Introduction

Microsoft Office 2003 is very tightly integrated with SharePoint by utilizing its web services. Windows SharePoint Services comes with sixteen different web services. SharePoint Portal Server 2003 supports an additional five web services. The web services provided by SharePoint do provide a vast array of features. But not all SharePoint features are accessible through them. If required you can build your own web service on top of SharePoint leveraging the managed SharePoint server API itself. The web service interfaces make it very easy to integrate SharePoint capabilities right into your application.

This article is not a detailed documentation of every web method and web service provided by SharePoint. It is rather an introduction to its capabilities and how to use them. You can download the Windows SharePoint Services SKD or the SharePoint Portal Server SKD for a complete reference of all web services and also of the server API itself. Please refer to this article for a guide how to install and administrate SharePoint or this article for a guide how to use and customize SharePoint portals.

How to add a Windows SharePoint web service reference

You can add a web reference to each SharePoint web service through your Visual Studio .NET IDE. In your Solution Explorer right click on your project and select "Add Web Reference" from your popup menu. The table below shows the URLs to use for each web service provided by WSS. Enter the URL to the web service and click the Go button. This will show you in the dialog box a summary of all available web methods. Next enter the name of the web reference and then click Add Reference.

Setting the web service user credentials

The SharePoint web services only accept calls from existing SharePoint users and do also enforce access security. Import the System.Net namespace into your project and then use the NetworkCredential class to set the user credential to use for the web service call. Here is a code snippet:

public static XmlNode VersionsGetVersions(string SharePointHost, string UserName, string Password, string Domain, string FileName)
{
// proxy object to call the Versions web service
Versions.Versions VersionsService = new Versions.Versions();
// the user credentials to use
VersionsService.Credentials = new NetworkCredential(UserName, Password, Domain);
VersionsService.Url = SharePointHost + "_vti_bin/Versions.asmx";
// gets the file versions
XmlNode Result = VersionsService.GetVersions(FileName);
// dispose the web service object
VersionsService.Dispose();
return Result;
}

For example, first you create an instance of the Versions web service. Then you assign a new instance of the NetworkCredential class to the Credentials property on the created web service object. We pass along the user name, password and the user's domain name to the NetworkCredential object. Next you set the web service URL, which might very well be different from the one used when you created the web reference. Finally you invoke the desired web method, in the code snippet above the GetVersions() web method. The web method takes a file name and returns a XML document with all available versions of this file (Document libraries can have versioning enabled and then keep a history for each version). At the end you call Dispose() on the web service object to free up any underlying unmanaged resources.

If the user does not exist in SharePoint or does not have the permission to perform the operation then a WebException is thrown by SharePoint. The returned HTTP status is 401, which means unauthorized request. There are some inconsistencies across all web services. For example some web methods take a XML string as input while others take an XmlNode as input. Most web methods return the result as XmlNode while others return a XML string and while others again return complex data structures. But after you get used to these inconsistencies it is very easy to use these web services and integrate SharePoint capabilities right into your application.

A summary of the "Windows SharePoint Services" web services

The following table provides an overview what capabilities are exposed through the "Windows SharePoint Services" web services. Each web service is targeted towards a specific area although there is some overlap. You for example can use the Lists web service and the Site Data web service to work with SharePoint lists, or you can use the Site Data web service and the Webs web service to work with sites meta-data and sub-sites. Please refer to the attached "SharePoint web service browser" sample application which provides a windows form interface to browse all web services and all its web methods. It enables you to play with each web method or web service and better understand its usage. It also displays to each web service and web method the detailed SDK help page.

A summary of the SharePoint Portal Server web services

SharePoint Portal Server provides the same web services as Windows SharePoint Services. It also provides the following five additional web services.

The table below shows the URLs to use for each web service provided by SharePoint Portal Server. You can add them the same way as the WSS web services described above.

Namespaces used in the returned SharePoint XML documents

Many of the web methods return its result in form of an XML document. Most root nodes have a namespace URI associated with it. Here is an example XML document returned by the GetListCollection() web method (on the Lists web service). Please note that this is just a partial XML snippet for demonstration purpose:

Naturally we would think of running an XPath query like "//List" using the SelectNodes() method on the XmlDocument or XmlNode object. We expect it to return all the List nodes of this XML document. But the result returned is empty. The reason being that you need to query within the namespace associated with the root node. But how do you do that if there is no namespace qualifier (or prefix) associated with the namespace URI. We need to use the XmlNamespaceManager class to associate a namespace prefix to the namespace URI. Here is the code snippet:

First we create a new XmlDocument object and load the XML string of the passed along XmlNode into it. This way we can manipulate the XML document as needed without affecting the original XmlNode object itself. Then we create an XmlNamespaceManger object and assign it to the XmlDocument object. This we do by passing along the NameTable property of the XmlDocument. Next we add all the namespace URI's with its namespace prefixes. There are five different namespaces you will run into frequently (see declared constants). Finally we run the XPath query and return the collection of matching XML nodes. The namespace shown in our sample XML snippet gets the "sp" namespace prefix associated so our XPath query would change to "//sp:List". This will now return all matching XML nodes.

