[Maria-developers] Java Connector Coding till 5th June
Hi Everyone, The work done till 5th June: 1.I started studying the connector immediately after my semester exams got over(5th May). 2. Understood the relationship between different classes. 3.Read the MySql documentation for text protocol and map the commands from documentation onto code.This thing gave a clear idea about how things are moving from client to server. 4.Setup the code on Ubuntu using eclipse and tested against database. Setup the Team branch in launchpad. 5.Debug the test classes to see how different classes are interlinked and understood that MySQLProtocol.java is the heart of our JDBC driver. 6.Then I started reading Client Server Protocol documentation i.e ServerSide prepared statement and try to see how and where I have to code it. 7.Then I saw that there is a class MySqlServerSidePreparedStatement.java, Initially I coded the prepareStatement() ,close(),and execute() in that class seperately. But after (Code review) discussion with Massimo, we donot need to use that class. Instead use MySqlPreparedStatement.java to do the same work.So made changes accordingly. 8.I had pushed some of the code which I have written to launchpad and discussed with Massimo last week. 9.Last week I was struck with Wireshark on windows and ubuntu both. I was unable to see the packets going to database and seeing the response. 10.On Monday the problem was resolved as I was using the wrong interface.I should have used loopback.io(127.0.0.1) instead on ubuntu(thanks to Georg). Unfortunately the thing does not work on windows.Tried a lot many times. 11.Now I am working on the execute method of client server protocol as I am getting exception while using that method.Wireshark is playing a great role in how the packets are flowing.
From now I will do weekly blogging and keep everyone updated.
Thanks & Regards Puneet.
Hi Puneet,
I'm curious. What were the arguments for not using this class? That class MySqlServerSidePreparedStatement.java was created for exactly the purpose of implementing server-side prepared statements (user could choose implementation based on parameter, e.g userServerPrepStmts like in Connector/J). If the idea is that people do not need client-side prepared statements, and server-side the only correct way to go, this is, based on my experience, incorrect. Often, people would want parametrized statements without the overhead of P_S (prepare, execute, close).
Instead use MySqlPreparedStatement.java to do the same work.So made changes accordingly.
Hi Vladislav, Honestly, initially I had thought of using MySqlServerSidePreparedstatement. But after discussion with Georg, I understood it was an overhead. Even when discussed during code review with Massimo we decided to add the *useserverprepstmts *feature using MySqlPreparedStatement and not to use MySqlServerSidePreparedstatement. Because this class just had a prepare and close and not a clear idea why this class was created and almost all methods are empty. We are not removing client side prepared statement feature, both client and server side prepared statement are there and will be used as per the needs.I am just trying to add a *useserverprepstmts* feature usingMySqlPreparedStatement and will be activated from the jdbc url i.e* jdbc:mysql://localhost:3306/test?useServerPrepStmts=true*. If useServerPrepStmts is not used client side prepared statements will be used. Regards Puneet. On Sat, Jun 7, 2014 at 3:02 PM, Vladislav Vaintroub <wlad@montyprogram.com> wrote:
This is easy to explan and can also be easily found with bzr, or Launchpad. The file was added in revision 424 http://bazaar.launchpad.net/~maria-captains/mariadb-java-client/trunk/revisi... .. The comment says "CONJ21- allow ResultSetMetaData to be retrieved from preparedStatement, before statement is executed. Fix is using server-side prepared statement functionality - prepare command will return result set metadata among other information. Introduce MySQLServerSidePreparedStatement class, which in the future will be able to provide full-featured PreparedStatement functionality, using server side prepared statements internally." This is the fix for the bug https://mariadb.atlassian.net/browse/CONJ-21 , to allow users to retrieve ResultSetMetadata priorto /without the execution of statement. This is only possible with server-side "prepare", no other way around it The class was meant to be expanded in the future, as the comment said.
Right, this makes sense.
Hi Vladislav, Honestly, initially I had thought of using
Yes I am trying to add the new functionality using MySQLPreparedStatement. Even when discussed during code review with Massimo we decided to add this
class was created and almost all methods are empty.
