I have several schemas that inherit one or more elements from a collection of 'common' schemas. In this particular instance, I'm importing one of these schemas to make use of a single complex type defined in it.
When I generate the java objects from the schema, I get my schema types, and the element I referenced as expected, however I also get objects generated for the 30+ other types from the common schema.
I want to use the common schema, because I want to rely on automated builds for updating my schema when the common schema changes, but I do not want the extra java classes generated.
Suggestions ?
There's no out of the box approach to achieve what you want. The reason I am offering an opinion here is rather to point out (maybe for others) some issues one needs to take into account no matter which route ones go.
The 'extra' label is not always straightforward. Substitution group members are interesting. In Java, think about a class (A) using an interface (I), and a class (B:I) implementing (I). Some may say there's no dependency between A and B, while others would require B in the distribution. If you replace (I) with a concrete class, things become even less clear - consider that the substitution group head doesn't need to be abstract; or if the type of the substitution group head is anyType (Object in Java).
More so, if the XML processing was designed to accommodate xsi:type then it is even harder to tell (by looking at the schema) what is expected to work where.
Tools such as QTAssistant (I am associated with it) have a default setting that will pull in all strict dependencies (A and I above); and either ALL that might work (B above), or nothing else. Anything in between, the user needs to manually define what goes in the release. This is called automatic XSD refactoring and could be used easily in your scenario.
Related
I have a UML class Student that has an attribute id. I want to write a query in OCL to find a particular Student by only knowing its id. Should I use allInstances()? Or derive? I'm not very familiar with OCL.
Usually OCL is used to express some constraints on an UML model, in relation to a given class instance (context or self) and you’ll start navigating from a specific instance.
But OCL was developed as a formal specification language that can be used to specify more than only constraints, and in particular queries as explained in section 7.1. of the OCL specifications.
If you want to express something regarding all the possible instances of a class MyClass, you would then start your clause with:
MyClass.allInstances()
Wich is a set containing all the instances of the given class. Typically, you would then operate on this set to further specify some model features.
For example, to express uniqueness of an id, you would write a Boolean clause on this set (based on example of section 7.5.10 of the OCL specs)
MyClass.allInstances()->forAll(e1, e2 | e1 <> e2 implies e1.id <> e2.id)
One of the operation you can perform on such set is to create a subset by selecting elements that match a certain condition, and this should answer your question:
MyClass.allInstances()->select(c|c.id='...')
Additional thoughts:
OCL is an abstract language. Nothing is said on how this expression will be implemented. It could be a large inefficient iteration over an in-memory collection, or a very effective SQL query. OCL will help you to define what the result should be, but not how to really get it. So performance should not be your concern at this level of abstraction.
Now, you didn’t tell the purpose of your OCL query. If it is to explain how database queries will be performed, you could see some advantages in separation of concerns: identify the relevant classes and reusable queries and enrich your model using the repository pattern: a repository is a (singleton) class MyClassRepository that acts as a container of all objects of a given MyClass in the database. You would then define operation for manipulating and querying the database. Typically, you’ll have a couple of getXxxx() operation like getById() that return one or a set of several instances. First it will make explicit what is to be implemented as a database functionality, second the new operations can be used to simplify some OCL expressions.
Yes. allInstances() is the easy solution, but potentially the least efficient and not necessarily flexible.
If your application and constraints (for one School) are expanded to multiple schools you may realize that actually you wanted the Student at a particular School, so it is often better to go to the logical context and invoke a method on the School to return a given Student. Perhaps this is what you meant by 'derive'. The implementation of School.students->at(id) might well use a Map giving multiple gains, through not searching the whole model for every access and through having a fast access to what you have already got.
I'm trying to follow DDD principles for my current project. Unfortunately I have to use RFCs due to technical constraints, so no OData and no REST. It's quite a long question I hope it's OK to ask this in Stackoverflow.
In any case, I have an entity class WorkOrder with a list of Operation objects.
I have a WorkOrderRepository class with a SAVE method that only receives a WorkOrder object and is able to save everything (header data, address, etc) in one go. No matter if it's creation, update or deleted. The repository hides the BAPI calls from the rest.
Now I want to implement the logic to add/update/remove Operations to the work order object and I'm not sure even if the names I give to the methods are correct. Maybe they should be insert/edit/delete... I'm quite confused with this since in every place I look they use different names.
