The Creo Parametric-Related Classes contain methods that directly manipulate objects in Creo Parametric. Examples of these objects include models, features, and parameters.

Compact data classes are data-only classes. They are used for arguments and return values for some Web.Link methods. They do not represent actual objects in Creo Parametric.

Unions are classes containing potentially several different value types. Every union has a discriminator property with the pre-defined name discr. This method returns a value identifying the type of data that the union object holds. For each union member, a separate property is used to access the different data types. It is illegal to attempt to read any property except the one that matches the value returned from the discriminator. However, any property that switches the discriminator to the new value type can be modified.

The following is an example of a Web.Link union:

class ParamValue
{
    pfcParamValueType            discr;
    string                       StringValue;
    integer                      IntValue;
    boolean                      BoolValue;
    number                       DoubleValue;
    integer                      NoteId;
};

Sequences are expandable arrays of primitive data types or objects in Web.Link. All sequence classes have the same methods for adding to and accessing the array. Sequence classes are typically identified by a plural name, or the suffix seq.

Arrays are groups of primitive types or objects of a specified size. An array can be one or two dimensional. The online reference documentation indicates the exact size of each array class.

In Web.Link, an enumeration class defines a limited number of values which correspond to the members of the enumeration. Each value represents an appropriate type and may be accessed by name. In the pfcFeatureType enumeration class the value FEATTYPE_HOLE represents a Hole feature in Creo Parametric. Enumeration classes in Web.Link generally have names of the form pfcXYZType or pfcXYZStatus.

Some modules in Web.Link have one class that contains special static functions used to create and access some of the other classes in the package. These module classes have the naming convention: "M"+ the name of the module, as in MpfcSelect.

PTC recommends constructing web pages in a way that will work for Windows.

For Chromium browser, the Web.Link classes must be instantiated in the following way:

pfcCefCreate (className);

Use the function pfcCreate() in any situation where a Web.Link object or class must be initialized using its string name. For convenience, these and other useful Web.Link utilities are provided in a file in the example set located at:

<creo_weblink_loadpoint>/weblinkexamples /jscript/pfcUtils.js

Although JavaScript is not strongly typed, the interfaces in Web.Link do expect variables and arguments of certain types. The following primitive types are used by Web.Link and its methods:

These variable types, as well as all explicit object types, are listed in the Web.Link documentation for each property and method argument.

PTC recommends that Web.Link applications ensure that values passed to Web.Link classes are of the correct type.

Many methods in Web.Link are shown in the online documentation as having optional arguments.

For example, the pfcModelItemOwner.ListItems() method takes an optional Type argument.

pfcModelItems ListItems (/*optional*/ pfcModelItemType  Type);

You can pass the JavaScript value keyword void null in place of any such optional argument. The Web.Link methods that take optional arguments provide default handling for void null parameters which is described in the online documentation.

Some methods in Web.Link have an optional return. Usually these correspond to lookup methods that may or may not find an object to return. For example, the pfcBaseSession.GetModel() method returns an optional model:

/*optional*/ pfcModel GetModel(string Name, 
                               pfcModelType Type);

Web.Link might return void null in certain cases where these methods are called. You must use appropriate value checks in your application code to handle these situations.

Web.Link and the JavaScript language provides several methods to identify the type of an object.

Many Web.Link classes provide read access to a type enumerated class. For example, the pfcFeature class has a pfcFeature.FeatType property, returning a pfcFeatureType enumeration value representing the type of the feature. Based upon the type, a user can recognize that the pfcFeature object is actually a particular subtype, such as pfcComponentFeat, which is an assembly component.

Web.Link signals error conditions via exceptions. Exceptions may be caught and handled via a try/catch block surrounding Web.Link code. If exceptions are not caught, they may be ignored by the web browser altogether, or may present a debug dialog box to the user.

Descriptions for Web.Link exceptions may be accessed in a platform-independent way using the JavaScript utility function pfcGetExceptionDescription(), included in the example files in pfcUtils.js. This function returns the full exception description as [Exception type]; [additional details]. The exception type will be the module and exception name, for example, pfcExceptions.XToolkitCheckoutConflict.

The additional details will include details which were contained in the exception when it was thrown by the PFC layer, like conflict descriptions for exceptions caused by server operations and error details for exceptions generated during drawing creation.