In KNIME there are a few nodes dedicated to work with and on the KNIME server.
We have already seen the Quickform nodes to design a GUI for the Web Portal of the KNIME Server. Today we will check the "Explorer" nodes.

If you type "Explorer" in the search box of the KNIME workbench, you will get these two nodes: "Explorer Browser" and "Explorer Writer". These two nodes respectively defines a path for a file (existing or not) on a KNIME Server and copies a file onto a location on a KNIME Server.
In today's example I used "Explorer Browser" to find and read a node on a KNIME server and "Explorer Writer" to copy a local file to a location on the KNIME server.

First of all, we need a KNIME Server, with Team Space installed.
Then you need Team Space installed on your local machine (just installed, not enabled with a license file).

f you have data files on the server (we will see in another post how to place data files on the server), you should see them in the KNIME Explorer when you log in.
Now, if you drag and drop any of the data files into your workflow editor, you will automatically get a "File Reader" node configured to read this file directly from the server. Notice that the URL used in the "File Reader" node does not use the "file://" protocol anymore, but the new "knime://" protocol which refers to a KNIME server. You should get something like:    
       knime://knime-server-demo/KNIME_Server/data/Sentiment_Rating.csv

However, if you want to read the file on the server in a more dynamic way, you can use the "Explorer Browser" to browse your server and look for the directory containing your file. Below, you can see the configuration window of the "Explorer Browser" node. The "Browse" button allows you to browse the workflows and files on the server. The "Explorer Browser" node outputs a flow variable containing the defined path. This path can then be used as setting in a "File Reader" node.

Once you have your data, at the end of your workflow execution, you might want to save them again on the server. To do that, you need:
1. to create a temporary local folder with the "Create Temp Dir" node
2. to transform the folder path into a file path by adding a filename (I used here a "Java Edit Variable" node)
3. to write the data into your just defined local filepath via a "CSV Writer" node
4. to upload the temporary file to its final destination on the server using an "Explorer Writer" node.
Below is the configuration window of the "Explorer Writer" node. It requires:
- the filepath of the file to upload in the form of a flow variable
- the target location on the server

And below you can see the full workflow that I used to read and write data from and back to the KNIME server.

To continue on the line of what is new in KNIME 2.6, this post is dedicated to a special new Quick Form node: The "Column Filter Quickform".

The "Column Filter Quickform" node presents a UI mask to select one or more data columns during a workflow execution. Practically, it is like a dynamic "Column Filter" node, where data columns can be selected on the fly at each workflow run.

In a workflow, for example, I was modelling fund returns based on 3 proxies returns, one fund of choice at a time. In the following data table I have the choice of modelling Fund 1, Fund 2, Fund 3, Fund 4, or Fund 5 based on Proxy 1, Proxy 2, and Proxy 3. In order to select a different fund each time, I need to use a "Column Filter" Quickform" node.

So, after the "File Reader" node I placed a "Column Filter Quickform" node. Its configuration window allows for the selection of one or more data columns via the usual Include/Exclude frame with the Add/Remove buttons. And so far it looks like a "Column Filter" node.
In addition, it also asks for an explanatory label about what we have to select here, some description of what the selection is for, a weight, and a variable name. The node in fact, when executed, creates a variable with the name given in the box "variable name" and the name(s) of the selected data column(s) as content. The "weight" setting ... well, let's keep the "weight" setting in mind for later.

After execution then this node creates:
     1. a flow variable named "kept_columns" containing value "Fund 4"
     2. an empty data table with the selected column

Since the "Column Filter Quickform" produces an empty data table but with right structure, I still need to fill it with the original values of column "Fund 4". To do that I can use a "Reference Column Filter" node using the output of the Quick Form as a reference for the original data table. At this point I have an output table containing only the selected data column with the original values.

If I pack this sequence of nodes ("Column Filter Quickform" + "Reference Column Filter" + and maybe some additional nodes) into a meta-node, the meta-node acquires a "Configure" option in the context menu. The configuration window of the meta-node now shows the include/Exclude frame of the Quick Form to select the data column(s) plus its label and description.

If I want to make the UI of the meta-node for the column selection cleaner, I can place a "Column Filter" node (a static one) before the "Column Filter Quickform" to hide the non selectable columns from the Quick Form UI. In this case, I would only leave the data columns "Fund *" available for the Quickform node.

Similarly to the meta-node, the KNIME server shows the "Column Filter Quickform" UI when executing the workflow. Indeed, the KNIME Server step-wise execution stops at each Quick Form node, showing the corresponding UI mask.

Remember the "Weight" setting? If you pack more than one Quick Form node into a meta-node, the meta-node configuration window as well as the UI mask in the Server step-wise execution will show more than one selecting frames. The positioning of those frames inside the window/mask, depends on the "weight" setting. The bigger the "weight", the heavier, and therefore the lower positioned, the corresponding frame in the window/mask.

And this is the final content of the meta-node.

The biggest change of KNIME 2.6 with respect to the previous KNIME versions lies, in my opinion, in the Quick Form category and covers two aspects of the KNIME software.

The first change is, in fact, just the plain number of Quickform nodes available. The figure below shows the Quick Form category in KNIME 2.5 and in KNIME 2.6 and you can see how many new Quick Form nodes have been added in KNIME 2.6.

The second change in terms of Quickforms is in the workflow execution on the KNIME Server. Now, when executing a workflow on the Web Portal, execution stops at every Quickform node, presents the corresponding mask, and allows for the selection of the Quickform value(s). This, combined with the higher number of Quickform nodes available, allows for more complete, more powerful, and more flexible GUI.

The screenshot below for example shows  the forms from 2 Quickforms embedded inside a meta-node, a Column Selection Quickform node and a String Input node, during the execution of a workflow on the KNIME Web Portal. Combining Quickform nodes in a workflow can produce very informative input forms.