I have two classes. One Attribut of class1 is connected to another attribut of class2. This was done with the help of the context menue of the connector in the proximity of one class, it is called Link to element feature. The same is done on the other side of the connector to select the other attribut of the other class. So the connector directly connects two attributes and not the classes itselves. I haven´t found the tables, where this infomation is stored, so I dont find the appropiate SQL to find connected (or not connected) attributes.
Here's the way for notes using Link to..
PDATA1 = 'Attribute'
PDATA2 = t_attribute.ID of the attribute
PDATA3 = name of the attribute
PDATA4 has 'Yes' (I don't recall what that's used for so you can probably ignore it
First SQL:
SELECT PDATA2 FROM t_object WHERE Object_Type='Note' AND PDATA1 = 'Attribute'
will give you the ID. Just put that in another SQL:
SELECT * FROM t_attribute WHERE ID = (above SQL)
and you have the attribute details. Or if you want to find the unmapped one just build a dissection with the found IDs from the first with the existing attribute IDs.
For associations using Link to... it's a bit more tricky. First off, any such connectors have the relevant information stored in t_connector.StyleEx like e.g.
LFEP={69A30E17-23AB-4641-9573-9BDBAA988D52}L;
LF<dir>P=<guid><pos>; connector is attached to attribute/operation
<dir> = S or E meaning Start (source) or End (target) <guid> = ea_guid of t_attribute or t_operation
<pos> is the edge (L or R) where the connector had been attached to in the moment when the link has been created. This is a superfluous information since the renderer will attach the link to whatever place is relevant.
There can be one LFSP, one LFEP or both be present in one StyleEx property
(from my Inside book)
Now you can filter that information with a SQL or (what I prefer) with a little script, since doing complex SQL string operations are not my expertise.
Using Camunda as the tool for orchestration of the microservices. At later time, I find the process_instances_id generated necessary for continuing a particular process by using it in messageEventReceived(). Code as follows:
val processid = getProcessID(key1, key2)
val runtimeService = processengine.getRuntimeService
val subscription = runtimeService.createEventSubscriptionQuery
.eventType("message")
.eventName(eventname)
.processInstanceId(executionid)
.singleResult
runtimeService.messageEventReceived(subscription.getEventName, subscription.getExecutionId)
As of this moment the processid is saved and then retrieved from the database using the getProcessID(...) function when necessary. Is this proper?
Does camunda already have the list of process_ids in its own database? If so, how do I retrieve a particular process instance id just giving composite key(s)? Is that even possible?
It is the common way. You can also use the public api to get the process instance and his id via the process definition key.
See the following example from the documentation:
runtimeService.createProcessInstanceQuery()
.processDefinitionKey("invoice")
.list();
For your given example there is also a simpler way. It is possible to correlate the message via the runtime service.
See this example from the documenation:
runtimeService.createMessageCorrelation("messageName")
.processInstanceBusinessKey("AB-123")
.setVariable("payment_type", "creditCard")
.correlate();
You can use
runtimeService.createProcessInstanceQuery().list();
the query supports fluent criteria for filtering, for example on process_key, variables, businessKey ...
For my current project I need to load a dataset and different ontologies and expose everything as linked data using Fuseki with TDB and Pubby. Pubby will take a data set from a single location and create URIs based on that location, therefore if we need multiple different locations (as in the case with 2–3 separate ontologies), that would be easy to do with Pubby by adding another data set.
The concept of dataset seems to also apply to Fuseki.
Essentially I will need to expose three types of URIs:
www.mywebsite.com/project/data
www.mywebsite.com/project/data/structure
www.mywebsite.com/project/ontology
In order to create such URIs with Pubby 0.3.3. you will have to specify lines like these:
conf:dataset [
conf:sparqlEndpoint <sparql_endpoint_url_ONE>;
conf:sparqlDefaultGraph <sparql_default_graph_name_ONE>;
conf:datasetBase <http://mywebsite.com/project/>;
conf:datasetURIPattern "(data)/.*";
(...)
]
Each data set specified in Pubby will take its data from a certain URL (typically a SPARQL endpoint).
For ontologies you will have a dataset that uses the second a datasetURIPattern like this one:
conf:dataset [
conf:sparqlEndpoint <sparql_endpoint_url_TWO>;
conf:sparqlDefaultGraph <sparql_default_graph_name_TWO>;
conf:datasetBase <http://mywebsite.com/project/>;
conf:datasetURIPattern "(ontology)/.*";
(...)
]
As you can see the differences would be at the following: conf:sparqlEndpoint (the SPARQL endpoint), conf:sparqlDefaultGraph (the default Graph), conf:datasetURIPattern (needed for creating the actual URIs with Pubby).
