What is best way to test smartServer servlets?

Question

I have the following Servlet method which I want to create test for it using junit or Cactus.I've tried Junit but in testing implementation classes but I'm a newbie in testing WebServices so I will really appreciate any help.

public DSResponse executeFetch(DSRequest req) throws Exception { 
DSResponse resp = new DSResponse(); 

String maID = (String) req.getCriteria().get("memberActivityID"); 
MemberActivityImpl memberImpl = new MemberActivityImpl(); 

MemberActivity memberAct = new MemberActivity(); 

if (req.getDataSourceName().equals("memberActivity")) { 
if (maID != null) { 
// Fetch the MemberActivity based on the memberActivityID criteria 
memberAct = memberImpl.getMemberActivity(maID); 

List<Map> resultList = new LinkedList<Map>(); 

if( memberAct != null && memberAct.getMemberID() != null ) 
    // Pass the memberAct to the client 
    Map<String, Object> result = new HashMap<String, Object>(); 
    result.put("name", memberAct.getName()); 
    result.put("type", memberAct.getType()); 
    result.put("memberID", memberAct.getMemberID()); 
    if (memberAct.getGoal() != null) { 
        result.put("goal", memberAct.getGoal());} 
        resultList.add(result); 
    } 
    resp.setData(resultList); 
} else { 
    resp.setFailure(); 
} 

`