Functions

The HCD application programming interface provides the functions described in Figure 211. The functions are listed as you need them while requesting data from the HCD HOM services. The constants you have to specify for HRB_FUNCTION and HRB_OBJ_CODE are included in the figure.

Figure 211. Functions provided by the HOM services

Task	Fields in Request Block (HRB)		Explanation
Task	HRB_FUNCTION=	HRB_OBJ_CODE=	Explanation
1. Set up the connection to the HCD API
Setup connection	HRB_SETUP	HRB_HCD	Establish the HCD environment by passing the setup function in the request block. Input: HCD session interface (HSI) record.
2. Open the IODF
Open IODF	HRB_OPEN	HRB_IODF	Open an IODF, for which you have read authority, by passing the HRB_OPEN function in the request block.
3. Request data for HCD objects
Get Processor	HRB_GET	HRB_PROCESSOR	Issue a request with the GET function to retrieve data from the IODF. The request returns the address and the length of the data output block. Issue a request with the HRB_DGET function to obtain the retrieved information. Note: Issue HRB_GET and HRB_MGET before requesting additional data, because the new request deletes all data and messages from the previous request.
Get Channel Subsystem	HRB_GET	HRB_CSS
Get Channel Path	HRB_GET	HRB_CHANNEL
Get Switch	HRB_GET	HRB_SWITCH
Get Physical Control Unit	HRB_GET	HRB_PCU
Get Device	HRB_GET	HRB_DEVICE
Get Activation Status	HRB_ACT_STATUS	HRB_IODF	The request allows you to identify the currently active IODF, processor, and so on. Output: Activation status interface (ASI) record.
4. Get the data from the previous GET request
Data Get	HRB_DGET	HRB_DATA	Issue the request with the address and length of the output area to obtain the data retrieved with the previous GET function. Output: Interface record for the object.
Message Get	HRB_MGET	HRB_MESSAGE	Check the return and reason code of the previous GET request. If the return code is warning, error, or severe, issue the request with the address and length of the output area to obtain the messages. Output: Message interface (MSI) record.
5. Close the IODF
Close IODF	HRB_CLOSE	HRB_IODF	When you do not need the IODF anymore, close the IODF by issuing a request with the close function.
6. Terminate the connection to the HCD API
Terminate connection	HRB_TERMINATE	HRB_HCD	When you do not need the HOM services anymore, terminate the connection by issuing a request with the terminate function.