There are three ways access modules are engaged when multiple FILE_READER instances are used:
- When the FileName attribute specifies a single file name, only the access module for the main instance will be sent Open and Read requests. The worker instances will be sent other requests (such as Init and Shutdown), but not Open and Read requests.
- When the FileName attribute includes a wildcard, one or more access modules will be sent Open and Read requests, depending upon how many files match the wildcard syntax. For example, if there are 5 FILE_READER instances but only 3 files match the wildcard syntax, then 3 access modules will be sent Open and Read requests. Access modules for the other two instances will be sent other requests (such as Init and Shutdown), but not Open and Read requests.
- When the FileName attribute is not defined but the AccessModuleInitStr attribute is defined, then the access modules for all FILE_READER instances will be sent Open and Read requests. It is up to the access module itself to know which file to open (possibly based on information in the initialization string).