Filter
Top Products
Using the VPO Application Programming Interfaces
The VPO Interfaces
Chapter 4 181
Figure 4-6 Using the Legacy Link Interface to Integrate a Legacy System
Data From
Legacy
System?
No
Call opcif_open() 3 times
Open 3 interface instances to:
(1) send messages, (2) receive action
requests, (3) send action responses
opcif_read()
Read action request
originating from VPO server
Pass action requestto legacy
system
opcif_write()
Write message or action
response to VPO server
START
Yes
Call opcif_close() 3 times
Close all interface
instances
STOP
Establish communication with legacy
system
Wait for incoming data:
- From Legacy System:messages or action
responses
- From VPO server: action requests
No
Yes
Data From
VPO Server?
No
Yes
Terminate?
opcdata_create(),
opcdata_set_...()
Create and set fields for
either a message or an
action response
Read data originating from
legacy system