Skip to main content

Types of Subscriptions Filter on Windows Azure Service Bus

Service Bus from Windows Azure is a great services to distribute messages to multiple subscribers. A topic can have one or more subscriptions. A message added to the topic will be send to all subscriptions that are register in that moment.
To be able to control what kind of messages are send to each subscription we can define filters. A filter is added on each subscription and specify what messages will be accepted by subscription.
The types of filters that can used are:

Correlation Filter
This is used when you want to accept messages that has a specific correlation value. This value can be set directly to the BrokenMessage and is great if you have messages with different priority or rank.
CorrelationFilter filter = new CorrelationFilter(“low”);
namespaceManager.CreateSubscription(topicPath, subscriptionName, filter);

BrokenMessage message = new BrokenMessage();
message.CorrelationId = “low”;

This filter give us the ability to specify what kind of messages will be accepted in a subsection based on a custom rules. This rule can be related to the properties list of a BrokenMessage that are specific by the producer or system properties (SessionId for example is a system property).
The syntax is very simple and is based on SQL92 standard and T/SQL. If you know to write a query in SQL than you will not have problem to use this filter. The syntax give us the possibility to use = != < > <> IS IN LIKE EXISTS ESCAPE NO + - * / AND OR …
For a normal use this is enough to define rules over subscriptions.
SqlFilter filter = new SqlFilter(“CustomProperty == 1”);
namespaceManager.CreateSubscription(topicPath, subscriptionName, filter);
BrokenMessage message = new BrokenMessage();
message.Properties[“CustomProperty”] = 1;
The “user” or “sys” prefix need to be used when you refers to properties that are in different scope. The “sys” refers to properties that are on BrokenMessage (like Correlationid or SessionId).

This is a filter that can be used to block all the messages to the given subscription. This can be used if you create a subscription and you don’t want to accept message to it (temporarily). Also, this can be used when you have a subscription and you don’t want to receive message anymore to it, but you don’t want to delete it.
FalseFilter filter = new FalseFilter()
namespaceManager.CreateSubscription(topicPath, subscriptionName, filter);

This filter is similar with SqlFilter. It will accept the message that respect the specific rule.

We looked over what kind of filter can be defined over a subscription. I think that FalseFilter can be very useful when you are in production and you need to control what messages are receive by one of subscription. For example in a scenario when a client didn’t pays the monthly subscription and you want to stop temporary his subscription. Is more simple that deleting it or set a SqlFilter – “ 1 <> 1”.


Popular posts from this blog

ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded

Today blog post will be started with the following error when running DB tests on the CI machine:
threw exception: System.InvalidOperationException: The Entity Framework provider type 'System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer' registered in the application config file for the ADO.NET provider with invariant name 'System.Data.SqlClient' could not be loaded. Make sure that the assembly-qualified name is used and that the assembly is available to the running application. See for more information. at System.Data.Entity.Infrastructure.DependencyResolution.ProviderServicesFactory.GetInstance(String providerTypeName, String providerInvariantName) This error happened only on the Continuous Integration machine. On the devs machines, everything has fine. The classic problem – on my machine it’s working. The CI has the following configuration:

TeamCity.NET 4.51EF 6.0.2VS2013
It seems that there …

How to check in AngularJS if a service was register or not

There are cases when you need to check in a service or a controller was register in AngularJS.
For example a valid use case is when you have the same implementation running on multiple application. In this case, you may want to intercept the HTTP provider and add a custom step there. This step don’t needs to run on all the application, only in the one where the service exist and register.
A solution for this case would be to have a flag in the configuration that specify this. In the core you would have an IF that would check the value of this flag.
Another solution is to check if a specific service was register in AngularJS or not. If the service was register that you would execute your own logic.
To check if a service was register or not in AngularJS container you need to call the ‘has’ method of ‘inhector’. It will return TRUE if the service was register.
if ($injector.has('httpInterceptorService')) { $httpProvider.interceptors.push('httpInterceptorService&#…

Fundamental Books of a Software Engineer (version 2018)

More then six years ago I wrote a blog post about fundamental books that any software engineer (developer) should read. Now it is an excellent time to update this list with new entries.

There are 5 different categories of books, that represent the recommended path. For example, you start with Coding books, after that, you read books about Programming, Design and so on.
There are some books about C++ that I recommend not because you shall know C++, only because the concepts that you can learn from it.


Writing solid codeCode completeProgramming Pearls, more programming pearls(recommended)[NEW] Introduction to Algorithms


Refactoring (M. Fowler)Pragmatic ProgrammerClean code[NEW] Software Engineering: A Practitioner's Approach[NEW] The Mythical Man-Month[NEW] The Art of Computer Programming


Applying UML and Patterns (GRASP patterns)C++ coding standards (Sutter, Alexandrescu)The C++ programming language (Stroustrup, Part IV)Object-oriented programming (Peter Coad)P…