Weekend Scripter: Use PowerShell to Explore an RSS Feed from a Blog

Summary: Microsoft Scripting Guy, Ed Wilson, talks about using Windows PowerShell to explore an RSS feed from the Hey, Scripting Guy! Blog.

Microsoft Scripting Guy, Ed Wilson, is here. It is just a few days until I speak at the Central Ohio Windows PowerShell User Group. The Scripting Wife and I will be there on October 2, 2012. For registration information and a précis of my talk, see the Central Ohio PowerShell Users Group site.

On the weekend, I like to play around with Windows PowerShell. I also like to experiment with new tea combinations. This morning I am sipping a nice Monkey Picked Oolong tea with little jasmine buds, lemon grass, and hibiscus flower. I sweetened the tea with a little bit of crushed cinnamon stick. Yum!

I ran across an old blog post the other day that was written by a guy who was really pleased that Windows PowerShell enabled him to reduce a 25-line script to five lines to retrieve RSS feeds. In Windows PowerShell 3.0, that is one line. Here is the line to retrieve an RSS feed from the Hey, Scripting Guy! Blog.

[xml]$hsg = Invoke-WebRequest http://blogs.technet.com/b/heyscriptingguy/atom.aspx

The important thing here is to ensure that I use the [xml] type accelerator to convert the returned information into an XMLDocument object. After I have the returned information, I view it in the Windows PowerShell console. I see there is a Feed property as shown here.

PS C:\> [xml]$hsg = Invoke-WebRequest http://blogs.technet.com/b/heyscriptingguy/atom

.aspx

PS C:\> $hsg

 

xml                          xml-stylesheet              feed

—                          ————–              —-

version=”1.0″ encoding=”U… type=”text/xsl” href=”ht… feed

When I access the Feed property, I see a number of interesting items, the most important of which is the Entry property. These properties are shown here.

PS C:\> $hsg.feed

 

xmlns     : http://www.w3.org/2005/Atom

lang      : en-US

title     : title

subtitle  : subtitle

id        : http://blogs.technet.com/b/heyscriptingguy/atom.aspx

link      : {link, link}

generator : generator

updated   : 2012-09-09T00:01:00Z

entry     : {entry, entry, entry, entry…}

This is where Windows PowerShell 3.0 really comes in handy. I can directly access the collection of entries by using dotted notation. It is cool and powerful. In the following example, I show only the first record.

PS C:\> $hsg.feed.entry

 

title     : PowerTip: Redirect PowerShell Warning Messages to a Text File

link      : link

id        : http://blogs.technet.com/b/heyscriptingguy/archive/2012/09/20/powertip-r

            edirect-powershell-warning-messages-to-a-text-file.aspx

published : 2012-09-20T18:59:00Z

updated   : 2012-09-20T18:59:00Z

content   : content

author    : author

category  : {category, category, category, category}

Of interest to me are the blog posts with their publication dates. I can easily retrieve a list of blog titles and dates as shown here.

PS C:\> $hsg.feed.entry | select title, published

 

title                                      published

—–                                      ———

PowerTip: Redirect PowerShell Warning M… 2012-09-20T18:59:00Z

Use PowerShell Redirection Operators fo… 2012-09-20T07:01:00Z

PowerTip: Display PowerShell Informatio… 2012-09-19T18:59:00Z

Use PowerShell to Create Intelligent De… 2012-09-19T07:01:00Z

PowerTip: Use Show-Command to See Power… 2012-09-18T18:59:00Z

Create a PowerShell Scheduled Job          2012-09-18T07:01:00Z

PowerTip: Examine Automatic Variables      2012-09-17T18:59:00Z

PowerShell and User Access Logging         2012-09-17T07:01:00Z

PowerTip: Easily Find the PowerShell 3…. 2012-09-16T18:59:00Z

Weekend Scripter: Get Detailed PowerShe… 2012-09-16T07:01:00Z

PowerTip: Quickly Find System Updates v… 2012-09-15T18:59:00Z

Weekend Scripter: What Does a PowerShel… 2012-09-15T07:01:00Z

PowerTip: Where Did that PowerShell Cmd… 2012-09-14T18:59:00Z

Easily Unblock All Files in a Directory… 2012-09-14T07:01:00Z

PowerTip: Use PowerShell to Easily Read… 2012-09-13T18:59:00Z

Use PowerShell to Simplify Access to XM… 2012-09-13T07:01:00Z

PowerTip: Easily Find WMI Class Schema … 2012-09-12T18:59:00Z

Use PowerShell to Troubleshoot ???Provi… 2012-09-12T07:01:00Z

The Scripting Guy Talks About PowerShel… 2012-09-11T19:41:00Z

PowerTip: Discovering PowerShell Functions 2012-09-11T18:59:00Z

Bespoke Scripting? What Do You Want in … 2012-09-11T07:01:00Z

PowerTip: Working with the Maximum Hist… 2012-09-10T18:59:00Z

Increase PowerShell Command History to … 2012-09-10T07:01:00Z

PowerTip: Two Quick Ways to Check Varia… 2012-09-09T18:59:00Z

Weekend Scripter: PowerShell Saturday S… 2012-09-09T07:01:00Z

One problem with the previous output is that the dates and times are a bit difficult for me to understand. I use a hash table to change the display of the date as shown here.

