I begin with the broker notification system.
I use SqlDependency to notify data updates beetween application instances.
Overall, it works well. But sometimes, after a while, I don't receive no more notifications.In SQL management activity monitor, processes keep "BROKER_RECEIVE_WAITFOR" wait type.Also, I notice this error in SQL Server 2008 R2 log : "The query notification dialog on conversation handle closed due to the following error ... (-8470) Remote service has been dropped".Is there a particular setting to avoid shutdown dialog notifications ?Thanks in advance for your help.
Related
So, I've created event notification on the server (for server-related messages), the command is something like that:
create event notification NAME on server for EVENT_NAME to service SERVICE_NAME, 'current database'
In general, it works great, but when I drop my database, the conversation between the server and my service become broken (because the service has been deleted as well with a queue). But my event notification is still there (because it was created on the server), so I continue to receive messages that just all stored in msdb.sys.transmission_queue and the typical message is:
The Service Broker in the target database is unavailable: 'The service broker is administratively disabled.'.
My idea is to drop that event on db drop, but I have no idea how to do that, and it should work for the case when a backup is applied to the database. Or maybe there is another approach for that case. I'm using MSSQL 2017.
Thanks.
Im trying to get SQL Notifications to work with BizTalk, but im struggling a one point.
The Binding of the Receivelocation is the following:
The SQL Server is supporting Notifications, and the connection string is correct.
When i start the Receivelocation it is working exactly one time in a correct way, but when i disable it and start it again, i get the following error in the eventlog.
The Messaging Engine failed to add a receive location
"RL.MDM.SQL" with URL
"mssql://.//Database?InboundId=GetNewMDMChanges" to the adapter
"WCF-SQL". Reason:
"Microsoft.ServiceModel.Channels.Common.TargetSystemException: The
notification callback returned an error. Info=Invalid.
Source=Statement. Type=Subscribe.
I cant start the Receivelocation again till i Execute the following command on the Database to enable the Broker.
alter database MDMDEV set enable_broker with rollback immediate;
The strange thing here is when i check if the broker is still enabled before i execute the command above, i see that the broker is indeed still enabled.
So the command to enable the broker fixes my problem for exactly one other notification and than i have to do this again.
Has anybody ever had this problem or can tell me what im doing wrong?
Thanks in advance.
Regarding the Notifications feature in general, my recommendation is to not use it.
With both SQL Server and Oracle, the Notifications feature is quite fragile and will stop receiving event with no warning or error. When this happens, the only way to recover is Disable/Enable the Receive Location.
Basically, I have found it not reliable enough to use in production apps.
If you or your organization own the database, Polling [+ Triggers if needed] are 100% reliable.
This article describes some different Polling scenarios: BizTalk Server: SQL Patterns for Polling and Batch Retrieve
i would like to setup a JMS Queue on a Glassfish v3 Server for saving some protocoll informations on a sql server.
My first try ended up in lot's of deadlocks on the sql server.
My first question is: Are the messages in a queue processes after each other or in parallel. How do it set it up to process the messages after each other. Time does not play a role. I want to bring only a minimum load to the sql server.
The second: Where can i see how much messages are waiting in the queue for processing?
I had a look into the monitoring of glassfish and also the
http://server:adminport/__asadmin/get?monitor=true&pattern=server.applications.ear.test.war.TestMessageDrivenBean.*
But i could not see a "tobeprocessed" value or s.t. like that.
Many thanks,
Hasan
The listener you bind to the queue will process messages as they arrive. It responds to an onMessage event. You don't have to set up anything.
You do have to worry about what happens if the queue backs up because the listener(s) can't keep up.
You should also configure an error queue where messages that can't be processed go.
Have you thought about making the queue and database operation transactional? That way the message is put back on the queue if the database INSERT fails. You'll need an XA JDBC driver and a transaction manager to do it.
