Microsoft SharePoint 2007 Technologies

574 18.4 Data Connections

instance, it would make sense to create a template part containing all the

appropriate address fields and then insert this template part into each of the

form templates that needed that information.

18.4 Data Connections

InfoPath form templates contain one or more connections to data sources.

The default data source is the main data source and stores the data entered

onto the form by the user. Additional secondary data sources can be associated

with the form to help populate controls on the form, such as a drop-down

list box. For example, you could have a list box on your form that retrieves its

contents from a SharePoint list when the form is opened.

Data sources are configured through the use of data connections, which

are also referred to as query connections. The data connections can be stored

directly with the form template, or they can be stored in a Data Connection

Library. A Data Connection Library (DCL) is a special type of document

Figure 18.10

Controls filtered on

compatibility

settings.

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library that comes with SharePoint Server 2007 and is used to store data con-

nection files. Two types of data connection files can be stored in the DCL: an

Office Data Connection (ODC) file and a Universal Data Connection

(UDC) file. InfoPath form templates use UDC-type data connections, and

the files generally have a .udcx or a .xml extension. Figure 18.11 shows the

contents of a UDC file generated by InfoPath 2007 and stored in a local

DCL in a SharePoint site. This specific data connection only retrieves infor-

mation from the SharePoint list; it does not update data in the list.

The UDC file format has been around since FrontPage 2003. If you

browse the Microsoft site for information on the schema, you will find that

there are actually two versions of the UDC file format; InfoPath uses the

V2.0 version. If you want to create a UDC data connection file for use with

InfoPath form templates, you can build the .udcx file from scratch using

Notepad and the examples provided by MSDN, or you can leverage the Data

Connection Wizard that comes with InfoPath 2007 (Figure 18.12). The

Data Connection Wizard provides tools with which you can set up the con-

nection and store it directly with the form template. The wizard extracts all

the relevant information needed to perform your query.

You can then use the wizard to convert this data connection into a UDC

file and store it directly into a DCL on the SharePoint server (Figure 18.13).

If you can store the connection information with the form template, why

would you want to go to the bother of creating a UDC file? One of the main

Figure 18.11

Universal data

connection

(.udcx) file.

576 18.4 Data Connections

advantages of using UDC files to store data connection information is that it

allows you to share the same data connection information among many form

templates, without requiring each template to hold its own copy of the con-

nection data (as was the case with InfoPath 2003). It also greatly improves

the maintenance and upkeep of connection information; should the data

source move, you only have to update the data connection information in

one file instead of editing each form template that leverages the data connec-

tion. Additionally, data connections stored in a UDC file support cross-

domain connections, which means that you can connect to data outside of

the current domain boundary. Such connections are not possible unless the

data connection uses a UDC file. Figure 18.14 shows the error displayed to

the user when a form template attempts to make a cross-domain connection

without the use of a UDC file. If we were to replace the data connection

causing the error with a data connection that uses a UDC file, we would still

receive this error if the cross-domain access setting in the Forms Services con-

figuration settings was not enabled. This setting is disabled by default. How-

ever, remember that if you enable cross-domain access for user form

templates, it applies to all user form templates, which if misused has the

potential to cause unscheduled downtime. If your form template needs to

make a cross-domain connection, you should either make the template a

fully trusted form template or ask your administrator to create a data connec-

tion in the centrally managed connection library.

Figure 18.12

Data Connections

Wizard.

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When you convert a data connection into a UDC file you are given the

option of selecting the connection link type. The connection link type to the

Figure 18.13

Convert data

connection to

UDC file.

Figure 18.14

Cross-domain data

connection error.