# CAS Visual Debugger

## Introduction

The CAS Visual Debugger is a tool to run text analysis engines in UIMA and view the results. The tool is implemented as a stand-alone GUI tool using Java's Swing library.

This is a developer's tool. It is intended to support you in writing text analysis annotators for UIMA (Unstructured Information Management Architecture). As a development tool, the emphasis is not so much on pretty pictures, but rather on navigability. It is intended to show you all the information you need, and show it to you quickly (at least on a fast machine ;-).

The main purpose of this application is to let you browse all the data that was created when you ran an analysis engine over some text. The display mimics the access methods you have in the CAS API in terms of indexes, types, feature structures and feature values.

As in the CAS, there is special support for annotations. Clicking on an annotation will select the corresponding text, and conversely, you can display all annotations that cover a given position in the text. This will be explained in more detail in the section on the main display area.

As usual, the graphics in this manual are for illustrative purposes and may not look 100% like the actual version of CVD you are running. This depends on your operating system, your version of Java, and a variety of other factors.

### Running CVD

You will usually want to start CVD from the command line, or from Eclipse. To start CVD from the command line, you minimally need the uima-core and uima-tools jars. Below is a sample command line for sh and its offspring.

    java -cp ${UIMA_HOME}/lib/uima-core.jar:${UIMA_HOME}/lib/uima-tools.jar
        org.apache.uima.tools.cvd.CVD

However, there is no need to type this. The ${UIMA_HOME}/bin directory contains a cvd.sh and cvd.bat file for Unix/Linux/MacOS and Windows, respectively.

In Eclipse, you have a ready to use launch configuration available when you have installed the UIMA sample project (see ). Below is a screenshot of the the Eclipse Run dialog with the CVD run configuration selected.

Eclipse run dialog with CVD selected

### Command line parameters

You can provide some command line parameters to influence the startup behavior of CVD. For example, if you want to run a certain analysis engine on a certain text over and over again (for debugging, say), you can make CVD load the annotator and text at startup and execute the annotator. Here's a list of the supported command line options.

Command line options

Option | Description
--- | ---
`-text <textFile>` | Loads the text file `<textFile>`
`-desc <descriptorFile>` | Loads the descriptor `<descriptorFile>`
`-exec` | Runs the pre-loaded annotator; only allowed in conjunction with `-desc`
`-datapath <datapath>` | Sets the data path to `<datapath>`
`-ini <iniFile>` | Makes CVD use alternative ini file `<textFile>` (default is ~/annotViewer.pref)
`-lookandfeel <lnfClass>` | Uses alternative look-and-feel `<lnfClass>`

## Error Handling

On encountering an error, CVD will pop up an error dialog with a short, usually incomprehensible message. Often, the error message will claim that there is more information available in the log file, and sometimes, this is actually true; so do go and check the log. You can view the log file by selecting the appropriate item in the "Tools" menu.

Sample error dialog

## Preferences File

The program will attempt to read on startup and save on exit a file called annotViewer.pref in your home directory. This file contains information about choices you made while running the program: directories (such as where your data files are) and window sizes. These settings will be used the next time you use the program. There is no user control over this process, but the file format is reasonably transparent, in case you feel like changing it. Note, however, that the file will be overwritten every time you exit the program.

If you use CVD for several projects, it may be convenient to use a different ini files for each project. You can specify the ini file CVD should use with the

    -ini <iniFile>

parameter on the command line.

## The Menus

We give a brief description of the various menus. All menu items come with mnemonics (e.g., Alt-F X will exit the program). In addition, some menu items have their own keyboard accelerators that you can use anywhere in the program. For example, Ctrl-S will save the text you've been editing.

### The File Menu

The File menu lets you load, create and save text, load and save color settings, and import and export the XCAS format. Here's a screenshot.

The File menu

Below is a list of the menu items, together with an explanation.

- New Text...