Quick overview of our topology:
Web sites sending commands to an nServiceBus server, which accepts the commands and then publishes the correct pub/sub events. This service also has message handlers that can do some process against the DB in response to the command, for instance:
1 user registers on web site
2 web site sends nServicebus command to nServicebus service on another server.
3 nServicebus server has a handler for that specific type of command, which logs something to the database and sends a welcome email
Since instituting this architecture we started to get deadlocks on the DB. I have traced it down to MSDTC on the database server. If I turn that service OFF on the database server nServicebus starts throwing up errors, which to me shows that nServiceBus has been enlisting the DB update in the transaction.
I don't wish this to happen, I want to handle the DB failing myself, I only want the transaction to ensure the message is delivered to my nServicebus proxy service. I don't want a transaction from the web all the way through 2 servers to the DB and back.
Any suggestions?
EDIT: this post provides some clues, however I'm not entirely sure it's the proper way to proceed.. NServiceBus - Problem with using TransactionScopeOption.Suppress in message handler
EDIT2: The reason that we want the DB work outside the scope of the transaction is that the intent is to 'asynchronously' process these commands on another server so as not to slow down the web site and/or cause users to wait for these long running aggregation commands. If the DB is within the scope of the transaction, is that blocking execution on the website at the point where the original command is fired to the distributor? Is there a better nServicebus architecture for this scenario? We want the command to fire quickly and return control to the web site so the user can quickly proceed and not have to wait for our longish running DB command, which is updating aggregate counts and sending emails etc.
I wouldn't recommend having the DB work outside the context of the NServiceBus transaction. Instead, try reducing the isolation level of the transactions. This can be done by calling:
.IsolationLevel(System.Transactions.IsolationLevel.ReadCommited)
in the fluent configuration. You'll have to put this after .MsmqTransport() in v2.6. In v3.0 you can put this call almost anywhere.
RESPONSE TO EDIT2:
Just using NServiceBus will achieve your objective of not slowing down the website, regardless of the level of the transactions run on the other server. The use of transactions is to provide a guarantee that messages won't be lost in case of failure and also that you won't have to write your own deduplication logic.
I am making a Windows service which needs to continuously check for database entries that can be added at any time to tell it to execute some code. It is looking to see if it's status is set to pending, and it's execute time entry is > than the current time. Is the only way to do this to just run select statements over and over? It might need to execute the code every minute which means I need to run the select statement every minute looking for entries in the database. I'm trying to avoid unneccesary cpu time because I'm probably going to end up paying for cpu cycles on the hosting provider
Be aware that Notification Services is only for SQL 2005, and has been dropped from SQL 2008.
Rather than polling the database for changes, I would recommend writing a CLR stored procedure that is called from a trigger, which is raised when an appropriate change occurs (e.g. insert or update). The CLR sproc alerts your service which then performs its work.
Sending the service alert via a TCP/IP or HTTP channel is a good choice since you can deploy your service anywhere, just by modifying some configuration parameter that is read by the sproc. It also makes it easy to test the service.
I would use an event driven model in your service. The service waits on an auto-reset event, starting a block of work when the event is raised. The sproc communications channel runs on another thread and sets the event on each incoming request.
Assuming the service is doing a block of work and a set of multiple pending requests are outstanding, this design ensures that those requests trigger just 1 more block of work when the current one is finished.
You can also have multiple workers waiting on the same event if overlapping processing is desired.
Note: for external network access the CREATE ASSEMBLY statement will require the PERMISSION_SET option to be set to EXTERNAL_ACCESS.
Given you talk about the service provider, I suspect one of the main alternatives will not be open to you, which is notification services. It allows you to register for data changed events and be notified, without the need to poll the database. It does however require service broker enabled for it to work, and that potentially could be a problem if it is hosted - some companies keep it switched off.
The question is not tagged to a specific database just SQL, the notification services is a SQL Server facility.
If you're using SQL Server and open to a different approach, check out SQL Server Notification Services.
Oracle also provides notifications, the call it Database Change Notification