It is not however clear to me how can I have separate URIs for the data sets when using Fuseki. When using Sesame, for example, I just create two different repositories and this trick works like charm when publishing data with Pubby. Not immediately clear with
The examples from the official Fuseki documentation present a single dataset (read-only or not, etc), but none of them seem to present such a scenario. There is no immediate example where there is a clear separation between the TBox and the ABox, even though this is a fundamental principle of Linked Data (see Keeping ABox and TBox Split).
As far as I understand this should be possible, but how? Also is it correct that the TBox and ABox can be reunited under a single SPARQL endpoint later by using (tdb:unionDefaultGraph true ;).
The dataset concept is not unique to Jena Fuseki; it's quite central in SPARQL. A dataset is a collection of named graphs and a default graph. The prefix of a URI has nothing to do with where triples about it are stored (whether in a named graph or in the default graph).
It sounds like you want to keep your ABox triples in one named graph and your TBox triples in another. Then, if the default graph is the union of the named graphs, you'll see the contents of both in the default graph. You can do that in Fuseki.
While creating an app in Laravel 4 after reading T. Otwell's book on good design patterns in Laravel I found myself creating repositories for every table on the application.
I ended up with the following table structure:
Students: id, name
Courses: id, name, teacher_id
Teachers: id, name
Assignments: id, name, course_id
Scores (acts as a pivot between students and assignments): student_id, assignment_id, scores
I have repository classes with find, create, update and delete methods for all of these tables. Each repository has an Eloquent model which interacts with the database. Relationships are defined in the model per Laravel's documentation: http://laravel.com/docs/eloquent#relationships.
When creating a new course, all I do is calling the create method on the Course Repository. That course has assignments, so when creating one, I also want to create an entry in the score's table for each student in the course. I do this through the Assignment Repository. This implies the assignment repository communicates with two Eloquent models, with the Assignment and Student model.
My question is: as this app will probably grow in size and more relationships will be introduced, is it good practice to communicate with different Eloquent models in repositories or should this be done using other repositories instead (I mean calling other repositories from the Assignment repository) or should it be done in the Eloquent models all together?
Also, is it good practice to use the scores table as a pivot between assignments and students or should it be done somewhere else?
I am finishing up a large project using Laravel 4 and had to answer all of the questions you are asking right now. After reading all of the available Laravel books over at Leanpub, and tons of Googling, I came up with the following structure.
One Eloquent Model class per datable table
One Repository class per Eloquent Model
A Service class that may communicate between multiple Repository classes.
So let's say I'm building a movie database. I would have at least the following following Eloquent Model classes:
Movie
Studio
Director
Actor
Review
A repository class would encapsulate each Eloquent Model class and be responsible for CRUD operations on the database. The repository classes might look like this:
MovieRepository
StudioRepository
DirectorRepository
ActorRepository
ReviewRepository
Each repository class would extend a BaseRepository class which implements the following interface:
interface BaseRepositoryInterface
{
public function errors();
public function all(array $related = null);
public function get($id, array $related = null);
public function getWhere($column, $value, array $related = null);
public function getRecent($limit, array $related = null);
public function create(array $data);
public function update(array $data);
public function delete($id);
public function deleteWhere($column, $value);
}
A Service class is used to glue multiple repositories together and contains the real "business logic" of the application. Controllers only communicate with Service classes for Create, Update and Delete actions.
So when I want to create a new Movie record in the database, my MovieController class might have the following methods:
public function __construct(MovieRepositoryInterface $movieRepository, MovieServiceInterface $movieService)
{
$this->movieRepository = $movieRepository;
$this->movieService = $movieService;
}
public function postCreate()
{
if( ! $this->movieService->create(Input::all()))
{
return Redirect::back()->withErrors($this->movieService->errors())->withInput();
}
// New movie was saved successfully. Do whatever you need to do here.
}
It's up to you to determine how you POST data to your controllers, but let's say the data returned by Input::all() in the postCreate() method looks something like this:
$data = array(
'movie' => array(
'title' => 'Iron Eagle',
'year' => '1986',
'synopsis' => 'When Doug\'s father, an Air Force Pilot, is shot down by MiGs belonging to a radical Middle Eastern state, no one seems able to get him out. Doug finds Chappy, an Air Force Colonel who is intrigued by the idea of sending in two fighters piloted by himself and Doug to rescue Doug\'s father after bombing the MiG base.'