But the most important are my 2 specific doubts:
Should I have only 1 RFC that receives all the updates to a WorkOrder entity including header, operations? Or should I create 1 RFC per operation that only handles one operation at a time? Bear in mind that the UI mockup expects that the user can add/delete multiple operations before clicking a SAVE button and RFC has implicit commit, and that to my knowledge a DDD entity should be updated always in one call.
Option 1:
FUNCTION ZWORKORDER_HDR_UPD
IMPORTING
VALUE(I_WORKORDER_ID) TYPE AUFNR
VALUE(I_WORKORDER_HDR_CHG) TYPE ZWORKORDER_HDR_CHG
VALUE(I_WORKORDER_HDR_UPD) TYPE ZWORKORDER_HDR_UPD "X structure for the BAPI
VALUE(I_OPERATIONS_CHG) TYPE ZOPERATIONS_CHG
VALUE(I_OPERATIONS_UPD) TYPE ZOPERATIONS_UPD
VALUE(I_OPERATIONS_DEL) TYPE ZOPERATIONS_DEL
EXPORTING
VALUE(E_ERRORS) TYPE BAPIRET2_T.
Option 2
FUNCTION ZWORKORDER_OPERATION_CRT
IMPORTING
VALUE(I_WORKORDER_ID) TYPE AUFNR
VALUE(I_OPERATION) TYPE ZOPERATION_CHG
EXPORTING
VALUE(E_ERRORS) TYPE BAPIRET2_T.
FUNCTION ZWORKORDER_OPERATION_UPD
IMPORTING
VALUE(I_WORKORDER_ID) TYPE AUFNR
VALUE(I_OPERATION_CHG) TYPE ZOPERATION_CHG
VALUE(I_OPERATION_UPD) TYPE ZOPERATION_UPD
EXPORTING
VALUE(E_ERRORS) TYPE BAPIRET2_T.
FUNCTION ZWORKORDER_OPERATION_DEL
IMPORTING
VALUE(I_WORKORDER_ID) TYPE AUFNR
VALUE(I_OPERATION_ID) TYPE ZOPERATION_ID
EXPORTING
VALUE(E_ERRORS) TYPE BAPIRET2_T.
How should my Workorder methods look to handle this? I'm specially confused with the update method, since I'm not sure if I should first get the existing operation and then update it or let the parent class do it. But maybe my approaches are completely wrong from the root.
Option 1:
workorder->add_operation( i_operation ). "Pass flat structure from RFC? Or first create object?
workorder->update_operation( i_operation_chg
i_operation_upd ).
workorder->delete_operation( i_operation_id ).
Option 2:
workorder->add_operation( ).
operation = workorder->get_operation(i_operation_chg->get_id())
operation->update( i_operation_chg
i_operation_upd ).
operation->delete_operation( i_operation_id ).
The simplest solution is always the best (KISS and YAGNI principles). It doesn't really matter if you create 1 or 3 RFC-enabled function module, so if you can achieve your goal with one function module, then do it with one.
I think you need to have two RFC-enabled function modules. One to validate the maintained operations (do the validations as far as possible), but that should not save anything to the database, and another one called after the user clicks the SAVE button, to save the whole "WorkOrder", including the maintained operations (at this time, there will be the complete validation also).
If you don't need to define an "operation" class for something else, right now, then keep it simple, no need to instantiate an object. Note that you may create an "operation" class with private static methods, and being a friend of the "workorder" class (only this class can use the operation class), just to organize better your code.
PS: although I don't know what is "Domain-Driven Design", I don't see how your question is related to it, because it just looks like simple program design.
We also work with DDD, although luckily not with RFCs but instead Gateway/OData. Since REST by defintion is stateless we always commit in our application service layer.
What we do is have three "DDD" entities
app_Service, domain_service, repository (and also some data containers like aggregates), where the app_service in your case would expose the methods create, update and delete, and possibly also validate.
Then I would write four thin RFCs (crud + validate) that basically passes the data to the app service.
As for being able to handle multiple updates in each save, we always model our OData (your RFC) after the UI requirements, then it's the app_service task to make sense of the data from a system point of view.
We make heavy use of Abap Clean Code (it's even part of our ATC check), and they clearly state that you should have seperate methods, which is also OO best practices.
https://github.com/SAP/styleguides/blob/master/clean-abap/CleanABAP.md#split-methods-instead-of-adding-optional-parameters
I'm new to Dita, so I apologize for any ignorance.
I'm using XJC to compile the base (and only the base) Dita 1.3 schema into Java classes. When I attempted to compile all the XSD files, I received errors with elements and groups being redefined. None of the XJC bindings I attempted to write would fix it.
