RIA Services, how do I organize the services? - web-services

I am working on a project that is going to be using RIA services. The visual studio solution file has 2 projects, one for the UI and the other for the domain logic. The initial approach was to have multiple domain service classes inside of the domain logic project (to keep it organized). After receiving a certain compile error I came across this issue with RIA.
http://forums.silverlight.net/forums/p/111058/257398.aspx
So my question is, if I have to use one service file it is going to have thousands of stubs and queries because of the magnitude of the database/project, how would I go about organizing this. An even better question would be, Is there a workaround to the problem listed in that forums post I linked.
Thanks in advance for the responses.

We ran into a similar situation. Although the design still smells a bit because the DomainService class has a lot of methods, we were able to organize a bit.
Choose a way to divide up the responsibilities of the DomainService class. We chose to do this by Entity, but it could be along some other line. You can create a separate file for each responsibility, although each file contains a partial class implementation of your DomainService. Our naming convention for each file was DomainService.Entity.cs
Another thing we did was create a separate DomainService for some cross-cutting concerns. We have one for logging messages from the Silverlight client back to the server, and one for authentication only.

Related

Create a separate app for my REST API or place it inside my working app?

I'm building simple gis system on geodjango.
The app displays a set of maps and I'm also attempting to provide a RESTFUL API for these maps.
I'm facing a decision whether to create a separate app for the API or to work inside my existing app.
The two apps are logically separate but they share the same models.
So what is considered better?
Although a case can be made for either of the approaches, I think keeping the APIs inside their associated apps would be a better one. Since the code in APIs is going to depend on the models, or other utility methods anyway, keeping APIs in the same app would lead to more cohesive code. Besides the very ideology behind Django apps is that they can be isolated and reused.
There used to be a similar case with storing the templates. In the initial days of Django, people used to prefer to store all the templates altogether in the same global folder (with subdirectories by the names of the app), however, in recent times even Django has started discouraging the said approach in the favour of storing templates in the respective app itself.
#hspandher's answer is very solid and will allow for most of your needs to be implemented.
There is though another approach which may be a bit more complicated to achieve but gives you all the space you may need for experimentation and reusability potential:
Separate everything:
Backend:
Isolate your API from its visualization (see frontend below) and make it completely autonomous and self-contained.
That can be achieved by separating your apps inside your Django project and expose the corresponding APIs which must be the only way for an external factor (ex. client, another app etc.) to "talk" with any one of your apps.
Frontend:
Assuming that you have your APIs exposed, you effectively separated the visualization from the logic and therefore you have many options on how to visualize your maps.
For example, you can now build a React app which can make requests to your API and visualize the responses by using any of those tools: leaflet.js, D3.js, or anything that you like really.
Summary:
The benefits of this separation are:
Separation of logic and implementation.
Better maintainability.
Many tool and technology options to use.
Reusability.
As a side note, you can read about 12 factor method and think about using it in your implementation.

Java EE -- using the same stateful object for several users

Even though I've been in Java SE for quite some time now, I started EE & web w/ Java only about a month ago, so pardon if the question seems a bit noobish...
So here's the situation: I'm trying to write a JS based multi-player game with real-time interaction (let's say chess in this example, though it really doesn't matter what particular game it is, could be tennis or w/ever). The clients would interact with the server through JS calls, sending the move etc. Now, while I could just receive the move from one client & pass it straight on to the other player, not maintaining the game state on the server would mean putting a huge sign out saying "user JS scripts welcome" (and that's out of experience -- "hacked" a crapload of that kind myself). This brings me to my problem -- how do I share a stateful object between several sessions? One idea that came to mind was a singleton storing a Hashmap of stateful beans & then each session could retrieve the bean by it's hash, but I've no idea how right that is (and it seems rather complex for a fairly common thing like that). Tieing it to application scope seems overkill as well...
P.S. I do understand that the object would need concurrency managing etc, I just can't seem to put my finger on how to get it shared...
EDIT: I'm sorry I didn't mention it before -- using Glassfish, EE6.
You have a business process scenario which is defined according to Seam framework documentation as follows
The business process spans multiple interactions with multiple users, so this state is shared between multiple users, but in a well-defined manner. The current task determines the current business process instance, and the lifecycle of the business process is defined externally using a process definition language, so there are no special annotations for business process demarcation.
Here you can see a Seam business process management Tutorial
Notice Seam uses JBoss BPM behind the scenes to handle its business process context. If you just want to use plain JBoss BPM capabilities, you can see here how to integrate with JBoss
See also JBoss BPM User guide
Solved. Shared it via ServletContext, which I initially thought wouldn't work 'cause FacesServlet is a separate one, thought it has smthn like a different container either.

Is anyone using a ColdFusion framework that has specific path requirements without mapping or locating resources in the server root?

