Frequently asked questions

Why do I get the error “Execute failed: Selenium data not available. Please re-run the complete workflow.” when executing my workflow?#q1

The Selenium Nodes depend on a running Web Driver for execution. Due to this fact, it’s not possible to partially re-run a saved workflow after re-opening it, as (1) the Web Driver instance is usually not available any longer and (2) all steps in the workflow thus have to be re-executed. In such cases, please re-execute the workflow beginning from the Start WebDriver node.

I want to use browsers which are running on a remote system. Is that possible?#q4

Sure thing. Select the option RemoteWebDriver in the WebDriver Factory node. You can either set up your own Selenium server by following the instructions given here or use existing services such as BrowserStack. The latter offer a great variety of different platforms, browsers and versions and are therefore perfect for running tests of your web applications.

Are you affiliated with the KNIME AG or SeleniumHQ?#q5

No.

We are not affiliated with the KNIME AG. We deliberately are not a “KNIME Partner”, but an independent company. We strongly believe that only this way we can provide you with the best and most innovative solutions and services and avoid any conflicts of interest which would stem from a coupling with the KNIME AG.

What can I do in case something is not working as expected, I’m missing a specific functionality or I have suggestions for additional features?#q6

We’re there to help. However, in case of unexpected behaviour, please perform these simple steps of self-service first:

  1. Ensure that you’re running the latest version of the Selenium Nodes (go to File → Update KNIME),
  2. Ensure that you’re running the latest version of KNIME.
  3. Ensure that you’re running an up-to-date browser.

If this does not help, simply drop us an email and include:

  1. A minimal, runnable sample workflow in case you have any specific issues.
  2. Information about your system configuration (operating system, version, recent changes to your setup).
  3. In case you’re reporting any errors or failing functionality, the log output of the execution when the problem occurs. Therefore enable the DEBUG log level in KNIME’s preferences KNIME → KNIME GUI and re-run the failing action if necessary.
During execution of my workflow I receive an error message which says “Error communicating with the remote browser. It may have died.” or “There are no open windows!” or something similar.#q7

The Selenium Nodes rely on a running browser instance, which must not be closed. During execution, an actual browser instance is started which is then controlled through the KNIME workflow. If you want to run your workflow without any browser windows, use headless Chrome or Firefox.

My company’s or ISP’s firewall or proxy server blocks access to the software site. Is there any possibility to download the Selenium Nodes anyway?#q11

You can download zipped versions of the software sites, by simply appending `.zip` to the URLs shown [here](https://seleniumnodes.com/download). Download the file, add a new software site as shown in the download instructions, but instead of entering a URL, hit the Archive… button and select the downloaded ZIP file. Proceed as outlined in the instructions. Attention: Keep in mind, that you will have to take care of keeping your installation up-to-date by manually downloading new versions regularly.

How can I download files with the Selenium Nodes?#q14

One issue when you want to download files is the “Save file” dialog which pops up — as soon as this dialog has opened, there is no way to interact with the browser through Selenium any longer.

Fortunately, Chrome-based browsers provide a mechanism to skip this dialog and to download the file to a specified location without any user interaction. For this, open the “Start WebDriver” or “WebDriver Factory” node, ensure that you use “Chrome" or “Chromium (bundled)”, select the Snippet “Download Files Template” and click “Merge”. Then expand the entries in the “Capabilities” section and edit the value for the entry default_directory to a local path on your computer. From then on, links which would trigger a download will automatically be saved in the specified location.

If you want to download files, which do not trigger a download (e.g. images on a webpage), then the above trick will not help. There’s the following workarounds instead:

  1. In case, the download does not require any cookies or further HTTP headers to be present, simply get the file through KNIME’s Download or Palladian’s HTTP Retriever node. You can still use the Selenium nodes, but as final step extract the href destination from your link with the Extract Attribute node and use the extracted URL for downloading.
  2. If you cannot download the file through previous method, because the server expects certain HTTP headers, you can get the file through a JavaScript snippet which performs an XMLHttpRequest within the browser session, and hand the file content back to KNIME as a string where you can process it further. This workaround is intended only for smaller files, because the entire file content has to be kept in memory. An example workflow can be found on the examples page.
Although I have entered my valid license information, I get the error message “No license specified. Please obtain a license and enter it on the Selenium preference page in order to use the Selenium nodes.” What’s wrong?#q17

For running on a KNIME Server please check #q27.

In order to run workflows in batch mode, please export your KNIME preferences to an .epf file using the corresponding menu entry and specify the path to this file on the command line through the following parameter: -preferences=/path/to/preferences.epf

How can payments be made?#q18

Payments can be made by credit card and you will receive your license code within seconds. We accept Visa, MasterCard, or American Express cards. Your credit card statement will mention “seleniumnodes.com” as payment receiver. We use Stripe for credit card payments.

Alternatively, you can pay through wire transfer. Following your order, we will send you an invoice which contains our bank information including IBAN and BIC. We’ll send the license code as soon as we have received your payment.

If you require special order procedures, please see #q29.

Feel free to drop us a line, in case you need to address any payment questions upfront.

What’s new? Is there a changelog?#q19

Yes, Sir. This way please!

Where’s my trial license? I’ve requested a trial license but not received any email!#q20

You should receive your trial license within twelve hours maximum. In fact, it’s only a matter of minutes in most cases. It is always worth having a look whether the email might have ended up in your spam folder erroneously.

In case you suspect any issues, send us an email and we’re glad to help!

