You have to add `xsl` namespace to `XmlNamespaceManager`:

    var document = new XmlDocument();
    document.Load(...);
    var nsmgr = new XmlNamespaceManager(document.NameTable);
    nsmgr.AddNamespace(&quot;xsl&quot;, &quot;http://www.w3.org/1999/XSL/Transform&quot;);

    var nl = document.SelectNodes(&quot;//xsl:import/@href&quot;, nsmgr);

The document can be traversed by `GetElementsByTagName` and it doesn&#39;t necessarily need using `XmlNamespaceManager`:

    var nodes = document.GetElementsByTagName(&quot;xsl:import&quot;);
    var href =  nodes[0].Attributes[&quot;href&quot;];

[Fiddle][1]


  [1]: https://dotnetfiddle.net/AqQ9So

```
var document = new XmlDocument();
document.LoadXml(rawData);

var nsmgr = new XmlNamespaceManager(document.NameTable);
nsmgr.AddNamespace(&quot;cbc&quot;, &quot;urn:xxx&quot;); //for example
nsmgr.AddNamespace(&quot;cac&quot;, &quot;urn:yyy&quot;);            

XmlElement xmlElem = document.DocumentElement;
var node = xmlElem.SelectSingleNode(&quot;cac:AccountingSupplierParty/cac:Party/cac:PartyIdentification/cbc:ID[@schemeID=&#39;VKN&#39;]/text()&quot;, nsmgr);
var nodeText = node.InnerText;
```

[![enter image description here][1]][1]


  [1]: https://i.stack.imgur.com/dP8El.png


All namespaces that will be used in XML should be added.  
Then you can access the values of the relevant nodes using `xpath`.


I am using Flask and MongoDB. I am trying to convert the content of request.form into something suitable for saving via PyMongo. It seems like something that should come up often enough to have a ready-made solution.

So what Flask give me is something like:

    ImmutableMultiDict([(&#39;default&#39;, u&#39;&#39;), (&#39;required&#39;: u&#39;on&#39;), (&#39;name&#39;, u&#39;short_text&#39;), (&#39;name&#39;, u&#39;another&#39;), (&#39;submit&#39;, u&#39;Submit&#39;)])

And what I am looking to get is something close to this:

    {
      &#39;default&#39;: &#39;&#39;,
      &#39;name&#39;: [&#39;short_text&#39;, &#39;another&#39;],
      &#39;required&#39;: true
    }


In Flask convert form POST object into a representation suitable for mongodb

When selecting from multiple tables in MySQL, both of the following queries return the same result set.

Is one of these queries _better_ or more efficient than the other? From my testing on a small dataset (~2k rows in each table) they both return the same result set in around the same execution time.

**Query 1:**

    SELECT
        *
    FROM
        products,
        product_meta,
        sales_rights
    WHERE 
        (
            products.id = product_meta.product_id
            AND products.id = sales_rights.product_id
        )
        AND (...)
    LIMIT 0,10;
&lt;br /&gt;
**Query 2:**

    SELECT
        *
    FROM
        products
    INNER JOIN product_meta ON products.id = product_meta.product_id
    JOIN sales_rights ON product_meta.product_id = sales_rights.product_id 
    WHERE
        (...)
    LIMIT 0,10;


Multiple Table Select vs. JOIN (performance)

I am trying to call `SelectNode` from `XmlDocument` class and trouble due to this error:

&gt; Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function.

My code:

       public void Add(ref XmlDocument xmlFormat, String strName)
       {
            XmlDocument dom;
            XSLTemplate xsl = null;
            String strPath = &quot;&quot;;
            XmlNodeList nl;
            XmlAttribute na;
            int n;
    
            nl = (XmlNodeList)xmlFormat.SelectNodes(&quot;//xsl:import/@href&quot;,nsm);
        }

and xsl:

