ConnectorLib Java 25.1
ConnectorLib Java SDK Programming Guide

# Implement Custom Fetch Actions

You can implement custom fetch actions in a ConnectorLib Java connector.

Action | Description | Method to override
--- | --- | ---
`action=Fetch&FetchAction=MyAction` | Perform custom fetch actions on a repository. | ``customFetch``

To implement a custom fetch action, override the `customFetch` method on the `ConnectorBase` interface.

The ``customFetch`` method is passed the name of the fetch action that was called in the request. The name is always in upper case, because action names are case-insensitive. You can use the ``customFetch`` method to handle as many fetch action names as necessary, however the action names `SYNCHRONIZE`, `COLLECT`, `HOLD`, and so on, are reserved by the connector for the standard fetch actions.

The `customFetch` method is also passed a `CustomFetchTask` object. The `CustomFetchTask` object provides access to a request object which provides all of the action parameters. You can obtain the request object by calling the method `getRequest()` on the `CustomFetchTask` object. To retrieve a single parameter call the method `getParameter(parameterName)` on the request object, or to retrieve a list of all parameters use the method `getParameters()`. These methods return parameter objects. To obtain the name and value of a parameter, call the methods `getName()` and `getValue()` on the parameter object. You can also use the method `getValue(defaultValue)` to read a parameter value and use a default value if the parameter is not set.

Other resources, including a collection of identifiers and an ingester, are available through the `CustomFetchTask` object. You can use these in your implementation of the custom fetch action.

The ``customFetch`` method can run many times for a single request; each time it is passed a different `CustomFetchTask` instance. The number of times that the ``customFetch`` method runs is determined as follows:

- The ``customFetch`` method runs for each distinct configuration file section name embedded in the identifiers (provided by the `identifiers` or `identifiersXML` action parameters) or included in the request (using the `configsection` or `tasksections` parameters). The `configsection` parameter accepts a single name. The `tasksections` parameter accepts a comma-separated list of names.
- If no configuration file sections are provided by identifiers or by the `configsection` or `tasksections` parameters, then the `customFetch` method runs one time for each task listed in the `[FetchTasks]` section of the configuration file.

- If no fetch tasks are configured in the connector's configuration file, the `customFetch` method does not run and the following warning is written to the connector's logs:

  `WARNING: Custom fetch action is not associated with any task configuration sections, no tasks will be executed`

Your code must use the parameters from the request to perform the action and populate the action response. You can obtain the response object by calling the method `getResponse()` on the `CustomFetchTask` object. Set the value of XML elements in the response by calling the method `setValue(elementName, value)` on the response object.

You can add attributes and nested elements to the action response using XPath-like expressions with element indexes. For example:

           Response.setValue("document[0]/metadata[7]/@name", "MyField");

Your implementation of the ``customFetch`` method should return `false` only if the fetch action name is not supported. In all other cases, return `true`. If another failure occurs then throw an exception from the ``customFetch`` method, giving the reason for the failure.

The following sample code shows how a custom fetch action might be implemented for a basic connector. This example provides `action=fetch&FetchAction=count`, and counts the files below a list of paths:

          boolean customFetch(String action, CustomFetchTask task)
          {
             if (action.equalsIgnoreCase("COUNT"))
             {
                String[] paths = task.getTaskConfig().readStringArray("DirectoryPathCSVs");

                int count = 0;
                for (String path : paths)
                {
                    // Count files below path
                }
                task.getResponse().setValue("file_count", count.toString());

                return true;
             }

             return false;
          }

Copyright 2024 Open Text
Version 25.1 | Last updated January 2025

Send documentation feedback

Close

Send documentation feedback

To send feedback using your default email client, open an email window.

Otherwise, send your feedback and the information below to MFI-swpdl.idoldocsfeedback@opentext.com.

We appreciate your feedback!

Product: Knowledge Discovery ConnectorLib Java 25.1

Topic Title: Implement Custom Fetch Actions