3.4. Integration of External Tools

3.4.1. Basic Concepts

The Tool Integration concept of RCE is used to integrate external tools for calculations, simulations and so on into RCE and use them in a workflow as a component. The tools must fulfill these requirements:

  • The external tool must be callable via command line

  • It must have a non-interactive mode which is called via command line

  • Input for the tool must be provided through command line arguments or files

If these requirements are fulfilled, a configuration file can be created that is used for the integration.

If you use RCE with a graphical user interface this can be done with the help of an wizard which guides you through the settings. This wizard can be found in the menu Tool Integration -> Integrate Tool.... Required fields are marked with an asterisk (*). When the wizard is finished and if everything is correct, the integrated tool will automatically show up in the Workflow Editor palette.

Note

The wizard has a dynamic help, which is shown by clicking on the question mark on the bottom left or by pressing F1. It will guide you through the pages of the wizard.

3.4.2. Directory Structure for Integrated Tools

When executing an integrated tool, a certain directory structure is created in the chosen working directory. This structure depends on the options you have chosen in the integration wizard. The two options that matter are "Use a new working directory each run" and "Tool copying behavior".

Root Working Directory: This is the directory you choose in the "Tool Integration Wizard" as "Working Directory" on the "Launch Settings" page.

Config Directory: In this directory, the configuration file that may be created by the tool integration will be created by default. The configuration files can be created from the properties that are defined for the tool on the "Tool Properties" page.

Input Directory: All inputs of type "File" and "Directory" will be copied here. They will have a subdirectory that has the same name as the name of the input (e.g. the input "x" of type "File" will be put into "Input Directory/x/filename").

Output Directory: All outputs of type "File" and "Directory" can be written into this directory. After that, you can use the placeholder for this directory to assign these outputs to RCE outputs in the post execution script. To write, e.g., the output directory into an output "x" of type "Directory" the following line in the post execution script would be required: ${out:x} = "${dir:output}"

Tool Directory: This is the directory where the actual tool is located. If the tool should not be copied, it will be exactly the same directory that you choose, otherwise it will be the same as the chosen directory but copied to the working directory.

Working Directory: A working directory is always the location, where all the other directories will be created. If the option "Use a new working directory on each run" is disabled, this will always be the same as the "Root Working Directory". Otherwise, a new directory is created each run (the name will be the run number) and is the working directory for the run.

3.4.3. Copying of Integrated Tools

When a component is created in the integration wizard, a configuration file is created.

All configuration files from the tool integration are stored in the directory <profile folder>/integration/tools/

In this directory, there is a separation between different kinds of integration realized through one subdirectory for each. The common folder always exists.

In these subdirectories, the integrated tools are stored, again separated through into a subdirectory for each. The name of the directory is the name of integration of the tool.

If an integrated tool is copied to another RCE instance or another machine, the directory of the tool must be copied, containing a configuration.json and some optional files. It must be put in the equivalent integration type directory of the target RCE instance. After that, RCE automatically reads the new folder and if everything is valid, the tool will be integrated right away.

Note

If you want to delete a tool folder that contains some documentation, this can cause an error. If you have this problem, first empty the documentation folder and delete the empty folder the documentation folder at first (it must be empty), afterwards you can delete the tool folder.

3.4.3.1. Tool Execution Return Codes

The tools are executed by using a command line call on the operating system via the "Execution Script". When the tool finished executing (with or without error), its exit code is handed back to the execution script and can be analyzed in this script. If in the script nothing else is done, the exit code is handed back to RCE. When there is an exit code that is not "0", RCE assumes that the tool crashed and thus lets the component crash without executing the "Post Script". Using the option "Exit codes other than 0 is not an error" can prevent the component to crash immediately. With this option enabled, the post script wil be executed in any way and the exit code from the tool execution can be read by using the placeholder from "Additional Properties". In this case, the post script can run any post processing and either not fail the component, so the workflow runs as normal, or let the compoennt crash after some debugging information was written using the Script API "RCE.fail("reason")".

3.4.4. Integration of CPACS Tools

3.4.4.1. Additional concepts of CPACS Tool Integration

Extending the common Tool Integration concept, the CPACS Tool Integration has some additional features.

  • Parameter Input Mapping (optional): Substitutes single values in the incoming CPACS content, based on an XPath configured at workflow design time as a dynamic input of the component

  • Input Mapping: Generates the tool input XML file as a subset of the incoming CPACS file XML structure, specified by a mapping file

  • Tool Specific Input Mapping (optional): Adds tool specific data to the tool input file, based on a mapping file and a data XML file

  • Output Mapping: Merges the content of the tool output XML file into the origin incoming CPACS file, based on a mapping file

  • Parameter Output Mapping (optional): Generates output values as single values of the CPACS result file, based on an XPath configured at workflow design time as a dynamic output of the component

  • Execution option to only run on changed input: If enabled, the integrated tool will only run on changed input. Therefore the content of the generated tool input file is compared to the last runs content. Additionally the data of the static input channels are compared to the previous ones.

All the features listed above can be configured in the tool integration wizard on the dedicated CPACS Tool Properties page.

The mappings can be specified by XML or XSLT as shown in the following examples. RCE differentiates between these methods in accordance to the corresponding file extension (.xml or .xsl).

