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Joomla contact form doesn't pass W3C validation

- by aramaz

Hi, I get the following error when I try to validate a contact page on my site: document type does not allow element "script" here The element named above was found in a context where it is not allowed. This could mean that you have incorrectly nested elements -- such as a "style" element in the "body" section instead of inside "head" -- or two elements that overlap (which is not allowed). One common cause for this error is the use of XHTML syntax in HTML documents. Due to HTML's rules of implicitly closed elements, this error can create cascading effects. For instance, using XHTML's "self-closing" tags for "meta" and "link" in the "head" section of a HTML document may cause the parser to infer the end of the "head" section and the beginning of the "body" section (where "link" and "meta" are not allowed; hence the reported error). I am using Joomla 1.5.7, and the doctype is <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> Any idea how to fix this?

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Remove redundant entries, scala way

- by andersbohn

Edit: Added the fact, that the list is sorted, and realizing 'duplicate' is misleading, replaced that with 'redundant' in the title. I have a sorted list of entries stating a production value in a given interval. Entries stating the exact same value at a later time adds no information and can safely be left out. case class Entry(minute:Int, production:Double) val entries = List(Entry(0, 100.0), Entry(5, 100.0), Entry(10, 100.0), Entry(20, 120.0), Entry(30, 100.0), Entry(180, 0.0)) Experimenting with the scala 2.8 collection functions, so far I have this working implementation: entries.foldRight(List[Entry]()) { (entry, list) => list match { case head :: tail if (entry.production == head.production) => entry :: tail case head :: tail => entry :: list case List() => entry :: List() } } res0: List[Entry] = List(Entry(0,100.0), Entry(20,120.0), Entry(30,100.0), Entry(180,0.0)) Any comments? Am I missing out on some scala magic?

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Where exactly should I attach script in HTML

- by bzxcv7

I have read about several ways to embed Javascript in HTML document. First, in head section: <head> ... <script src="abc.js"></script> </head> Second, in the end of document's body: <body>  <script src="abc.js"></script> </body> First way is more esthetic, but second version assures that all the items in DOM are loaded. I use HTML5 (but probably it doesn't matters) Which way is better and why?

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Remove duplicates in entries, scala way

- by andersbohn

I have a list of entries stating a production value in a given interval. Entries stating the exact same value at a later time adds no information and can safely be left out. case class Entry(minute:Int, production:Double) val entries = List(Entry(0, 100.0), Entry(5, 100.0), Entry(10, 100.0), Entry(20, 120.0), Entry(30, 100.0), Entry(180, 0.0)) Experimenting with the scala 2.8 collection functions, so far I have this working implementation: entries.foldRight(List[Entry]()) { (entry, list) => list match { case head :: tail if (entry.production == head.production) => entry :: tail case head :: tail => entry :: list case List() => entry :: List() } } res0: List[Entry] = List(Entry(0,100.0), Entry(20,120.0), Entry(30,100.0), Entry(180,0.0)) Any comments? Am I missing out on some scala magic?

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What is problem with below class

- by user258367

class LinkedList { private: int data; LinkedList *ptr; public: LinkedList(int i_data) { data = i_data; ptr = 0; { ~LinkedList() { delete ptr ; } void insert(LinkedList *node) { while(this->next != 0) this = this->next; this->next = node; } I will be creating a head node like head = new LinkedList(4) and then will be calling like head->insert(new LinkedList(5)) and subsequently . Can you please tell me does above class represent a linkedlist . i think yes it has node which contain address of next node . Please correct me if i am wrong

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Haskell, list of natural number

- by Hellnar

Hello, I am an absolute newbie in Haskell yet trying to understand how it works. I want to write my own lazy list of integers such as [1,2,3,4,5...]. For list of ones I have written ones = 1 : ones and when tried, works fine: *Main> take 10 ones [1,1,1,1,1,1,1,1,1,1] How can I do the same for increasing integers ? I have tried this but it indeed fails: int = 1 : head[ int + 1] And after that how can I make a method that multiplies two streams? such as: mulstream s1 s2 = head[s1] * head[s2] : mulstream [tail s1] [tail s2]

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Conditional jump or move depends on uninitialised value - freeing a linked list

- by user720491

I want to free a linked list in C. All is working fine, but Valgrind is telling me Conditional jump or move depends on uninitialised value(s) at 0x401400: mtf_destroy Here's the code: list_elt *head; void mtf_init() { list_elt *current; head = malloc(sizeof(list_elt)); current = head; for (int i = 0; i < LIST_SIZE-1; i++) { current->value = (BYTE) i; current->next = malloc(sizeof(list_elt)); current = current->next; } current->value = LIST_SIZE-1; } void mtf_destroy(list_elt *elt) { if (elt->next != NULL) mtf_destroy(elt->next); free(elt); } How can I solve this? Thanks!

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ajax echo returns javascript code!

- by StevanSteve

Hi, i have an ajax call. Php page (A) called by ajax requires some other php page (B). Page "B" is php file looking something like this <html> <head> javascript code </head> <body> PHP Code </body> Inside of "head" tags is javascript code. Now, Page "A" includes page "B", but instead of expected result, it echoes pure javascript code from included page "B"! How to prevent that?

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Google PageSpeed, optimizing Google's own elements

- by mowgli

I'm trying Google's PageSpeed online service Ironically, it's primarily highlighting Google's own services as something that needs improvement on my site 1) jQuery from Google: blocking. So I moved all javascript from <head> to the end of the document before </body>. That helped 2) Linking to external Google Font CSS (in <head>): blocking. But the font is critical to the design of the page and should load before much else 3) Google Analytics: Caching is not good. (Google has set it internally to 2 hours expiration). Don't know how to change this (this is also placed at the bottom of page) The Google Font is highlighted as a big priority to change. How can I fix this? Where/how should I call the the font?

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ASP.NET Podcast Show #148 - ASP.NET WebForms to build a Mobile Web Application

