# ppxBegin

Begins a series of switching commands.

#### Prototype

DWORD ppxBegin ( CTAHD ctahd )

Argument | Description
ctahd | Context handle returned by ctaCreateContext or ctaAttachContext.

#### Return values

Return value | Description
SUCCESS |
CTAERR_OUT_OF_MEMORY | Unable to allocate memory.
CTAERR_SVR_COMM | Natural Access server communication error.
PPXERR_COMM_FAILURE | Problems were encountered when communicating with the PPX server.
PPXERR_INVALID_COMMAND | Another ppxBegin is active on the context.

#### Details

ppxBegin starts a series of switching commands. When ppxSubmit is called, the PPX service determines if each operation is valid and if there are valid paths for all connections. If the PPX service cannot make all the requested operations, the system is returned to its state before ppxBegin was called.

After verifying the commands and paths, the PPX service calls the functions to perform the operations. If an error occurs when making the connections, the system is returned to its state before ppxBegin was called.

Only one begin or submit transaction can be active on a given context.

Refer to Managing groups of connections for more information.

#### See also

ppxBeginCancel