  Clears the text area. Text you type is written to an anonymous buffer. You can use "Save Text As..." to save the text you typed to a file. Note: whenever you modify the text, be it through typing, loading a file or using the "New Text..." menu item, previous analysis results will be lost. Since the previous analysis is specific to the text, modifying the text invalidates the analysis.

- Open Text File

  Loads a new text file into the viewer. The next time you run an analysis engine, it will run the text you loaded last. Depending on the annotator you're using, the program may run slow with very large text files, so you may want to experiment.

- Save Text File

  Saves the currently open text file. If no file is currently loaded (either because you haven't loaded a file, or you've used the "New Text..." menu item), this menu item is disabled (and Ctrl-S will do nothing).

- Save Text As...

  Save the text to a file of your choosing. This can be an existing file, which is then overwritten, or it can be a new file that you're creating.

- Change Code Page

  Allows you to change the code page that is used to load and save text files. If you're sure the text you're loading is in ASCII or one of the 8-bit extensions such as ISO-8859-1 (ISO Latin1), there is probably nothing you need to do. Just load the text and look at the display. If you see no funny characters or square boxes, chances are your selected code page is compatible with your text file. Note that the code page setting is also in effect when you save files. You can observe the effects with a hex editor or by just looking at the file size. For example, if you save the default text `This is where the text goes.` to a file on Windows using the default code page, the size of the file will be 28 bytes. If you now change the code page to UTF-16 and save the file again, the file size will be 58 bytes: two bytes for each character, plus two bytes for the byte-order mark. Now switch the code page back to the default Windows code page and reload the UTF-16 file to see the difference in the editor. CVD will display all code pages that are available in the JVM you're running it on. The first code page in the list is the default code page of your system. This is also CVD's default if you don't make a specific choice. Your code page selection will be remembered in CVD's ini file.

- Load Color Settings

  Load previously saved color settings from a file (see Tools/Customize Annotation Display). It is highly recommended that you only load automatically generated files. Strange things may happen if you try to load the wrong file format. On startup, the program attempts to load the last color settings file that you loaded or saved during a previous session. If you intend to use the same color settings as the last time you ran the program, there is therefore no need to manually load a color settings file.

- Save Color Settings

  Save your customized color settings (see Tools/Customize Annotation Display). The file is a Java properties file, and as such, reasonably transparent. What is not transparent is the encoding of the colors (integer encoding of 24-bit RGB values), so changing the file by hand is not really recommended.

- Read Type System File

  Load a type system file. This allows you to load an XCAS file without having to have access to the corresponding annotator.

- Write Type System File

  Create a type system file from the currently loaded type definitions. In addition, you can save the current CAS as a XCAS file (see below). This allows you to later load the type system and XCAS to view the CAS without having to rerun the annotator.

- Read XMI CAS File

  Read an XMI CAS file. Important: XMI CAS is a serialization format that serializes a CAS without type system and index information. It is therefore impossible to read in a stand-alone XMI CAS file. XMI CAS files can only be interpreted in the context of an existing type system. Consequently, you need to first load the Analysis Engine that was used to create the XMI file, to be able to load that XMI file.

- Write XMI CAS File

  Writes the current analysis out as an XMI CAS file.

- Read XCAS File

  Read an XCAS file. Important: XCAS is a serialization format that serializes a CAS without type system and index information. It is therefore impossible to read in a stand-alone XCAS file. XCAS files can only be interpreted in the context of an existing type system. Consequently, you need to load the Analysis Engine that was used to create the XCAS file to be able to load it. Loading a XCAS file without loading the Analysis Engine may produce strange errors. You may get syntax errors on loading the XCAS file, or worse, everything may appear to go smoothly but in reality your CAS may be corrupted.

- Write XCAS File

  Writes the current analysis out as an XCAS file.

- Exit

  Exits the program. Your preferences will be saved.

### The Edit Menu

The Edit menu
The "Edit" menu provides a standard text editing menu with Cut, Copy and Paste, as well as unlimited Undo.

