Unable to capture return values in web services api

Question

At the time of login to web services if my server is down ,
it returns following error :
java.lang.StringIndexOutOfBoundsException: String index out of range: -1
        at java.lang.String.substring(String.java:1438)
        at java.lang.String.substring(String.java:1411)
I want to capture this error so that i can try another server to login. how do i capture this error
Another place where i want to capture the return Value is when i look for a report on the server
rh = boBIPlatform.get("path://InfoObjects/Root Folder/"src_folder"/" + reportName +
                           "@SI_SCHEDULEINFO,SI_PROCESSINFO" ,oGetOptions);
oInfoObjects = rh.getInfoObjects();
CrystalReport = (CrystalReport)oInfoObjects.getInfoObject(0);
Here if the report is not there on the server , it returns a null handler exception.
but if i try catching it by checking my responsehandler is null  like rh == null  it does not catch it.
Any help will be appreciated
thanks
Rakesh Gupta

Answer 1

Ted : i have two cases
1)   server = server_st.nextToken();
    providerURL = "http://"server"/dswsbobje/services";
    sessConnURL = new URL(providerURL + "/session");
   Connection boConnection = new Connection(sessConnURL);
   Session boSession = new Session(boConnection);
  EnterpriseCredential boEnterpriseCredential = new    EnterpriseCredential();
              boEnterpriseCredential.setLogin(userid);
  boEnterpriseCredential.setPassword(pwd);
  boEnterpriseCredential.setAuthType(auth);
SessionInfo boSI = boSession.login(boEnterpriseCredential);
I have got a list of servers running web servcies stored in my tokens. when i pass the first server name say " test:8080" and that server is down , i want to catch somewhere in the code above that it did not get the connection so that i can loop back and try with the second server say test1:8080
This is for failover purposes.
at present when i was trying to capture return value of boSI it  breaks giving the error
java.lang.StringIndexOutOfBoundsException: String index out of range: -1
at java.lang.String.substring(String.java:1438)
at java.lang.String.substring(String.java:1411)
2nd case :
I am geeting reports from the server and scheduling them:
i run the following code which works fine if reports is there
rh = boBIPlatform.get("path://InfoObjects/Root Folder/"src_folder"/" + reportName +
"@SI_SCHEDULEINFO,SI_PROCESSINFO" ,oGetOptions);
oInfoObjects = rh.getInfoObjects();
CrystalReport = (CrystalReport)oInfoObjects.getInfoObject(0);
Here if  the  report  is not there on the server  then i should be able to catch from the response handle rh that it has got a null value.
but rh does not return a null value 
the code ultimately throws a null handle at the following line
CrystalReport = (CrystalReport)oInfoObjects.getInfoObject(0);
i am not able to catch the null value there also.
hope you got my issue.