    &lt;xsl:stylesheet version=&quot;1.0&quot; xmlns:xsl=&quot;http://www.w3.org/1999/XSL/Transform&quot;&gt;
    	&lt;xsl:import href=&quot;stylesheets/r_adresetiket.xsl&quot; /&gt;
    	&lt;xsl:template match=&quot;/&quot;&gt;
    		&lt;xsl:call-template name=&quot;retouradres&quot;&gt;
    			&lt;xsl:with-param name=&quot;_retouradres&quot; select=&quot;data/adresetiket/_retouradres&quot; /&gt;
    			&lt;xsl:with-param name=&quot;minofdir&quot; select=&quot;data/adresetiket/afzendgegevens/afzendgegevens&quot; /&gt;
    			&lt;xsl:with-param name=&quot;checked&quot; select=&quot;data/adresetiket/LB&quot; /&gt;
    		&lt;/xsl:call-template&gt;
    	&lt;/xsl:template&gt;
    &lt;/xsl:stylesheet&gt;





Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function

I am trying to call <code>SelectNode</code> from <code>XmlDocument</code> class and trouble due to this error:
> Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function.
My code:
<pre><code class="hljs language-ini"> public void Add(ref XmlDocument xmlFormat, String strName)
 {
 XmlDocument dom;
 XSLTemplate xsl = null;
 String strPath = "";
 XmlNodeList nl;
 XmlAttribute na;
 int n;

 nl = (XmlNodeList)xmlFormat.SelectNodes("//xsl:import/@href",nsm);
 }
</code></pre>
and xsl:
<pre><code class="hljs language-ini">&#x3C;xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
	&#x3C;xsl:import href="stylesheets/r_adresetiket.xsl" />
	&#x3C;xsl:template match="/">
		&#x3C;xsl:call-template name="retouradres">
			&#x3C;xsl:with-param name="_retouradres" select="data/adresetiket/_retouradres" />
			&#x3C;xsl:with-param name="minofdir" select="data/adresetiket/afzendgegevens/afzendgegevens" />
			&#x3C;xsl:with-param name="checked" select="data/adresetiket/LB" />
		&#x3C;/xsl:call-template>
	&#x3C;/xsl:template>
&#x3C;/xsl:stylesheet>
</code></pre>

&gt; **Possible Duplicate:**  
&gt; [Set timeout to an operation](https://stackoverflow.com/questions/2265412/set-timeout-to-an-operation)  

&lt;!-- End of automatically inserted text --&gt;

How can i set timeout for a line of code in c#.
For example
`RunThisLine(SomeMethod(Some Input), TimeSpan.FromSeconds(10))`
run `SomeMethod` with 10 second time out.
Thanks in advance.

How to set timeout for a line of c# code

I&#39;ve to detect if two time periods are overlapping.&lt;br/&gt;
Every period has a start date and an end date.&lt;br/&gt;
I need to detect if my first time period (A) is overlapping with another one(B/C). &lt;br/&gt;
In my case, if the start of B is equal to the end of A, they are not overlapping(the inverse too) &lt;br/&gt;
I found the following cases:

![enter image description here][1]


So actually I&#39;m doing this like this:

    tStartA &lt; tStartB &amp;&amp; tStartB &lt; tEndA //For case 1
    OR
    tStartA &lt; tEndB &amp;&amp; tEndB &lt;= tEndA //For case 2
    OR
    tStartB &lt; tStartA  &amp;&amp; tEndB &gt; tEndA //For case 3


(The case 4 is taken in the account either in case 1 or in case 2)

It **works**, but it seems not very efficient.

So, first is there an existing class in c# that can modelize this(a time period), something like a timespan, but with a fixed start date.

Secondly: Is there already a c# code(like in the `DateTime` class) which can handle this?

Third: if no, what would be your approach to make this comparison the most fast?


  [1]: http://i.stack.imgur.com/AIBUV.png

Algorithm to detect overlapping periods

Is there a way to find out the number of listeners (clients connected to a hub?)

I&#39;m trying to run/start a task if at least one client is connected, otherwise do not start it:

    [HubName(&quot;taskActionStatus&quot;)]
    public class TaskActionStatus : Hub, IDisconnect
    {
        static CancellationTokenSource tokenSource;
        
        public void GetTasksStatus(int? siteId)
        {
            tokenSource = new CancellationTokenSource();
            CancellationToken ct = tokenSource.Token;

            ITaskRepository taskRepository = UnityContainerSetup.Container.Resolve&lt;ITaskRepository&gt;();

            // init task for checking task statuses
            var tasksItem = new DownloadTaskItem();
            taskRepository.GetTasksStatusAsync(siteId, tasksItem, ct);

