I am quite new to the Achrimate 3.0 and I am trying to make my model in it. I put an example below. My goal is to model this stream of data where I have a Source System which is creating output files in specific format -> next Step is Pulling the data by processing component and looking for some values in connected DB -> final step is then deliver this data (pushed by processing component) to Target Systems.
Q1: What relationship is correct to Application Component and Interface? In the picture is triggering (but maybe FLOW fits better) ?
Q2: Database is joined via Access relationship ?
Q3: For my purposes it will need to hold information about DB (columns+types+notes) structure in the diagram, any tips, how to manage it in Archimate ?
Diagram Example Here:
First, it would be nice to read the specification (http://pubs.opengroup.org/architecture/archimate3-doc/chap09.html#_Toc489946063).
Are you sure that you use only application layer? If so, then the interface is not defined correctly, the interface that you specified is rather related to the technology layer.
So:
Wrong interface (IMHO). Figure 67: Application Layer Metamodel of spec show you how elements can be linked on this layer.
Database can be represent as component, not DataObject.
In my experience - no good way. Use the standard reverse engineering mechanism. Associate the resulting UML objects with the Archimate elements if you need it.
Related
I am new to domain driven design and trying to learn and implement in my project. My project structure up till now similar to this.
Maintainance Folder Maintainance.Data(Class
Library) Maintainance.Domain(Class Library)
Maintainance.Domin.Tests(test project)
MovieBooking Folder MovieBooking.Data(Class
Library) MovieBooking.Domain(Class Library)
MovieBooking.Domain.Tests(test project)
SharedKernel Common things
Web Application MovieBooking MVC Web
Application(which have reference to MovieBooking Domain)
In Maintainance boundned context I am keeping all CRUD, GetAll type things for say Movie, Country, Category, Subcategory entities in Maintainance DBContext.
Now in MovieBooking data layer I will also need to use these entities (mostly to display name or dropdown fills in view, kind of subset needed - not all properties needed, only few like Id, name)
There are few ways I can access this entities in Movie booking Bounded Context
Via web services - Need to create web api for common entities like Movie,Country,Category,Subcategory and call web api in web project (to fill Dropdowns or get name from entities)
Via Reference Context (Seperate Dbcontext) - Need to configure Dbset and then map a database view (with only require fields) to Dbset
Example :
modelBuilder.Entity().ToTable(ViewName);
For (1) it can be long term implmentation solution for me
(2) I have to create view (with only few properties) for each require table and it will increase my number of views in my DB drastically as I have enterprise level application.
Is there any other way I can achieve this? Anything I am missing in DDD to look for ?
Option 2, while it will save you time, is actually a very bad idea from the DDD perspective as it allows for violations of the transactional boundary guarantees that each aggregate is meant to enforce\represent.
Option 1 seems a better option, although there are still quite a bit of wiggle room for interpretation based on your brief description of your proposed solution. If I understood correctly, it is generally recommended to follow the below:
Do not expose your aggregate state directly since this exposes internals and increases coupling. Simple create meaningful DTO's and use something like Automapper to map your Aggregates to DTO's easilly and with little effort before sending it over.
Have a duplicate of the DTO definition in your client. This will reduce coupling and allow for easier deployments.
I strongly recommend reading the DDD orange book although I have to say that I cannot recall specifically on which chapter this is discussed. You will also benefit a lot by reading about hexagonal architecture (and I would search for that term in the orange book to find more info about your question).
There is actually one alternative that I can think of: if you're publishing events from your BC's you can create a workflow to translate the domain events to "public" events and then in the other BC listen for the public events that you need to and store the data that you need somewhere inside there. The difficulty of this ranges from very easy to quite problematic depending on your infrastructure. Be aware that it is not a very good idea to re-use your domain events for transmitting data to other BC's since this closely couples the two BC's.
I hope this helps. Please do not hesitate to elaborate if I did not understood the question well enough.
I am implementing a database search algorithm which searches over many collections in a MongoDB and returns optimized results based on the state of the entire database. I have no problems with the implementation, but the nomenclature and how I should structure the file system is bugging me. Where in the model-view-controller pattern should I place read only operations? Is it a service? It has a controller but I hardly think it satisfies the criteria to be a model.
This question is extremely language dependant and the features that exist within that language. I will speak from a PHP point of view.
Search functions should go into the model, the model backs up as a data provider in the MVC pattern. A single central point from which to dish out instances of it self.
Some MVCs implement what is known as factory classes. They are specifically designed to sit outside of the MVCs normal pattern to be able to provide data: http://en.wikipedia.org/wiki/Factory_method_pattern . As someone who has used this pattern I can say it gets complicated and unmanageable very quickly. That is why I prefer to backup the model as a data provider itself, it merely requires class organisation.
Model View Controller architecture is pretty much the equivalent of a three or four tier solution in a client server setup and the same rules apply.
Complex and intensive database functionality lives with the tool that is best suited to the task and is most re-usable and in this case I would argue that the RDBMS would be the best option in the vast majority of RDBMS's as it is the RDBMS that best knows how to manipulate it's data, work out query plans etc...
It could also be argued that the model layer would be the most natural place from a purist coding point of view where you have all your data access in one layer.
It is highly unlikely that it would ever be advantageous to place this sort of functionality in the least re-usable layer i.e. the controller/view
This is of course only my opinion and I suspect you will get many alternative opinions but ( can not for the life of me think that from a performance point of view that yopur logic belongs anywhere other than at the database level
UPDATE
A model is the guardian of all data. if a view or controller wants data, it asks the model for that data. The view or controller shouldn't care about how the data is obtained or where it comes from. It's about separation of concerns. So that leaves the question. Do I place the code to query the database in the model or in the RDBMS?
