KNIME is a powerful workflow system. It allows to import data from some sources and process them in a workflow graphically designed by the user.
There are special openBIS KNIME nodes for importing/exporting data from/to openBIS. KNIME version 2.7.2 or higher is required.
- Start KNIME application.
- Click on menu item 'Install New Software...' of menu 'Help'. An installation dialog pops up.
- Click on the add button. A dialog titled 'Add Repository' pops up.
- Enter a name like 'KNIME Community Nodes' and the URL http://update.knime.org/community-contributions/3.1
- Check the check box of 'openBIS Knime Nodes' in section 'Community Contributions - Bioinformatics & NGS' and click twice the next button.
- Accept the license agreements.
- Click the finish button.
- Ignore the security warning and restart KNIME application.
All openBIS KNIME nodes can be found in Node Repository under Community Nodes -> openBIS:
Drag and drop a node into the project and double-click on the node. A node setting dialog opens for entering parameters.
All nodes need
- URL of openBIS server, like
- User credentials
When configuring a node in the node setting dialog the user is asked for these parameters in the section 'Connection Parameters':
After pressing the button connect a connecting to the openBIS server will be established. This is needed for editing additional node parameters. For example, the combo boxes of the reader nodes have to be populated.
For a data set registration node the credentials combo box is only filled if all nodes of the upstream part of the workflow are successfully configured.
The OK button closes the node setting dialog. The connection parameters and all other parameters will be stored and used when executing a workflow.
Definining openBIS URLs
Contrary to the previous version of openBIS KNIME nodes (Version 13.04.0 and earlier) the URL field in the node setting dialog is no longer a text field but a combo box with URLs. This list of predefined URLs is initially empty. It has to be created by the following preference page:
Defining User Credentials for Authentication
For security reasons it is not recommended to specify user ID and password directly for each openBIS node. Instead named credentials should be used. This has the advantage to enter user ID and password only once for a workflow with several openBIS nodes.
Named credentials are defined for a particular workflow. They are called workflow credentials and can be specified via the context menu of the workflow:
Each set of credentials has a name (which is used in the combo box), a user ID (called 'Login') and a password:
The credentials are saved with the workflow except of the passwords. The user will be asked for the passwords after loading a workflow.
If user ID and password are entered directly in the node setting dialog the KNIME master key on the preferences page KNIME -> Master Key should be activated. Otherwise passwords will be stored unencrypted!
openBIS Query Reader
This node allows to run parametrized SQL queries on openBIS. The combo box shows a list of available queries. After choosing one additional parameters have to be entered.
openBIS Report Reader
This node allows to get a report for a specified data set. The combo box shows a list of available report. After choosing a report a data set should be entered. The button with three dots lets pop up a dialog for convenient way to choose a data set.
openBIS Data Set File Importer
This nodes allows to download a particular file from a specified data set. Data set code, file path and a local folder for downloads have to be specified. The output of the node is not a table put an object of type
org.knime.core.data.uri.URIPortObject. Other nodes with input ports of this type can access the downloaded file. Such nodes exist in GenericKnimeNodes of the Community Nodes (which are a part of openMS KNIME Nodes). Also 'openBIS Data Set Registration (URI Port)' is such a node.
The absolute path of the downloaded file is also available as a flow variable
absolute-file-path. This allows to connect a openBIS Data Set File Importer with a file reader which supports absolute file paths in flow variables like the CSV Reader node. The mechanism of connecting both nodes via flow variable ports is explained in the next section where a CSV Writer node is connected with an openBIS Data Set Registration node.
This importer node also creates the following KNIME flow variables:
openbis.EXPERIMENT, and optionally
openbis.SAMPLE. These variables contain data set code, experiment identifier, and sample identifier, respectively. The flow variable
openbis.SAMPLE identifier only appears if the data set is directly link to a sample. KNIME flow variables are available to other nodes downstream.
openBIS Data Set Registration (Flow Variable Port)
This node allows to register a file as a data set. The path of the file to be registered is the value a flow variable specified in the node settings dialog. In addition the user has to specify owner type and data set type.
The owner identifier (which is either a data set code, an experiment identifier, or a sample identifier depending on the chosen owner type) can be chosen by a chooser dialog. If the owner field is empty one of the flow variables s
openbis.SAMPLE will be used.
This node is usually used in combination with a writer node which stores data (e.g. data table) in a file. Writer nodes are end nodes of a workflow. But it is possible to append another node downstream by using the flow variable port. Normally the flow variable ports are not visible. To make them visible choose item 'Show Flow Variable Ports' of the context menu of the node. Two red circle will appear at the upper corners of the node symbol:
Now add a node of type 'openBIS Data Set Registration (Flow Variable Port)' and connect the upper right circle of the writer node with the input node of the registration node. A click on 'Hide Flow Variable Ports' of the context menu of the writer node hides the upper left circle:
Next you need to tell the registration node which flow variable has the path to the file to be registered. This needs two steps:
- The configuration parameter of the writer has to be made available as a flow variable. This can be done in tab 'Flow Variables' of the node settings dialog. It lists all configuration parameters. If a name is specified in the text field of a certain parameter its value will be available as a flow variable of specified name for the downstream nodes. Here is the example for CSV Writer:
This works for all writers. There is an easier way for CSV Writer: On the Settings tab there is small button named 'v=?'. Clicking on this button opens a dialog where the flow variable for the file name can directly be specified by using 'Create Variable':
- In the registration node the flow variable specified in the first step has to be chosen as the file variable:
openBIS Data Set Registration (URI Port)
This nodes allows to register a file as a data set. The file to be registered is the first one in the list of URIs of the port object of type
org.knime.core.data.uri.URIPortObject. The user has to specify owner type and data set type in the node settings dialog.