),
'actors' => array(
0 => 'Louis Gossett Jr.',
1 => 'Jason Gedrick',
2 => 'Larry B. Scott'
),
'director' => 'Sidney J. Furie',
'studio' => 'TriStar Pictures'
)
Since the MovieRepository shouldn't know how to create Actor, Director or Studio records in the database, we'll use our MovieService class, which might look something like this:
public function __construct(MovieRepositoryInterface $movieRepository, ActorRepositoryInterface $actorRepository, DirectorRepositoryInterface $directorRepository, StudioRepositoryInterface $studioRepository)
{
$this->movieRepository = $movieRepository;
$this->actorRepository = $actorRepository;
$this->directorRepository = $directorRepository;
$this->studioRepository = $studioRepository;
}
public function create(array $input)
{
$movieData = $input['movie'];
$actorsData = $input['actors'];
$directorData = $input['director'];
$studioData = $input['studio'];
// In a more complete example you would probably want to implement database transactions and perform input validation using the Laravel Validator class here.
// Create the new movie record
$movie = $this->movieRepository->create($movieData);
// Create the new actor records and associate them with the movie record
foreach($actors as $actor)
{
$actorModel = $this->actorRepository->create($actor);
$movie->actors()->save($actorModel);
}
// Create the director record and associate it with the movie record
$director = $this->directorRepository->create($directorData);
$director->movies()->associate($movie);
// Create the studio record and associate it with the movie record
$studio = $this->studioRepository->create($studioData);
$studio->movies()->associate($movie);
// Assume everything worked. In the real world you'll need to implement checks.
return true;
}
So what we're left with is a nice, sensible separation of concerns. Repositories are only aware of the Eloquent model they insert and retrieve from the database. Controllers don't care about repositories, they just hand off the data they collect from the user and pass it to the appropriate service. The service doesn't care how the data it receives is saved to the database, it just hands off the relevant data it was given by the controller to the appropriate repositories.
Keep in mind you're asking for opinions :D
Here's mine:
TL;DR: Yes, that's fine.
You're doing fine!
I do exactly what you are doing often and find it works great.
I often, however, organize repositories around business logic instead of having a repo-per-table. This is useful as it's a point of view centered around how your application should solve your "business problem".
A Course is a "entity", with attributes (title, id, etc) and even other entities (Assignments, which have their own attributes and possibly entities).
Your "Course" repository should be able to return a Course and the Courses' attributes/Assignments (including Assignment).
You can accomplish that with Eloquent, luckily.
(I often end up with a repository per table, but some repositories are used much more than others, and so have many more methods. Your "courses" repository may be much more full-featured than your Assignments repository, for instance, if your application centers more around Courses and less about a Courses' collection of Assignments).
The tricky part
I often use repositories inside of my repositories in order to do some database actions.
Any repository which implements Eloquent in order to handle data will likely return Eloquent models. In that light, it's fine if your Course model uses built-in relationships in order to retrieve or save Assignments (or any other use case). Our "implementation" is built around Eloquent.
From a practical point of view, this makes sense. We're unlikely to change data sources to something Eloquent can't handle (to a non-sql data source).
ORMS
The trickiest part of this setup, for me at least, is determing if Eloquent is actually helping or harming us. ORMs are a tricky subject, because while they help us greatly from a practical point of view, they also couple your "business logic entities" code with the code doing the data retrieval.
This sort of muddles up whether your repository's responsibility is actually for handling data or handling the retrieval / update of entities (business domain entities).
Furthermore, they act as the very objects you pass to your views. If you later have to get away from using Eloquent models in a repository, you'll need to make sure the variables passed to your views behave in the same way or have the same methods available, otherwise changing your data sources will roll into changing your views, and you've (partially) lost the purpose of abstracting your logic out to repositories in the first place - the maintainability of your project goes down as.
Anyway, these are somewhat incomplete thoughts. They are, as stated, merely my opinion, which happens to be the result of reading Domain Driven Design and watching videos like "uncle bob's" keynote at Ruby Midwest within the last year.
I like to think of it in terms of what my code is doing and what it is responsible for, rather than "right or wrong". This is how I break apart my responsibilities:
Controllers are the HTTP layer and route requests through to the underlying apis (aka, it controls the flow)
Models represent the database schema, and tell the application what the data looks like, what relationships it may have, as well as any global attributes that may be necessary (such as a name method for returning a concatenated first and last name)
Repositories represent the more complex queries and interactions with the models (I don't do any queries on model methods).
Search engines - classes that help me build complex search queries.
With this in mind, it makes sense every time to use a repository (whether you create interfaces.etc. is a whole other topic). I like this approach, because it means I know exactly where to go when I'm needing to do certain work.
I also tend to build a base repository, usually an abstract class which defines the main defaults - basically CRUD operations, and then each child can just extend and add methods as necessary, or overload the defaults. Injecting your model also helps this pattern to be quite robust.
Think of Repositories as a consistent filing cabinet of your data (not just your ORMs). The idea is that you want to grab data in a consistent simple to use API.