- by Wallym

Check the podcast site for the original url. This is the video and source code for an ASP.NET WebForms app that I wrote that is optimized for the iPhone and mobile environments. Subscribe to everything. Subscribe to WMV. Subscribe to M4V for iPhone/iPad. Subscribe to MP3. Download WMV. Download M4V for iPhone/iPad. Download MP3. Link to iWebKit. Source Code: <%@ Page Title="MapSplore" Language="C#" MasterPageFile="iPhoneMaster.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="AT_iPhone_Default" %> <asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server"></asp:Content><asp:Content ID="Content2" ContentPlaceHolderID="Content" Runat="Server" ClientIDMode="Static"> <asp:ScriptManager ID="sm" runat="server" EnablePartialRendering="true" EnableHistory="false" EnableCdn="true" /> <script type="text/javascript" src="http://maps.google.com/maps/api/js?sensor=true"></script> <script language="javascript" type="text/javascript">  </script> <asp:HiddenField ID="Latitude" runat="server" /> <asp:HiddenField ID="Longitude" runat="server" /> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js%22%3E%3C/script> <script language="javascript" type="text/javascript"> $(document).ready(function () { GetLocation(); setupMapDiv(); setupPlaceIveBeen(); }); function GetLocation() { if (navigator.geolocation != null) { navigator.geolocation.getCurrentPosition(getData); } else { var mess = document.getElementById('<%=Message.ClientID %>'); mess.innerHTML = "Sorry, your browser does not support geolocation. " + "Try the latest version of Safari on the iPhone, Android browser, or the latest version of FireFox."; } } function UpdateLocation_Click() { GetLocation(); } function getData(position) { var latitude = position.coords.latitude; var longitude = position.coords.longitude; var hdLat = document.getElementById('<%=Latitude.ClientID %>'); var hdLon = document.getElementById('<%=Longitude.ClientID %>'); hdLat.value = latitude; hdLon.value = longitude; } </script> <asp:Label ID="Message" runat="server" /> <asp:UpdatePanel ID="upl" runat="server"> <ContentTemplate> <asp:Panel ID="pnlStart" runat="server" Visible="true"> <div id="topbar"> <div id="title">MapSplore</div> </div> <div id="content"> <ul class="pageitem"> <li class="menu"> <asp:LinkButton ID="lbLocalDeals" runat="server" onclick="lbLocalDeals_Click"> <asp:Image ID="imLocalDeals" runat="server" ImageUrl="~/Images/ArtFavor_Money_Bag_Icon.png" Height="30" /> <span class="name">Local Deals.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbLocalPlaces" runat="server" onclick="lbLocalPlaces_Click"> <asp:Image ID="imLocalPlaces" runat="server" ImageUrl="~/Images/Andy_Houses_on_the_horizon_-_Starburst_remix.png" Height="30" /> <span class="name">Local Places.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbWhereIveBeen" runat="server" onclick="lbWhereIveBeen_Click"> <asp:Image ID="imImHere" runat="server" ImageUrl="~/Images/ryanlerch_flagpole.png" Height="30" /> <span class="name">I've been here.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbMyStats" runat="server"> <asp:Image ID="imMyStats" runat="server" ImageUrl="~/Images/Anonymous_Spreadsheet.png" Height="30" /> <span class="name">My Stats.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="menu"> <asp:LinkButton ID="lbAddAPlace" runat="server" onclick="lbAddAPlace_Click"> <asp:Image ID="imAddAPlace" runat="server" ImageUrl="~/Images/jean_victor_balin_add.png" Height="30" /> <span class="name">Add a Place.</span> <span class="arrow"></span> </asp:LinkButton> </li> <li class="button"> <input type="button" value="Update Your Current Location" onclick="UpdateLocation_Click()"> </li> </ul> </div> </asp:Panel> <div> <asp:Panel ID="pnlCoupons" runat="server" Visible="false"> <div id="topbar"> <div id="title">MapSplore</div> <div id="leftbutton"> <asp:LinkButton runat="server" Text="Return" ID="ReturnFromDeals" OnClick="ReturnFromDeals_Click" /></div></div> <div class="content"> <asp:ListView ID="lvCoupons" runat="server"> <LayoutTemplate> <ul class="pageitem" runat="server"> <asp:PlaceHolder ID="itemPlaceholder" runat="server" /> </ul> </LayoutTemplate> <ItemTemplate> <li class="menu"> <asp:LinkButton ID="lbBusiness" runat="server" Text='<%#Eval("Place.Name") %>' OnClick="lbBusiness_Click"> <span class="comment"> <asp:Label ID="lblAddress" runat="server" Text='<%#Eval("Place.Address1") %>' /> <asp:Label ID="lblDis" runat="server" Text='<%# Convert.ToString(Convert.ToInt32(Eval("Place.Distance"))) + " meters" %>' CssClass="smallText" /> <asp:HiddenField ID="hdPlaceId" runat="server" Value='<%#Eval("PlaceId") %>' /> <asp:HiddenField ID="hdGeoPromotionId" runat="server" Value='<%#Eval("GeoPromotionId") %>' /> </span> <span class="arrow"></span> </asp:LinkButton></li></ItemTemplate></asp:ListView><asp:GridView ID="gvCoupons" runat="server" AutoGenerateColumns="false"> <HeaderStyle BackColor="Silver" /> <AlternatingRowStyle BackColor="Wheat" /> <Columns> <asp:TemplateField AccessibleHeaderText="Business" HeaderText="Business"> <ItemTemplate> <asp:Image ID="imPlaceType" runat="server" Text='<%#Eval("Type") %>' ImageUrl='<%#Eval("Image") %>' /> <asp:LinkButton ID="lbBusiness" runat="server" Text='<%#Eval("Name") %>' OnClick="lbBusiness_Click" /> <asp:LinkButton ID="lblAddress" runat="server" Text='<%#Eval("Address1") %>' CssClass="smallText" /> <asp:Label ID="lblDis" runat="server" Text='<%# Convert.ToString(Convert.ToInt32(Eval("Distance"))) + " meters" %>' CssClass="smallText" /> <asp:HiddenField ID="hdPlaceId" runat="server" Value='<%#Eval("PlaceId") %>' /> <asp:HiddenField ID="hdGeoPromotionId" runat="server" Value='<%#Eval("GeoPromotionId") %>' /> <asp:Label ID="lblInfo" runat="server" Visible="false" /> </ItemTemplate> </asp:TemplateField> </Columns> </asp:GridView> </div> </asp:Panel> <asp:Panel ID="pnlPlaces" runat="server" Visible="false"> <div id="topbar"> <div id="title"> MapSplore</div><div id="leftbutton"> <asp:LinkButton runat="server" Text="Return" ID="ReturnFromPlaces" OnClick="ReturnFromPlaces_Click" /></div></div> <div id="content"> <asp:ListView ID="lvPlaces" runat="server"> <LayoutTemplate> <ul id="ulPlaces" class="pageitem" runat="server"> <asp:PlaceHolder ID="itemPlaceholder" runat="server" /> <li class="menu"> <asp:LinkButton ID="lbNotListed" runat="server" CssClass="name" OnClick="lbNotListed_Click"> Place not listed <span class="arrow"></span> </asp:LinkButton> </li> </ul> </LayoutTemplate> <ItemTemplate> <li class="menu"> <asp:LinkButton ID="lbImHere" runat="server" CssClass="name" OnClick="lbImHere_Click"> <%#DisplayName(Eval("Name")) %>  <%# Convert.ToString(Convert.ToInt32(Eval("Distance"))) + " meters" %> <asp:HiddenField ID="hdPlaceId" runat="server" Value='<%#Eval("PlaceId") %>' /> <span class="arrow"></span> </asp:LinkButton></li></ItemTemplate></asp:ListView> </div> </asp:Panel> <asp:Panel ID="pnlImHereNow" runat="server" Visible="false"> <div id="topbar"> <div id="title"> MapSplore</div><div id="leftbutton"> <asp:LinkButton runat="server" Text="Places" ID="lbImHereNowReturn" OnClick="lbImHereNowReturn_Click" /></div></div> <div id="rightbutton"> <asp:LinkButton runat="server" Text="Beginning" ID="lbBackToBeginning" OnClick="lbBackToBeginning_Click" /> </div> <div id="content"> <ul class="pageitem"> <asp:HiddenField ID="hdPlaceId" runat="server" /> <asp:HiddenField ID="hdPlaceLat" runat="server" /> <asp:HiddenField ID="hdPlaceLon" runat="server" /> <asp:HiddenField ID="hdPlaceTitle" runat="server" /> <asp:Button ID="btnImHereNow" runat="server" Text="I'm here" OnClick="btnImHereNow_Click" /> <asp:Label ID="lblPlaceTitle" runat="server" /><br /> <asp:TextBox ID="txtWhatsHappening" runat="server" TextMode="MultiLine" Rows="2" style="width:300px" /><br /> <div id="divImHere" style="width:300px; height:300px"></div> </div> </ul> </asp:Panel> <asp:Panel runat="server" ID="pnlIveBeenHere" Visible="false"> <div id="topbar"> <div id="title"> Where I've been</div><div id="leftbutton"> <asp:LinkButton ID="lbIveBeenHereBack" runat="server" Text="Back" OnClick="lbIveBeenHereBack_Click" /></div></div> <div id="content"> <asp:ListView ID="lvWhereIveBeen" runat="server"> <LayoutTemplate> <ul id="ulWhereIveBeen" class="pageitem" runat="server"> <asp:PlaceHolder ID="itemPlaceholder" runat="server" /> </ul> </LayoutTemplate> <ItemTemplate> <li class="menu" runat="server"> <asp:LinkButton ID="lbPlaceIveBeen" runat="server" OnClick="lbPlaceIveBeen_Click" CssClass="name"> <asp:Label ID="lblPlace" runat="server" Text='<%#Eval("PlaceName") %>' /> at <asp:Label ID="lblTime" runat="server" Text='<%#Eval("ATTime") %>' CssClass="content" /> <asp:HiddenField ID="hdATID" runat="server" Value='<%#Eval("ATID") %>' /> <span class="arrow"></span> </asp:LinkButton> </li> </ItemTemplate> </asp:ListView> </div> </asp:Panel> <asp:Panel runat="server" ID="pnlPlaceIveBeen" Visible="false"> <div id="topbar"> <div id="title"> I've been here </div> <div id="leftbutton"> <asp:LinkButton ID="lbPlaceIveBeenBack" runat="server" Text="Back" OnClick="lbPlaceIveBeenBack_Click" /> </div> <div id="rightbutton"> <asp:LinkButton ID="lbPlaceIveBeenBeginning" runat="server" Text="Beginning" OnClick="lbPlaceIveBeenBeginning_Click" /> </div> </div> <div id="content"> <ul class="pageitem"> <li> <asp:HiddenField ID="hdPlaceIveBeenPlaceId" runat="server" /> <asp:HiddenField ID="hdPlaceIveBeenLatitude" runat="server" /> <asp:HiddenField ID="hdPlaceIveBeenLongitude" runat="server" /> <asp:Label ID="lblPlaceIveBeenName" runat="server" /><br /> <asp:Label ID="lblPlaceIveBeenAddress" runat="server" /><br /> <asp:Label ID="lblPlaceIveBeenCity" runat="server" />, <asp:Label ID="lblPlaceIveBeenState" runat="server" /> <asp:Label ID="lblPlaceIveBeenZipCode" runat="server" /><br /> <asp:Label ID="lblPlaceIveBeenCountry" runat="server" /><br /> <div id="divPlaceIveBeen" style="width:300px; height:300px"></div> </li> </ul> </div> </asp:Panel> <asp:Panel ID="pnlAddPlace" runat="server" Visible="false"> <div id="topbar"><div id="title">MapSplore</div><div id="leftbutton"><asp:LinkButton ID="lbAddPlaceReturn" runat="server" Text="Back" OnClick="lbAddPlaceReturn_Click" /></div><div id="rightnav"></div></div><div id="content"> <ul class="pageitem"> <li id="liPlaceAddMessage" runat="server" visible="false"> <asp:Label ID="PlaceAddMessage" runat="server" /> </li> <li class="bigfield"> <asp:TextBox ID="txtPlaceName" runat="server" placeholder="Name of Establishment" /> </li> <li class="bigfield"> <asp:TextBox ID="txtAddress1" runat="server" placeholder="Address 1" /> </li> <li class="bigfield"> <asp:TextBox ID="txtCity" runat="server" placeholder="City" /> </li> <li class="select"> <asp:DropDownList ID="ddlProvince" runat="server" placeholder="Select State" /> <span class="arrow"></span> </li> <li class="bigfield"> <asp:TextBox ID="txtZipCode" runat="server" placeholder="Zip Code" /> </li> <li class="select"> <asp:DropDownList ID="ddlCountry" runat="server" onselectedindexchanged="ddlCountry_SelectedIndexChanged" /> <span class="arrow"></span> </li> <li class="bigfield"> <asp:TextBox ID="txtPhoneNumber" runat="server" placeholder="Phone Number" /> </li> <li class="checkbox"> <span class="name">You Here Now:</span> <asp:CheckBox ID="cbYouHereNow" runat="server" Checked="true" /> </li> <li class="button"> <asp:Button ID="btnAdd" runat="server" Text="Add Place" onclick="btnAdd_Click" /> </li> </ul></div> </asp:Panel> <asp:Panel ID="pnlImHere" runat="server" Visible="false"> <asp:TextBox ID="txtImHere" runat="server" TextMode="MultiLine" Rows="3" Columns="40" /><br /> <asp:DropDownList ID="ddlPlace" runat="server" /><br /> <asp:Button ID="btnHere" runat="server" Text="Tell Everyone I'm Here" onclick="btnHere_Click" /><br /> </asp:Panel> </div> </ContentTemplate> </asp:UpdatePanel> </asp:Content> Code Behind .cs file: using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using LocationDataModel; public partial class AT_iPhone_Default : ViewStatePage{ private iPhoneDevice ipd; protected void Page_Load(object sender, EventArgs e) { LocationDataEntities lde = new LocationDataEntities(); if (!Page.IsPostBack) { var Countries = from c in lde.Countries select c; foreach (Country co in Countries) { ddlCountry.Items.Add(new ListItem(co.Name, co.CountryId.ToString())); } ddlCountry_SelectedIndexChanged(ddlCountry, null); if (AppleIPhone.IsIPad()) ipd = iPhoneDevice.iPad; if (AppleIPhone.IsIPhone()) ipd = iPhoneDevice.iPhone; if (AppleIPhone.IsIPodTouch()) ipd = iPhoneDevice.iPodTouch; } } protected void btnPlaces_Click(object sender, EventArgs e) { } protected void btnAdd_Click(object sender, EventArgs e) { bool blImHere = cbYouHereNow.Checked; string Place = txtPlaceName.Text, Address1 = txtAddress1.Text, City = txtCity.Text, ZipCode = txtZipCode.Text, PhoneNumber = txtPhoneNumber.Text, ProvinceId = ddlProvince.SelectedItem.Value, CountryId = ddlCountry.SelectedItem.Value; int iProvinceId, iCountryId; double dLatitude, dLongitude; DataAccess da = new DataAccess(); if ((!String.IsNullOrEmpty(ProvinceId)) && (!String.IsNullOrEmpty(CountryId))) { iProvinceId = Convert.ToInt32(ProvinceId); iCountryId = Convert.ToInt32(CountryId); if (blImHere) { dLatitude = Convert.ToDouble(Latitude.Value); dLongitude = Convert.ToDouble(Longitude.Value); da.StorePlace(Place, Address1, String.Empty, City, iProvinceId, ZipCode, iCountryId, PhoneNumber, dLatitude, dLongitude); } else { da.StorePlace(Place, Address1, String.Empty, City, iProvinceId, ZipCode, iCountryId, PhoneNumber); } liPlaceAddMessage.Visible = true; PlaceAddMessage.Text = "Awesome, your place has been added. Add Another!"; txtPlaceName.Text = String.Empty; txtAddress1.Text = String.Empty; txtCity.Text = String.Empty; ddlProvince.SelectedIndex = -1; txtZipCode.Text = String.Empty; txtPhoneNumber.Text = String.Empty; } else { liPlaceAddMessage.Visible = true; PlaceAddMessage.Text = "Please select a State and a Country."; } } protected void ddlCountry_SelectedIndexChanged(object sender, EventArgs e) { string CountryId = ddlCountry.SelectedItem.Value; if (!String.IsNullOrEmpty(CountryId)) { int iCountryId = Convert.ToInt32(CountryId); LocationDataModel.LocationDataEntities lde = new LocationDataModel.LocationDataEntities(); var prov = from p in lde.Provinces where p.CountryId == iCountryId orderby p.ProvinceName select p; ddlProvince.Items.Add(String.Empty); foreach (Province pr in prov) { ddlProvince.Items.Add(new ListItem(pr.ProvinceName, pr.ProvinceId.ToString())); } } else { ddlProvince.Items.Clear(); } } protected void btnImHere_Click(object sender, EventArgs e) { int i = 0; DataAccess da = new DataAccess(); double Lat = Convert.ToDouble(Latitude.Value), Lon = Convert.ToDouble(Longitude.Value); List<Place> lp = da.NearByLocations(Lat, Lon); foreach (Place p in lp) { ListItem li = new ListItem(p.Name, p.PlaceId.ToString()); if (i == 0) { li.Selected = true; } ddlPlace.Items.Add(li); i++; } pnlAddPlace.Visible = false; pnlImHere.Visible = true; } protected void lbImHere_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; ListViewItem lvi = (ListViewItem)(((LinkButton)sender).Parent); HiddenField hd = (HiddenField)lvi.FindControl("hdPlaceId"); long PlaceId = Convert.ToInt64(hd.Value); double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); Place pl = da.GetPlace(PlaceId); pnlImHereNow.Visible = true; pnlPlaces.Visible = false; hdPlaceId.Value = PlaceId.ToString(); hdPlaceLat.Value = pl.Latitude.ToString(); hdPlaceLon.Value = pl.Longitude.ToString(); hdPlaceTitle.Value = pl.Name; lblPlaceTitle.Text = pl.Name; } protected void btnHere_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; string WhatsH = txtImHere.Text; long PlaceId = Convert.ToInt64(ddlPlace.SelectedValue); double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); da.StoreUserAT(UserName, PlaceId, WhatsH, dLatitude, dLongitude); } protected void btnLocalCoupons_Click(object sender, EventArgs e) { double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); } protected void lbBusiness_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; GridViewRow gvr = (GridViewRow)(((LinkButton)sender).Parent.Parent); HiddenField hd = (HiddenField)gvr.FindControl("hdPlaceId"); string sPlaceId = hd.Value; Int64 PlaceId; if (!String.IsNullOrEmpty(sPlaceId)) { PlaceId = Convert.ToInt64(sPlaceId); } } protected void lbLocalDeals_Click(object sender, EventArgs e) { double dLatitude = Convert.ToDouble(Latitude.Value); double dLongitude = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); pnlCoupons.Visible = true; pnlStart.Visible = false; List<GeoPromotion> lgp = da.NearByDeals(dLatitude, dLongitude); lvCoupons.DataSource = lgp; lvCoupons.DataBind(); } protected void lbLocalPlaces_Click(object sender, EventArgs e) { DataAccess da = new DataAccess(); double Lat = Convert.ToDouble(Latitude.Value); double Lon = Convert.ToDouble(Longitude.Value); List<LocationDataModel.Place> places = da.NearByLocations(Lat, Lon); lvPlaces.DataSource = places; lvPlaces.SelectedIndex = -1; lvPlaces.DataBind(); pnlPlaces.Visible = true; pnlStart.Visible = false; } protected void ReturnFromPlaces_Click(object sender, EventArgs e) { pnlPlaces.Visible = false; pnlStart.Visible = true; } protected void ReturnFromDeals_Click(object sender, EventArgs e) { pnlCoupons.Visible = false; pnlStart.Visible = true; } protected void btnImHereNow_Click(object sender, EventArgs e) { long PlaceId = Convert.ToInt32(hdPlaceId.Value); string UserName = Membership.GetUser().UserName; string WhatsHappening = txtWhatsHappening.Text; double UserLat = Convert.ToDouble(Latitude.Value); double UserLon = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); da.StoreUserAT(UserName, PlaceId, WhatsHappening, UserLat, UserLon); } protected void lbImHereNowReturn_Click(object sender, EventArgs e) { pnlImHereNow.Visible = false; pnlPlaces.Visible = true; } protected void lbBackToBeginning_Click(object sender, EventArgs e) { pnlStart.Visible = true; pnlImHereNow.Visible = false; } protected void lbWhereIveBeen_Click(object sender, EventArgs e) { string UserName = Membership.GetUser().UserName; pnlStart.Visible = false; pnlIveBeenHere.Visible = true; DataAccess da = new DataAccess(); lvWhereIveBeen.DataSource = da.UserATs(UserName, 0, 15); lvWhereIveBeen.DataBind(); } protected void lbIveBeenHereBack_Click(object sender, EventArgs e) { pnlIveBeenHere.Visible = false; pnlStart.Visible = true; } protected void lbPlaceIveBeen_Click(object sender, EventArgs e) { LinkButton lb = (LinkButton)sender; ListViewItem lvi = (ListViewItem)lb.Parent.Parent; HiddenField hdATID = (HiddenField)lvi.FindControl("hdATID"); Int64 ATID = Convert.ToInt64(hdATID.Value); DataAccess da = new DataAccess(); pnlIveBeenHere.Visible = false; pnlPlaceIveBeen.Visible = true; var plac = da.GetPlaceViaATID(ATID); hdPlaceIveBeenPlaceId.Value = plac.PlaceId.ToString(); hdPlaceIveBeenLatitude.Value = plac.Latitude.ToString(); hdPlaceIveBeenLongitude.Value = plac.Longitude.ToString(); lblPlaceIveBeenName.Text = plac.Name; lblPlaceIveBeenAddress.Text = plac.Address1; lblPlaceIveBeenCity.Text = plac.City; lblPlaceIveBeenState.Text = plac.Province.ProvinceName; lblPlaceIveBeenZipCode.Text = plac.ZipCode; lblPlaceIveBeenCountry.Text = plac.Country.Name; } protected void lbNotListed_Click(object sender, EventArgs e) { SetupAddPoint(); pnlPlaces.Visible = false; } protected void lbAddAPlace_Click(object sender, EventArgs e) { SetupAddPoint(); } private void SetupAddPoint() { double lat = Convert.ToDouble(Latitude.Value); double lon = Convert.ToDouble(Longitude.Value); DataAccess da = new DataAccess(); var zip = da.WhereAmIAt(lat, lon); if (zip.Count > 0) { var z0 = zip[0]; txtCity.Text = z0.City; txtZipCode.Text = z0.ZipCode; ddlProvince.ClearSelection(); if (z0.ProvinceId.HasValue == true) { foreach (ListItem li in ddlProvince.Items) { if (li.Value == z0.ProvinceId.Value.ToString()) { li.Selected = true; break; } } } } pnlAddPlace.Visible = true; pnlStart.Visible = false; } protected void lbAddPlaceReturn_Click(object sender, EventArgs e) { pnlAddPlace.Visible = false; pnlStart.Visible = true; liPlaceAddMessage.Visible = false; PlaceAddMessage.Text = String.Empty; } protected void lbPlaceIveBeenBack_Click(object sender, EventArgs e) { pnlIveBeenHere.Visible = true; pnlPlaceIveBeen.Visible = false; } protected void lbPlaceIveBeenBeginning_Click(object sender, EventArgs e) { pnlPlaceIveBeen.Visible = false; pnlStart.Visible = true; } protected string DisplayName(object val) { string strVal = Convert.ToString(val); if (AppleIPhone.IsIPad()) { ipd = iPhoneDevice.iPad; } if (AppleIPhone.IsIPhone()) { ipd = iPhoneDevice.iPhone; } if (AppleIPhone.IsIPodTouch()) { ipd = iPhoneDevice.iPodTouch; } return (iPhoneHelper.DisplayContentOnMenu(strVal, ipd)); }} iPhoneHelper.cs file: using System;using System.Collections.Generic;using System.Linq;using System.Web; public enum iPhoneDevice{ iPhone, iPodTouch, iPad}/// <summary>/// Summary description for iPhoneHelper/// </summary>/// public class iPhoneHelper{ public iPhoneHelper() { // // TODO: Add constructor logic here // } // This code is stupid in retrospect. Use css to solve this problem public static string DisplayContentOnMenu(string val, iPhoneDevice ipd) { string Return = val; string Elipsis = "..."; int iPadMaxLength = 30; int iPhoneMaxLength = 15; if (ipd == iPhoneDevice.iPad) { if (Return.Length > iPadMaxLength) { Return = Return.Substring(0, iPadMaxLength - Elipsis.Length) + Elipsis; } } else { if (Return.Length > iPhoneMaxLength) { Return = Return.Substring(0, iPhoneMaxLength - Elipsis.Length) + Elipsis; } } return (Return); }} Source code for the ViewStatePage: using System;using System.Data;using System.Data.SqlClient;using System.Configuration;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls; /// <summary>/// Summary description for BasePage/// </summary>#region Base class for a page.public class ViewStatePage : System.Web.UI.Page{ PageStatePersisterToDatabase myPageStatePersister; public ViewStatePage() : base() { myPageStatePersister = new PageStatePersisterToDatabase(this); } protected override PageStatePersister PageStatePersister { get { return myPageStatePersister; } } }#endregion #region This class will override the page persistence to store page state in a database.public class PageStatePersisterToDatabase : PageStatePersister{ private string ViewStateKeyField = "__VIEWSTATE_KEY"; private string _exNoConnectionStringFound = "No Database Configuration information is in the web.config."; public PageStatePersisterToDatabase(Page page) : base(page) { } public override void Load() { // Get the cache key from the web form data System.Int64 key = Convert.ToInt64(Page.Request.Params[ViewStateKeyField]); Pair state = this.LoadState(key); // Abort if cache object is not of type Pair if (state == null) throw new ApplicationException("Missing valid " + ViewStateKeyField); // Set view state and control state ViewState = state.First; ControlState = state.Second; } public override void Save() { // No processing needed if no states available if (ViewState == null && ControlState != null) return; System.Int64 key; IStateFormatter formatter = this.StateFormatter; Pair statePair = new Pair(ViewState, ControlState); // Serialize the statePair object to a string. string serializedState = formatter.Serialize(statePair); // Save the ViewState and get a unique identifier back. key = SaveState(serializedState); // Register hidden field to store cache key in // Page.ClientScript does not work properly with Atlas. //Page.ClientScript.RegisterHiddenField(ViewStateKeyField, key.ToString()); ScriptManager.RegisterHiddenField(this.Page, ViewStateKeyField, key.ToString()); } private System.Int64 SaveState(string PageState) { System.Int64 i64Key = 0; string strConn = String.Empty, strProvider = String.Empty; string strSql = "insert into tblPageState ( SerializedState ) values ( '" + SqlEscape(PageState) + "');select scope_identity();"; SqlConnection sqlCn; SqlCommand sqlCm; try { GetDBConnectionString(ref strConn, ref strProvider); sqlCn = new SqlConnection(strConn); sqlCm = new SqlCommand(strSql, sqlCn); sqlCn.Open(); i64Key = Convert.ToInt64(sqlCm.ExecuteScalar()); if (sqlCn.State != ConnectionState.Closed) { sqlCn.Close(); } sqlCn.Dispose(); sqlCm.Dispose(); } finally { sqlCn = null; sqlCm = null; } return i64Key; } private Pair LoadState(System.Int64 iKey) { string strConn = String.Empty, strProvider = String.Empty, SerializedState = String.Empty, strMinutesInPast = GetMinutesInPastToDelete(); Pair PageState; string strSql = "select SerializedState from tblPageState where tblPageStateID=" + iKey.ToString() + ";" + "delete from tblPageState where DateUpdated<DateAdd(mi, " + strMinutesInPast + ", getdate());"; SqlConnection sqlCn; SqlCommand sqlCm; try { GetDBConnectionString(ref strConn, ref strProvider); sqlCn = new SqlConnection(strConn); sqlCm = new SqlCommand(strSql, sqlCn); sqlCn.Open(); SerializedState = Convert.ToString(sqlCm.ExecuteScalar()); IStateFormatter formatter = this.StateFormatter; if ((null == SerializedState) || (String.Empty == SerializedState)) { throw (new ApplicationException("No ViewState records were returned.")); } // Deserilize returns the Pair object that is serialized in // the Save method. PageState = (Pair)formatter.Deserialize(SerializedState); if (sqlCn.State != ConnectionState.Closed) { sqlCn.Close(); } sqlCn.Dispose(); sqlCm.Dispose(); } finally { sqlCn = null; sqlCm = null; } return PageState; } private string SqlEscape(string Val) { string ReturnVal = String.Empty; if (null != Val) { ReturnVal = Val.Replace("'", "''"); } return (ReturnVal); } private void GetDBConnectionString(ref string ConnectionStringValue, ref string ProviderNameValue) { if (System.Configuration.ConfigurationManager.ConnectionStrings.Count > 0) { ConnectionStringValue = System.Configuration.ConfigurationManager.ConnectionStrings["ApplicationServices"].ConnectionString; ProviderNameValue = System.Configuration.ConfigurationManager.ConnectionStrings["ApplicationServices"].ProviderName; } else { throw new ConfigurationErrorsException(_exNoConnectionStringFound); } } private string GetMinutesInPastToDelete() { string strReturn = "-60"; if (null != System.Configuration.ConfigurationManager.AppSettings["MinutesInPastToDeletePageState"]) { strReturn = System.Configuration.ConfigurationManager.AppSettings["MinutesInPastToDeletePageState"].ToString(); } return (strReturn); }}#endregion AppleiPhone.cs file: using System;using System.Collections.Generic;using System.Linq;using System.Web; /// <summary>/// Summary description for AppleIPhone/// </summary>public class AppleIPhone{ public AppleIPhone() { // // TODO: Add constructor logic here // } static public bool IsIPhoneOS() { return (IsIPad() || IsIPhone() || IsIPodTouch()); } static public bool IsIPhone() { return IsTest("iPhone"); } static public bool IsIPodTouch() { return IsTest("iPod"); } static public bool IsIPad() { return IsTest("iPad"); } static private bool IsTest(string Agent) { bool bl = false; string ua = HttpContext.Current.Request.UserAgent.ToLower(); try { bl = ua.Contains(Agent.ToLower()); } catch { } return (bl); }} Master page .cs: using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls; public partial class MasterPages_iPhoneMaster : System.Web.UI.MasterPage{ protected void Page_Load(object sender, EventArgs e) { HtmlHead head = Page.Header; HtmlMeta meta = new HtmlMeta(); if (AppleIPhone.IsIPad() == true) { meta.Content = "width=400,user-scalable=no"; head.Controls.Add(meta); } else { meta.Content = "width=device-width, user-scalable=no"; meta.Attributes.Add("name", "viewport"); } meta.Attributes.Add("name", "viewport"); head.Controls.Add(meta); HtmlLink cssLink = new HtmlLink(); HtmlGenericControl script = new HtmlGenericControl("script"); script.Attributes.Add("type", "text/javascript"); script.Attributes.Add("src", ResolveUrl("~/Scripts/iWebKit/javascript/functions.js")); head.Controls.Add(script); cssLink.Attributes.Add("rel", "stylesheet"); cssLink.Attributes.Add("href", ResolveUrl("~/Scripts/iWebKit/css/style.css") ); cssLink.Attributes.Add("type", "text/css"); head.Controls.Add(cssLink); HtmlGenericControl jsLink = new HtmlGenericControl("script"); //jsLink.Attributes.Add("type", "text/javascript"); //jsLink.Attributes.Add("src", ResolveUrl("~/Scripts/jquery-1.4.1.min.js") ); //head.Controls.Add(jsLink); HtmlLink appleIcon = new HtmlLink(); appleIcon.Attributes.Add("rel", "apple-touch-icon"); appleIcon.Attributes.Add("href", ResolveUrl("~/apple-touch-icon.png")); HtmlMeta appleMobileWebAppStatusBarStyle = new HtmlMeta(); appleMobileWebAppStatusBarStyle.Attributes.Add("name", "apple-mobile-web-app-status-bar-style"); appleMobileWebAppStatusBarStyle.Attributes.Add("content", "black"); head.Controls.Add(appleMobileWebAppStatusBarStyle); } internal string FindPath(string Location) { string Url = Server.MapPath(Location); return (Url); }}

