Introducing Web Friendly Feeds aka Friendly Feeds

PhaniRajuYN — Thu, 19 Mar 2009 01:40:00 GMT

Hello all , with the recent release of ADO.NET Data v1.5 Services CTP 1 , we introduced a new feature called as “Web Friendly Feeds”.
What is this feature about ?

This is what the markup for one of the the resources of Customers looks like in ADO.NET Data Services v1 .

<?xml version="1.0" encoding="utf-8" standalone="yes" ?> 
<entry 
xml:base=http://localhost:26503/northwind.svc/ 

xmlns:d=http://schemas.microsoft.com/ado/2007/08/dataservices 
xmlns:m=http://schemas.microsoft.com/ado/2007/08/dataservices/metadata 
xmlns="http://www.w3.org/2005/Atom">
  <id>http://localhost:26503/northwind.svc/Customers('ALFKI')</id> 
  <title type="text" /> 
  <updated>2009-03-18T20:30:20Z</updated> 
  <author>
  <name /> 
  </author>
 <category term="NorthwindModel.Customers" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> 
 <content type="application/xml">
 <m:properties>
  <d:CustomerID>ALFKI</d:CustomerID> 
  <d:CompanyName>Alfreds Futterkiste</d:CompanyName> 
  <d:ContactName>Maria Anders</d:ContactName> 
  <d:ContactTitle>Sales Representative</d:ContactTitle> 
  <d:Address>Obere Str. 57</d:Address> 
  <d:City>Berlin</d:City> 
  <d:Region m:null="true" /> 
  <d:PostalCode>12209</d:PostalCode> 
  <d:Country>Germany</d:Country> 
  <d:Phone>030-0074321</d:Phone> 
  <d:Fax>030-0076545</d:Fax> 
  </m:properties>
  </content>
</entry>

In the markup above , a couple of things are missing

1) The <title> element is empty

<title type="text" />

2) The author/name element is empty

<author>
    <name /> 
</author>

In v 1.5 , through Friendly Feeds , we will now be able to assign a property of the “Customers” entity type to turn up in these element locations in the atom:entry payload.

Now , let’s say that we wanted to map the “ContactName” as the author name element of the entry element and Title to be “ContactTitle” as the title of the entry element.
Then , the payload would look like this :

<entry >
  <id>http://localhost:26503/northwind.svc/Customers('ALFKI')</id> 
  <title type="text">Sales Representative</title> 
  <updated>2009-03-18T20:46:42Z</updated> 
 <author>
  <name>Maria Anders</name> 
  </author>
<category term="NorthwindModel.Customers" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> 
 <content type="application/xml">
 <m:properties>
  <d:CustomerID>ALFKI</d:CustomerID> 
  <d:CompanyName>Alfreds Futterkiste</d:CompanyName> 
  <d:ContactName>Maria Anders</d:ContactName> 
  <d:ContactTitle>Sales Representative</d:ContactTitle> 
  <d:Address>Obere Str. 57</d:Address> 
  <d:City>Berlin</d:City> 
  <d:Region m:null="true" /> 
  <d:PostalCode>12209</d:PostalCode> 
  <d:Country>Germany</d:Country> 
  <d:Phone>030-0074321</d:Phone> 
  <d:Fax>030-0076545</d:Fax> 
  </m:properties>
  </content>
</entry>

This also means , that IE now displays the Title & author Name elements when you browse to the “Customers” entity set .

Which elements in the atom:entry element can I map to an entity type properties ?

entry:author/email
entry:author/name
entry:author/uri
entry:published
entry:rights
entry:summary
entry:title

Once a property is mapped , if keeping the value of the property in the entry:contents section doesn’t make sense,can I remove it ?
Yes , absolutely , in the above case , we can remove the ContactName & ContactTitle elements from being repeated in the <contents> section.
Ex:

<entry>
  <id>http://localhost:26503/northwind.svc/Customers('ALFKI')</id> 
  <title type="text">Sales Representative</title> 
  <updated>2009-03-18T21:04:20Z</updated> 
  <author>
  <name>Maria Anders</name> 
  </author>
  <category term="NorthwindModel.Customers" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> 
 <content type="application/xml">
 <m:properties>
  <d:CustomerID>ALFKI</d:CustomerID> 
  <d:CompanyName>Alfreds Futterkiste</d:CompanyName> 
  <d:Address>Obere Str. 57</d:Address> 
  <d:City>Berlin</d:City> 
  <d:Region m:null="true" /> 
  <d:PostalCode>12209</d:PostalCode> 
  <d:Country>Germany</d:Country> 
  <d:Phone>030-0074321</d:Phone> 
  <d:Fax>030-0076545</d:Fax> 
  </m:properties>
  </content>
  </entry>