If you find yourself just doing Model::all(), Model::find(), Model::create() you probably won't benefit much from abstracting away a repository. On the other hand, if you want to do a bit more business logic to your queries or actions, you may want to create a repository to make an easier to use API for dealing with data.
I think you were asking if a repository would be the best way to deal with some of the more verbose syntax required to connect related models. Depending on the situation, there are a few things I may do:
Hanging a new child model off of a parent model (one-one or one-many), I would add a method to the child repository something like createWithParent($attributes, $parentModelInstance) and this would just add the $parentModelInstance->id into the parent_id field of the attributes and call create.
Attaching a many-many relationship, I actually create functions on the models so that I can run $instance->attachChild($childInstance). Note that this requires existing elements on both side.
Creating related models in one run, I create something that I call a Gateway (it may be a bit off from Fowler's definitions). Way I can call $gateway->createParentAndChild($parentAttributes, $childAttributes) instead of a bunch of logic that may change or that would complicate the logic that I have in a controller or command.
We are in the middle of designing a new feature for our API and we stumbled across a dilemma.
We have two different types of resources with a 1-N relationship.
Representations and Layers.
A Representation can contain multiple Layers. A Layer can belong only to one Representation.
The thing we are stuck with is that we need to maintain an order for the Layers in a Representation.
And we came up with two approaches:
First approach: Linked List
Each Layer knows about its previous layer. In the DB this is achieved by having a "parent" field in the Layers table that contains the id of another Layer. The first Layer will have a "parent" set to NULL.
This then is exposes through the API by the following URIs:
Create
GET /Representations/{repID}/layers
gets all the layers for a representation. The order can be worked out by going through all the layers and look at the Parent field.
POST /Representations/{repID}/layers
body:
Label: (string)
Parent: LayerId
This is used to create and insert a Layer in a specific position, by specifying the Parent in the request body. If you set Parent to NULL the newly created Layer will be the first Layer in the order.
If you omit the Parent field, the newly created Layer will be positioned at the bottom of the order.
Problem with this is that, in the response, we need to notify the api consumer that other layers have changed order because of the new insertion.
Update
PUT /Representations/{repID}/layers/{layerId}
body:
Label: (string)
Parent: LayerId
Again you can specify a new Parent to re-order the layer and again we will need to send back some information about all the other layers that have changed.
Delete
DELETE /Representations/{repID}/layers/{layerId}
need to send back some information about all the other layers that have changed.
Second approach: Layers Order as its own resource
The idea is that layers themselves don't have a notion of order. They are merely a resource.
Then you get a layersorder resource which is in charge of keeping the information about the order of the layers.
So you will still have the CRUD functionality for layers:
GET - POST - PUT - DELETE
but when you want to know anything about their order, or you want to change their order, you will use the following uri:
/Representation/{repId}/layersorder
This resource will support only two methods
GET /Representations/{repID}/layersorder
gets back an ordered list of Layers Ids in this Representation.
PUT /Representations/{repID}/layersorder
body:
[] - Array of Layers Ids in the new order.
Updates the order of the layers. you need to pass an Array of Layers ids in the new order as the body of the request. (e.g. [1,3,2,4,6,5] )
as per the first approach, whenever you add or remove a Layer you will need to notify the api consumer that another resource has been updated. In the first approach that was the list of layers affected by the change, in this approach is the new order of the layers (the layersorder resource).
I would like to hear opinions and also examples of similar situations and how you solved the problem.
thanks.
I've experienced part of what you are describing.
When doing a PUT/POST that affects an entity (or entities), I like to return the full object after the change. Hopefully the return object isn't massive, but if I were using your API, with the first approach ... I would enjoy doing a PUT/POST and updating a layer and then getting back the full Representation object with the updated Layer information.
It just makes it easy for me to confirm my changes and also start working immediately in my code with the new structure. I would dislike doing the PUT/POST and then having to do an additional GET to see the change.
For the second approach ... the more work I have to do to make an API call, the more frustrated I get. I'm not sure if I read it right, but to do a PUT with the second approach, it seems like I have to construct the entire representation and layer objects to update one piece of data. That would be frustrating.
I would prefer the syntax of the first approach, but with the concepts from the second. In other words, this is the document I would expect to see after a PUT/POST/GET:
{
"type" : "Representation",
"id" : 1,
"layers" : [
{ "id" : 1, "name" : "the first layer", "order" : 1, "parent" : "" },
{ "id" : 2, "name" : "the second layer", "order" : 2, "parent" : 1 },
{ "id" : 3, "name" : "the third layer", "order" : 3, "parent" : 1 }
]
}
It's sorted for me already so I don't have to do that work, but also has the information used to produce the sorting just in case. I've done this with REST APIs and it seems to work great for the users.