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Kaiden and the Arachnoid Cyst

- by Martin Hinshelwood

Some of you may remember when my son Kaiden was born I posted pictures of him and his sister. Kaiden is now 15 months old and is progressing perfectly in every area except that and we had been worried that he was not walking yet. We were only really concerned as his sister was walking at 8 months. Figure: Kai as his usual self Jadie and I were concerned over that and that he had a rather large head (noggin) so we talked to various GP’s and our health visitor who immediately dismissed our concerns every time. That was until about two months ago when we happened to get a GP whose daughter had Hyper Mobility and she recognised the symptoms immediately. We were referred to the Southbank clinic who were lovely and the paediatrician confirmed that he had Hyper Mobility after testing all of his faculties. This just means that his joints are overly mobile and would need a little physiotherapy to help him out. At the end the paediatrician remarked offhand that he has a rather large head and wanted to measure it. Sure enough he was a good margin above the highest percentile mark for his height and weight. The paediatrician showed the measurements to a paediatric consultant who, as a precautionary measure, referred us for an MRI at Yorkhill Children's hospital. Now, Yorkhill has always been fantastic to us, and this was no exception. You know we have NEVER had a correct diagnosis for the kids (with the exception of the above) from a GP and indeed twice have been proscribed incorrect medication that made the kids sicker! We now always go strait to Yorkhill to save them having to fix GP mistakes as well. Monday 24th May, 7pm The scan went fantastically, with Kaiden sleeping in the MRI machine for all but 5 minutes at the end where he waited patiently for it to finish. We were not expecting anything to be wrong as this was just a precautionary scan to make sure that nothing in his head was affecting his gross motor skills. After the scan we were told to expect a call towards the end of the week… Tuesday 25th May, 12pm The very next day we got a call from Southbank who said that they has found an Arachnoid Cyst and could we come in the next day to see a Consultant and that Kai would need an operation. Wednesday 26th May, 12:30pm We went into the Southbank clinic and spoke to the paediatric consultant who assured us that it was operable but that it was taking up considerable space in Kai’s head. Cerebrospinal fluid is building up as a cyst is blocking the channels it uses to drain. Thankfully they told us that prospects were good and that Kai would expect to make a full recovery before showing us the MRI pictures. Figure: Normal brain MRI cross section. This normal scan shows the spaces in the middle of the brain that contain and produce the Cerebrospinal fluid. Figure: Normal Cerebrospinal Flow This fluid is needed by the brain but is drained in the middle down the spinal column. Figure: Kai’s cyst blocking the four channels. I do not think that I need to explain the difference between the healthy picture and Kai’s picture. However you can see in this first picture the faint outline of the cyst in the middle that is blocking the four channels from draining. After seeing the scans a Neurosurgeon has decided that he is not acute, but needs an operation to unblock the flow. Figure: OMFG! You can see in the second picture the effect of the build up of fluid. If I was not horrified by the first picture I was seriously horrified by this one. What next? Kai is not presenting the symptoms of vomiting or listlessness that would show an immediate problem and as such we will get an appointment to see the Paediatric Neurosurgeon at the Southern General hospital in about 4 weeks. This timescale is based on the Neurosurgeon seeing the scans. After that Kai will need an operation to release the pressure and either remove the cyst completely or put in a permanent shunt (tube from brain to stomach) to bypass the blockage. We have updated his notes for the referral with additional recent information on top of the scan that the consultant things will help improve the timescales, but that is just a guess. All we can do now is wait and see, and be watchful for tell tail signs of listlessness, eye problems and vomiting that would signify a worsening of his condition. Technorati Tags: Personal

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Inside the Concurrent Collections: ConcurrentBag

