Stream Alias - concept for naming of data files
OverviewA stream alias is a short name of one type of data file. In stead of referring to a file using its full path and file name, the software offers a method to use a general specifier for all files of the same type, which is called an alias.
Because each recording file of the same type uses the same alias, it is possible for post-processing applications (that analyze the measurements) to load such a recording, without knowing its exact file name. The software just asks the data manager for the file with a certain alias, and then the manager returns the intended file of the measurement that is currently selected by the user.
Alias as part of the file nameBy default the alias is part of the file name of a recording, as a second extension. A file name commonly looks like this:
[unique file name body].[alias].[extension]
An example of a file name is: 20111125_000639.WaveForms.Poly5
In this example WaveForms is the alias.
Requirements for the use of aliasesA measurement, or measurement session, may contain multiple files. Those files could even be in different file formats and have different properties. Each file contains one part of the data that forms the measurement. Therefore, one measurement can only contain each Stream Alias once.
ExampleSuppose you have a data recording application that stores numerical and waveform data from some measurement device. You have done a series of three measurements in the lab.
On disk, the recorded data files may look like this:
20170824T123521 20170824_123521.Waveforms.poly5 20170824_123521.Numericals.csv Record.xses 20170824T132433 20170824_132433.Waveforms.poly5 20170824_132433.Numericals.csv Record.xses 20170824T155612 20170824_155612.Waveforms.poly5 20170824_155612.Numericals.csv Record.xses
In this example, the first measurement is called '20170824T123521' (this is a file folder on disk) and it contains two data files that were recorded during the same time. The third file 'Record.xses' contains a description of the measurement and is added by the Data Manager.
The other measurements show the same file structure (because recorded with one and the same app), only using different files names.
If this data set is imported in the Data Manager, then the software recognizes that the recording files have a stream alias, because the file names have a second extension. For each of the three measurements, it can be summarized that the measurements contains two different sources of data; one is called Waveforms, and the other Numericals.
An application that knows how to process waveform data, now can simply refer to Waveforms in a selected measurement session, without knowing the exact file name.