XMLAppender

Categories

Format Specific

Web

Assembles several XML documents into one.

The transformer has two input ports, one accepting a single XML document, and another accepting multiple XML fragments.

By default, the XMLAppender works by inserting every incoming XML fragment to the end of the main XML document. The Append Path In Document and Append Fragments As parameters may be used to control where the fragments are inserted in the document.

Configuration

Input Ports

Input features containing the main XML document.

Input features containing the XML fragments.

Output Ports

This is the output for the main XML document with the appended fragments.

Multiple main documents are allowed only if the Group By parameter is used, otherwise duplicate main documents are output via this port. The main documents are considered a duplicate of each other when the values of their composite Group By key equal.

Fragments with no corresponding Group By main XML document are output via this port.

Parameters

Group By

Use this parameter to organize multiple main documents and fragments into groups. Multiple main XML documents are allowed when their composite Group By key differ. Unused documents and fragments, those without corresponding keys, are routed to the UnusedDocument and UnusedFragment ports, respectively.
Complete Groups

When All Features Received: This is the default behavior. Processing will only occur in this transformer once all input is present.

When Group Changes (Advanced): This transformer will process input groups in order. Changes of the value of the Group By parameter on the input stream will trigger processing on the currently accumulating group. This may improve overall speed (particularly with multiple, equally-sized groups), but could cause undesired behavior if input groups are not truly ordered.

There are two typical reasons for using When Group Changes (Advanced) . The first is incoming data that is intended to be processed in groups (and is already so ordered). In this case, the structure dictates Group By usage - not performance considerations.

The second possible reason is potential performance gains.

Performance gains are most likely when the data is already sorted (or read using a SQL ORDER BY statement) since less work is required of FME. If the data needs ordering, it can be sorted in the workspace (though the added processing overhead may negate any gains).

Sorting becomes more difficult according to the number of data streams. Multiple streams of data could be almost impossible to sort into the correct order, since all features matching a Group By value need to arrive before any features (of any feature type or dataset) belonging to the next group. In this case, using Group By with When All Features Received may be the equivalent and simpler approach.

Note: Multiple feature types and features from multiple datasets will not generally naturally occur in the correct order.

As with many scenarios, testing different approaches in your workspace with your data is the only definitive way to identify performance gains.
XML Document Input

Selecting from the list enables that selection's corresponding parameter:

  • Attribute with XML Document: Choose the attribute containing the main XML document.
  • XML Document Filename: Browse to the XML file.
Append Fragment As

This parameter controls how the fragments are inserted into the document in relation to a selected or matched element. The possible values for the parameter are:

  • Preceding Children
  • Succeeding Children
  • Preceding Siblings
  • Succeeding Siblings

The values are to be understood in relation to the selected or matched element, which is specified by the Append Path In Document parameter.

The default value for this parameter is Succeeding Children.
Append Path In Document

This parameter specifies a single element, or a path to a single element, in the document. Each element in the path is separated by a forward slash, ‘/’. A wildcard, ‘*’, may also be used as the prefix or local-name of the element (for example, ‘*:e’, ‘p:*’, or just ‘*’, which translates to ‘*:*’).

The parameter’s default value is the empty string. This will match or select the root element.

Consider the following XML document:

<data>

<metadata>…</metadata>

<initialize>…</initialize>

<!--Insert XML fragments here -->

<finalize>…</finalize>

</data>

To insert fragments after the <initialize> element we can either:

1) Specify Append Path In Document as "data/initialize", and

2) Set Append Fragments As to Succeeding Siblings

or:

1) Specify Append Path In Document as "data/finalize", and

2) Set Append Fragments As to Preceding Siblings
XML Fragment Input

Selecting from the list enables that selection's corresponding parameter:

  • Attribute with XML Fragment: Choose the attribute containing the XML Fragment.
  • XML Fragment Filename: Browse to the XML file.
XML Output Type

Selecting from the list enables that selection's corresponding parameter:

  • Attribute with XML Output: Choose the attribute to hold the appended results.
  • XML Output File: Specifies the file to contain the appended results.
Output Encoding

This parameter is used to select the encoding for the appended results.

Pretty Print

The parameter specifies if the XML output should be pretty-printed with indentation.
Indent Size

This parameter specifies the size of a single indentation.
Replace Tabs with Spaces

By default, the tab character is used for pretty printing, use this parameter to replace the tabs with spaces.
Text Indent

By default, the text within a tag is left untouched. If this parameter is set to Yes, the text will be pretty printed. If a tag contains both a text value element and another nested tag element, the second of either the text value or nested tag will not be pretty printed. The example below shows a block of XML code on the left along with its pretty printed output on the right.

Example Pretty Printed

<example>

<example>

text value

text value #text value is the first element

<nestedTag>

<nestedTag> #<nestedTag> is the second element

some value

some value

</nestedTag>

</nestedTag>

</example>

</example>

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

String Functions

These functions manipulate and format strings.

Special Characters

 A set of control characters is available in the Text Editor.

Math Functions

Math functions are available in both editors.
Date/Time Functions Date and time functions are available in the Text Editor.

Math Operators

These operators are available in the Arithmetic Editor.

FME Feature Functions

These return primarily feature-specific values.

FME Parameters

FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters Create your own editable parameters.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.

Row Reordering

Enabled once you have clicked on a row item. Choices include:

  • Add a row
  • Remove a row
  • Move current row up one
  • Move current row down one
  • Move current row to top
  • Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

  • Cut a row - delete and copy to clipboard
  • Copy a row to the clipboard
  • Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

FME Community

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