- by Simon Cooper

Unlike the other concurrent collections, ConcurrentBag does not really have a non-concurrent analogy. As stated in the MSDN documentation, ConcurrentBag is optimised for the situation where the same thread is both producing and consuming items from the collection. We'll see how this is the case as we take a closer look. Again, I recommend you have ConcurrentBag open in a decompiler for reference. Thread Statics ConcurrentBag makes heavy use of thread statics - static variables marked with ThreadStaticAttribute. This is a special attribute that instructs the CLR to scope any values assigned to or read from the variable to the executing thread, not globally within the AppDomain. This means that if two different threads assign two different values to the same thread static variable, one value will not overwrite the other, and each thread will see the value they assigned to the variable, separately to any other thread. This is a very useful function that allows for ConcurrentBag's concurrency properties. You can think of a thread static variable: [ThreadStatic] private static int m_Value; as doing the same as: private static Dictionary<Thread, int> m_Values; where the executing thread's identity is used to automatically set and retrieve the corresponding value in the dictionary. In .NET 4, this usage of ThreadStaticAttribute is encapsulated in the ThreadLocal class. Lists of lists ConcurrentBag, at its core, operates as a linked list of linked lists: Each outer list node is an instance of ThreadLocalList, and each inner list node is an instance of Node. Each outer ThreadLocalList is owned by a particular thread, accessible through the thread local m_locals variable: private ThreadLocal<ThreadLocalList<T>> m_locals It is important to note that, although the m_locals variable is thread-local, that only applies to accesses through that variable. The objects referenced by the thread (each instance of the ThreadLocalList object) are normal heap objects that are not specific to any thread. Thinking back to the Dictionary analogy above, if each value stored in the dictionary could be accessed by other means, then any thread could access the value belonging to other threads using that mechanism. Only reads and writes to the variable defined as thread-local are re-routed by the CLR according to the executing thread's identity. So, although m_locals is defined as thread-local, the m_headList, m_nextList and m_tailList variables aren't. This means that any thread can access all the thread local lists in the collection by doing a linear search through the outer linked list defined by these variables. Adding items So, onto the collection operations. First, adding items. This one's pretty simple. If the current thread doesn't already own an instance of ThreadLocalList, then one is created (or, if there are lists owned by threads that have stopped, it takes control of one of those). Then the item is added to the head of that thread's list. That's it. Don't worry, it'll get more complicated when we account for the other operations on the list! Taking & Peeking items This is where it gets tricky. If the current thread's list has items in it, then it peeks or removes the head item (not the tail item) from the local list and returns that. However, if the local list is empty, it has to go and steal another item from another list, belonging to a different thread. It iterates through all the thread local lists in the collection using the m_headList and m_nextList variables until it finds one that has items in it, and it steals one item from that list. Up to this point, the two threads had been operating completely independently. To steal an item from another thread's list, the stealing thread has to do it in such a way as to not step on the owning thread's toes. Recall how adding and removing items both operate on the head of the thread's linked list? That gives us an easy way out - a thread trying to steal items from another thread can pop in round the back of another thread's list using the m_tail variable, and steal an item from the back without the owning thread knowing anything about it. The owning thread can carry on completely independently, unaware that one of its items has been nicked. However, this only works when there are at least 3 items in the list, as that guarantees there will be at least one node between the owning thread performing operations on the list head and the thread stealing items from the tail - there's no chance of the two threads operating on the same node at the same time and causing a race condition. If there's less than three items in the list, then there does need to be some synchronization between the two threads. In this case, the lock on the ThreadLocalList object is used to mediate access to a thread's list when there's the possibility of contention. Thread synchronization In ConcurrentBag, this is done using several mechanisms: Operations performed by the owner thread only take out the lock when there are less than three items in the collection. With three or greater items, there won't be any conflict with a stealing thread operating on the tail of the list. If a lock isn't taken out, the owning thread sets the list's m_currentOp variable to a non-zero value for the duration of the operation. This indicates to all other threads that there is a non-locked operation currently occuring on that list. The stealing thread always takes out the lock, to prevent two threads trying to steal from the same list at the same time. After taking out the lock, the stealing thread spinwaits until m_currentOp has been set to zero before actually performing the steal. This ensures there won't be a conflict with the owning thread when the number of items in the list is on the 2-3 item borderline. If any add or remove operations are started in the meantime, and the list is below 3 items, those operations try to take out the list's lock and are blocked until the stealing thread has finished. This allows a thread to steal an item from another thread's list without corrupting it. What about synchronization in the collection as a whole? Collection synchronization Any thread that operates on the collection's global structure (accessing anything outside the thread local lists) has to take out the collection's global lock - m_globalListsLock. This single lock is sufficient when adding a new thread local list, as the items inside each thread's list are unaffected. However, what about operations (such as Count or ToArray) that need to access every item in the collection? In order to ensure a consistent view, all operations on the collection are stopped while the count or ToArray is performed. This is done by freezing the bag at the start, performing the global operation, and unfreezing at the end: The global lock is taken out, to prevent structural alterations to the collection. m_needSync is set to true. This notifies all the threads that they need to take out their list's lock irregardless of what operation they're doing. All the list locks are taken out in order. This blocks all locking operations on the lists. The freezing thread waits for all current lockless operations to finish by spinwaiting on each m_currentOp field. The global operation can then be performed while the bag is frozen, but no other operations can take place at the same time, as all other threads are blocked on a list's lock. Then, once the global operation has finished, the locks are released, m_needSync is unset, and normal concurrent operation resumes. Concurrent principles That's the essence of how ConcurrentBag operates. Each thread operates independently on its own local list, except when they have to steal items from another list. When stealing, only the stealing thread is forced to take out the lock; the owning thread only has to when there is the possibility of contention. And a global lock controls accesses to the structure of the collection outside the thread lists. Operations affecting the entire collection take out all locks in the collection to freeze the contents at a single point in time. So, what principles can we extract here? Threads operate independently Thread-static variables and ThreadLocal makes this easy. Threads operate entirely concurrently on their own structures; only when they need to grab data from another thread is there any thread contention. Minimised lock-taking Even when two threads need to operate on the same data structures (one thread stealing from another), they do so in such a way such that the probability of actually blocking on a lock is minimised; the owning thread always operates on the head of the list, and the stealing thread always operates on the tail. Management of lockless operations Any operations that don't take out a lock still have a 'hook' to force them to lock when necessary. This allows all operations on the collection to be stopped temporarily while a global snapshot is taken. Hopefully, such operations will be short-lived and infrequent. That's all the concurrent collections covered. I hope you've found it as informative and interesting as I have. Next, I'll be taking a closer look at ThreadLocal, which I came across while analyzing ConcurrentBag. As you'll see, the operation of this class deserves a much closer look.

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Security Issues with Single Page Apps