Great , what else can I do with this new feature ?
Well, did I mention you can embed your own markup in the <entry> element for an entity type !!!

consider the following entity type , BlogPost , which looks like this

public class BlogPost {
        public double Lat { get; set; }
        public double Long { get; set; }
        public int BlogPostID { get; set; }
        public string Title { get; set; }
        public string Body { get; set; }
        public string Author { get; set; }
        public string PostURI { get; set; }
        public string ContentSummary{get;set;}
}

This type represents the entry for a blog post , and also contains the Geographical location information about where the post was made ( Lat /Long)
and also the author information. Now , if this data was exposed via a Data Service, the payload would contain the Lat/Long/Published fields as part of
the entry:content element and wouldn’t have any special meaning.
The author element should be the Author field of the atom:entry , and the Published field to be the atom:published.
the Lat & Long fields should be a georss element that shows the location at which the Blog Post was made.
In short , it should look like this :

<entry>
  <id>http://localhost/AstoriaBoard/Services/BlogSvc.svc/Posts(1)</id> 
  <title type="text">Entities, How many ways do I count thee ?</title> 
  <summary type="html">
          <img class='imgClass' width='150px' height='150px' src='/AStoriaBoard/mug.jpg'/><br/>Its a common ask that we introduce aggregatin
   </summary> 
  <published>2009-03-18T14:29:43-07:00</published> 
  <updated>2009-03-18T21:29:43Z</updated> 
 <author>
  <name>Phani Raj</name> 
  </author>
  <link rel="edit" title="BlogPost" href="Posts(1)" /> 
  <category term="Blogs.BlogPost" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> 
 <content type="application/xml">
 <m:properties>
  <d:BlogPostID m:type="Edm.Int32">1</d:BlogPostID> 
  <d:Body>Its a common ask that we introduce aggregating mechanisms in Data services 
          so that one can do a Count of the number of entities present in an EntitySet easily. 
          In this blog post , I will outline one method of implementing a “Count” method that works for you. 
          The interface to the count method will be</d:Body> 
  <d:Author>Phani Raj</d:Author> 
  <d:PostURI m:null="true" /> 
  </m:properties>
  </content>
 <geo xmlns="http://www.georss.org/georss">
   <long>-80.244445</long> 
   <lat>25.730752</lat> 
 </geo>
 </entry>

Now that we got this markup , I feel like we should do something with it . How about showing this information on a MAP ?
I know !! We have a mapping solution , Virtual Earth , lets try and see if we can feed this feed to Virtual Earth and make it see our GeoRss markup.
Recently , ( November 2008 ), the Live team released the Map control as an asp.net control . Download it here :http://dev.live.com/tools/

Add this control to an aspx page in the same website as the Data Service .

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <style>
        .imgClass{
            border: solid 2px #99ccff;}
    </style>
</head>
<body>
    <form id="form1" runat="server">
    <script language="javascript">
        function pageLoad() {
            HookUpWorkAround();
        }
    </script>
    <div id="mapContainer">
        <ve:Map ID="geoRssMap" runat="server" Height="600px" Width="75%" ZoomLevel="4" />
    </div>
    <asp:ScriptManager ID="scrpManager" runat="server">
        <Scripts>
            <asp:ScriptReference Path="~/Scripts/VEWorkAround.js" />
        </Scripts>
    </asp:ScriptManager>
    </form>
</body>
</html>

In the code-behind file ,

using System;
using Microsoft.Live.ServerControls.VE;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //Clear out any mapped locations 
        geoRssMap.Clear();
        //Create a new shapelayer to import
        ShapeLayer geoRssLayer = new ShapeLayer();
        //Point the shape layer at the data source returning the mapping information
        ShapeSourceSpecification georssSpec = new ShapeSourceSpecification(
                    DataType.GeoRSS, "Services/BlogSvc.svc/Posts", geoRssLayer
                    );
        //Bind the feed to the map
        geoRssMap.ImportShapeLayerData(georssSpec, null, false);
    }
}

You might be wondering why we need the HookUpWorkAround() function and what it does , I’ll explain that in a later blog post .
After this , set the web page as the startup page and browse to the page in FireFox , I’ll explain why Firefox in a later blog post .
And voila !! This is what the page looks like :

You can download the sample project that demonstrates this feature by clicking on the link at the bottom of this post

All this demonstrates the what and not the how , we shall discuss the how in future blog posts.

In the meantime ,enjoy this sample app and try out your own mashups.

With Great Power comes Great Response.write("Ability") : geoRss

Introducing Web Friendly Feeds aka Friendly Feeds