Reading that MySQL doesn't have similar to SqlDependency.
What is the best snippet to notify other users if a cell changed?
Most of the current posts suggest pooling as recommended approach but can't find proper code to study for VB.NET Winform without using third party service such Nub.
What I guess could work is to create a CRON job at http server to fetch if that cell(s) changed then store a flag in a secure file; then rather than keep checking MySQL database on interval; watch that flag on server's file system and continue routine. Still this approach doesn't look the proper way.
Related
Is it possible to get data through REST API from Jira directly to mysql without using rest client in Java/Python etc?
I need to get and regularly update data from there to my database.
I'd have to say no but I could be wrong. You're looking for the ability of mysql to run something like PHP, java, python, vb that could access another server and pass the results to a SQL script.
However, even if you could do it, I don't think it's a very good idea because there is probably more complexity to the problem than you envision right now. There will be issues of outages, backups, picking up where you left off, changing current issues when status changes, new comments, etc. The only way to guarantee synchronization is to dump the jira database and load it completely into your database, something a REST API isn't really intended to do. If you have access to the JIRA system, just ask them for a database dump. If your using someone else jira system, they probably won't appreciate the load you will place on their API and will shut you out.
I am developing a Delphi XE7 application with data stored in an online Mysql database. For the database access I use FireDAC. Because the application can be used on more than one computer simultaneously I need to be notified when a table is changed, so I can update the displayed information on each computer. FireDAC has a component called TFDEventAlerted which sounded like exactly what I need for this. But this component gives an error when activating (calling Register): [FireDAC][Phys][MySQL]-303. Capability is not supported.
I am not sure what this means, but after reading more about the component it seems Mysql does not support this type of events? If so: can anyone tell me whether there is another solution to accomplish the same?
Any help would be appreciated as I cannot seem to find a good solution.
Native MySQL doesn't have the push-notification feature you're hoping to use. To make this work you'll need to poll (to regularly run a query) to look for changes.
There are some ways to overcome this limitation if the scale of your system makes polling infeasible. You could add a user-defined function to your MySQL server, like this one to send messages: https://github.com/mysqludf/lib_mysqludf_stomp#readme
This won't work if you don't own the MySQL server; most hosting services won't allow you to install UDFs.
Or, you could build a message publish/subscribe app. This is pretty easy to do with the Amazon simple queuing service or with rabbitmq. But it's a different kind of system design from what you are probably used to.
In my article series about Firebird Database Events I proposed a solution based on message-oriented middleware. The middle tier of your application then would notify all interested parties about certain database events. Middle tier code would be database independent, all you need is a message broker who is specialized in reliable message delivery. An imaginary example for a 'after post' event handler is shown below:
procedure TAppDataModule.PurchaseOrderAfterPost(DataSet: TDataSet);
var
Notification: INotification;
begin
Notification := NotificationService.CreateNotification(PURCHASE_ORDER_TABLE_UPDATED);
Notification.SetIntProperty(PURCHASE_ORDER_ID, PurchaseOrderID.AsInteger);
NotificationService.Send(Notification);
end;
Popular free/libre open source message brokers are for example Apache ActiveMQ and RabbitMQ.
TFDEventAlerted control is not for MySQL database. That database doesn't support event model. If you want update data in "real time" then you must add manual request for changed data
Here are steps:
Add new field to your database table like "last_updated";
Fill that field by now() value on update or insert actions (by trigger or sql);
Add timer to delphi app and add request by SELECT MAX(last_updated) AS last_updated FROM my_table for last updated time;
If that time is new then request updated data by SELECT * FROM my_table WHERE last_updated >= :need_last_updated.
I'm building a simple commenting system using node and i need to configure this in a PHP project running in Apache server. So, i need to trigger node.js when some changes made in MySQL database table present in the Apache server. So, i need to know whether it is possible to do this in a Apache server? If so, then how to do that? Any idea or suggestions on this are greatly welcome. Please help...
I guess there are few options you could take, but I don't think you can get some sort of triggered action from within MySQL or Apache. IMHO, you these are the approaches you can take:
you can expose a HTTP API from node and every time you need to notify the node app, you could simply insert the data into MySQL using PHP and then issue a simple GET request to trigger node.
You could use some sort of queuing system (rabbitmq, redis, etc.) to manage the messages to and from the two application, hence orchestrating the flow of the data between the two apps (and later the db).
you could poll the database from node and check for new rows to be available. This is fairly inefficient and quite tricky, but it sounds more close to what you want.
Hey i need some help here, i am developing a vb.net desktop application using visual Studio 2010 and mysql v5.5 whose database will be located in a main server hence the applications will have to communicate with the the database to get/post information.
My problem however is that, i want my applications to have a real time update of the database content such that if user1 updates the database, it immediately reflects that in user2's application. I have read articles that recommend use of triggers and Stored Procedures in mysql syntax to do this but i have no idea how this will work.
I have a table called 'Store' , when a user enters an item in table store, i'd like the application to know it and update the Item and its contents in a listbox or datagrid.
How do i capture these events in my vb.net code?
I hope i am clear enough, if not please ask. All your suggestions will be highly appreciated!
I think the easiest way to solve the problem would be to periodically get the records from the server and update the local list appropriately. On your client application you could store the last time the list was updated, and send that as a parameter when you do the get and get all the items that were created after that time (that way you only get new items).
Another possible solution would be to have a client register with the server application (so the server keeps track of all the clients) and when you create a new record you send that new record to all the clients, which would be listening for that event.
It's sort of hard to say what the 'best' approach is in your situation. How is your code designed (what's the architecture)? Are connections between the client and server applications persistent? Is there a server application that your client application talks to or is each client directly talking to the database?
For some security issues I'm in an envorinment where third party apps can't access my DB. For this reason I should have some service/tool/script (dunno what yet... i'm open to the best option, still reading to see what I'm gonna do...)
which enables me to generate on a regular basis(daily, weekly, monthly) some csv file with all new/modified records for a certain application.
I should be able to automate this process and also export at any time a new file.
So it should keep track for each application which records he still needs.
Each application will need some data in some other format (csv/xls/sql), also some fields will be needed for some application and some aren't... It should be fairly flexible...
What is the best option for me? Creating some custom tables for each application? Based on that extracting modified data?
I think you best thing here, assuming you have access to the server to let you set this up is to make a small command line program that can do the relativley simple task you need. Languages like pearl are good for this sort of thing I do believe.
once you have that 'tool' made you can schedule it through the OS of the server to run ever set amount of time. Either schedule task for a windows server or a cronjob for a linux server.
You can also (with out having to set up the scheduled task if you don't / can't want to) enable this small command line application to be called via 'CGI' this is a special way of letting applications on the server be executed at will by a web user. If you do enable this though, I suggest you add some sort of locking system so that it can only be run every so often and to stop it being run five times at once.
EDIT
You might also want to just look into database replication or adding read only users. This saves a hole lot of arseing around. Try to find a solution that dose not split or duplicate data. You can set up users to only be able to access certain parts of the database system in certain ways, such as SELECT data