Session History

The Database will preserve the full session history. Thus at any point it is possible to find out what was changed when and by whom. The system can report on changes down to the attribute level.

The list of facilities include:

• Comparing elements to an old session

• Dataling out changes since a given session

• Setting a comparison session

• Creating a stamp

• Various pseudo attributes

Comparing Elements to an Old Session

The DIFF command can be used to report on changes. For example, if you were to modify a couple of attributes on an equipment, and add a new primitive, then the DIFF command could be used to report on the changes. The output from the command might be:

• Local comparison for Database items

  /VESS1

  /VESS1 [=15752/201] has been modified

• Member list has changed

  List member /EXTRACYL created

• Description has changed

  Old value= my description

  New value= my new description

• Area has changed

  Old value= 999

  New value= 100

• /EXTRACYL [=15752/1326] has been created

  2 changed elements found

By default, the DIFF command will report the changes made by you in the current working session, that is to say, since the last savework. It is also possible to specify a given session number, a date and time, or a stamp (refer to Create a Stamp) in order to see the differences since then.

Dataling out Changes Since a Given Session

The OUTPUT command may be used to record changes since a given session. The Data Listing (DATAL) file will then contain the commands that reproduce the updates made since the given session. The file can then be read back in to reproduce the changes. This is convenient where bits of data have been copied between projects, and the copied data needs to be updated with changes made to the original.

Reverse changes can also be output. The DATAL file will then contain the commands that remove the updates made since the given session. This is a convenient way for restoring part of a model back to how it was at an earlier point.