I have a problem with WCF seemingly not including attributes such as Category when passing entities around.
I have a class wrapped around an EF entity, used to populate a property grid on a thick client.
I am trying to retrieve information from the server, using WCF, and to replicate the property grid on the client side. I have tested the code, and in the host, I am able to determine the category of the elements in the instance.
When I request an instance from an ASP.NET site, however, it seems that I cannot retrieve the category information. All I get is, Misc, so I assume that means when I serialize it, the attributes get stripped.
Information specific to .NET is not passed in metadata. Therefore, the information is not used in creating the proxy classes that you create using svcutil or "Add Service Reference". This is why attributes, or non-default constructors, or methods, or indexers, do not appear in proxy classes.
You should try to do without this sort of information. However, if you really need it, you can put those types into a separate assembly, and share it with the client. This will mean that you have to update all of your clients when you update that assembly.
Related
I'm working on a project structured as N-Tier / 3-Tier Architectural Style. The layers (client-server) communicate with each other by HTTP and WCF. I want to use AppInsights to track everything in the project. However, I'm confused about where in the project to create or add AppInsight packages. I have created two instances of resources under one resource group on Azure. Then, I configured inst. key and other things regarding projects in the solution. Although I overrode handle attribute with mine(as explained in AppInsights docs), I couldn't see all call methods and exception tracks from client to server along with layers. Is it not possible to track exceptions in that project type or I'm mistaken?
UPDATE for additional info to define problem clearly: When I use one resource and one instrumentation key, AppInsights defines well whole project and shows relation of my solution and its dependencies. But, when one request failed due to exception in the server, I can't reach whole exception trace, just last method where request is asked from server. Because of that I use two resource instance, one for server and one for client(not real client, its like middle layer).
if you are using multiple apps/keys and multiple layers, you might need to introduce custom code to set/pass through something like a correlationId through http headers, and code that reads and uses that as application insights's "operation id". If you do the work across different applications/ikeys, searching across the apps will become more complicated.
instead, you might want to use just one ikey across all the layers, and instead use different ikeys for different environments, like dev/staging/prod instead.
there are some examples of reading/using operationId, like this blog post:
http://blog.marcinbudny.com/2016/04/application-insights-for-owin-based.html#.WBkL24WcFaQ
where someone does something similar with OWIN.
For Exception tracking, if the exceptions are happening at one of the other asp.net layers, you might need to enable some extra settings to collect exceptions or more information for them:
http://apmtips.com/blog/2016/06/21/application-insights-for-mvc-and-mvc-web-api/
I was looking through an old project and wanted to see if anyone had a suggestion on how to hide certain methods from being called by various layers. This was a 3 tier project, webapplication -> web service -> database
In the application there is a User object for example. When a User was being updated, the webapplication would create a User object and pass it to the webservice. The webservice would use the DataAccessLayer to save the User object to the database. After looking at this I was wondering if instead I should have made a Save method in the User class. This way the service and simply call the Save on the User object which would trigger the db update.
However doing it this way would expose the Save to be called from the webapplication as well, correct? Since the webapplication also has access to the same User object.
Is there anyway around this, or is it better to avoid this altogether?
There is a separation of concerns by keepeing the User object as object that only holds data with no logic in it. you better keep it separated for the following reasons:
As you stated, it is a bad practice since the Save' functionality will be exposed to other places/classes where it is irrelevant for them (This is an important for programming generally).
Modifying the service layer - I guess you are using WCF web service as you can transfer a .NET object (c#/VB) to the service via SOAP. If you put the saving logic in the 'User' object, you can't replace it another webservice that receives a simple textual data structures like JSON or XML or simply doesn't support .NET objects.
Modifying the data storage layer - If you want, for example, to store the data inside a different place like other database such as MongoDB, RavenDB, Redis or what ever you want, you will have to reimplement each class that responsible for updating the data. This is also relevant for Unit Testing and Mocking, making them more complicated to interrogate.