The owner identifier (which is either a data set code, an experiment identifier, or a sample identifier depending on the chosen owner type) can be chosen by a chooser dialog. If the owner field is empty one of the flow variables
openbis.SAMPLE will be used.
openBIS Aggregation Service Report Reader
This nodes allows to get an aggregation service report. Only aggregation services where the service key starts with
knime- can be chosen by the user in the node settings dialog. After the service has been chosen the aggregation service will be invoked with the parameter
_REQUEST_ set to
getParameterDescriptions. The service has to return a table where each row defines the name of the parameter and optionally its type. This is used to created an appropriated form in the node settings dialog. The values specified by the user will be used to invoke the aggregation service when the node is executed. The result will be available as a KNIME table. See also section KNIME Aggregation Service Specifications.
openBIS Aggregated Data File Importer
This nodes allows to invoke an aggregation service which returns a name of a file in the session workspace which will be downloaded and made available for nodes with input ports of type
org.knime.core.data.uri.URIPortObject. Such nodes exist in GenericKnimeNodes of the Community Nodes. Also 'openBIS Data Set Registration (URI Port)' is such a node.
Only aggregation services where the service key starts with
knime-file- can be chosen by the user in the node settings dialog. The communication protocol between this node and openBIS is as for nodes of type 'openBIS Aggregation Service Report Reader'. The only difference is that the returned table has only one row with one cell which contains the file name.
KNIME Aggregation Service Specifications
Nodes of type 'openBIS Aggregation Service Report Reader' and 'openBIS Aggregated Data File Importer' rely on aggregation services which follow a certain protocol. In order to distinguish these services from other aggregation services the service key (i.e. core plugins ID) has to start with
knime-. The specifications of such services are the following:
- If there is a parameter
getParameterDescriptionsdescriptions of all parameters will be returned in the form specified as follows:
- The table has the columns
- Each row has a non-empty unique value of column
name. It specifies the name of the parameter. It is also shown in node settings dialog.
- The type columns contains either an empty string or
DATA_SET.The default type is
VARCHARwhich is represented in the node settings dialog by a single-line text field. The types
DATA_SETare also single line text field with an additional button to open an appropriate chooser.
- The type
VOCABULARYisn't useful without a list of terms in the following form:
VOCABULRY:<term 1>, <term 2>, ....
VOCABULARY:Strong, Medium, Weak
- The table has the columns
- If there is no parameter
_REQUEST_or its value isn't
getParameterDescriptionsthe aggregation service can assume that all parameters as defined by the parameters description are present. Some of them might have empty strings as values.
- An exception should be returned as a table with five columns where the first column is
_EXCEPTION_. If such a table is returned an exception with stack trace will be created and thrown in KNIME. It will appear in KNIME log. For each row either the first cell isn't empty or the five other cells are not empty. In the first case the value of the first column is of the form <exception class>:<exception message>. If the first column is empty the row represents a stack trace entry where the other columns are interpreted as class name, method name, file name, and line number.
In order to simplify KNIME aggregation services a Helper API in Java is available openbis-knime-server.jar. It should be added to openBIS installation in folder
KNIME Aggregation Service Helper API
The helper API contains the two classes
ch.systemsx.cisd.openbis.knime.server.AggregationFileCommand which should be extend when writing an aggregation service for nodes of type 'openBIS Aggregation Service Report Reader' and 'openBIS Aggregated Data File Importer', respectively.
The subclasses should override the method
defineParameters(). Its argument is a
ParameterDescriptionsBuilder which simplifies creation of parameter descriptions.
AggregationFileCommand is subclassed the method
aggregate()/ should be overridden. The
aggregate() methods gets the original arguments which are the parameters binding map and the ISimpleTableModelBuilderAdaptor. The
createFile() methods gets only the parameters binding map. It returns the name of the file in the session workspace.
The aggregation service should instanciate the subclass and invoke
handleRequest() with the parameters binding map and the table model builder adaptor.
ParameterDescriptionsBuilder has the method
parameter(). It creates a
ParameterDescriptionBuilder based on the specified parameter name. The
ParameterDescriptionBuilder has the methods
dataSet() which specify the parameter type. Only
vocabulary() has an argument: The string array of vocabulary terms.
Example for an Aggregation Service Report Reader
Example for an Aggregated Data File Importer