Example for an input or tool specific XML mapping :

<?xml version="1.0" encoding="UTF-8"?>
<map:mappings xmlns:map="http://www.rcenvironment.de/2015/mapping" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <map:mapping>
        <map:source>/cpacs/vehicles/aircraft/model/reference/area</map:source>
        <map:target>/toolInput/data/var1</map:target>
    </map:mapping>

</map:mappings>

And input or tool specific XSLT mapping:

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="cpacs_schema.xsd">
 <xsl:output method="xml" media-type="text/xml" />
 <xsl:template match="/">
  <toolInput>
   <data>
    <var1>
     <xsl:value-of select="/cpacs/vehicles/aircraft/model/reference/area" />
    </var1>
   </data>
  </toolInput>
 </xsl:template>
</xsl:stylesheet>

Example of an output XML mapping:

<?xml version="1.0" encoding="UTF-8"?>
<map:mappings xmlns:map="http://www.rcenvironment.de/2015/mapping" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <map:mapping mode="delete">
        <map:source>/toolOutput/data/result1</map:source>
        <map:target>/cpacs/vehicles/aircraft/model/reference/area</map:target>
    </map:mapping>

</map:mappings>

And output XSLT mapping:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" exclude-result-prefixes="xsi">
  <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
  <!--Define Variable for toolOutput.xml-->
  <xsl:variable name="toolOutputFile" select="'./ToolOutput/toolOutput.xml'"/>
  <!--Copy complete Source (e.g. CPACSInitial.xml) to Result (e.g. CPACSResult.xml)-->
  <xsl:template match="@* | node()">
    <xsl:copy>
      <xsl:apply-templates select="@* | node()"/>
    </xsl:copy>
  </xsl:template>
  <!--Modify a value of an existing node-->
    <xsl:template match="/cpacs/vehicles/aircraft/model/reference/area">
    <area>  
    <xsl:value-of select="document($toolOutputFile)/toolOutput/data/result1"/>
    </area>
    </xsl:template>
</xsl:stylesheet>

Please ensure to use the proper namespace for map (xmlns:map="http://www.rcenvironment.de/2015/mapping") in XML mapping files.

The figure below illustrates how the additional features are used in the run process of an user-integrated CPACS tool.

Figure 3.7. Run process of an user-integrated CPACS Tool

Run process of an user-integrated CPACS Tool

3.4.4.2. Integrate a CPACS Tool into a Client Instance

  1. Start RCE as Client

  2. Open the Tool Integration Wizard by clicking the Integrate Tool... in the File menu.

    Note

    You will always find further help by clicking the ? on the bottom left corner on each page of the wizard or by pressing F1.

  3. Choose the option Create a new tool configuration from a template.

    Note

    The CPACS templates delivered with RCE are designed to match the conventions of the old CPACS tool wrapper (respectively ModelCenter tool wrapper). Most of the properties are preconfigured and do not need to be changed.

  4. Select one of the CPACS templates. Click Next.

  5. Fill in the Tool Description page. Click Next.

  6. On the Inputs and Outputs page you will find preconfigured static in- and outputs, that will match the old tool wrapper conventions. If your tool needs additional in- or outputs, feel free to configure.Click Next.

  7. Skip the page Tool Properties by clicking Next since it is not relevant for tools that match the conventions of the old CPACS tool wrapper.

  8. Add a launch setting for the tool by clicking the Add button on the Launch Settings page. Configure the path of the CPACS tool and fill in a version, click OK. If you would like to allow users of your tool to choose that the temp directory won’t be deleted at all after workflow execution, check the property Never delete working directory(ies). Not to delete the working directory can be very useful for users for debugging purposes, at least if they have access to the server’s file system. But this option can result in disc space issues as the amount required grows continuously with each workflow execution. It is recommended to check that option during integrating the tool and uncheck it before publishing the tool. Click Next.

  9. The CPACS Tool Properties are preconfigured to match the folder structure defined for the old CPACS tool wrapper. In most cases you do not have to change this configuration. If you are using XSLT mapping, please select the corresponding mapping files. If your tool does not work with static tool specific input, please deselect this property. Click Next.

  10. In the Execution command(s) tab on the Execution page, you need to define your execution command itself as well as optional pre and post commands. Commands will be processed sequentially line by line. An example for a typical Windows command including pre and post commands will look like the following:

    rem pre-command
    pre.bat
    
    rem tool-execution
    YourTool.exe ToolInput/toolInput.xml ToolOutput/toolOutput.xml
    
    rem post-command
    post.bat

  11. Click Save and activate and your tool will appear immediately in the palette and is be ready to use.

  12. If not already done, do not forget to publish your tool (cf. Section 3.5, “Tool publishing and authorization” ) after testing it locally. To check if your tool is successfully published to the RCE network open the tab Network View at the bottom and checkout Published Components after expanding the entry of your RCE instance.

3.4.4.3. Integrate a CPACS Tool into a Server Instance in Headless Mode

The way to integrate a CPACS tool on a server running RCE in headless mode is as follows: Perform the steps to integrate a CPACS tool on a client instance and make sure that the path of the CPACS tool configured on the Launch Settings page (step 8) matches the absolute tool path on your server system. Afterwards, you will find the configuration files inside your rce profile folder at the following location:

/integration/tools/cpacs/[YourToolName]

Copy the folder [YourToolName] to the same location inside the profile folder running with your headless server instance. Use the "auth" commands (cf. Section 3.5, “Tool publishing and authorization” ) to publish your tool. If the server instance is already running, your tool will be available immediately after publishing.