            // subscribe to event [ listener ]
            tasksItem.Changed += new EventHandler&lt;TaskEventArgs&gt;(UpdateTasksStatus);
        }

        public void UpdateTasksStatus(object sender, TaskEventArgs e)
        {
            Clients.updateMessages(e.Tasks);
        }

        // when browsing away from page
        public Task Disconnect()
        {
            try
            {
                tokenSource.Cancel();
            }
            catch (Exception)
            {
                //
            }
            
            return null;
        }
    }

thanks

Get number of listeners, clients connected to SignalR hub

Take the following code (usable as a Console Application):

    static void Main(string[] args)
    {
        int i = 0;
        i += i++;
        Console.WriteLine(i);
        Console.ReadLine();
    }

The result of `i` is 0. I expected 2 (as some of my colleagues did). Probably the compiler creates some sort of structure that results in `i` being zero.

The reason I expected 2 is that, in my line of thought, the right hand statement would be evaluated first, incrementing i with 1. Than it is added to i. Since i is already 1, it is adding 1 to 1. So 1 + 1 = 2. Obviously this is not what&#39;s happening.

Can you explain what the compiler does or what happens at runtime? Why is the result zero?

*Some-sort-of-disclaimer: I&#39;m absolutely aware you won&#39;t (and probably shouldn&#39;t) use this code. I know I never will. Nevertheless, I find it is interesting to know why it acts in such a way and what is happening exactly.*

For i = 0, why is (i += i++) equal to 0?

OK this is one I&#39;ve been trying to figure out for a few days now. We have an application on Windows Phone 7 where phones join a multicast group and then send and receive messages to the group to talk to each other. Note - this is phone to phone communication.

Now I&#39;m trying to port this application to Windows Phone 8 - using the &#39;Convert to Phone 8&#39; feature in Visual Studio 2012 - so far so good. Until I try to test the phone to phone communication. The handsets seem to join the group fine, and they send the datagrams OK. They even receive the messages that they send to the group - however, no handset ever receives a message from another handset.

Here is the sample code behind to my page:

    // Constructor
    public MainPage()
    {
        InitializeComponent();
    }

    // The address of the multicast group to join.
    // Must be in the range from 224.0.0.0 to 239.255.255.255
    private const string GROUP_ADDRESS = &quot;224.0.1.1&quot;;

    // The port over which to communicate to the multicast group
    private const int GROUP_PORT = 55562;
 
    // A client receiver for multicast traffic from any source
    UdpAnySourceMulticastClient _client = null;

    // Buffer for incoming data
    private byte[] _receiveBuffer;

    // Maximum size of a message in this communication
    private const int MAX_MESSAGE_SIZE = 512;

    private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
    {
        _client = new UdpAnySourceMulticastClient(IPAddress.Parse(GROUP_ADDRESS), GROUP_PORT);
        _receiveBuffer = new byte[MAX_MESSAGE_SIZE];

        _client.BeginJoinGroup(
            result =&gt;
            {
                _client.EndJoinGroup(result);
                _client.MulticastLoopback = true;
                Receive();
            }, null);
    }

    private void SendRequest(string s)
    {
        if (string.IsNullOrWhiteSpace(s)) return;

        byte[] requestData = Encoding.UTF8.GetBytes(s);

        _client.BeginSendToGroup(requestData, 0, requestData.Length,
            result =&gt;
            {
                _client.EndSendToGroup(result);
                Receive();
            }, null);
    }

    private void Receive()
    {
        Array.Clear(_receiveBuffer, 0, _receiveBuffer.Length);
        _client.BeginReceiveFromGroup(_receiveBuffer, 0, _receiveBuffer.Length,
            result =&gt;
            {
                IPEndPoint source;

                _client.EndReceiveFromGroup(result, out source);

                string dataReceived = Encoding.UTF8.GetString(_receiveBuffer, 0, _receiveBuffer.Length);

                string message = String.Format(&quot;[{0}]: {1}&quot;, source.Address.ToString(), dataReceived);
                Log(message, false);

                Receive();
            }, null);
    }
    
    private void Log(string message, bool isOutgoing)
    {
        if (string.IsNullOrWhiteSpace(message.Trim(&#39;\0&#39;)))
        {
            return;
        }

