Issueing transaction and rolling back in service scripts

[???-31]

I wrote a simple service below to update user information from mashups.

var result;
try{
   // (I want to do) tx = getTransaction();
    var user = Users[userName];
    user.lastName = lastName;
    user.firstName = firstName;
    // throw new Exception(); (A)
    user.emailAddress = emailAddress;
    var param = {description : description};
    user.SetDescription(param);
    // oldGroup -> newGroup
    if((oldGroup && newGroup) && (oldGroup != newGroup)){
        param = {member: userName};
        Groups[newGroup].AddMember(param);
        // throw new Exception(); (B)
        Groups[oldGroup].DeleteMember(param);
    }
   // (I want to do) tx.commit();
    result = "Information is successfully updated.";
    logger.info("Info of " + userName + "is updated.");
}
catch(err){
   // (I want to do) tx.rollback();
    result = "Failed: " + err.message;
    logger.error(result);
}

This script actually works, but IF error occurs, on line (A) or (B) for example, ｔｈｅ consistency of user data can be broken.

If I can issue transaction and do Commit or Rollback, this problem will be solved.

Are there any way to do this, or alternative ideas to do something like this?

Regards,

S.Yamabe

[CarlesColl]

There's no Commit / Rollback ( Transactional ) feature on Server Side Javascript, it's automatically handled by platform.

Try throwing a fake exception where you have // throw new Exception(), how to do it: throw "EXCEPTION_TEXT", but don't capture it, let platform capture the exception, this should cause a Rollback by the platform.

[???-31]

Carles,

Thank you for your advice.

I've modified my script, but still not working...

var result;
try{
    var user = Users[userName];
    user.lastName = lastName;
    null.length; // throws exception
    user.firstName = firstName;
    user.emailAddress = emailAddress;
    var param = {description : description};
    user.SetDescription(param);
    if((oldGroup && newGroup) && (oldGroup != newGroup)){
        param = {member: userName};
        Groups[newGroup].AddMember(param);
        Groups[oldGroup].DeleteMember(param);
    }
    result = "Information is successfully updated.";
    logger.info("Info of " + userName + "is updated.");
}
catch(err){
    // throw an uncaught exception for rollback
    throw "Failed: " + err.message
}

When running this script, I want to leave any properties unchanged.

However, "lastName" is actually changed and saved...

Looking into the log, the exception seems to be caught by Server.

Execution error in service script [UserManageServices UpdateUserInfo] : Failed: Cannot read property "length" from null

Does the script above do exactly what you mean?

Regards,

S.Yamabe

[CarlesColl]

Hi S.Yamabe,

Well the DataBase get's on an unstable state, as if you restart tomcat you will get previous value , hence the Rollback really happens.. -- Maybe we should open a case for this, to investigate if it --> Scaring.

But by the way, it may not work exactly with users that with Things... A Thing can be Restarted a User not.

Carles.

[???-31]

Carles,

Thank you. Let me confirm what you mean. (because I'm not very good at understanding English.. )

1. For my script, it is required for Tomcat to be restarted so that I get the previous value of lastName.

2. If the object entities are "Thing"s, restart is(should be) not required.

3. User entities may not be rollback-able.

Are these true?

S.Yamabe

[CarlesColl · Accepted solution]

1. Yes

2. I don't really know, tests should be done ( the same thing you did with User but with a Thing )

3. May not yes. Well, in reality when you restart Tomcat it will Rollback, which it's worst, as you are working with an unstable state until you restart...

[???-31]

I understood the current "specification".

in reality when you restart Tomcat it will Rollback

I know that. But as an online systems, it is fatal that restart is required for each exception.

So I should consider rollback is N/A so far.

And, of course, I also think this is the worse problem,

you are working with an unstable state until you restart...

Anyway, I hope any improvements for these problems for the future.