Some real life examples of using the SharePoint web services

The following examples demonstrate how you can leverage the SharePoint web services to interact tightly with SharePoint from within your application. The detailed code for each example can be found in the attached "SharePoint explorer" sample application. The description below explains which web service and web method to use to obtain the desired SharePoint information.

Example 1 - Get the collection of SharePoint lists, fields and views

In the first example we want to get the collection of SharePoint lists. For each list we want to get all the defined list fields (fields you can use to store information) and finally all views associated with the list. Here are the web methods to call:

• On the Lists web service call the GetListCollection() web method to get the collection of all SharePoint lists. This returns an XML document with all SharePoint lists.
• Next you run the "//sp:List" XPath query to get all matching List nodes. The Title attribute of each matching node contains the name of the SharePoint list.
• For each SharePoint list we call the GetList() web method on the Lists web service, passing along the list name. This returns a XML document with detailed information about the list including the list of fields.
• Next you run the "//sp:Field" XPath query to get all the matching Field nodes. The Name attribute contains the field name.
• For each SharePoint list we call the GetViewCollction() web method on the Views web service, passing along again the list name. This returns a XML document listing all views for the list.
• Finally you run the "//sp:View" XPath query to get all the matching View nodes. The Name attribute contains the name of the view.

Example 2 - Get the list of users and site-groups

In this example we want to get the list of site users and to which site group each user belongs. We also want to get the list of site groups and which users belong to each site group.

• On the Users-and-Groups web service we call the GetUserCollectionFromWeb() web method. This returns an XML document with all the site users.
• Next you run the "//d:User" XPath query to get all the matching User nodes. The Name attribute contains the user name and the LoginName attribute the user's login name.
• For each user we call the GetRoleCollectionFromUser() web method on the Users-and-Groups web service passing along the user's login name. This returns a XML document with all the site groups the user belongs to.
• Next you run the "//d:Role" XPath query to get all the matching Role nodes. The Name attribute contains the site group name.
• To get the list of site groups call the GetRoleCollectionFromWeb() web method on the Users-and-Groups web service. This returns an XML document with all site groups.
• Next you run again the "//d:Role" XPath query to get all the matching Role nodes. The Name attribute contains the site group name.
• Finally call for each site group the GetUserCollectionFromRole() web method on the Users-and-Groups web service passing along the site group name. This returns an XML document with all the users belonging to this site group.
• Next you run again the "//d:User" XPath query to get all the matching User nodes. The Name attribute contains the user name and the LoginName attribute the user's login name.

Example 3 - Get the list of sites, site-templates and list-templates

With the last example we want to get a list of all sites in the site collection. We want to get for the site collection the list of site templates. Additionally we want for each site the list of list templates.

• First we call the GetAllSubWebCollection() web method on the Webs web service. This returns an XML document with all sites in the site collection.
• Next run the "//sp:Web" XPath query to return all matching Web nodes. The Url attribute contains the absolute URL for the site.
• Then we call the GetSiteTemplates() web method on the Sites web service. This returns an array of available site templates in the site collection, which is an array of the type Sites.Templates. The attached sample application converts all structures to an XML document using reflection, so you can run XPath queries against it (see the method SharePoint.SitesGetSiteTemplates()).
• Next run the "//SharePointServices.Sites.Templates" XPath query which returns all matching template nodes. The Title attribute contains the template title and the Name attribute the SharePoint template name.
• For each site we call the GetListTemplates() web method on the Webs web service. Before calling the web service object you need to set the URL to the site URL (returned by GetAllSubWebCollection()). This way we make sure that t he call is to the site itself and returns the list templates of that site. This returns an XML document with all list templates.
• To finish run the "//sp:SiteTemplate" XPath query to return all matching SiteTemplate nodes. The DisplayName attribute contains the name of the list template.

Summary

SharePoint comes with a vast number of web services and web methods which enable you to tightly integrate SharePoint capabilities into your application. It is very easy to learn and use these web services and web methods. Please refer to the attached "SharePoint web service browser" example which provides a complete wrapper class for all existing (about 150) web methods. This removes the burden of adding all the web references and worrying about the details how to instantiate each web method, etc. The sample application provides a user interface to explore all web methods. You can browse the web services and web methods, display the SDK help page, enter the input values, execute the web method and look at the displayed output values.

The second example - "SharePoint explorer" provides a much more comprehensive sample of how to use and work with the SharePoint web services and web methods. It retrieves as much information and displays the data in lists and tree nodes (always running simple XPath queries against the result-set). The user interface allows you to traverse through the related data. You can also write your own web services using the managed SharePoint server API. Here is a sample application which provides a document check-in and check-out capability through a new web service.