        // Always make sure to do this on the UI thread.
        Deployment.Current.Dispatcher.BeginInvoke(
        () =&gt;
        {
            string direction = (isOutgoing) ? &quot;&gt;&gt; &quot; : &quot;&lt;&lt; &quot;;
            string timestamp = DateTime.Now.ToString(&quot;HH:mm:ss&quot;);
            message = timestamp + direction + message;
            lbLog.Items.Add(message);

            // Make sure that the item we added is visible to the user.
            lbLog.ScrollIntoView(message);
        });

    }
    
    private void btnSend_Click(object sender, RoutedEventArgs e)
    {
        // Don&#39;t send empty messages.
        if (!String.IsNullOrWhiteSpace(txtInput.Text))
        {
            //Send(txtInput.Text);
            SendRequest(txtInput.Text);
        }
    }

    private void btnStart_Click(object sender, RoutedEventArgs e)
    {
        SendRequest(&quot;start now&quot;);
    }

In order to simply test out the UDP stack, I downloaded the sample from MSDN found [here](http://code.msdn.microsoft.com/wpapps/Multicast-Sockets-Sample-51190c11) and I tested this on a pair of Windows Phone 7 devices and it works as expected. Then I converted to Windows Phone 8 and deployed to my handsets, again the devices seem to initiate their connection, and the user can enter their name. However, again the devices can&#39;t see or communicate with other devices.

Finally I implemented a simple communication test using the new DatagramSocket implementation, and again I see successful initiation, but no inter-device communication.

This is the same code behind page using the datagram socket implementation:

    // Constructor
    public MainPage()
    {
        InitializeComponent();
    }

    // The address of the multicast group to join.
    // Must be in the range from 224.0.0.0 to 239.255.255.255
    private const string GROUP_ADDRESS = &quot;224.0.1.1&quot;;

    // The port over which to communicate to the multicast group
    private const int GROUP_PORT = 55562;

    private DatagramSocket socket = null;

    private void Log(string message, bool isOutgoing)
    {
        if (string.IsNullOrWhiteSpace(message.Trim(&#39;\0&#39;)))
            return;

        // Always make sure to do this on the UI thread.
        Deployment.Current.Dispatcher.BeginInvoke(
        () =&gt;
        {
            string direction = (isOutgoing) ? &quot;&gt;&gt; &quot; : &quot;&lt;&lt; &quot;;
            string timestamp = DateTime.Now.ToString(&quot;HH:mm:ss&quot;);
            message = timestamp + direction + message;
            lbLog.Items.Add(message);

            // Make sure that the item we added is visible to the user.
            lbLog.ScrollIntoView(message);
        });
    }
    
    private void btnSend_Click(object sender, RoutedEventArgs e)
    {
        // Don&#39;t send empty messages.
        if (!String.IsNullOrWhiteSpace(txtInput.Text))
        {
            //Send(txtInput.Text);
            SendSocketRequest(txtInput.Text);
        }
    }

    private void PhoneApplicationPage_Loaded(object sender, RoutedEventArgs e)
    {
        socket = new DatagramSocket();
        socket.MessageReceived += socket_MessageReceived;

        try
        {
            // Connect to the server (in our case the listener we created in previous step).
            await socket.BindServiceNameAsync(GROUP_PORT.ToString());
            socket.JoinMulticastGroup(new Windows.Networking.HostName(GROUP_ADDRESS));
            System.Diagnostics.Debug.WriteLine(socket.ToString());
        }
        catch (Exception exception)
        {
            throw;
        }
    }

    private async void SendSocketRequest(string message)
    {
        // Create a DataWriter if we did not create one yet. Otherwise use one that is already cached.
        //DataWriter writer;
        var stream = await socket.GetOutputStreamAsync(new Windows.Networking.HostName(GROUP_ADDRESS), GROUP_PORT.ToString());
        //writer = new DataWriter(socket.OutputStream);
        DataWriter writer = new DataWriter(stream);

        // Write first the length of the string as UINT32 value followed up by the string. Writing data to the writer will just store data in memory.
       // stream.WriteAsync(
        writer.WriteString(message);