Why should I buy a license at all? Ordering a new trial license each month is sooooo much cheaper!!!1#q21

As our terms and conditions to which you agreed during installation clearly state, the trial licenses are intended for a one time evaluation period. A trial license gives you the opportunity to explore the full functionality of the Selenium Nodes entirely free of charge and without any risk or obligation.

Developing, maintaining, and supporting the Selenium Nodes takes a great amount of time and effort. We hope you see the benefits of our software during the trial phase. Should you want to continue using the Selenium Nodes after the trial period, it is mandatory to purchase a regular license — this will support the constant improvement of the Selenium Nodes.

What is Chrome or Firefox in “headless” mode and how can I use it?#q22

Headless mode means, that these browsers can optionally run without showing any windows and other UI elements, which brings a natural speedup and makes them perfect for testing and automation especially when running in a server environment.

Headless Chrome is available since Chrome 60 on all operating systems, headless Firefox since Firefox 56.

To enable the headless mode, open the Start WebDriver or WebDriver Factory node configuration, select either Chrome or Firefox as a WebDriver, and then add the Headless capability from the Snippets menu by clicking the Merge button.

I’m a developer and I want to add functionality to the Selenium Nodes!#q23

Awesome! The Selenium Nodes provide several extension points which you can use to plug your own features. To get started, please have a look at the sample code and documentation in this GitHub repository.

KNIME freezes or crashes on Linux when I try to open a node configuration dialog (e.g. for the “WebDriver Factory”)#q24

This is a known Eclipse vs. GTK 3 issue (see here, here, and here). Please follow these instructions in the KNIME FAQs to fix the problem.

Potentially you’ll have to install WebKit afterwards in order to make the “Node Description” view work again.

Will I enter a yearly subscription by buying a license?#q25

No. Your purchase will be for a one year license which will not be automatically extended. To continue using the Selenium Nodes after one year, simply purchase a new license.

When trying to use Internet Explorer with Selenium Nodes, I see an error which says “Unable to get browser”#q26

This issue can be avoided by modifying IE’s security settings as described here.

Do these nodes run on a KNIME server and are there any dedicated installation instructions for the KNIME Server?#q27

Yes, the Selenium Nodes work on a KNIME Server.

You can install the nodes on a KNIME Server either through (a) the GUI or (b) the P2 Director command line application (e.g. when you do not have GUI access). More information can be found in the section “Installing additional extensions” in the “KNIME Server Administration Guide”. When you use the P2 Director, please take the update site URL matching your KNIME version from here and install the following features:

  • ws.palladian.nodes.selenium.feature.feature.group
  • ws.palladian.nodes.selenium.driver.chromium.feature.feature.group

After installation, the license needs to be provided to the “KNIME Executor”. For this, please follow the instructions under “Preferences file” in the “KNIME Server Administration Guide”.

To find out about licensing options for the KNIME Server, please get in touch!

I am a student or work in education and would like to use the Selenium Nodes within my thesis or for teaching in the class room. Do you have any special offers?#q28

Please get in touch.

Can I order the software through our enterprise-specific “purchase order” or “vendor platform” procedures?#q29

Yes. If the purchasing process requires any additional steps, documents, or vendor registration procedures which cannot entirely be covered by our simple “self-service” flow, we’ll be happy to support you with that. Get in touch to discuss your requirements and receive an individual quotation.

Do you work with suppliers or resellers?#q30

Yes. Please see our reseller information and for questions not answered there, get in touch.

Do the Selenium Nodes send any usage data or telemetry information back to your company?#q31

No. Our software does not submit any usage data back to us. Our monetization happens only by selling software licenses and consulting services.

However, please note that this software is used for running browsers and thus naturally connects to the web. It is in your own responsibility to ensure that any data processing with our software follows your local laws and company policies.

I see an error message “This version of ChromeDriver only supports Chrome version x” when trying to run my workflow. How to fix?#q32

When a new browser version is released, we usually have an update ready to ensure compatibility. You can check our changelog here.

However, instead we recommend to use the “Chromium (bundled)” option in the Start WebDriver resp. WebDriver Factory options. This will use an included Chromium version which is always compatible with the KNIME nodes. If the entry “Chromium (bundled)” doesn’t show up for you in the node configuration, please install “Selenium Nodes for KNIME: Chromium” through the “Install Extensions” prodedure (File → Install KNIME Extension …).

I explicitly need to work with an older web browser which is not up-to-date. My workflow shows an error message that the WebDriver only supports newer browser versions (e.g. “This version of Microsoft Edge WebDriver only support Microsoft Edge version 102. Current Edge version is 99.0.1150.55 …”) or similar.#q33

Generally, we strongly recommend to keep your browsers up-to-date. If this is not possible, you can specify your own WebDriver versions which fit your browser version. Go to the KNIME preferences KNIME → Selenium, expand the section Path to Driver Binaries, and select the locally downloaded driver version (on Mac/Linux this is a binary file without file extension, on Windows the file ends with .exe).

You can get the driver binaries for various browsers from the following locations:

The Selenium Nodes look like a great tool to solve my problems. However I do not have the time to build the workflows myself. Can you help me with that?#q34

We also offer consulting services around the topics web information extraction, automation and integration, text mining and classification. We have years of experience with a variety of different projects and customers.

Your advantage: We’re not tied to KNIME or other specific technologies or vendors – we do not want to sell you a specific product but a holistic solution. Get in touch with us by email to discuss your projects and receive a quotation!