This is easy to explan and can also be easily found with bzr, or Launchpad. The file was added in revision 424 http://bazaar.launchpad.net/~maria-captains/mariadb-java-client/trunk/revisi... .. The comment says "CONJ21- allow ResultSetMetaData to be retrieved from preparedStatement, before statement is executed. Fix is using server-side prepared statement functionality - prepare command will return result set metadata among other information. Introduce MySQLServerSidePreparedStateme nt class, which in the future will be able to provide full-featured PreparedStatement functionality, using server side prepared statements internally." This is the fix for the bug https://mariadb.atlassian.net/browse/CONJ-21 , to allow users to retrieve ResultSetMetadata priorto /without the execution of statement. This is only possible with server-side "prepare", no other way around it The class was meant to be expanded in the future, as the comment said. I think we all were looking for this reason as to why this class were created and with above answer, now I am convinced. The advantages of creating a new class MySQLServerSidePreparedStatement will be a *clear separation of concerns*. :) I will discuss with my mentors this week and take the necessary steps.Will continue posting about the steps taken. Regards Puneet. On Sun, Jun 8, 2014 at 2:04 AM, Vladislav Vaintroub <wlad@montyprogram.com> wrote:
Hi Puneet,
The advantages of creating a new class MySQLServerSidePreparedStatement will be a clear separation of concerns. :)
Back when created this class , I thought something along the lines of usual OO technique - single interface, 2 different concrete implementations classes . Connection.prepareStatement()would serve then as a factory method -dependent on useServerPrepStmt connection parameter it would create either MySQLPreparedStatement or MySQLServerSidePreparedStatement I am by no means a big fan of everything object-oriented or of design patterns , however in this case the alternative to server-side specific implementation class seems to be a lots of "if" statements mixed into in existing MySQLPreparedStatement methods .Given that PreparedStatement itself is a rather large interface, I'm afraid that code will go spaghetti way rather easily.
I will discuss with my mentors this week and take the necessary steps.Will continue posting about the steps taken.
Hi Vladislav, Back when created this class , I thought something along the lines of usual OO technique - single interface, 2 different concrete implementations classes . Connection.prepareStatement() would serve then as a factory method -dependent on useServerPrepStmt connection parameter it would create either MySQLPreparedStatement or MySQLServerSidePreparedStatement I agree with your concerns and initially it was coded in the above way. The answer which you gave : This is easy to explan and can also be easily found with bzr, or Launchpad. The file was added in revision 424 http://bazaar.launchpad.net/~maria-captains/mariadb-java-client/trunk/revisi... .. The comment says "CONJ21- allow ResultSetMetaData to be retrieved from preparedStatement, before statement is executed. Fix is using server-side prepared statement functionality - prepare command will return result set metadata among other information. Introduce MySQLServerSidePreparedStateme nt class, which in the future will be able to provide full-featured PreparedStatement functionality, using server side prepared statements internally." This is the fix for the bug https://mariadb.atlassian.net/browse/CONJ-21 , to allow users to retrieve ResultSetMetadata priorto /without the execution of statement. This is only possible with server-side "prepare", no other way around it The class was meant to be expanded in the future, as the comment said. Thanks for the above .Neither me nor my mentors were aware about this I guess and that's the reason we decided to add the useServerPrepStmts feature using MySQLPreparedStatement. I will discuss with my mentors and continue posting on the steps being taken. Thanks & Regards Puneet. On Sun, Jun 8, 2014 at 4:08 PM, Vladislav Vaintroub <wlad@montyprogram.com> wrote:
Hi Vladislav, I had discussed with my mentor regarding the MySQLServerSidePreparedStatement. We are planning to go the same way as discussed in the above mails i.e clear the seperation of concerns MySQLServerSidePreparedStatement will extend from the MYSQLPreparedStatement in order to avoid code duplication as its a big interface. *prepareStatement()* will be a factory method in MySQLConnection to provide the MySQLPreparedStatement or MYSQLServerSidePreparedStatement instance depending on *useServerPrepStmts* value. Your suggestions are welcome. Thanks and Regards Puneet. On Sun, Jun 8, 2014 at 5:31 PM, Puneet Dewan <puneetd30@gmail.com> wrote:
participants (2)
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Puneet Dewan -
Vladislav Vaintroub