        // Write the locally buffered data to the network.
        try
        {
            await writer.StoreAsync();
            Log(message, true);
            System.Diagnostics.Debug.WriteLine(socket.ToString());
        }
        catch (Exception exception)
        {
            throw;
        }
        finally
        {
            writer.Dispose();
        }
    }

    void socket_MessageReceived(DatagramSocket sender, DatagramSocketMessageReceivedEventArgs args)
    {
        try
        {
            uint stringLength = args.GetDataReader().UnconsumedBufferLength;
            string msg = args.GetDataReader().ReadString(stringLength);

            Log(msg, false);
        }
        catch (Exception exception)
        {
            throw;
        }
    }

Last night I took the handsets home to test them on my home wireless network, low and behold I get successful device communication. 

So to recap - my legacy Windows Phone 7 code runs fine on my work network. The port to Windows Phone 8 (no actual code change) does not send inter-device communication. This code does work on my home network. The code runs with the debugger attached and there are no signs of errors or exceptions anywhere during execution.

The handsets I&#39;m using are: 

Windows Phone 7 - Nokia Lumia 900 (* 2), Nokia Lumia 800 (* 3)
Windows Phone 8 - Nokia Lumia 920 (* 1), Nokia Limia 820 (* 2)

These are all running the latest OS, and are in developer mode.
Development environment is Windows 8 Enterprise running Visual Studio 2012 Professional

I cant tell you much about the work wireless network - other than the Phone 7 devices have no trouble. 

As for the home wireless network i used, that&#39;s just a basic BT Broadband router with none of the &#39;out the box&#39; settings altered.

Clearly there is an issue with the way that the two network are configured, but there is also very clearly an issue with the way Windows Phone 8 implements UDP messages.

Any input would be appreciated as this is driving me mad right now.

UDP multicast group on Windows Phone 8

I am trying to implement an if -else statement in XSLT but my code just doesn&#39;t parse.  Does anyone have any ideas?


      &lt;xsl:variable name=&quot;CreatedDate&quot; select=&quot;@createDate&quot;/&gt;
      &lt;xsl:variable name=&quot;IDAppendedDate&quot; select=&quot;2012-01-01&quot; /&gt;
      &lt;b&gt;date: &lt;xsl:value-of select=&quot;$CreatedDate&quot;/&gt;&lt;/b&gt; 
    
      &lt;xsl:if test=&quot;$CreatedDate &gt; $IDAppendedDate&quot;&gt;
        &lt;h2&gt; mooooooooooooo &lt;/h2&gt;
      &lt;/xsl:if&gt;
      &lt;xsl:else&gt;
        &lt;h2&gt; dooooooooooooo &lt;/h2&gt;
      &lt;/xsl:else&gt;



How to implement if-else statement in XSLT?

Currently I&#39;m using either a WebView or a TextView to show some dynamic data coming from a webservice in one of my apps. 
If the data contains pure text, it uses the TextView and applies a style from styles.xml.
If the data contains HTML (mostly text and images) it uses the WebView.

However, this WebView is unstyled. Therefor it looks a lot different from the usual TextView.
I&#39;ve read that it&#39;s possible to style the text in a WebView simply by inserting some HTML directly into the data. This sounds easy enough, but I would like to use the data from my Styles.xml as the values required in this HTML so I won&#39;t need to change the colors et cetera on two locations if I change my styles.

So, how would I be able to do this? I&#39;ve done some extensive searching but I have found no way of actually retrieving the different style attributes from your styles.xml.  Am I missing something here or is it really not possible to retrieve these values?

The style I&#39;m trying to get the data from is the following:

    &lt;style name=&quot;font4&quot;&gt;
        &lt;item name=&quot;android:layout_width&quot;&gt;fill_parent&lt;/item&gt;
        &lt;item name=&quot;android:layout_height&quot;&gt;wrap_content&lt;/item&gt;
        &lt;item name=&quot;android:textSize&quot;&gt;14sp&lt;/item&gt;
        &lt;item name=&quot;android:textColor&quot;&gt;#E3691B&lt;/item&gt;
        &lt;item name=&quot;android:paddingLeft&quot;&gt;5dp&lt;/item&gt;
        &lt;item name=&quot;android:paddingRight&quot;&gt;10dp&lt;/item&gt;
        &lt;item name=&quot;android:layout_marginTop&quot;&gt;10dp&lt;/item&gt;
        &lt;item name=&quot;android:textStyle&quot;&gt;bold&lt;/item&gt;
    &lt;/style&gt;

I&#39;m mainly interested in the textSize and textColor.