After digging through the schema, I found that mapGrp.xsd/mapMod.xsd and topicGrp.xsd/topicMod.xsd contained the same group and element definitions. This explains why XJC would fail when including all of the XSD files. The XSD parser itself cannot handle these duplicate entries.
So I generated basemap.xsd and basetopic.xsd separately and cleaned up the generated code so I could run a diff against the two directories.
I found that the two schema's have some elements specific to maps and topics. For example, the map schema has DitavalmetaClass and DvrKeyscopePrefixClass while the topic schema doesn't. And the topic schema contains AbstractClass and BodyClass while the map schema doesn't. But the majority of classes are shared between the two schema's.
As for the classes that are shared, there are only three that have some differences between the two schema's (LinktextClass, MetadataClass, and SearchtitleClass). Even then, they aren't big changes, just some differences in what they can contain.
My question is, why couldn't the shared classes go under one common Grp/Mod schema that's shared between topic's and map's and redefine those three classes? Can I change the two schema's so they share the same elements and groups without breaking any of the other schema's that extend the base schema?
Maps and topics are two distinct document types. They share some element types in common but are otherwise completely independent document types.
Note also that DITA does not have "a single grammar" in the way that other XML applications do (or appear to do).
DITA is explicitly architected to allow controlled extension from the base grammars so that you can do any of the following:
Configure a given map or topic type to include or exclude specific elements, either other topic types (in the case of topics) or specific element "domains" (sets of "mix-in" elements). Thus there can be two different working grammars for "topic" documents that allow different sets of elements.
Add "constraint" module that restrict existing content models or attribute lists in some way (for example, disallow a base element type in a specific context).
Define your own new element types and attributes via "specialization"
Thus any attempt to generate things like Java classes or database schemas for DITA in any sort of static way are doomed to fail in the general case.
If you are implementing code that needs to operate on any conforming DITA document then it needs to be more flexible and operate on elements in terms of their #class values, not their tag names.
If it is sensible for you to generate Java classes from the XSDs you must treat each top-level map and topic type (map, bookmap, subjectScheme, learningMap, topic, concept, task, general-task, reference, glossentry, etc.) as a distinct class hierarchy--you cannot combine them in a single hierarchy because they will have different content model rules for the same element types.
You should definitely read the DITA Architecture specification:
http://docs.oasis-open.org/dita/v1.2/os/spec/architectural_specification.html#architectural_specification
Cheers,
Eliot
The DITA 1.3 XML Schemas are not manually put together anymore. They are being generated automatically from Relax NG schemas which are the officially supported schemas by the specification. Maybe you should also take a look at the DITA 1.2 XML Schemas, those were manually written and they might be better modeled to reuse more element definitions.
Is there a way to require an element depending on the enumeration value entered for another element?
Basically, what I'm trying to do is have an user interface type defined by an enumeration. Depending on the interface type, some fields may or may not be required.
I understand this could be achieved either by making the elements optional, and handling the conditional logic in the Code, or by making different complex types for every possible interface type. However, I want the rules to be apparent to anyone reading the schema, so the Code solution wouldn't be ideal, and adding a ton of complex types, even though they share most of their required fields in common, would add a lot more to the xml parsing logic.
Is it possible to have all this logic contained in the schema to simplify validation and parsing?
This kind of conditional mandatory/optional element inclusion is not possible with XSD.
You can do that using RelaxNG.
You will have a good technical data interface with this kind of schema (describing exactly the structure you want, with a tool like Jing for validation).
And then, if you want to use object mapping, you can use Trang to convert your RelaxNG schema to an XML Schema (the XML Schema will be little more loosy, the true data interface beeing described in RelaxNG).
Does anybody know where I can find documentation on how to write annotation schemas for Callisto? I'm looking to write something a little more complicated than I can generate from a DTD -- that only gives me the ability to tag different kinds of text mentions. I'm looking to create a schema that represents a single type of relationship between five or six different kinds of textual mentions (and some of these types of mentions have attributes that I need to assign values to), and possibly having a second type of relationship between the first two instances of the first type of relationship.
(Alternatively, does anybody know of any software that would be better for this kind of schema? I've been looking at WordFreak, but it's a little clumsy, and it doesn't support attributes on its textual mentions.)
Creating an XML DTD with one XML tag for each type of textual mention (and attributes on the tags to indicate the attributes), and using an "id" attribute on every tag that the annotator has to fill in himself (a monotonically increasing integer). Then I used the DTD schema generator to create a Callisto schema.