XQuery Debugger

XQuery Debugging Perspective

04:09
XQuery Debugger

Save time when developing complicated XQuery expressions by using oXygen XQuery debugger. oXygen can debug and profile expressions run over the MarkLogic XML database, or using the Saxon EE processors.

oXygen provides a special layout when entering in debugging mode to show the XML source (optional) and the XQuery documents side by side and to show also the result and special XQuery debugging views and toolbars. The perspective allows you to use the common XML and XQuery editor features.

oXygen XQuery Debugger

The XQuery debugger support is based on the Saxon EE XQuery processor which is bundled with oXygen.

Full Control Over the XQuery Debugging Process

oXygen provides all the usual debugging capabilities: step into, step over, step out, run, run to cursor, run to end, pause, stop. The current XML and XQuery nodes reached by the debugging process are shown (see the right part in the image that follows) with the following details: an arrow icon to show the action performed on it (entering/leaving), the name, the resource and the line. By clicking the arrow the text sections corresponding to the XML and XQuery nodes are highlighted in the editor.

Control toolbar

Output Result is Linked to the Generating XQuery Element.

Allows you to easily find out what element from the XQuery document generated a section of the output. For this you just have to click on the Output text view. The editor will highlight the line in the XQuery document that generated the output.

The following image shows the right part of the debugging perspective, with the XQuery source in the left and the output in the right. The "<name>J. D. Salinger</name>" fragment of the output was generated by the highlighted name element of the input XQuery file.

Output is linked to the XSLT element

Pause the Debugger Execution with Breakpoints

Breakpoints can be set on the XQuery document used in the transformation. The breakpoints appear in the left bar of the XQuery editor, as a red dot, and they can be created easily by using the shortcut key or by clicking the breakpoints area.

XQuery Breakpoints

Conditional Breakpoints

A condition can be attached to a breakpoint set in the Debugger perspective so that processing stops only if the condition is true.

Break Conditions

XQuery Call Stack View

The current stack containing XQuery instructions can be inspected at any time during the debugging process. The Stack view shows the sequence of XQuery instructions currently executed by the debugger.

Call stack

Trace History View

Entering and leaving node events are logged and made available in a view to show the history of the processor execution. You can click the entries in the list to see the corresponding instructions highlighted in the editor associated with the XQuery file where the instruction is defined.

Trace history

Save the Debug Trace

It is possible to save the element trace obtained from a debug session as XML. This permits comparing different debug runs.

Save XSLT trace

Tree View For Presenting Node Set Values

The current context node value or the values of variables that are evaluated to tree fragment or list of nodes are presented in tree views, thus giving access to the whole variable content. This is useful especially in debugging XQuery transformations that keep intermediary results in variables.

The user can easily locate the nodes from the tree by simply clicking on them: the editor will select the corresponding XQuery instruction.

Nodes values view

XQuery Variables View

The debugger lists all XQuery variables and parameters that are visible in the current XQuery context together with their scope and actual value. The view is updated as the XQuery processor changes the context during the transformation.

Variables and parameters view

Dynamic XQuery Output Generation

The output is dynamically presented as it is generated by the XQuery transformation process. The user can examine directly the output as XML source.

Scenario Based XQuery Debugging Session

oXygen has a powerful transformation support based on reusable scenarios. The same scenarios can be used for debugging. The XQuery Debugger will be initialized with the information from the XQuery scenario (source document location, transformation parameters) when the Debug scenario action is executed. This allows to easily manage and trigger different debugging sessions.

XQuery Profiler

You can profile your XQuery queries to identify the performance issues using two comprehensive data views of the activated templates: an Invocation Tree view and a Hotspots view. The profiling information can be saved to XML or HTML formats.

Profiling is available only for the Saxon XQuery processor which is bundled with oXygen.

Invocation Tree view

Using the Invocation Tree view, also named a call tree, you can examine how XQuery instructions are processed in a top down manner. The profiling result shows the duration time for each of the style-instruction including the time needed for its children and then, when an instruction is expanded, you can see how the instruction time is composed from child instruction times.

Invocation tree view

Hotspots view

Using the profiler Hotspots view you can immediately detect the time the processor spent in each instruction. The hotspot only presents the inherent time of the instruction, that is the total time of processing that instruction minus the time for processing its children instructions. When a hotspot is expanded you can see all the different paths that instruction was called from (a reverse invocation tree), each path being labeled with the number of invocations, the instruction time on that path and what percentage from the instruction total execution that path contributes.

Hotspots view