VI Trace Process Object

The Visual Integrator (VI) Trace process object debugs VI scripts by writing intermediate column values either to standard output or trace files. The Trace object can limit the trace data to certain rows or columns of the input data.

Icon for the VI Trace process object

The Format attribute options horizontal and column_header generate data that you can process with VI or Builder. This provides a way to snapshot an intermediate result of a VI script, for example, when there are calculated fields.

The Trace process object has Closedthree panes where you set attributes.

VI Trace Object All Panes

You set attributes for the Trace process object in the Closedobject attributes pane.

Example of VI Trace process object's attributes pane

Attribute Description
Input

Defines the object from which the data flow arrives. Use one of the following methods to attach the Trace object to an input data flow object:

  • Right-click the input data flow object, and click New Object after this > Process > Trace.

  • Place a Trace object on the task flow, and click its Input attribute's browse button. Move the pointer to the task flow, and note that a dotted-line connector is attached to the Trace object. Attach this connector to the input data flow object.

    NOTE: The Trace object's Input attribute is now populated with the name of the input data flow object.
Format

Defines the format for the trace information. This required attribute specifies one of the following formats:

  • vertical—Writes the trace output as labeled column values, one value per line. Multiple rows are separated with blank lines. ClosedFor example:

    Example of VI Trace process object's output with vertical format

  • horizontal—Writes the trace output as rows of values separated by delimiters. The columns are not labeled. ClosedFor example:

    Example of VI Trace process object's output with horizontal format

  • column_headers (defatul)—Writes the trace output as rows of values separated by delimiters, with a single heading row labeling the columns. This format is similar to the column_headers value for the File_Type attribute in the Fileout output object. ClosedFor example:
Delimiter

Specifies the delimiter that is used to separate columns for variable format files. If not specified, ASCII tab is used. Choices are:

  • space
  • tab \t
  • comma ,
  • semicolon ;
  • pipe |
Append

Specifies whether or not to append information to an existing trace file.

  • true—Trace information is appended to the end of the existing trace file. Ensure that columns of the appended data match the columns in the existing file.
  • false (default)—Trace information overwrites any existing trace file

Case_Sensitive

Controls whether comparisons are case-sensitive.

  • true—Comparisons are case-sensitive.
  • false (default)—Comparisons are case-insensitive.
Disable

Disables tracing for the object. When this attribute is set to true, you can keep the Trace object in the VI script for later use without any data flow consequences.

  • true—No tracing is performed.
  • false (default)—Tracing is performed.
Verbose

Determines if the trace rows are labeled with the object name and row number.

  • true (default)—Trace rows are labeled. For Format attribute values set to horizontal or column_headers, the verbose data appears in two columns named Trace and Row.
  • false—Trace rows are not labeled. For Format attribute values set to horizontal or column_headers, the non-verbose format generates data useful for VI or Builder. This is a convenient way to capture intermediate results.
Qual_Str Defines a qualification string used to filter rows to be traced. Only traces rows between the start and end row number that match the specified criteria. For information about qualification string syntax, see VI Qual Process Object.
Start Defines the starting row number used to display trace information. The first row is row number one. Any rows before the start row are not traced. If this attribute is blank, tracing starts with the first row.
End Defines the ending row number used to display trace information. Any rows after the end row are not traced. If this attribute is blank, tracing is not limited by an ending row number.
Limit Defines the maximum number of rows that output as trace information. This attribute is applied after the Qual_Str attribute and works differently than the Start and End attributes in that the limit count applies to output rather than input rows.
Dictionary_File Specifies a dictionary file that is written with the format of the trace output. The dictionary file can be an old-style or new-style dictionary. Use this attribute only with non-verbose horizontal output. Use the browse button to navigate to the dictionary file.

Each object has an area where you can enter comments.

It is a DI best practice to enter a note for every object in a VI script. You can set a VI preference to give a warning for each object without a note. For more information, see Visual Integrator Preferences.

ClosedTrace process object with comments

Example of VI Trace process object with comments

The ClosedTrace column grid displays the input columns where you can set which columns are traced and the output order.

Example of a VI Trace process object's column grid

Attribute

 Description
Input Column Displays the name of each input column. This attribute is read-only.
Source Object Displays the name and object type of the source object. Double-click the Source Object for a column to change the task flow focus to that object.
Keep Order

Manages the order that columns display in the output data flow. By default, columns that are passed to the next object in the data flow are displayed in the order they appear in the Input Column column. You can change this order by typing a number in the Keep Order column.
Columns Defines the set of columns that are displayed in the output data flow. Select each input column that you want to trace.