- by Stephen.Walther

Last week, I was asked to do a code review of a Single Page App built using the ASP.NET Web API, Durandal, and Knockout (good stuff!). In particular, I was asked to investigate whether there any special security issues associated with building a Single Page App which are not present in the case of a traditional server-side ASP.NET application. In this blog entry, I discuss two areas in which you need to exercise extra caution when building a Single Page App. I discuss how Single Page Apps are extra vulnerable to both Cross-Site Scripting (XSS) attacks and Cross-Site Request Forgery (CSRF) attacks. This goal of this blog post is NOT to persuade you to avoid writing Single Page Apps. I’m a big fan of Single Page Apps. Instead, the goal is to ensure that you are fully aware of some of the security issues related to Single Page Apps and ensure that you know how to guard against them. Cross-Site Scripting (XSS) Attacks According to WhiteHat Security, over 65% of public websites are open to XSS attacks. That’s bad. By taking advantage of XSS holes in a website, a hacker can steal your credit cards, passwords, or bank account information. Any website that redisplays untrusted information is open to XSS attacks. Let me give you a simple example. Imagine that you want to display the name of the current user on a page. To do this, you create the following server-side ASP.NET page located at http://MajorBank.com/SomePage.aspx: <%@Page Language="C#" %> <html> <head> <title>Some Page</title> </head> <body> Welcome <%= Request["username"] %> </body> </html> Nothing fancy here. Notice that the page displays the current username by using Request[“username”]. Using Request[“username”] displays the username regardless of whether the username is present in a cookie, a form field, or a query string variable. Unfortunately, by using Request[“username”] to redisplay untrusted information, you have now opened your website to XSS attacks. Here’s how. Imagine that an evil hacker creates the following link on another website (hackers.com): <a href="/SomePage.aspx?username=<script src=Evil.js></script>">Visit MajorBank</a> Notice that the link includes a query string variable named username and the value of the username variable is an HTML <SCRIPT> tag which points to a JavaScript file named Evil.js. When anyone clicks on the link, the <SCRIPT> tag will be injected into SomePage.aspx and the Evil.js script will be loaded and executed. What can a hacker do in the Evil.js script? Anything the hacker wants. For example, the hacker could display a popup dialog on the MajorBank.com site which asks the user to enter their password. The script could then post the password back to hackers.com and now the evil hacker has your secret password. ASP.NET Web Forms and ASP.NET MVC have two automatic safeguards against this type of attack: Request Validation and Automatic HTML Encoding. Protecting Coming In (Request Validation) In a server-side ASP.NET app, you are protected against the XSS attack described above by a feature named Request Validation. If you attempt to submit “potentially dangerous” content — such as a JavaScript <SCRIPT> tag — in a form field or query string variable then you get an exception. Unfortunately, Request Validation only applies to server-side apps. Request Validation does not help in the case of a Single Page App. In particular, the ASP.NET Web API does not pay attention to Request Validation. You can post any content you want – including <SCRIPT> tags – to an ASP.NET Web API action. For example, the following HTML page contains a form. When you submit the form, the form data is submitted to an ASP.NET Web API controller on the server using an Ajax request: <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title></title> </head> <body> <form data-bind="submit:submit"> <div> <label> User Name: <input data-bind="value:user.userName" /> </label> </div> <div> <label> Email: <input data-bind="value:user.email" /> </label> </div> <div> <input type="submit" value="Submit" /> </div> </form> <script src="Scripts/jquery-1.7.1.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { user: { userName: ko.observable(), email: ko.observable() }, submit: function () { $.post("/api/users", ko.toJS(this.user)); } }; ko.applyBindings(viewModel); </script> </body> </html> The form above is using Knockout to bind the form fields to a view model. When you submit the form, the view model is submitted to an ASP.NET Web API action on the server. Here’s the server-side ASP.NET Web API controller and model class: public class UsersController : ApiController { public HttpResponseMessage Post(UserViewModel user) { var userName = user.UserName; return Request.CreateResponse(HttpStatusCode.OK); } } public class UserViewModel { public string UserName { get; set; } public string Email { get; set; } } If you submit the HTML form, you don’t get an error. The “potentially dangerous” content is passed to the server without any exception being thrown. In the screenshot below, you can see that I was able to post a username form field with the value “<script>alert(‘boo’)</script”. So what this means is that you do not get automatic Request Validation in the case of a Single Page App. You need to be extra careful in a Single Page App about ensuring that you do not display untrusted content because you don’t have the Request Validation safety net which you have in a traditional server-side ASP.NET app. Protecting Going Out (Automatic HTML Encoding) Server-side ASP.NET also protects you from XSS attacks when you render content. By default, all content rendered by the razor view engine is HTML encoded. For example, the following razor view displays the text “<b>Hello!</b>” instead of the text “Hello!” in bold: @{ var message = "<b>Hello!</b>"; } @message If you don’t want to render content as HTML encoded in razor then you need to take the extra step of using the @Html.Raw() helper. In a Web Form page, if you use <%: %> instead of <%= %> then you get automatic HTML Encoding: <%@ Page Language="C#" %> <% var message = "<b>Hello!</b>"; %> <%: message %> This automatic HTML Encoding will prevent many types of XSS attacks. It prevents <script> tags from being rendered and only allows <script> tags to be rendered which are useless for executing JavaScript. (This automatic HTML encoding does not protect you from all forms of XSS attacks. For example, you can assign the value “javascript:alert(‘evil’)” to the Hyperlink control’s NavigateUrl property and execute the JavaScript). The situation with Knockout is more complicated. If you use the Knockout TEXT binding then you get HTML encoded content. On the other hand, if you use the HTML binding then you do not:  <div data-bind="text:someProp"></div>  <div data-bind="html:someProp"></div> <script src="Scripts/jquery-1.7.1.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { someProp : "<script>alert('Evil!')<" + "/script>" }; ko.applyBindings(viewModel); </script> So, in the page above, the DIV element which uses the TEXT binding is safe from XSS attacks. According to the Knockout documentation: “Since this binding sets your text value using a text node, it’s safe to set any string value without risking HTML or script injection.” Just like server-side HTML encoding, Knockout does not protect you from all types of XSS attacks. For example, there is nothing in Knockout which prevents you from binding JavaScript to a hyperlink like this: <a data-bind="attr:{href:homePageUrl}">Go</a> <script src="Scripts/jquery-1.7.1.min.js"></script> <script src="Scripts/knockout-2.1.0.js"></script> <script> var viewModel = { homePageUrl: "javascript:alert('evil!')" }; ko.applyBindings(viewModel); </script> In the page above, the value “javascript:alert(‘evil’)” is bound to the HREF attribute using Knockout. When you click the link, the JavaScript executes. Cross-Site Request Forgery (CSRF) Attacks Cross-Site Request Forgery (CSRF) attacks rely on the fact that a session cookie does not expire until you close your browser. In particular, if you visit and login to MajorBank.com and then you navigate to Hackers.com then you will still be authenticated against MajorBank.com even after you navigate to Hackers.com. Because MajorBank.com cannot tell whether a request is coming from MajorBank.com or Hackers.com, Hackers.com can submit requests to MajorBank.com pretending to be you. For example, Hackers.com can post an HTML form from Hackers.com to MajorBank.com and change your email address at MajorBank.com. Hackers.com can post a form to MajorBank.com using your authentication cookie. After your email address has been changed, by using a password reset page at MajorBank.com, a hacker can access your bank account. To prevent CSRF attacks, you need some mechanism for detecting whether a request is coming from a page loaded from your website or whether the request is coming from some other website. The recommended way of preventing Cross-Site Request Forgery attacks is to use the “Synchronizer Token Pattern” as described here: https://www.owasp.org/index.php/Cross-Site_Request_Forgery_%28CSRF%29_Prevention_Cheat_Sheet When using the Synchronizer Token Pattern, you include a hidden input field which contains a random token whenever you display an HTML form. When the user opens the form, you add a cookie to the user’s browser with the same random token. When the user posts the form, you verify that the hidden form token and the cookie token match. Preventing Cross-Site Request Forgery Attacks with ASP.NET MVC ASP.NET gives you a helper and an action filter which you can use to thwart Cross-Site Request Forgery attacks. For example, the following razor form for creating a product shows how you use the @Html.AntiForgeryToken() helper: @model MvcApplication2.Models.Product <h2>Create Product</h2> @using (Html.BeginForm()) { @Html.AntiForgeryToken(); <div> @Html.LabelFor( p => p.Name, "Product Name:") @Html.TextBoxFor( p => p.Name) </div> <div> @Html.LabelFor( p => p.Price, "Product Price:") @Html.TextBoxFor( p => p.Price) </div> <input type="submit" /> } The @Html.AntiForgeryToken() helper generates a random token and assigns a serialized version of the same random token to both a cookie and a hidden form field. (Actually, if you dive into the source code, the AntiForgeryToken() does something a little more complex because it takes advantage of a user’s identity when generating the token). Here’s what the hidden form field looks like: <input name=”__RequestVerificationToken” type=”hidden” value=”NqqZGAmlDHh6fPTNR_mti3nYGUDgpIkCiJHnEEL59S7FNToyyeSo7v4AfzF2i67Cv0qTB1TgmZcqiVtgdkW2NnXgEcBc-iBts0x6WAIShtM1″ /> And here’s what the cookie looks like using the Google Chrome developer toolbar: You use the [ValidateAntiForgeryToken] action filter on the controller action which is the recipient of the form post to validate that the token in the hidden form field matches the token in the cookie. If the tokens don’t match then validation fails and you can’t post the form: public ActionResult Create() { return View(); } [ValidateAntiForgeryToken] [HttpPost] public ActionResult Create(Product productToCreate) { if (ModelState.IsValid) { // save product to db return RedirectToAction("Index"); } return View(); } How does this all work? Let’s imagine that a hacker has copied the Create Product page from MajorBank.com to Hackers.com – the hacker grabs the HTML source and places it at Hackers.com. Now, imagine that the hacker trick you into submitting the Create Product form from Hackers.com to MajorBank.com. You’ll get the following exception: The Cross-Site Request Forgery attack is blocked because the anti-forgery token included in the Create Product form at Hackers.com won’t match the anti-forgery token stored in the cookie in your browser. The tokens were generated at different times for different users so the attack fails. Preventing Cross-Site Request Forgery Attacks with a Single Page App In a Single Page App, you can’t prevent Cross-Site Request Forgery attacks using the same method as a server-side ASP.NET MVC app. In a Single Page App, HTML forms are not generated on the server. Instead, in a Single Page App, forms are loaded dynamically in the browser. Phil Haack has a blog post on this topic where he discusses passing the anti-forgery token in an Ajax header instead of a hidden form field. He also describes how you can create a custom anti-forgery token attribute to compare the token in the Ajax header and the token in the cookie. See: http://haacked.com/archive/2011/10/10/preventing-csrf-with-ajax.aspx Also, take a look at Johan’s update to Phil Haack’s original post: http://johan.driessen.se/posts/Updated-Anti-XSRF-Validation-for-ASP.NET-MVC-4-RC (Other server frameworks such as Rails and Django do something similar. For example, Rails uses an X-CSRF-Token to prevent CSRF attacks which you generate on the server – see http://excid3.com/blog/rails-tip-2-include-csrf-token-with-every-ajax-request/#.UTFtgDDkvL8 ). For example, if you are creating a Durandal app, then you can use the following razor view for your one and only server-side page: @{ Layout = null; } <!DOCTYPE html> <html> <head> <title>Index</title> </head> <body> @Html.AntiForgeryToken() <div id="applicationHost"> Loading app.... </div> @Scripts.Render("~/scripts/vendor") <script type="text/javascript" src="~/App/durandal/amd/require.js" data-main="/App/main"></script> </body> </html> Notice that this page includes a call to @Html.AntiForgeryToken() to generate the anti-forgery token. Then, whenever you make an Ajax request in the Durandal app, you can retrieve the anti-forgery token from the razor view and pass the token as a header: var csrfToken = $("input[name='__RequestVerificationToken']").val(); $.ajax({ headers: { __RequestVerificationToken: csrfToken }, type: "POST", dataType: "json", contentType: 'application/json; charset=utf-8', url: "/api/products", data: JSON.stringify({ name: "Milk", price: 2.33 }), statusCode: { 200: function () { alert("Success!"); } } }); Use the following code to create an action filter which you can use to match the header and cookie tokens: using System.Linq; using System.Net.Http; using System.Web.Helpers; using System.Web.Http.Controllers; namespace MvcApplication2.Infrastructure { public class ValidateAjaxAntiForgeryToken : System.Web.Http.AuthorizeAttribute { protected override bool IsAuthorized(HttpActionContext actionContext) { var headerToken = actionContext .Request .Headers .GetValues("__RequestVerificationToken") .FirstOrDefault(); ; var cookieToken = actionContext .Request .Headers .GetCookies() .Select(c => c[AntiForgeryConfig.CookieName]) .FirstOrDefault(); // check for missing cookie or header if (cookieToken == null || headerToken == null) { return false; } // ensure that the cookie matches the header try { AntiForgery.Validate(cookieToken.Value, headerToken); } catch { return false; } return base.IsAuthorized(actionContext); } } } Notice that the action filter derives from the base AuthorizeAttribute. The ValidateAjaxAntiForgeryToken only works when the user is authenticated and it will not work for anonymous requests. Add the action filter to your ASP.NET Web API controller actions like this: [ValidateAjaxAntiForgeryToken] public HttpResponseMessage PostProduct(Product productToCreate) { // add product to db return Request.CreateResponse(HttpStatusCode.OK); } After you complete these steps, it won’t be possible for a hacker to pretend to be you at Hackers.com and submit a form to MajorBank.com. The header token used in the Ajax request won’t travel to Hackers.com. This approach works, but I am not entirely happy with it. The one thing that I don’t like about this approach is that it creates a hard dependency on using razor. Your single page in your Single Page App must be generated from a server-side razor view. A better solution would be to generate the anti-forgery token in JavaScript. Unfortunately, until all browsers support a way to generate cryptographically strong random numbers – for example, by supporting the window.crypto.getRandomValues() method — there is no good way to generate anti-forgery tokens in JavaScript. So, at least right now, the best solution for generating the tokens is the server-side solution with the (regrettable) dependency on razor. Conclusion The goal of this blog entry was to explore some ways in which you need to handle security differently in the case of a Single Page App than in the case of a traditional server app. In particular, I focused on how to prevent Cross-Site Scripting and Cross-Site Request Forgery attacks in the case of a Single Page App. I want to emphasize that I am not suggesting that Single Page Apps are inherently less secure than server-side apps. Whatever type of web application you build – regardless of whether it is a Single Page App, an ASP.NET MVC app, an ASP.NET Web Forms app, or a Rails app – you must constantly guard against security vulnerabilities.

