restart your Mac and press and hold the Command + R keys during the boot-up process. This is one of several hidden startup options on a Mac. Reinstall Mac OS X Most people know Recovery Mode as the place you go to reinstall OS X on your Mac. Recovery Mode will download the OS X installer files from teh Intenret if you don’t have them locally, so they don’t take up space on your disk and you’ll never have to hunt for an opearign system disc. Better yet, it will download up-to-date installation files so you don’t have to spend hours installing operating system updates later. Microsoft could learn a lot from Apple here. Restore From a Time Machine Backup Instead of reinstalling OS X, you can choose to restore your Mac from a time machine backup. This is like restoring a system image on another operating system. You’ll need an external disk containing a backup image created on the current computer to do this. Browse the Web The Get Help Online link opens the Safari web browser to Apple’s documentation site. It’s not limited to Apple’s website, though — you can navigate to any website you like. This feature allows you to access and use a browser on your Mac even if it isn’t booting properly. It’s ideal for looking up troubleshooting information. Manage Your Disks The Disk Utility option opens the same Disk Utility you can access from within Mac OS X. It allows you to partition disks, format them, scan disks for problems, wipe drives, and set up drives in a RAID configuration. If you need to edit partitions from outside your operating system, you can just boot into the recovery environment — you don’t have to download a special partitioning tool and boot into it. Choose the Default Startup Disk Click the Apple menu on the bar at the top of your screen and select Startup Disk to access the Choose Startup Disk tool. Use this tool to choose your computer’s default startup disk and reboot into another operating system. For example, it’s useful if you have Windows installed alongside Mac OS X with Boot Camp. Add or Remove an EFI Firmware Password You can also add a firmware password to your Mac. This works like a BIOS password or UEFI password on a Windows or Linux PC. Click the Utilities menu on the bar at the top of your screen and select Firmware Password Utility to open this tool. Use the tool to turn on a firmware password, which will prevent your computer from starting up from a different hard disk, CD, DVD, or USB drive without the password you provide. This prevents people form booting up your Mac with an unauthorized operating system. If you’ve already enabled a firmware password, you can remove it from here. Use Network Tools to Troubleshoot Your Connection Select Utilities > Network Utility to open a network diagnostic tool. This utility provides a graphical way to view your network connection information. You can also use the netstat, ping, lookup, traceroute, whois, finger, and port scan utilities from here. These can be helpful to troubleshoot Internet connection problems. For example, the ping command can demonstrate whether you can communicate with a remote host and show you if you’re experiencing packet loss, while the traceroute command can show you where a connection is failing if you can’t connect to a remote server. Open a Terminal If you’d like to get your hands dirty, you can select Utilities > Terminal to open a terminal from here. This terminal allows you to do more advanced troubleshooting. Mac OS X uses the bash shell, just as typical Linux distributions do. Most people will just need to use the Reinstall Mac OS X option here, but there are many other tools you can benefit from. If the Recovery Mode files on your Mac are damaged or unavailable, your Mac will automatically download them from Apple so you can use the full recovery environment.

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