Calling external web services and displaying data

Users can create external web service calls and display these data in a datagrid in the form.

NOTE: Other controls can also be connected with a web service call. In that case only the first attribute for the first record will be used and if the value is valid for that control it will be displayed properly.

To define a new web service call all of the followng properties must be defined:

• A custom Name for referencing the web service call
• The external Url of the web service
• The specific Method to call from the above web service
• The Xml Namespace used by the Web Service. This is required for a well formed request to the service.

• The Handle Namespace option to allow for simpler xpath queries (see below)
• The Parameters with their respective values. Each parameter is defined as pair of strings (ParameterName];[ParameterValue) and each pair is seperated by a pipeline (|) from the next one. For example, if two parameters exist, FirstName and LastName and their respective values are John Smith then one should input the following: FirstName;John|LastName;Smith. One can also enter the same values or edit them, using the provided pop-up form.

NOTE: As with everything that has to do with XML, the above values are case sensitive.

When all the above fields are filled properly pressing the Test button shows the result that the web service provides, to confirm their validity. If any error occurs while calling the web service the resulting error will be displayed instead.

 

The second part of a web service call, consists of defing an XPath Query to be used for extracting the needed information. For each element returned a row will be displayed in the DataGrid with all of its attributes (Auto Populate)

If Handle Namespaces is selected simple xpath queries can be used, e.g.: //z:row[@ows__Level=2].
If Handle Namespaces is not selected the xpath cannot contain prefixed elements and one should reside to the use of local-name(), e.g. //*[local-name() = ‘row’][@ows__Level=’1′].

Any element of the form can be referenced inside the XPath Query, by enclosing its name inside brackets. For example: //sales[@customerId={c_customer_id}.
The {c_customer_id} will be replaced with its specific value before Xpath Querying the Web Service Call result.

You can also select specific Attributes to display using their names, seperated by a semicolon (;), e.g. ows_UniqueId;ows_FileLeafRef.

A different name can be used for displaying purposes, other than the name of the Attribute, if a similar list of headers is filled in the Headers textbox. The Headers should match the respective Attributes one-to-one. If fewer Headers are provided the remainng attributes will use the default (the Attribute’s name). If more Headers are provided they will be ignored.

Example :

Once the user has defined a Web Service call, he can then connect it to a WebServiceDataGrid control. In the Advanced tab one has to select a Value Type of Web Service Call, and then pick a specific web service call from the list box Web Service Post Url. The control will display the matching data using the xpath query and the (optionally) defined attributes in a read-only grid.

The same advanced parametrization can be used in all controls but the resulting value might not be valid. For example a checkbox will parse 0 as not checked and 1 as checked but any other value will be ignored and the checkbox will remain not checked.

NOTE: If the web service is external and in a different domain with .xap file, you will have to place the clientaccesspolicy.xml file in site root folder as shown in the instructions here.