Note that standard keyboard accelerators Ctrl-X, Ctrl-C, Ctrl-V and Ctrl-Z can be used for Cut, Copy, Paste and Undo, respectively. The text area supports other standard keyboard operations such as navigation HOME, Ctrl-HOME etc., as well as marking text with Shift- <ArrowKey>.

### The Run Menu

The Run menu
In the Run menu, you can load and run text analysis engines.

- Load AE

  Loads and initializes a text analysis engine. Choosing this menu item will display a file open dialog where you should choose an XML descriptor of a Text Analysis Engine to process the current text. Even if the analysis engine runs fast, this will take a while, since there is a lot of setup work to do when a new TAE is created. So be patient. When you develop a new annotator, you will often need to recompile your code. Gladis will not reload your annotator code. When you recompile your code, you need to terminate the GUI and restart it. If you only make changes to the XML descriptor, you don't need to restart the GUI. Simply reload the XML file.

- Run AE

  Before you have (successfully) loaded a TAE, this menu item will be disabled. After you have loaded a TAE, it will be enabled, and the name changes according to the name of the TAE you have loaded. For example, if you've loaded "The World's Fastest Parser", you will have a menu item called "Run The World's Fastest Parser". When you choose the item, the TAE is run on whatever text you have currently loaded. After a TAE has run successfully, the index window in the upper left-hand corner of the screen should be updated and show the indexes that were created by this run. We will have more to say about indexes and what to do with them later.

- Run AE on CAS

  This allows you to run an analysis engine on the current CAS. This is useful if you have loaded a CAS from an XCAS file, and would like to run further analysis on it.

- Run collectionProcessComplete

  When you select this item, the analysis engine's collectionProcessComplete() method is called.

- Performance Report

  After you've run your analysis, you can view a performance report. It will show you where the time went: which component used how much of the processing time.

- Recently used

  Collects a list of recently used analysis engines as a short-cut for loading.

- Language

  Some annotators do language specific processing. For example, if you run lexical analysis, the results may be quite different depending on what the analysis engine thinks the language of the document is. With this menu item, you can manually set the document language. Alternatively, you can use an automatic language identification annotator. If the analysis engines you're working with are language agnostic, there is no need to set the language.

### The tools menu

The tools menu contains some assorted utilities, such as the log file viewer. Here you can also set the log level for UIMA. A more detailed description of some of the menu items follows below.

#### View Type System

Brings up a new window that displays the type system. This menu item is disabled until the first time you have run an analysis engine, since there is no type system to display until then. An example is shown above.

You can view the inheritance tree on the left by expanding and collapsing nodes. When you select a type, the features defined on that type are displayed in the table on the right. The feature table has three columns. The first gives the name of the feature, the second one the type of the feature (i.e., what values it takes), and the third column displays the highest type this feature is defined on. In this example, the features "begin" and "end" are inherited from the built-in annotation type.

In the options menu, you can configure if you want to see inherited features or not (not yet implemented).

#### Show Selected Annotations

Annotations produced by a statistical named entity tagger

To enable this menu, you must have run an analysis engine and selected the ``AnnotationIndex'' or one of its subnodes in the upper left hand corncer of the screen. It will bring up a new text window with all selected annotations marked up in the text.

shows the results of applying a statistical named entity tagger to a newspaper article. Some annotation colors have been customized: countries are in reverse video, organizations have a turquois background, person names are green, and occupations have a maroon background. The default background color is yellow. This color is also used if there is more than one annotation spanning a certain text. Clearly, this display is only useful if you don't have any overlapping annotations, or at least not too many.

This menu item is also available as a context menu in the Index Tree area of the main window. To use it, select the annotation index or one of its subnodes, right-click to bring up a popup menu, and select the only item in the popup menu. The popup menu is actually a better way to invoke the annotation display, since it changes according to the selection in the Index Tree area, and will tell you if what you've selected can be displayed or not.

## The Main Display Area

The main display area has three sub-areas. In the upper left-hand corner is the index display, which shows the indexes that were defined in the AE, as well as the types of the indexes and their subtypes. In the lower left-hand corner, the content of indexes and sub-indexes is displayed (FS display). Clicking on any node in the index display will show the corresponding feature structures in the FS display. You can explore those structures by expanding the tree nodes. When you click on a node that represents an annotation, clicking on it will cause the corresponding text span to marked in the text display.

