<DriverAlias> & <DriverType>

<DriverAlias> elements are defined for each alias that an application may use. The <DriverAlias> may contain several <DriverType> elements.

<DriverType> elements are repeated for each driver type that applies to the <DriverAlias>. You can add any element needed to support a driver without requiring any changes to the Data Access Layer (DAL). Each <DriverType> element must contain Description, DriverLocator, and TransportType elements. The element values must be non-null, otherwise the DAL initialization will throw an exception. The elements contain the following:

• <Description> – A description string that may be used in debug messages.

• <DriverLocator> – The file name of the driver DLL to be loaded from the bin directory.

• <TransportType> – The transportation type is either InProcess or Remote.

• <DriverProperty> – This optional element may be specified several times with different name attribute values. It is used to specify driver-unique properties and to add CredentialName properties when the driver should use a credential type other than Default (Single Sign On [SSO]). For example, <DriverProperty Name="CredentialName">RequiresAuthorization</DriverProperty>.

Global driver properties (properties common to all driver aliases) include:

• <DriverProperty Name="ExecutionTimeOutMS"> – This element is the timeout (in milliseconds) that will be passed to the DAL driver along with the request to be executed. Whether or not this value will be actually used by the DAL driver is specific to the implementation of that driver. The default is 30000 milliseconds.

• <DriverProperty Name="RequestTimeOutMS"> – This element is the overall request timeout (in milliseconds) that will be monitored by a thread created on the client side when the request is submitted to the DAL driver. This timer can be used to detect and handle a DAL driver hanging while processing the request. If the DAL driver does not support an execution timeout, this property can be used to provide the same functionality. Otherwise, as it is likely not necessary, and it is expensive CPU-wise, you should avoid it.

  Note: This timer should be longer than the ExecutionTimeOutMS property to avoid race conditions. The default for most driver types is 90000 milliseconds, and a value of 0 milliseconds may be used to indicate an infinite request timeout. The exception is the PubSub driver type, which defaults to an infinite request timeout that cannot be overridden.