How to retrieve style attributes programmatically from styles.xml

I am new to XML and I am trying to understand the basics. I read the line below  in &quot;Learning XML&quot;, but it is still not clear, for me. Can someone point me to a book or website which explains these basics clearly?

From *Learning XML*:

&gt; The XML declaration describes some of the most general properties of
&gt; the document, telling the XML processor that it needs an XML parser to
&gt; interpret this document.

What does this mean?

I understand the `xml version` part - both doc and user of doc should &quot;talk&quot; in the same version of XML. But what about the `encoding` part? Why is that necessary?

Meaning of - &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;

I saw the line below in code for a DOM parser at [this tutorial][1].

    doc.getDocumentElement().normalize();

Why do we do this normalization ?   
I read the [docs][2] but I could not understand a word.

&gt; Puts all Text nodes in the full depth of the sub-tree underneath this Node

Okay, then can someone show me (preferably with a picture) what this tree looks like ?

Can anyone explain me why normalization is needed?  
What happens if we don&#39;t normalize ?


  [1]: http://www.mkyong.com/java/how-to-read-xml-file-in-java-dom-parser/
  [2]: http://docs.oracle.com/javase/6/docs/api/org/w3c/dom/Node.html#normalize%28%29

Normalization in DOM parsing with java - how does it work?

Short question:
I would like to select all nodes that do not match an attribute (@type !=&#39;x&#39;) but also attribute doesn&#39;t exist (??).
Currently, I&#39;m getting nothing back, because the other nodes have no attribute at all.

Background:
I have some XML. Note that one has type=&quot;feature&quot; but all others have no &#39;type&#39; attr.

    &lt;image type=&quot;feature&quot;&gt;&lt;description&gt;X&lt;/description&gt;&lt;url&gt;media/designer_glass_tile_04.jpg&lt;/url&gt;&lt;height&gt;&lt;/height&gt;&lt;width/&gt;&lt;/image&gt;
    &lt;image&gt;&lt;description&gt;Designer Glass 05&lt;/description&gt;&lt;url&gt;media/designer_glass_tile_05.jpg&lt;/url&gt;&lt;height&gt;&lt;/height&gt;&lt;width/&gt;&lt;/image&gt;
    &lt;image&gt;&lt;description&gt;Designer Glass 06&lt;/description&gt;&lt;url&gt;media/designer_glass_tile_06.jpg&lt;/url&gt;&lt;height&gt;&lt;/height&gt;&lt;width/&gt;&lt;/image&gt;
    &lt;image&gt;&lt;description&gt;Designer Glass 07&lt;/description&gt;&lt;url&gt;media/designer_glass_tile_07.jpg&lt;/url&gt;&lt;height&gt;&lt;/height&gt;&lt;width/&gt;&lt;/image&gt;
    &lt;image&gt;&lt;description&gt;Designer Glass 08&lt;/description&gt;&lt;url&gt;media/designer_glass_tile_08.jpg&lt;/url&gt;&lt;height&gt;&lt;/height&gt;&lt;width/&gt;&lt;/image&gt;


And a XSL style:


            &lt;div id=&quot;gallery&quot;&gt;
            	&lt;div id=&quot;feature&quot; &gt;
            		&lt;xsl:apply-templates select=&quot;image[@type=&#39;feature&#39;]&quot;/&gt;
                &lt;/div&gt;
                &lt;div id=&quot;thumbs&quot;&gt;
            		&lt;xsl:apply-templates select=&quot;image[@type!=&#39;feature&#39;]&quot;/&gt;
            	&lt;/div&gt;
            &lt;/div&gt;


xpath select by attribute when attribute not present

I have the following XML which I want to parse using Python&#39;s `ElementTree`:

&lt;!-- language: lang-xml --&gt;