Let me first say I am aware of this faq for Mach-II, which discusses using application specific mappings as a third option when:
locating the framework in the server root is not possible and
creating a server wide mapping to the Mach-II framework directory is impossible
Using application specific mappings would also work for other ColdFusion frameworks with similar requirements (ColdSpring). Here is my issue however: my (I should say "their") production servers are all running ColdFusion MX7, and application specific mappings were introduced in ColdFusion 8. I most likely will be unable to do option 1 or 2 because they involve creating server wide changes that could conflict with other applications (I don't have a final word on this but I am preparing for that to be the case).
That said, is there anybody out there who was in similar bind and has done an option 4, in any ColdFusion version, or with any similar framework? The only option 4 I can think of is modifying the entire framework to change this hardcoded path, and even if that worked it would be time consuming and risky. I'm fairly sure that if there was a simple modification or other simple solution it would already be included in the framework (maybe it's included in version 1.8 of Mach-II and I don't know about it yet).
Any thoughts on solving this problem or even unorthodox setups with libraries that have specific path requirements would be appreciated. Any thoughts from Team Mach-II would especially appreciated...we're on the same team here Matt! ;-)
EDIT
Apparently, the ColdBox framework includes a refactor.xml ANT task which includes a target that refactors the ColdBox code to use a different absolute path as a base along with several other useful refactoring targets. So problem solved for ColdBox users.
Looking at the build.xml for Mach-II (1.6 and 1.8) I don't see any target in there that would allow me to refactor the code. I thought about creating a feature request ticket for such a task for Mach-II but frankly I don't think creating such an ANT task is a big priority for the MachII team since the need really only relates to either
a) users of ColdFusion versions below 8
b) someone who wants to use multiple Mach-II versions in the same application, a use I doubt they want to support
The ColdSpring code I have doesn't come with any ANT tasks at all, although I do have unit tests, and I bet if I poked around the SVN I'd find a few build scripts.
Using Ant tasks to refactor and retest the code, or the simpler (and sort of cop out) solution of creating a separate ColdFusion instance for the application are the best answers I've been able to come up with. I don't need this application to exist in the shared scope of other applications, so my first solution is going to be to try and get a dedicated CF instance for this application.
I'm also going to look at the ColdBox refactor.xml ANT task however and see if I can modify it to work generically to recognize and refactor CFC references with modified absolute paths. If I complete this task I'll be sure to post the code somewhere and edit create an answer to link to it. If anybody else wants to take a crack at that or help me out with it feel free.
Until then I'll leave this question open and see if someone comes up with a better solution.
Fusebox is not so strict, I think.
In XML mode (maybe I call this not 100% correcly, just mean using the Application.cfm) it's just proper include in index.cfm, something like:
<cfinclude template="fusebox5/fusebox5.cfm" />
In non-XML mode it will need proper extending in the root Application.cfc:
<cfcomponent extends="path.to.fusebox5.Application" output="false">
All you need is to know the path.
Perhaps you could create a symbolic link and let the operating system resolve the issue for you?
I've been playing with FW/1 lately, and while it may look like you need to add a mapping and extend org.corfield.framework, you can actually move the framework.cfc file into your web root and just extend="framework". It's dead simple, and gets you straight into a great framework with no mess and very little overhead.
It should be as simple as dropping the 'MachII' folder at the root of your domain (i.e. example.com/MachII). No mappings are required to use Mach-II if you just deploy at the root of the domain of your website.
Also:
Please file a ticket for the ANT task you mentioned in your question. Team Mach-II would love to have this issue logged:
Enter a new ticket on the Mach-II Trac
If you want to tackle an ANT task for us, we can get stuff like this incorporated into the builds faster than waiting to for a Team member to work on the ticket. Code submissions from the community are welcome and appreciated.
We don't keep an eye on Stack Overflow very often so we invite you to join our official community group at called "Mach-II for ColdFusion" at Google Groups. The Google Group is the best place to ask questions or comments like this if you want feedback from the Team.

