(post courtesy Anand Nigam)

One of the cool things in SharePoint 2010 is the ability to show the Exchange Calendar on a SharePoint site, side by side. This is called as Calendar Overlay

This post will walk through how to configure this.

Step 1 (prerequisite)

1. I have a SharePoint Site http://fabrikam which looks like this

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2. I also have a calendar “MySharePointCalender” , with a few calendar events entered.

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3. I have my Exchange Calendar in Outlook, with a few meeting/events there as well.

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4. What we want is to see events from my Exchange calendar show up on the SharePoint calendar.

Step 2 (The actual process)

1. Open the SharePoint calendar  --> Calendar Tools –> Calendar Overlay –>New Calendar,

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Fill in the :

  • Name: Give a name to this calendar
  • Type: Select Exchange
  • Outlook Web Access URL: the OWA url of your organization.
  • Exchange Web Service URL: which can be determined as follows:

If your OWA URL is https://exch.contoso.com/owa, then the Exchange web Service URL would be https://exch.contoso.com/ews/exchange.asmx

(in other words, from the OWA URL , remove the trailing “owa” and add “ews/exchange.asmx”)

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Step 3 (The awaiting Error and the fix)

If you have not previously configured SharePoint to trust your Exchange server, you will receive the following error message:

Could not establish trust relationship for the SSL/TLS secure channel with authority ‘dc’. (GUID)

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Here is the fix

1. Get the CA Root Certificate for your domain

(Just a note, there are many ways to get the certificate, I’m taking the one that is less prone to error)

a. Go to the Server where you have the Certificate Authority installed. Open IIS and select the Server Certificates component.

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Double click on Server Certificates

Locate the Root Certificate of the CA from the list, here is the one what I have.

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(To double check if this it the Root certificate, open the certificate and see the certification path, It should have just one entry (root), that is the name of the Certification Authority, in your domain.). Below the image or my root certificate

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b. Now that we have located the certificate, Open it go to Details tab and Click Copy to File

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And now we have the Certificate exported to a file

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Copy this certificate to the SharePoint Server, and follow the below steps

a. Open Central administration > Security> Manage Trust

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b. Click on New, Provide a Name (I use RootCA), and navigate to the RootCA.cer file you exported in the previous step and Click OK

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Now refresh the same calendar and confirm that you can see the Exchange calendar event for the logged in user

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Step 4 (Enhance the default behavior)

Although we can now see the Exchange calendar, we can on only see the free/busy status, and not the actual details of the event. It would be good if we could have the details displayed here too. To display details:

1. Open Outlook> File > Options>

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2. Go to the Calendar Section > click Free/Busy Options

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3. Select any one of the options below, I have selected Full details. Click Apply and Ok and exit out of Outlook.  Now refresh the SharePoint calendar and see the difference.

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Additional reading:

Note: The calendar overlay is per user, meaning it will only show calendar items for the currently logged-in user.