State of GUI after running an analysis engine

shows the state after running the UIMA_Analysis_Example.xml aggregate from the uimaj-examples project. There are two indexes in the index display, and the annotation index has been selected. Note that the number of structures in an index is displayed in square brackets after the index name.

Since displaying thousands of sister nodes is both confusing and slow, nodes are grouped in powers of 10. As soon as there are no more than 100 sister nodes, they are displayed next to each other.

In our example, a name annotation has been selected, and the corresponding token text is highlighted in the text area. We have also expanded the token node to display its structure (not much to see in this simple example).

In , we selected an annotation in the FS display to find the corresponding text. We can also do the reverse and find out what annotations cover a certain point in the text. Let's go back to the name recognizer for an example.

Finding annotations for a specific location in the text

We would like to know if the Michael Baessler has been recognized as a name. So we position the cursor in the corresponding text span somewhere, then right-click to bring up the context menu telling us which annotations exist at this point. An example is shown in .

Selecting an annotation from the context menu will highlight that annotation in the FS display

At this point (), we only know that somewhere around the text cursor position (not visible in the picture), we discovered a name. When we select the corresponding entry in the context menu, the name annotation is selected in the FS display, and its covered text is highlighted. shows the display after the name node has been selected in the popup menu.

We're glad to see that, indeed, Michael Baessler is considered to be a name. Note that in the FS display, the corresponding annotation node has been selected, and the tree has been expanded to make the node visible.

NB that the annotations displayed in the popup menu come from the annotations currently displayed in the FS display. If you didn't select the annotation index or one of its sub-nodes, no annotations can be displayed and the popup menu will be empty.

### The Status Bar

At the bottom of the screen, some useful information is displayed in the status bar. The left-most area shows the most recent major event, with the time when the event terminated in square brackets. The next area shows the file name of the currently loaded XML descriptor. This area supports a tool tip that will show the full path to the file. The right-most area shows the current cursor position, or the extent of the selection, if a portion of the text has been selected. The numbers correspond to the character offsets that are used for annotations.

### Keyboard Navigation and Shortcuts

The GUI can be completely navigated and operated through the keyboard. All menus and menu items support keyboard mnemonics, and some common operations are accessible through keyboard accelerators.

You can move the focus between the three main areas using `Tab` (clockwise) and `Shift-Tab` (counterclockwise). When the focus is on the text area, the `Tab` key will insert the corresponding character into the text, so you will need to use `Ctrl-Tab` and `Ctrl-Shift-Tab` instead. Alternatively, you can use the following key bindings to jump directly to one of the areas: `Ctrl-T` to focus the text area, `Ctrl-I` for the index repository frame and `Ctrl-F` for the feature structure area.

Some additional keyboard shortcuts are available only in the text area, such as `Ctrl-X` for Cut, `Ctrl-C` for Copy, `Ctrl-V` for Paste and `Ctrl-Z` for Undo. The context menu in the text area can be evoke through the `Alt-Enter` shortcut. Text can be selected using the arrow keys while holding the `Shift` key.

The following table shows the supported keyboard shortcuts.

Keyboard shortcuts

Shortcut | Action | Scope
--- | --- | ---
`Ctrl-O` | Open text file | Global
`Ctrl-S` | Save text file | Global
`Ctrl-L` | Load AE descriptor | Global
`Ctrl-R` | Run current AE | Global
`Ctrl-I` | Switch focus to index repository | Global
`Ctrl-T` | Switch focus to text area | Global
`Ctrl-F` | Switch focus to FS area | Global
`Ctrl-X` | Cut selection | Text
`Ctrl-C` | Copy selection | Text
`Ctrl-V` | Paste selection | Text
`Ctrl-Z` | Undo | Text
`Alt-Enter` | Show context menu | Text