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Simple ViewModel Locator for MVVM: The Patients Have Left the Asylum

Ive been toying with some ideas for MVVM lately. Along the way I have been dragging some friends like Glenn Block and Ward Bell along for the ride. Now, normally its not so bad, but when I get an idea in my head to challenge everything I can be interesting to work with :). These guys are great and I highly encourage you all to get your own personal Glenn and Ward bobble head dolls for your home. But back to MVVM Ive been exploring the world of View first again. The idea is simple: the View is created,...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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Simple ViewModel Locator for MVVM: The Patients Have Left the Asylum

Ive been toying with some ideas for MVVM lately. Along the way I have been dragging some friends like Glenn Block and Ward Bell along for the ride. Now, normally its not so bad, but when I get an idea in my head to challenge everything I can be interesting to work with :). These guys are great and I highly encourage you all to get your own personal Glenn and Ward bobble head dolls for your home. But back to MVVM Ive been exploring the world of View first again. The idea is simple: the View is created,...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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Windows Azure Use Case: High-Performance Computing (HPC)

- by BuckWoody

This is one in a series of posts on when and where to use a distributed architecture design in your organization's computing needs. You can find the main post here: http://blogs.msdn.com/b/buckwoody/archive/2011/01/18/windows-azure-and-sql-azure-use-cases.aspx Description: High-Performance Computing (also called Technical Computing) at its most simplistic is a layout of computer workloads where a “head node” accepts work requests, and parses them out to “worker nodes'”. This is useful in cases such as scientific simulations, drug research, MatLab work and where other large compute loads are required. It’s not the immediate-result type computing many are used to; instead, a “job” or group of work requests is sent to a cluster of computers and the worker nodes work on individual parts of the calculations and return the work to the scheduler or head node for the requestor in a batch-request fashion. This is typical to the way that many mainframe computing use-cases work. You can use commodity-based computers to create an HPC Cluster, such as the Linux application called Beowulf, and Microsoft has a server product for HPC using standard computers, called the Windows Compute Cluster that you can read more about here. The issue with HPC (from any vendor) that some organization have is the amount of compute nodes they need. Having too many results in excess infrastructure, including computers, buildings, storage, heat and so on. Having too few means that the work is slower, and takes longer to return a result to the calling application. Unless there is a consistent level of work requested, predicting the number of nodes is problematic. Implementation: Recently, Microsoft announced an internal partnership between the HPC group (Now called the Technical Computing Group) and Windows Azure. You now have two options for implementing an HPC environment using Windows. You can extend the current infrastructure you have for HPC by adding in Compute Nodes in Windows Azure, using a “Broker Node”. You can then purchase time for adding machines, and then stop paying for them when the work is completed. This is a common pattern in groups that have a constant need for HPC, but need to “burst” that load count under certain conditions. The second option is to install only a Head Node and a Broker Node onsite, and host all Compute Nodes in Windows Azure. This is often the pattern for organizations that need HPC on a scheduled and periodic basis, such as financial analysis or actuarial table calculations. References: Blog entry on Hybrid HPC with Windows Azure: http://blogs.msdn.com/b/ignitionshowcase/archive/2010/12/13/high-performance-computing-on-premise-and-in-the-windows-azure-cloud.aspx Links for further research on HPC, includes Windows Azure information: http://blogs.msdn.com/b/ncdevguy/archive/2011/02/16/handy-links-for-hpc-and-azure.aspx

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Computer: Tea. Earl Gray. Hot.

- by Randolpho St. John

I just bought an awesome geek mug and thought I'd share: You can get it too, if you head over to Cafe Press.

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Infinite detail inside Perlin noise procedural mapping

- by Dave Jellison

I am very new to game development but I was able to scour the internet to figure out Perlin noise enough to implement a very simple 2D tile infinite procedural world. Here's the question and it's more conceptual than code-based in answer, I think. I understand the concept of "I plug in (x, y) and get back from Perlin noise p" (I'll call it p). P will always be the same value for the same (x, y) (as long as the Perlin algorithm parameters haven't changed, like altering number of octaves, et cetera). What I want to do is be able to zoom into a square and be able to generate smaller squares inside of the already generated overhead tile of terrain. Let's say I have a jungle tile for overhead terrain but I want to zoom in and maybe see a small river tile that would only be a creek and not large enough to be a full "big tile" of water in the overhead. Of course, I want the same net effect as a Perlin equation inside a Perlin equation if that makes sense? (aka. I want two people playing the game with the same settings to get the same terrain and details every time). I can conceptually wrap my head around the large tile being based on an "zoomed out" coordinate leaving enough room to drill into but this approach doesn't make sense in my head (maybe I'm wrong). I'm guessing with this approach my overhead terrain would lose all of the cohesiveness delivered by the Perlin. Imagine I calculate (0, 0) as overhead tile 1 and then to the east of that I plug in (50, 0). OK, great, I now have 49 pixels of detail I could then "drill down" into. The issue I have in my head with this approach (without attempting it) is that there's no guarantee from my Perlin noise that (0,0) would be a good neighbor to (50,0) as they could have wildly different "elevations" or p/resultant values returning from the Perlin equation when I generate the overhead map. I think I can conceive of using the Perlin noise for the overhead tile to then reuse the p value as a seed for the "detail" level of noise once I zoom in. That would ensure my detail Perlin is always the same configuration for (0,0), (1,0), etc. ad nauseam but I'm not sure if there are better approaches out there or if this is a sound approach at all.

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How to deal with a boss who is extremely competitive [closed]

- by user72101

Okay, so I recently joined this group. My boss who I reported to, left a while ago and my colleague was made the team lead. We both now report to the same head, but she heads the team I work in. I am not sure on how to deal with various situations. I would imagine a team lead who motivates the rest of the team, and not someone who would take credit for what others do. I am the only one who works at the same geographic location. She is very smart, no doubt about it. Things get to me, for example I work on an issue and email a dev team, she would respond on top of my emails and as she is the lead, people respond to her rather than to me. If there is an email addressed with the head on it, she would get it to faster than I do, even when she knew I am looking into it. The rest of the team keeps asking me questions or help. I find it hard to say no, and I try to help them as i feel I might need their help someday as well. I slack in my own work or I could have used the time to learn things. I feel that she should be the go to person and not me. If one gets the benefits of being a lead, why not the work that goes with it? I feel I am stuck in a very unfortunate situation and am totally helpless about it. Everyday it is something or the other. I work on a project for months and finally when it is about to go live and there was a minor issue and the head started asking questions, she completely stole my thunder on a call. She would not let me speak and I have to actually cut her off to speak up. The ideal would be not to give it a thought and just do the best I can,but I feel I am capable of much more and not able to give my best because of this constant war at work. Neetu

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Convert ddply {plyr} to Oracle R Enterprise, or use with Embedded R Execution

