Inconsistency in Camel Java DSL

[Christian Schneider <ch...@die-schneider.net>]

Hi all,

I have looked into the way Camel routes are built and I think I found an 
inconsistency that gives us a lot of dependency cycles.
There are two main packages involved: builder and model. I would 
describe their purpose in the following way.
The builder package contains classes that help building the camel routes 
in Java. It is responsible for providing a fluent Java DSL for writing 
routes and for instantiating the model classes.
The model package contains classes that form the tree that represents a 
camel route. While the builder package is java dsl specific the model is 
language agnostic.
I would say that builder needs to reference model as it has the 
responsibility to build the route tree. In the other direction model 
should not reference builder.

All the following I write is based on the asumption that above 
responsibilities are correct so I hope I got it right ;-)

If I understood the Fluent Builder Pattern correctly then a method of a 
builder class should return a builder class.

In camel this seems to be different. The RouteBuilder method from 
returns a RouteDefinition which extends a ProcessorDefinition. To make 
the java dsl work
the ProcessorDefinition also works like a builder. I think this mixes 
responsibilities and causes many cycles between builder and model.

My proposal is to remove any builder methods from any model classes and 
move them to the builder package. This means that RouteBuilder.from 
should return either a RouteBuilder or a ProcessorBuilder.
Processorbuilder is already existent but it does not seem to follow the 
builder pattern. I think it should contain all the builder methods that 
are currently in ProcessorDefinition (like to or loadBalance).
ProcessorDefinition should only help to store the static route tree and 
perhaps help to traverse it and of course it is the base class for all 
ProcessorDefinitions.

There remains one other thing I am not so sure about. Where to create 
for example the Processors? Should this be done in builder or in model 
or somewhere else?

What do you think?

Greetings

Christian

-- 

Christian Schneider
---
http://www.liquid-reality.de

Re: Inconsistency in Camel Java DSL

[alloyer <al...@gmail.com>]

Hi,Christian
I agree with you and I think the builder and model package have a little
inconsistency.
When I implement the groovy route editor today, I found that:
   1. In Xml schema editing mode, a RouteDefinition instance will be
constructed to receive the web console content.
   2. But in Groovy editing mode, a RouteBuilder instance is used because
through groovy mode, a class can generate a set of RouteDefinition
instances.

    RouteDefinition is a concept in model package while RouteBuilder is in
builder, which has a set of RouteDefinition instances in it. So when
executing the update operation, some inconsistent process are brought in.


Christian Schneider wrote:
> 
> Hi all,
> 
> I have looked into the way Camel routes are built and I think I found an 
> inconsistency that gives us a lot of dependency cycles.
> There are two main packages involved: builder and model. I would 
> describe their purpose in the following way.
> The builder package contains classes that help building the camel routes 
> in Java. It is responsible for providing a fluent Java DSL for writing 
> routes and for instantiating the model classes.
> The model package contains classes that form the tree that represents a 
> camel route. While the builder package is java dsl specific the model is 
> language agnostic.
> I would say that builder needs to reference model as it has the 
> responsibility to build the route tree. In the other direction model 
> should not reference builder.
> 
> All the following I write is based on the asumption that above 
> responsibilities are correct so I hope I got it right ;-)
> 
> If I understood the Fluent Builder Pattern correctly then a method of a 
> builder class should return a builder class.
> 
> In camel this seems to be different. The RouteBuilder method from 
> returns a RouteDefinition which extends a ProcessorDefinition. To make 
> the java dsl work
> the ProcessorDefinition also works like a builder. I think this mixes 
> responsibilities and causes many cycles between builder and model.
> 
> My proposal is to remove any builder methods from any model classes and 
> move them to the builder package. This means that RouteBuilder.from 
> should return either a RouteBuilder or a ProcessorBuilder.
> Processorbuilder is already existent but it does not seem to follow the 
> builder pattern. I think it should contain all the builder methods that 
> are currently in ProcessorDefinition (like to or loadBalance).
> ProcessorDefinition should only help to store the static route tree and 
> perhaps help to traverse it and of course it is the base class for all 
> ProcessorDefinitions.
> 
> There remains one other thing I am not so sure about. Where to create 
> for example the Processors? Should this be done in builder or in model 
> or somewhere else?
> 
> What do you think?
> 
> Greetings
> 
> Christian
> 
> -- 
> 
> Christian Schneider
> ---
> http://www.liquid-reality.de
> 
> 
> 

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