Well of course you have to have a method in a model for the view or controller to call in the first place so of course you need a model but what goes inside that method and where the actual query SQL lives is up to the designer. The point is, that so long as the query lives at model or database level you are hiding the implementation from the view or controller and are free to change the implementation whenever you wish without having to worry about the potentially many places it is called from.
So model or RDBMS is the answer. The solution chosen depends on the MVC tools you are using and the RDBMS you are using. Also remember that a model does not have to consist of a single method which is what you are implying you may be thinnking from your comment.
I am working on developing a set of assemblies that encapsulate parts of our domain that will be shared by many applications. Using the example of an order management system, one such assembly will contain all of the core operations an application can perform to/with an order. We are applying a simple version of CQS/CQRS so that all operations that change the state of the "system" are represented as public commands, such as CancelOrderCommand, ShipOrderCommand and CreateORderCommand. The command handlers are internal to the assembly.
The question I am struggling to answer is how to best expose the read model to consuming code?
The read model will be used by consuming code to perform queries. I don't know how all of the ways the read model will be used so the interface needs to be flexible to allow any query.
What complicates it for me is that I not only need to expose my aggregate root but there are also several "lookup" lists of related data that client applications may use. For example, each order has an associated OrderType which is data-driven (i.e., not an enum) and contains several properties that will drive some of our business rules that control what operations can/cannot be performed, etc. It is easy inside my module to manage this relationship; however, a client application that allows order creation will most likely need to display the list of possible OrderTypes to the user. As a result, I need to not only expose the list of Order aggregates but the supporting list of OrderTypes (and other lookup lists) from my read model.
How is this typically done?
I'm not sure what else to explain that will help trigger a solution, so please ask away...
I have never seen a CQRS based implementation expose a full dataset for ad-hoc querying so this is an interesting situation! In a typical CQRS scenario you would expose very specific queries because you may want to raise events when they are called (for caching for example - see this post for more details on that).
However since this is your design, let's not worry about "typical" or "correct" CQRS, I guess you just need a solution! One of the best new mechanisms for exposing data for flexible querying I have seen is the Open Data Protocol (OData). It will allow consumers to implement their own filtering, sorting and paging over a data source you expose.
Most implementations of this seem to deal with relational data. If you are dealing with a relational data source then OData might be a nice way to go. I suspect by your comment of "expose my aggregate root" that you might be using a document database? If so, there is one example I have seen of OData services on top of MongoDB: http://bloggingabout.net/blogs/vagif/archive/2012/10/11/mongodb-odata-provider-now-supports-arrays-and-nested-collections.aspx.
I hope that helps, OData is definitely worth looking into. It seems to be growing really quickly and is getting good support on both server and client technology platforms.
I'm starting to work with graph databases, and in my team we've started modeling a graph for our software. The problem comes when we try to "document" the model, to see the structure of our database. With SQL databases you only have to look at the SQL schema.
We've spent some time reading neo4j blogs and documentation, but we've seen that the usual way to show how a graph works is with a minimal graph showing some sample data (Random samples: sample1, sample2, etc). That's great for educational purposes, but we'd love to be able to do it in a little more formal way. We'd like to set what kind of node can relate with another one, and with what kind of relationship, that kind of stuff.
Using Spring you can wrap the graph with classes, but it's very specific to Java and OO model, and we're working with Erlang. We're looking for some kind of formal language (SQL Schema equivalent), or a E-R model equivalent, or something like that.
One way to do this is to put the "meta-model" of your graph (a type network) in the graph as well and then connect the instances (nodes) to their meta-model-type. So you can visualize the meta-model using the graph visualization and at the same time use the meta-model to enforce additional constraints (by storing constraint information in the meta-model and using that when the actual model is updated) and also use the type-nodes of the meta-model to quickly access all "instance"-nodes of this type.
What is the domain you want to model?
A quick idea - could you use a subset of UML? Graph modeling seems to be closer to the domain, so maybe that's reasonable.
What we do is a generalization of the "example data" approach, where we include cardinality on each side of a relationship, as well as type and direction. I also often include a node "type" in the diagram (or some other specification of it's role/relation to domain models) instead of example data, and of course note the expected properties, their types, and whether they are optional. It's less than formal, but has served well so far.
I reluctantly adopted a data mapper approach for my current project but I've been left a little confused.
Business Model
A worker has a name, a set of working hours, and a cost.
Data Model
A worker is made up of a labour type and a working pattern (three different tables). The cost of the worker is calculated based on a combination of the labour type and the working pattern.
My problem...
I seem to have two different models, one that represents business logic and one that represents data structure. I was of the understanding that my model should represent the business logic, but what happens when I want to insert a new worker? This is done using a form with two drop downs, the working pattern & the cost, the id's of which are not needed by the business model.
Confused? I am.
There is no real support for data models with the zend framework. But weierophinney does a realy good job to show how they could be implemented. Another very good description is this one.
Usually a model represents the data and includes the logic. The data model is a backend independed way to write/get data. For the model and the application it doesn't matter from where the data comes. Thus the datastorage can be exchanged without having to touch anything else.
Default data modelling in Zend Framework (Zend_Db_Table) isn't probably the best choice for object oriented data modelling.
Try using ORM like Doctrine (http://www.doctrine-project.org/) it allows you to create domain object model and almost transparently store it in database. This way you can have business model and data model combined in single classes.