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Initialization and termination rules

In regular OmniMark programs, there is no real distinction between process-start, process, and process-end rules except that they are performed in that order. Additionally, process-start and process-end rules can be used in any of the aided-translation-type programs. OmniMark doesn't distinguish what can be done with these rules, but process-start and process-end rules should be used only for performing processes that must be executed at the beginning or end of a program, respectively. Usually these processes include whole-program initiation and termination functions. process rules should be used for the main processing within a program.

process-start rules allow you to do processing and produce output at the earliest stages of a program, more or less adjacent to macro and function definitions and global variable declarations. One use of a process-start rule would be to allocate handles and connect to a database:

  process-start

  local SQL_Handle_type EnvironmentHandle
  local SQL_Handle_type ConnectionHandle
  local SQL_Handle_type StatementHandle
  local counter RetCode

  set RetCode to SQLAllocEnv (EnvironmentHandle)
  output "Allocating environment handle - "
  do when RetCode != SQL_SUCCESS
     output "failed%n"
     halt with 1
  else
     output "passed%n"
  done

  set RetCode to SQLAllocHandle
     ( SQL_HANDLE_DBC, EnvironmentHandle, ConnectionHandle )
  output "Allocating connection handle - "
  do when RetCode != SQL_SUCCESS
     output "failed%n"
     halt with 1
  else
     output "passed%n"
  done

  set RetCode to SQLConnect ( ConnectionHandle, "omodbc", 20, "", 0, "", 0 )
  output "Connecting to database - "
  do when RetCode != SQL_SUCCESS
     output "failed%n"
     halt with 1
  else
     output "passed%n"
  done

Similarly, a process-end rule could be used to disconnect from the database and free the handle resources:

  process-end

  set RetCode to SQLDisconnect ( ConnectionHandle )
  output "Disconnecting from database - "
  do when RetCode != SQL_SUCCESS
     output "failed%n"
     halt with 1
  else
     output "passed%n"
  done

  set RetCode to SQLFreeHandle (SQL_HANDLE_DBC, ConnectionHandle)
  output "Freeing connection handle resources - "
  do when RetCode != SQL_SUCCESS
     output "failed%n"
     halt with 1
  else
     output "passed%n"
  done

  set RetCode to SQLFreeHandle (SQL_HANDLE_ENV, EnvironmentHandle)
  output "Freeing environment handle resources - "
  do when RetCode != SQL_SUCCESS
     output "failed%n"
     halt with 1
  else
     output "passed%n"
  done

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