    &lt;rdf:RDF xml:base=&quot;http://dbpedia.org/ontology/&quot;
        xmlns:rdf=&quot;http://www.w3.org/1999/02/22-rdf-syntax-ns#&quot;
        xmlns:owl=&quot;http://www.w3.org/2002/07/owl#&quot;
        xmlns:xsd=&quot;http://www.w3.org/2001/XMLSchema#&quot;
        xmlns:rdfs=&quot;http://www.w3.org/2000/01/rdf-schema#&quot;
        xmlns=&quot;http://dbpedia.org/ontology/&quot;&gt;
    
        &lt;owl:Class rdf:about=&quot;http://dbpedia.org/ontology/BasketballLeague&quot;&gt;
            &lt;rdfs:label xml:lang=&quot;en&quot;&gt;basketball league&lt;/rdfs:label&gt;
            &lt;rdfs:comment xml:lang=&quot;en&quot;&gt;
              a group of sports teams that compete against each other
              in Basketball
            &lt;/rdfs:comment&gt;
        &lt;/owl:Class&gt;

    &lt;/rdf:RDF&gt;

I want to find all `owl:Class` tags and then extract the value of all `rdfs:label` instances inside them. I am using the following code:

&lt;!-- language: lang-py --&gt;

    tree = ET.parse(&quot;filename&quot;)
    root = tree.getroot()
    root.findall(&#39;owl:Class&#39;)

Because of the namespace, I am getting the following error.

&lt;!-- language: lang-py --&gt;

    SyntaxError: prefix &#39;owl&#39; not found in prefix map

I tried reading the document at http://effbot.org/zone/element-namespaces.htm but I am still not able to get this working since the above XML has multiple nested namespaces.

Kindly let me know how to change the code to find all the `owl:Class` tags.

Parsing XML with namespace in Python via &#39;ElementTree&#39;

Here is an example of the `app` namespace that I&#39;ve seen from a `res/menu/main.xml` file

    &lt;menu xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
    xmlns:app=&quot;http://schemas.android.com/apk/res-auto&quot;
    xmlns:tools=&quot;http://schemas.android.com/tools&quot;
    tools:context=&quot;.MainActivity&quot; &gt;
    &lt;item android:id=&quot;@+id/action_settings&quot;
        android:title=&quot;@string/action_settings&quot;
        android:orderInCategory=&quot;100&quot;
        app:showAsAction=&quot;never&quot; /&gt;
    &lt;/menu&gt;

What purpose does the `app` namespace serve? Is it a &quot;standard&quot; Android XML namespace? Are the same value options available for the same attribute placed in two different namespaces (e.g. `app:showAsAction` and `android:showAsAction`).

From the [docs][1]:
`android:showAsAction=[&quot;ifRoom&quot; | &quot;never&quot; | &quot;withText&quot; | &quot;always&quot; | &quot;collapseActionView&quot;]` 

i.e., would the line in the above example mean something else if the attribute were instead:

    android:showAsAction=&quot;never&quot;

It almost looks like it might be some sort of &quot;subclassing&quot; mechanism, but I can&#39;t seem to find any real documentation on the `app` namespace from Google/Android sources.


  [1]: http://developer.android.com/guide/topics/resources/menu-resource.html &quot;docs&quot;

What is the &#39;app&#39; Android XML namespace?

For the following XML fragment:

    &lt;project xmlns=&quot;http://maven.apache.org/POM/4.0.0&quot;
             xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;
             xsi:schemaLocation=&quot;http://maven.apache.org/POM/4.0.0 
                                 http://maven.apache.org/xsd/maven-4.0.0.xsd&quot;&gt;

What do the `xmlns`, `xmlns:xsi`, and `xsi:schemaLocation` attributes exactly mean? How are they related? What&#39;s the `:` for?

And there are 2 URLs in the `xsi:schemaLocation=`

 1. http://maven.apache.org/POM/4.0.0  (it happens to be the same as `xmlns` but it gives a 404 error when visiting.)
 2. http://maven.apache.org/xsd/maven-4.0.0.xsd  (this is an actual XSD doc)

If 1 doesn&#39;t exist, why still put it there?

Content Type	Original Author	Original Content on Stackoverflow
Question	rizwan ansari	View Question on Stackoverflow
Solution 1 - C#	Ria	View Answer on Stackoverflow
Solution 2 - C#	Daniel B	View Answer on Stackoverflow
Solution 3 - C#	Furkan ÇELİKCİ	View Answer on Stackoverflow

Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function

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