i would like to ask a little question about task adaptor in q2.
i have a class that extends TaskAdaptor and an xml class with to instantiate it.
so my question is, how do i get the object instance created by the xml in java?
Thank you very much for any help provided.
You use the NameRegistrar to get a reference to your object, but please keep in mind that the TaskAdaptor was created in the early Q2 days in order to reuse Tasks created to run under QSP (QSP was the original version, Q2 stands for 'QSP version 2').
I don't think we have any of those old tasks in the jPOS system now, so I wonder why you need the TaskAdaptor; if you have Tasks of your own, it might be easier to upgrade them to full QBeans (just by extending QBeanSupport or implementing the simple QBean interface).
Please take a look at http://jpos.org/doc/proguide-draft.pdf, there's a chapter about writing your own jPOS Services (aka QBeans).
Related
I'm currently using LTTng for such performances issues, and I want to use TRACEPOINT_EVENT_CLASS and TRACEPOINT_EVENT_INSTANCE as well.
But I don't understand the 2.10 version's documentation. I wonder why we need to define TP_ARGS in each event instance as well as defining it in the event class.
Because we can't modify TP_FIELDS to change the type of any field, or compose it from many arguments.
The TP_ARGS() portion of a TRACEPOINT_EVENT_INSTANCE is used to validate that each instance matches the TRACEPOINT_EVENT_CLASS. See ust-tracepoint-event.h for more context.
I recommend that you repost your question on our mailing list/irc channel so that we can have an actual discussion regarding this. The maintainer of lttng-ust and lttng-modules, Compudj will surely provide more context and might even be open to the introduction of a new macro allowing event instance declaration without the TP_ARGS() portion.
So this may be a more general question, but I feel it needs to be asked.
Time and time again I come across examples on Camel's documentation pages where I say "that's exactly what I want!... but it's in Java not Spring. How the heck do I convert it properly?"
So my question is: What is the rule of thumb for converting things?
Is there some conversion guide out there?
For example, I wanted to append a \n to the end of each line as the data comes through a socket into a file using the Netty4 component.
I see an example such as .transform().body(append("\n"))
How would I interpret that as Spring, to put in my Spring-based route?
Maybe this is just a thing that a person new to Camel struggles with and once you get the hang of it you can see the obvious answer. But I feel like I can't be the only one who's thinking this about the examples out there.
It seems like a lot of Java -> Spring conversion can be done in a 1 to 1 ratio, but that's not all the time.
Well, the mapping isn't straightforward and there isn't a 1-to-1 mapping available - generally, a Java DSL method invocation will in most cases translate to a tag in Spring XML DSL but the position of that tag is not always the same - in some cases Java DSL method invocation chains translate to tags being placed on the same level, sometimes (e.g. idempotent consumer) the chain translates to child tags of the first invocation.
I guess that the mapping was done this way because XML and Java are two very different languages and making the mapping 1-1 would have crippled the expressiveness of at least one, if not both, DSLs.
My advice would be to always import the XML schema and rely on your IDE's auto-completion and the documentations from the schema itself and Camel's online documentation.
You can run your camel context via mvn camel:run goal and then use a JMX client to connect to that process. There is an mbean in camel which provides a method called dumpRoutesAsXML or similar. Invoking that one will give u the xml equivalent of your context. But keep in mind that it only prints the routes and all stuff out of routes is discarded.
Hope that helps,
Lars
I couldn't find any reference with this functionality. Shall I just implement a helper method in the builder to read fields in StateTransition object and populate the chain configureTransition() call by myself??
Just to confirm not to reinvent the wheels.
UPDATE:
I'm trying to use StateMachineBuilder to configure with some pre-defined states and transitions in a properties file. In Builder, they use this chained call to generate configuration:
builder.configureTransitions().withExternal().source(s1)....
What I have in mind is, everything read from the file is stored in an object, the spring sm library has this StateTransition object. But as far as I know from the API, there is no way to use it directly to configure a state machine. Instead, I can read individual fields in the object and use the chained call above.
Thanks!
If you want to do it like that, what you mentioned is pretty much only option. Hopefully we get a real support for external state machine definition, i.e. tracked in https://github.com/spring-projects/spring-statemachine/issues/78.
I'm currently writing an application that plays podcasts. I'm representing all the feeds and the episodes within them as QStandardItem objects within a QStandardItemModel. Right now, I don't have a way to save this model--when the application closes, the feed model goes up in smoke. I looked at using QSettings, but that only works for datatypes that fall under QVariant.
Looking at this post gave me some hope, but I think I'm doing something wrong. I've got the following code in the constructor for my application.
//Expand QVatiant to use QStandardItemModel
qRegisterMetaType<QStandardItemModel>("QStandardItemModel");
That, however, gives me this error at compile time.
/ [...] QtSDK/Desktop/Qt/4.8.1/gcc/lib/QtGui.framework/Versions/4/Headers/qstandarditemmodel.h:424: error: 'QStandardItemModel::QStandardItemModel(const QStandardItemModel&)' is private
Ah. That reminds me of this caveat from the Qt documentation for QMetaType, here.
Any class or struct that has a public default constructor, a public copy constructor and a public destructor can be registered.
So, where do I go from here? Qt is behaving exactly as it should, so this approach won't work. I'm thinking of saving off the model as an xml file, but that seems like a ton of effort. This seems like a pretty common problem--I just don't know where to look for the answer.
Here's the best solution I could come up with: Create a method that saves the model into an XML document, and call it whenever I change the model (e.g. add or remove a podcast). I don't have the actual source code on hand, but since there's no real easy way to save the data structure wholesale, this is the best solution.
I would like to use ServiceTracker in order to consume the services published by our company.
Instead of creating new ServiceTracker for each service I want to consume I thought it would be better to create just one with a filter and then get the services from it:
Filter filter = ctx.createFilter("(" + Constants.OBJECTCLASS + "=com.mycomp*)");
tracker = new ServiceTracker(ctx, filter, null);
The problem with this approach is that I then need to iterate over the service references the tracker had found examine their objectClass property and see if I can assign it to the service object which is very cumbersome and error prone due to casting that is required.
Any other ideas how to cunsume multiple services using more elegant way?
I think it is the wrong question :-) From the question I infer that you have a method that takes a service from your company and you want that method called. That is, somewhere in your code you need to be informed about a specific type com.mycomp.X, that is, you're not interested in general services from your company, you have a clear type dependency. In your question you assume that they need to be dispatched centrally which is usually not robust, error prone, and a maintenance hotspot; every time you have a new company service you need to update the dispatch method.
A MUCH better solution seems to be to use Declarative services and use bndtools with annotations. In that model, each place where you need service:
#Component public class SomeMyCompComponent {
...
#Reference
void foo( com.mycomp.X x ) { ... }
...
}
In this model, you do not need to centrally maintain a dispatcher, any class can get the services it needs when they need it. This model also accurately handles multiple dependencies and lots more goodies.
Maybe I do not understand the problem correctly because I inferred the problem from the solution you required. However, I think you try to abuse the Service Tracker for a task it was not intended to do.
Unfortunately, DS is not build into the framework as we should have done :-(
You could subclass ServiceTracker and add methods to provide direct access to the service types in which you are interested. For example, you could store the services in a typesafe heterogeneous container [1]. Then you would be able to call method on your ServiceTracker subclass which take the type of the service you are interested in and they could be easily looked up in the typesafe heterogeneous container.
[1] Effective Java, 2nd Ed., Item 29.