PS C:\> $hsg.feed.entry | select title, @{LABEL=”Published”; EXPRESSION={[datetime]$_

.Published} }

 

title                                      Published

—–                                      ———

PowerTip: Redirect PowerShell Warning M… 9/20/2012 2:59:00 PM

Use PowerShell Redirection Operators fo… 9/20/2012 3:01:00 AM

PowerTip: Display PowerShell Informatio… 9/19/2012 2:59:00 PM

Use PowerShell to Create Intelligent De… 9/19/2012 3:01:00 AM

PowerTip: Use Show-Command to See Power… 9/18/2012 2:59:00 PM

Create a PowerShell Scheduled Job          9/18/2012 3:01:00 AM

PowerTip: Examine Automatic Variables      9/17/2012 2:59:00 PM

PowerShell and User Access Logging         9/17/2012 3:01:00 AM

PowerTip: Easily Find the PowerShell 3…. 9/16/2012 2:59:00 PM

Weekend Scripter: Get Detailed PowerShe… 9/16/2012 3:01:00 AM

PowerTip: Quickly Find System Updates v… 9/15/2012 2:59:00 PM

Weekend Scripter: What Does a PowerShel… 9/15/2012 3:01:00 AM

PowerTip: Where Did that PowerShell Cmd… 9/14/2012 2:59:00 PM

Easily Unblock All Files in a Directory… 9/14/2012 3:01:00 AM

PowerTip: Use PowerShell to Easily Read… 9/13/2012 2:59:00 PM

Use PowerShell to Simplify Access to XM… 9/13/2012 3:01:00 AM

PowerTip: Easily Find WMI Class Schema … 9/12/2012 2:59:00 PM

Use PowerShell to Troubleshoot ???Provi… 9/12/2012 3:01:00 AM

The Scripting Guy Talks About PowerShel… 9/11/2012 3:41:00 PM

PowerTip: Discovering PowerShell Functions 9/11/2012 2:59:00 PM

Bespoke Scripting? What Do You Want in … 9/11/2012 3:01:00 AM

PowerTip: Working with the Maximum Hist… 9/10/2012 2:59:00 PM

Increase PowerShell Command History to … 9/10/2012 3:01:00 AM

PowerTip: Two Quick Ways to Check Varia… 9/9/2012 2:59:00 PM

Weekend Scripter: PowerShell Saturday S… 9/9/2012 3:01:00 AM

Now that I have a DateTime object instead of a simple string, I can do other things, such as show the morning and afternoon postings of the Hey Scripting Guy! Blog.

PS C:\> $hsg.feed.entry | select title, @{LABEL=”Published”; EXPRESSION={[datetime]$_

.Published} } | select title, @{LABEL=”Morning/Afternoon”; EXPRESSION={if($_.publishe

d.timeofday.hours -gt 12) {“Afternoon”} ELSE {“Morning”}} } | sort ‘morning/afternoon

‘

title                                      Morning/Afternoon

—–                                      —————–

PowerTip: Redirect PowerShell Warning M… Afternoon

PowerTip: Working with the Maximum Hist… Afternoon

PowerTip: Discovering PowerShell Functions Afternoon

The Scripting Guy Talks About PowerShel… Afternoon

PowerTip: Easily Find WMI Class Schema … Afternoon

PowerTip: Use PowerShell to Easily Read… Afternoon

PowerTip: Two Quick Ways to Check Varia… Afternoon

PowerTip: Quickly Find System Updates v… Afternoon

PowerTip: Where Did that PowerShell Cmd… Afternoon

PowerTip: Examine Automatic Variables      Afternoon

PowerTip: Use Show-Command to See Power… Afternoon

PowerTip: Display PowerShell Informatio… Afternoon

PowerTip: Easily Find the PowerShell 3…. Afternoon

Weekend Scripter: Get Detailed PowerShe… Morning

PowerShell and User Access Logging         Morning

Weekend Scripter: What Does a PowerShel… Morning

Easily Unblock All Files in a Directory… Morning

Create a PowerShell Scheduled Job          Morning

Use PowerShell to Simplify Access to XM… Morning

Use PowerShell to Troubleshoot ???Provi… Morning

Use PowerShell to Create Intelligent De… Morning

Bespoke Scripting? What Do You Want in … Morning

Use PowerShell Redirection Operators fo… Morning

Increase PowerShell Command History to … Morning

Weekend Scripter: PowerShell Saturday S… Morning

Another cool thing that I can do is check the tags on my blogs. To do this, I use the Category property from the entry object. I group based on the terms of the categories, and then sort the list. This command is shown here.

$hsg.feed.entry.category | group term -NoElement | sort count –Descending

The command and associated output are shown in the image that follows.

That is about it for today—I need to get to work on my new Windows PowerShell book project.

I invite you to follow me on Twitter and Facebook. If you have any questions, send email to me at scripter@microsoft.com, or post your questions on the Official Scripting Guys Forum. See you tomorrow. Until then, peace.

Ed Wilson, Microsoft Scripting Guy