Admin interface to manage two related data sources

In the project there are two data sources: one is project's own database, another is (semi-)legacy web service. The problem is that admin part has to keep them in sync and manage both so that user doesn't have to know they're separate (or, do know, but they do not care).
Here's an example: there's list of languages. Both apps - project and legacy - need to use them. However, they both add their own meaning. For example, project may need active/inactive, and legacy will need language code.
But admin part has to manage everything - language name, active/inactive, language code. When loading, data from both systems has to be merged and presented, and when saved, data has to be updated in both systems.
Thus, what's the best way to represent this separated data (to be used in the admin page)? Notice that I use ASP.NET MVC / NHibernate.
How do I manage legacy data?
Do I connect admin part to legacy web service external interface - where it currently only has GetXXX() methods - and add the missed C[R]UD methods?
Or, do I connect directly to legacy database - which is possible since I do control it.
Where do I do split/merge of data - in the controller/service layer, or in the repository/data layer?
In the controller layer I'll do "var viewmodel = new ViewModel { MyData = ..., LegacyData = ... }; The problem - code cluttered with legacy issues.
In the data layer, I'll do "var model = repository.Get(id)" and model will contain data from both worlds, and when I do "repository.Save(entity)" it will update both data sources - in local db only project specific fields will be stored. The problems: a) possible leaky abstraction b) getting data from web service always while it is only need sometimes and usually for admin part only
a modification, use ICombinedRepository<Language> which will provide additional split/merge. Problems: still need either new model or IWithLegacy<Language, LegacyLanguage>...
Have a single "sync" method; this will remove legacy items not present in the project item list, update those that are present, create legacy items that are missed, etc...
Well, to summarize the main issues:
do I develop CRUD interface on web service or connect directly to its database (which is under my complete control, so that I may even later decide to move that web service part into the main app or make it use the main db)?
do I have separate classes for project's and legacy entities, thus managed separately, or have project's entities have all the legacy fields, managed transparently when saved/loaded?
Anyway, are there any useful tips on managing mostly duplicated data from different sources? What are the best practices?
In the non-admin part, I'd like to completely hide the notion of the legacy data. Which is what I do now, behind the repository interfaces. But for admin part it's not that clear or easy...
What you are describing here seems to warrant the need for an Anti-Corruption Layer. You can find solutions related to this topic here: DDD, Anti Corruption layer, how-to?
When you have two conceptual Bounded Contexts, but you're only using DDD for one of them, the Anti-Corruption layer comes into play. When reading from your data source (performing a get operation [R]), the anti-corruption layer will translate your legacy data into usable objects for your project. When writing to your data source (performing a set operation [CUD]), the anti-corruption layer will translate your DDD objects into objects understood by your legacy code.
Whether or not to use the existing Web Service depends on whether or not you're willing to change existing code. Sticking with DRY practices, you don't want to duplicate what you already have. If you want to keep the Web Service, you can add CUD methods inside the anti-corruption layer without impacting your legacy application.
In the anti-corruption layer, you will want to make use of adapters and facades to bring together separate classes for your DDD project and the legacy application.
The anti-corruption layer is exactly where you handle splitting and merging.
Let me know if you have any questions on this, as it can be a somewhat advanced topic. I'll try to answer as best I can.
Good luck!

Handling the Same Class Definition From Multiple Web Services

The situation:
We have a library project that houses much of our code for the various integrations we work on. Many of the integrations consume web service apis, and my supervisor doesn't want 5 gazillion web service references added to the project.
What we generally do, then, is add a reference to a new project and copy the References.vb to the solution and just call the generated code. Not terribly convenient if changes are made to the service, but it works.
Recently, I ran into a problem where we have to use 3 web services for the same integration. 2 of these contain the same class definitions, however, they're in different namespaces because they belong to different services. This became a problem for me because one of the services searches a user based on user ID, and the other pulls back blocks of users. Both return an object, or list of, that is exactly the same semantically. And I need to process the data the same, whether it came from one service or the other.
My solution, was to strip out the duplicated classes in the service and replace them with classes inherited from common base classes. This allowed me to work with both objects as if they were the same, however, it required modifying the generated web service proxy. Therefore this change will need to be made every time I need to regenerate the proxy.
I'm curious what you all might think a better solution to this would be.
You're going to regret playing games with copying Reference.vb and editing generated files.
Switch to WCF and you'll be able to tell it you want to reuse the types, instead of having multiple types that are more or less the same.
BTW, they would be "less" the same if not all of the web references are updated at the same time after a server change.
The other option would be to build an abstraction layer over top of the web service pre-generated proxies, such that when you make to the calls to the abstraction layer you can always use the same objects, as they are squeezed into (and out of) the web service proxies in the abstraction layer. This would also allow for unit testing :)
I think you really should be looking at WCF for 3.5+, but for .NET 2.0 look at something like WSCF (Web Services Contract First), which defines the contracts in XML and generates a set of libraries reusable across services. E.g You define a MyComany.WS.Common namespace and use that namespace in multiple projects. The code generation then builds a shared library of types which get used across all the web-services. We use this extensively in our .NET 2 solutions and it's great. We had to do some additional work around the code generation to get it to fit into our build process, but once that was done we never looked back.
We're migrating to .NET 3.5 over time, so the WSCF will become obsolete
Heres the link to the thinktecture site for WSCF.
wsdl.exe using the /sharetypes switch allows the same types to be used across multiple service definitions, provided the wire signatures are not correct. I was unable to use it in my situation, though, because the various wsdl contracts were carelessly namespaced.