[smila-user] Question about error: "Pipelet class could not be loaded."

[Stavroula Manolopoulou <manolop@xxxxxx>]

Hello,

I'm trying to incorporate a Twitter crawler written in Java for the CUbRIK project into SMILA. So far I have created a pipelet called "org.eclipse.smila.integration.TwitterPipelet" that contains the class "org.eclipse.smila.integration.TwitterPipelet.myTwitterPipelet". I have also created a pipeline called "TwitterPipeline.bpel" according to the instructions given here.

At this point I am trying to make my pipelet taking only one input, the query that is given from the user as a string, in order to start the crawler. I tried several things but although I get no error from the compiler, when I go to HTTP REST API to my pipelet, I get this:

    {
        "class": "org.eclipse.smila.integration.TwitterPipelet",
      - "parameters": [
               - { "name": "TwitterQuery",
                    "type":   "string"
                  } ],
        "description": "Find the image urls from tweets that are relevant to the query",
      - "errors": ["Pipelet class could not be loaded."]
    }

I have added to the bpel the following:

        <extensionActivity>
          <proc:invokePipelet name="invokeTwitterPipelet">
            <proc:pipelet class="org.eclipse.smila.integration.TwitterPipelet.myTwitterPipelet" />
            <proc:variables input="request" />
            <proc:configuration>
               <rec:Val key="TwitterQuery">TweetQ</rec:Val>
             </proc:configuration>
          </proc:invokePipelet>
        </extensionActivity>

and my pipelet looks like this:

    public class myTwitterPipelet implements Pipelet
    {
          private static final String TWITTER_QUERY = "TwitterQuery";
          private AnyMap _config;
   
          public void configure(final AnyMap config) throws ProcessingException
          {     _config = config;    }

         public String[] process(final Blackboard blackboard, final String[] recordIds) throws ProcessingException
         {
              //Read the input query:
              final ParameterAccessor paramAccessor = new ParameterAccessor(blackboard, _config);
              paramAccessor.setCurrentRecord(recordIds[0]);
              final String QueryStr = paramAccessor.getParameter(TWITTER_QUERY, null);

               //...
         }
         return null;
    }

It is not clear to me whether I have to declare the query input and where exactly, (i)to the configure function of my pipelet, (ii)the bpel pipeline, and/or (iii)the json file. Is this the reason why I get this error?


Thank you in advance
Stavroula Manolopoulou