David Weber

Greenhorn
+ Follow
since Nov 03, 2009
Merit badge: grant badges
For More
Cows and Likes
Cows
Total received
0
In last 30 days
0
Total given
0
Likes
Total received
0
Received in last 30 days
0
Total given
0
Given in last 30 days
0
Forums and Threads
Scavenger Hunt
expand Ranch Hand Scavenger Hunt
expand Greenhorn Scavenger Hunt

Recent posts by David Weber

Hey all,

I need your advice on the best DBMS and Setup (High-Scalability, High-Performance, High-Reliability) for the following scenario.

Current structure:
Currently I am using MySQL on one server, with INNODB.
But I plan to setup a cluster.

Tables:
Person Raw Data (blobs, this data is just archived and will possibly never be used)
Person (This object will be searched and looped for most application operations)
Person Address
Country

Database use:
The database will store about 3 billion people and their details.
My application (distributed-system) will need to verify people, and identify people.
(Unfortunately identification will require looping through every person until a match is found due to the nature of the identification, a simple "select * from `blah` where `blah` = 'abc' " wont work).

The requirements for my database:

  • Store Up to 3 billion people.
  • Retrieve all objects quickly. For identification loop.
  • Store about 15 blob objects with sizes 20-100kb per person
  • Need some way to join data, but mainly will only be using the person structure.
  • Identification and verification will need to be as quick as possible


  • Im thinking maybe MongoDB will be better suited to the task.

    Regards,

    David
    Hi all,

    Running rmi server with 6 clients:
    But the clients keep dropping

    stack trace:


    I get this every few minutes

    Really would appreciate any help concerning what is going wrong. will post source when I get home but please try help me out now as,
    I need to fix this urgently.

    Regards,

    David Weber
    14 years ago
    Hi Chris,

    What I've done is add a processing column to the orders table,

    and when someone is editing the order the client app sets that order's processing to true,

    and when the user exits the editor, the client app sets processing back to false.



    If someone tries to launch the editor on an order that is being edited a Message pops up, to try again later.

    I have added an override mechanism in case any orders get stuck on processing due to connection or app failure.

    What do you think?

    I know its not the safest and most efficient, but if only 10 users are using the system, this should suffice.

    I only have about 6 months exp with Java and about 2 months exp with SQL.
    Hi All,

    Questions:
  • Q1) In RMI with dynamic class downloading does the server and clients require the setting of a policy file?
  • Q2) Can one program the setting of the policy file into the client and server? if so, please show how.
  • Q3) Wat needs to be in the policy file, if one stub needs to be downloaded from a web server on the local intranet?
  • Q4) I set the codebase to my netbeans project folder - build - classes. I then copied the server and client to a falsh drive and from another pc ran both the client and server without modifying the codebase and it still worked, whats up with that?
  • Can I program the setting of the codebase to a folder in the client and server?



  • MOST IMPORTANT QUESTION:
  • Do I need dynamic class loading? I will not be changing anything after deployment, so how can I just put a stub in the client package?


  • I normally wouldn't bother anyone with these type of questions but googling has left me more confused than ever.

    Any help would be greatly appreciated,

    Regards,

    David Weber
    14 years ago
    Hi All,

    I have an RMI Server that allows clients to retrieve,edit and remove records from a database.

    How do I make sure that not more than one client can edit an order at the same time?

    So far the method below does all my database manipulation, but I don't think this is safe.



    I am really new to Concurrency and Synchronization,

    All orders are in a JTable and if you click the row a editor pops up, where a user may edit values and add products.
    The JTable is updated every second by the event dispatcher if the table is currently visible to the user.

    Please offer your advice as how I can safely allow multiple clients (up to 10) to view and edit records

    Much Thanks,

    David Weber

    Using:
    NetBeans 6.7
    JDK 6
    Thanks for your input guys,

    read up on concurrency and have now implemented ActionListener,
    using swing.timer to execute the table update every 3 seconds
    this is using the event-dispatch thread and so is safe to use for gui updating.

    I think my problem is Solved
    14 years ago
    Hi all,

    Here's my situation,

    I have a JFrame with a tabbed pane. Inside the tabbed pane is a table containing orders.

    These orders are received as an ArrayList from a rmi method which gets the orders from the database.

    Now I want the table to constantly be updated, as orders are being added/edited all the time.

    At the moment i'm simply implementing Runnable on my JFrame like this:



    Now seems to work fine, but i do get this exception if i'm currently selecting the table and it updates.



    Any of you Java 'gods' got any advice for me??

    Much appreciated guys,

    Regards,

    David
    14 years ago
    Thanks Scott,

    My mistake was using the standard jdcb.odbc.driver instead of the mysql.jdbc.driver

    Problem solved!
    Hi guys I am trying to retrieve the auto_incremented value from a MySQL Insert Statement,
    And I keep getting the following exception:



    I have googled and googled and so far no fix, have tried prepared statements as well as statements.

    My code:



    Any help will be great guys!, thanks in advance.

    Extra Info:

    Windows 7 32-bit
    NetBeans 6.7
    MySQL 5.1
    MySQL ODBC Connecter 5.1.5
    JDK 6

    Regards, David