#33 Provide RowSet implementation

open
None
5
2012-08-15
2005-03-29
Danny Yates
No

Hi Alin,

Is there any chance that you could add a RowSet
implementation any time soon?

In one thread on the user forum, you mentioned that you
hadn't done this because Sun provide a robust
implementation. Unfortunately, I would suggest that
Sun's implementation is anything other than robust.

For starters, Sun are doing something completely weird
with properties bundles, so that if you are in any locale
other than US (e.g. GB), then the RI fails. (The
workaround is to extract the US bundle, rename it as
GB and make it available to your app - but why?!)
Another issue is the one people keep mentioning with
doing toString() on a CLOB field.

These are just 2 of the issues facing me!

So, please, please, please, can I ask for a RowSet
implementation?

Thanks,

Dan.

Discussion

  • Alin Sinpalean
    Alin Sinpalean
    2005-03-30

    Logged In: YES
    user_id=564978

    Dan,

    I'm sorry to hear about your problems with the Sun RowSet
    implementation. You can, of course, ask for a RowSet
    implementation but I don't know who will find the time to do
    it and most importantly when. As you can see there are a
    number of other RFEs, as well as a number of patches and
    improvements that need to be done for more common functionality.

    The topic will remain open in the meantime; you can also try
    to provide even a simple implementation at first; it will be
    good as a base to start from and will probably encourage
    anyone with even a remote interest to add functionality to it.

    Alin.

     
  • Logged In: YES
    user_id=641437

    Dan,

    It is possible to get the Sun RowSet code to work but it
    does require a few changes to jTDS to work around bugs in
    the implementation. The RowSet in java 1.5 seems to have
    fixed the properties problem but there remain a number of
    others.

    Using the following code as example illustrates some of
    these other problems:

    public void test() throws Exception {
        Statement stmt = con.createStatement();
        stmt.execute("CREATE TABLE #TEST (id int primary
    

    key, txt text)");
    stmt.executeUpdate("INSERT INTO #TEST VALUES(1,
    'THIS IS A TEST')");
    stmt.executeUpdate("INSERT INTO #TEST VALUES(2, 'AS
    IS THIS')");
    stmt.executeUpdate("INSERT INTO #TEST VALUES(3, 'AND
    THIS')");
    JdbcRowSet jrs = new JdbcRowSetImpl(con);
    jrs.setType(ResultSet.TYPE_SCROLL_SENSITIVE); //
    Ignored!
    jrs.setCommand("SELECT * FROM #TEST");
    jrs.execute();
    assertTrue(jrs.absolute(2)); // Prove scrollable
    assertEquals("AS IS THIS", jrs.getString(2));
    jrs.updateString(2, "Hello from JDBCRowSet");
    jrs.updateRow(); // Prove updateable
    jrs.close();
    }

    Firstly the RowSet code outputs a message to stderr
    complaining that jTDS setTypeMap() method returned a not
    implemented SQLException. Why SUNs code calls this method
    with a null type map is beyond me. The quickest fix here is
    to alter jTDS to ignore the setTypeMap.

    Secondly the result set is not in fact updateable. This is
    because RowSet tries to create a SCROLL_INSENSTIVE /
    UPDATEABLE cursor. This option is not supported by SQL
    Server and is downgraded to a read only one instead. The SUN
    implementation ignores my attempt to override this in the
    example above. The only option for this problem is to amend
    jTDS Connection.prepareStatement to change insensitive to
    sensitive if the caller is also requesting an updateable
    cursor.

    You will note that I am using text columns that will be
    returned as CLOB objects but I am then using getString to
    access them and this works. If you use getObject in this
    circumstance you will return a CLOB and not a String, which
    is intentional. One option if this is unacceptable is to
    change jTSD to add a ClobImpl.toString method that returns
    the string value of the CLOB.

    A final irritation is that calling RowSet.close not only
    closes the internal result set and statement but also the
    connection object that I passed to the RowSet constructor.
    Only answer here is not to call close in which case the
    internal statement is never explicitly closed which is bad
    practice, alternatively use the setDataSource option and get
    the RowSet to obtain its own connection from a pool.

    I appreciate that hacking jTDS is not what you had in mind
    but as Alin pointed out building a full RowSet
    implementation from scratch is not a quick task

    Mike.

     
  • Andy Santosa
    Andy Santosa
    2005-07-27

    Logged In: YES
    user_id=773250

    I agree with Dan, I also feel that I need a good RowSet
    implementation, currently, I am using Sun RowSet
    Implementation but still in earlyAccess, I have to
    reverse-engineer the classes because there are some bugs
    (not just the Clob thing) but bugs in some functions, so I
    hope Alin can provide us with the RowSet implementation in
    the jTDS

    Thanks and Regards
    Andy Santosa

     
  • Alin Sinpalean
    Alin Sinpalean
    2005-07-29

    Logged In: YES
    user_id=564978

    Ok, then. If anyone is willing to provide some basic
    implementation, something to start from, I will try to
    maintain and improve it. Otherwise you might have to wait
    too long; remember, I also have a job.

    Alin.

     
  • Logged In: YES
    user_id=641437

    Alin,

    Despite my comments below from a few months ago, I have also
    come to the conclusion that the RI is badly flawed. A major
    problem is that the design of
    The RI makes it difficult to extend and customise which was
    my original idea and apparently Suns intention as well. In
    the end I just implemented my own versions partly because I
    wanted a working CachedRowSet and WebRowSet and partly for
    interest.

    I have tidied up this code and added some documentation and
    tried to make it integrate properly with the existing jTDS
    source tree. One issue is that, although I started off
    developing these classes with the jTDS driver in mind, I
    have actually been using them with PostgreSQL more. They
    will also work with the MS driver. As a result I have
    removed any direct dependencies on the jTDS driver itself
    and modified the build script to create a standalone rowset
    jar. I think this also helps to keep the actual driver
    compatible with java 1.3 but you may wish to re-integrate
    the code with jTDS rather than end up supporting two projects!

    If anyone wants to try this code out, download the latest
    CVS code for jTDS (or use the source distribution of 1.1)
    and expand the zip file (attached to this RFE) over the
    existing jTDS folder. If you are running under java 1.4 you
    will also need the Sun RI to be installed in the lib folder.
    NB. There isnt a problem with the localisation bug in this
    application, as the jTDS implementation does not use any of
    the com.sun.rowset classes.

    The code works for me and I have included a couple of test
    cases but I am sure there are many bugs to find. There is
    also major scope for optimisation especially in the
    RowSetWriter class. Unfortunately I lack the time and
    enthusiasm do much more in this area at present but I hope
    it will be a useful starting point.

    Mike.

     


Anonymous


Cancel   Add attachments