Types and structures

• Message tags: Message tags are numerical values that may be associated with messages to be sent or received using BMI. The sending and receiving process must use matching tags in order for a given communication to complete. Unexpected messages are the only exception; in that case only the sender must specify a tag.

  Tags provide a mechanism for PVFS to differentiate between various messages and associate them with specific tasks.

• ID's: ID's are opaque handles that a caller may use to keep track of operations that are currently in progress. ID's are assigned by BMI when an operation is posted and then used in subsequent tests to determine if the operation has completed.

• unexpected_info: This is a struct used to describe incoming unexpected messages. It is filled in by the testunexpected() and waitunexpected() calls (see below).