- by Mark Hornick

The plyr package contains a set of tools for partitioning a problem into smaller sub-problems that can be more easily processed. One function within {plyr} is ddply, which allows you to specify subsets of a data.frame and then apply a function to each subset. The result is gathered into a single data.frame. Such a capability is very convenient. The function ddply also has a parallel option that if TRUE, will apply the function in parallel, using the backend provided by foreach. This type of functionality is available through Oracle R Enterprise using the ore.groupApply function. In this blog post, we show a few examples from Sean Anderson's "A quick introduction to plyr" to illustrate the correpsonding functionality using ore.groupApply. To get started, we'll create a demo data set and load the plyr package. set.seed(1) d <- data.frame(year = rep(2000:2014, each = 3), count = round(runif(45, 0, 20))) dim(d) library(plyr) This first example takes the data frame, partitions it by year, and calculates the coefficient of variation of the count, returning a data frame. # Example 1 res <- ddply(d, "year", function(x) { mean.count <- mean(x$count) sd.count <- sd(x$count) cv <- sd.count/mean.count data.frame(cv.count = cv) }) To illustrate the equivalent functionality in Oracle R Enterprise, using embedded R execution, we use the ore.groupApply function on the same data, but pushed to the database, creating an ore.frame. The function ore.push creates a temporary table in the database, returning a proxy object, the ore.frame. D <- ore.push(d) res <- ore.groupApply (D, D$year, function(x) { mean.count <- mean(x$count) sd.count <- sd(x$count) cv <- sd.count/mean.count data.frame(year=x$year[1], cv.count = cv) }, FUN.VALUE=data.frame(year=1, cv.count=1)) You'll notice the similarities in the first three arguments. With ore.groupApply, we augment the function to return the specific data.frame we want. We also specify the argument FUN.VALUE, which describes the resulting data.frame. From our previous blog posts, you may recall that by default, ore.groupApply returns an ore.list containing the results of each function invocation. To get a data.frame, we specify the structure of the result. The results in both cases are the same, however the ore.groupApply result is an ore.frame. In this case the data stays in the database until it's actually required. This can result in significant memory and time savings whe data is large. R> class(res) [1] "ore.frame" attr(,"package") [1] "OREbase" R> head(res) year cv.count 1 2000 0.3984848 2 2001 0.6062178 3 2002 0.2309401 4 2003 0.5773503 5 2004 0.3069680 6 2005 0.3431743 To make the ore.groupApply execute in parallel, you can specify the argument parallel with either TRUE, to use default database parallelism, or to a specific number, which serves as a hint to the database as to how many parallel R engines should be used. The next ddply example uses the summarise function, which creates a new data.frame. In ore.groupApply, the year column is passed in with the data. Since no automatic creation of columns takes place, we explicitly set the year column in the data.frame result to the value of the first row, since all rows received by the function have the same year. # Example 2 ddply(d, "year", summarise, mean.count = mean(count)) res <- ore.groupApply (D, D$year, function(x) { mean.count <- mean(x$count) data.frame(year=x$year[1], mean.count = mean.count) }, FUN.VALUE=data.frame(year=1, mean.count=1)) R> head(res) year mean.count 1 2000 7.666667 2 2001 13.333333 3 2002 15.000000 4 2003 3.000000 5 2004 12.333333 6 2005 14.666667 Example 3 uses the transform function with ddply, which modifies the existing data.frame. With ore.groupApply, we again construct the data.frame explicilty, which is returned as an ore.frame. # Example 3 ddply(d, "year", transform, total.count = sum(count)) res <- ore.groupApply (D, D$year, function(x) { total.count <- sum(x$count) data.frame(year=x$year[1], count=x$count, total.count = total.count) }, FUN.VALUE=data.frame(year=1, count=1, total.count=1)) > head(res) year count total.count 1 2000 5 23 2 2000 7 23 3 2000 11 23 4 2001 18 40 5 2001 4 40 6 2001 18 40 In Example 4, the mutate function with ddply enables you to define new columns that build on columns just defined. Since the construction of the data.frame using ore.groupApply is explicit, you always have complete control over when and how to use columns. # Example 4 ddply(d, "year", mutate, mu = mean(count), sigma = sd(count), cv = sigma/mu) res <- ore.groupApply (D, D$year, function(x) { mu <- mean(x$count) sigma <- sd(x$count) cv <- sigma/mu data.frame(year=x$year[1], count=x$count, mu=mu, sigma=sigma, cv=cv) }, FUN.VALUE=data.frame(year=1, count=1, mu=1,sigma=1,cv=1)) R> head(res) year count mu sigma cv 1 2000 5 7.666667 3.055050 0.3984848 2 2000 7 7.666667 3.055050 0.3984848 3 2000 11 7.666667 3.055050 0.3984848 4 2001 18 13.333333 8.082904 0.6062178 5 2001 4 13.333333 8.082904 0.6062178 6 2001 18 13.333333 8.082904 0.6062178 In Example 5, ddply is used to partition data on multiple columns before constructing the result. Realizing this with ore.groupApply involves creating an index column out of the concatenation of the columns used for partitioning. This example also allows us to illustrate using the ORE transparency layer to subset the data. # Example 5 baseball.dat <- subset(baseball, year > 2000) # data from the plyr package x <- ddply(baseball.dat, c("year", "team"), summarize, homeruns = sum(hr)) We first push the data set to the database to get an ore.frame. We then add the composite column and perform the subset, using the transparency layer. Since the results from database execution are unordered, we will explicitly sort these results and view the first 6 rows. BB.DAT <- ore.push(baseball) BB.DAT$index <- with(BB.DAT, paste(year, team, sep="+")) BB.DAT2 <- subset(BB.DAT, year > 2000) X <- ore.groupApply (BB.DAT2, BB.DAT2$index, function(x) { data.frame(year=x$year[1], team=x$team[1], homeruns=sum(x$hr)) }, FUN.VALUE=data.frame(year=1, team="A", homeruns=1), parallel=FALSE) res <- ore.sort(X, by=c("year","team")) R> head(res) year team homeruns 1 2001 ANA 4 2 2001 ARI 155 3 2001 ATL 63 4 2001 BAL 58 5 2001 BOS 77 6 2001 CHA 63 Our next example is derived from the ggplot function documentation. This illustrates the use of ddply within using the ggplot2 package. We first create a data.frame with demo data and use ddply to create some statistics for each group (gp). We then use ggplot to produce the graph. We can take this same code, push the data.frame df to the database and invoke this on the database server. The graph will be returned to the client window, as depicted below. # Example 6 with ggplot2 library(ggplot2) df <- data.frame(gp = factor(rep(letters[1:3], each = 10)), y = rnorm(30)) # Compute sample mean and standard deviation in each group library(plyr) ds <- ddply(df, .(gp), summarise, mean = mean(y), sd = sd(y)) # Set up a skeleton ggplot object and add layers: ggplot() + geom_point(data = df, aes(x = gp, y = y)) + geom_point(data = ds, aes(x = gp, y = mean), colour = 'red', size = 3) + geom_errorbar(data = ds, aes(x = gp, y = mean, ymin = mean - sd, ymax = mean + sd), colour = 'red', width = 0.4) DF <- ore.push(df) ore.tableApply(DF, function(df) { library(ggplot2) library(plyr) ds <- ddply(df, .(gp), summarise, mean = mean(y), sd = sd(y)) ggplot() + geom_point(data = df, aes(x = gp, y = y)) + geom_point(data = ds, aes(x = gp, y = mean), colour = 'red', size = 3) + geom_errorbar(data = ds, aes(x = gp, y = mean, ymin = mean - sd, ymax = mean + sd), colour = 'red', width = 0.4) }) But let's take this one step further. Suppose we wanted to produce multiple graphs, partitioned on some index column. We replicate the data three times and add some noise to the y values, just to make the graphs a little different. We also create an index column to form our three partitions. Note that we've also specified that this should be executed in parallel, allowing Oracle Database to control and manage the server-side R engines. The result of ore.groupApply is an ore.list that contains the three graphs. Each graph can be viewed by printing the list element. df2 <- rbind(df,df,df) df2$y <- df2$y + rnorm(nrow(df2)) df2$index <- c(rep(1,300), rep(2,300), rep(3,300)) DF2 <- ore.push(df2) res <- ore.groupApply(DF2, DF2$index, function(df) { df <- df[,1:2] library(ggplot2) library(plyr) ds <- ddply(df, .(gp), summarise, mean = mean(y), sd = sd(y)) ggplot() + geom_point(data = df, aes(x = gp, y = y)) + geom_point(data = ds, aes(x = gp, y = mean), colour = 'red', size = 3) + geom_errorbar(data = ds, aes(x = gp, y = mean, ymin = mean - sd, ymax = mean + sd), colour = 'red', width = 0.4) }, parallel=TRUE) res[[1]] res[[2]] res[[3]] To recap, we've illustrated how various uses of ddply from the plyr package can be realized in ore.groupApply, which affords the user explicit control over the contents of the data.frame result in a straightforward manner. We've also highlighted how ddply can be used within an ore.groupApply call.

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HTML favicon wont show on google chrome

- by Nick

I am making a HTML page that is unpublished and that I just started. The first thing I wanted to do was add a favicon to appear next to the tile. I'm using google chrome an I noticed that other websites have favicons that appear next to the tile in the browser, but mine wont show up. I'm new to favicons. the site in in a folder on my desktop named site. This is the code: <!DOCTYPE html> <html> <head> <title></title> <link rel="shortcut icon" href="favicon.ico" /> </head> <body> </body> </html>

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Why has C prevailed over Pascal?

- by Konrad Morawski

My understanding is that in the 1980s and perhaps in the 1990s, too - Pascal and C were pretty much head-to-head as production languages. Is the ultimate demise of Pascal only due to Borland's neglection of Delphi? Or was there more of such bad luck; or perhaps something inherently wrong with Pascal (any hopes for its revival?). I hope it's not an open, unanswerable question. I'm interested in historical facts and observations one can back up, rather than likes and dislikes. I also failed to find a duplicate question, which actually surprised me somewhat.

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Make Firefox Show Google Results for Default Address Bar Searches

- by The Geek

Have you ever typed something incorrectly into the Firefox address bar, and then had it take you to a page you weren’t expecting? The reason is because Firefox uses Google’s “I’m Feeling Lucky” search, but you can change it. Scratching your head? Let’s take a quick run through what we’re talking about… Normally, if you typed in something like just “howtogeek” in the address bar, and then hit enter… you’ll be taken directly to the How-To Geek site. But how? Very simple! It’s the same place you would have been taken to if you typed “howtogeek” into Google, and then clicked the “I’m Feeling Lucky” button, which takes you to the first result. This is what Firefox does behind the scenes when you put something into the address bar that isn’t a URL. But what if you’d rather head to the search results page instead? Luckily, all you have to do is tweak an about:config parameter in Firefox. Just head into about:config in the address bar, and then filter for keyword.url like so: Double-click on the entry in the list, and then delete the &gfns=1 from the value. That’s the part of the URL that triggers Google to redirect to the first result. And now, the next time you type something into the address bar, either on purpose or because you typo’d it, you’ll be taken to the results page instead: About:Config tweaking is lots of fun. Similar Articles Productive Geek Tips Make Firefox Quick Search Use Google’s Beta Search KeysMake Firefox Built-In Search Box Use Google’s Experimental Search KeysCombine Wolfram Alpha & Google Search Results in FirefoxHow To Run 4 Different Google Searches at Once In the Same TabChange Default Feed Reader in Firefox 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 DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Looking for Good Windows Media Player 12 Plug-ins? Find Out the Celebrity You Resemble With FaceDouble Whoa ! Use Printflush to Solve Printing Problems Icelandic Volcano Webcams Open Multiple Links At One Go

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How To Disable Individual Plug-ins in Google Chrome

- by The Geek

Have you ever wondered how to disable useless or insecure browser plug-ins in Google Chrome? Here’s the lowdown on how to get rid of Java, Acrobat, Silverlight, and the rest of the plugins you probably want to get rid of. Disabling Plugins in Google Chrome If you head to about:plugins in your address bar, you’ll probably see a list of plugins, but won’t be able to disable them yet. What you’ll need to do is switch over to the Dev channel of Chrome, which gives you access to all the latest features—though you might be warned that sometimes the dev channel might be less stable than the release or beta channels. Ready to proceed? Head to the Dev Channel page, and then click the link to run the installer. You’ll be prompted to restart Chrome when you’re done. Note that Mac and Windows users can both run an installer to switch. Linux users will have to install a package. Note: Once you’ve switched to the Dev channel, you can’t really switch to the stable channel. You’ll have to uninstall Chrome and then reinstall the regular version. Now that you’ve switched to the dev channel and restarted your browser, head to about:plugins in the address bar, and then just disable each plugin you really don’t need. Plugins you can generally live without? Java, Acrobat, Microsoft Office, Windows Presentation Foundation, Silverlight. These will be on a case-by-case basis, of course, but the vast majority of large websites don’t require any of those. When it comes right down to it, the only plugin that most people require is Flash… and leave the “Default Plug-in” alone too. Special thanks to @jordanconway for pointing out the solution. Similar Articles Productive Geek Tips Disable YouTube Comments while using ChromeHow to Make Google Chrome Your Default BrowserSubscribe to RSS Feeds in Chrome with a Single ClickAdd Notes to Google Notebook from ChromeAccess Google Chrome’s Special Pages the Easy Way 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 DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Office 2010 Product Guides Google Maps Place marks – Pizza, Guns or Strip Clubs Monitor Applications With Kiwi LocPDF is a Visual PDF Search Tool Download Free iPad Wallpapers at iPad Decor Get Your Delicious Bookmarks In Firefox’s Awesome Bar

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Random number generation algorithm for human brains?

- by Magnus Wolffelt

Are you aware of, or have you devised, any practical, simple-to-learn "in-head" algorithms that let humans generate (somewhat "true") random numbers? By "in-head" I mean.. preferrably without any external tools or devices. Also, a high output (many random numbers per minute) is desirable. Asked this on SO but it didn't get much interest. Maybe this is better suited for programmers.. :) I'm genuinely curious about anything that people might have come up with on this problem.

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