We are mixing workflows, a workflow using receive activity's more at the end. But at the start we want to pass in some arguments (not using a receive activity!)
Our workflows are already being created and resumed using a dynamic endpoint with IWorkflowCreation and a class derived from WorkflowHostingEndpoint. In the OnGetCreationContext the creationgContext is filled with WorkflowArguments and the workflow runs. At a later part the receive activity's are creating a bookmark which can be resumed with a message. All seems nice.
But in a xamlx there are no WorkflowArguments, i understand why, except that i want them anyway. I though about an activity in which i can write some code to get the Arguments myself, but i do need some help here.
Or is there another way to pass along the WorkflowArguments into a xamls without using Messaging?
You can't pass arguments into a starting workflow service except through the SOAP message that starts it. But there is nothing preventing you from reading any properties in your workflow service. So it is perfectly fine to do read settings or something similar instead of passing them in at startup.
We have solved this exact situation by creating another WCF service which sits alongside our xamlx service on a slightly different url (e.g. /WorkflowMetadata) and this is where we implement a service method that returns a dictionary of string, type.
In the implementation of this service we simply read the xamlx and determine the arguments.
This is what we use to interrogate a target workflow in an activity designer when creating something like a launch-workflow activity.
Creating an activity will not work as that activity will need an instance in order to run. All you want is some metadata about the xamlx service. And if you are using a WorkflowCreationEndpoint to construct a creation context then you are probably only allowing a dictionary of string, object as the start parameters. Therefore standard metadata will not work. This left us with the only option being to provide another service beside the workflow which serves metadata.
Background here: http://blog.petegoo.com/index.php/2011/09/02/building-an-enterprise-workflow-system-with-wf4/
I'm working with a project in ASP.Net using Webforms. I'm using Entity Framework to save data on Microsoft SQL.
My question is:
Is possible to use a Static class to keep the ObjectContext of EF live and put/get entities NOT saved inside the ObjectContext?
I want to create an Object, then added with AddObject on the ObjectContext, But NOT to do the Savechanges. All this in one webform. And then, in other webform, access to the ObjectContext and get the Object when added.
It is this possible?
My rules to using ObjectContext:
Do not use static context.
Do not share context.
You are trying to violate both rules. If you do that your application will have undeterministic behavior. Create new ObjectContext instance for each request. It is the same as openning new connection and starting new transaction in the request instead of sharing one connection and one transaction among all of them.
Further explanation also here. Also check linked question in right column and you will see what type of problems people have just because of violating one or both mentioned rules.
Also in web application it becames even more interesting because ObjectContext is not thread safe.
You could add it to the application items collection. See this blog post for syntax and such.
http://www.informit.com/articles/article.aspx?p=27315&seqNum=3
Generally, you don't want to. An ObjectContext is intended to be a unit of work, alive for a single set of related transactions. In an ASP.NET application, that generally corresponds to a single request.
If you must keep it alive for multiple requests, I wouldn't use either a static class, nor the application context. Instead, I'd recommend using the Cache, and then attaching the callbacks to it that let you ensure all your transactions are committed before it gets evicted, just in case.
I am currently doing a CRUD project for school and basically they want us to have this kind of structure (3 projects):
Class Library
Contains all the data access logic (retrieving the data from the database with either LINQ of standard ADO.NET).
Web Service
Having a reference to the class library and offering [WebMethod]s that access the methods from the class library
ASP.NET Website
Having a service reference to the web service and using the WebMethods to retrieve the data
Which basically means that we cannot access the class library directly from the website:
Website
\
\
Web Service
\
\
Class Library
Now of course there are multiple solutions to choose from as to provide abstraction in the web service to separate for example methods that retrieve the articles and methods to retrieve the categories (which are two different entiries and have two seperate classes in the class libary):
I can either do one web service which will have all the methods (GetAllArticles, GetAllCategories, GetArticleByID, etc.) and the website only makes a reference to this one web service. But of course this will result in having all the methods in a single class (that is, a single web service)
Or I can create multiple web services (Articles.asmx, Categories.asmx etc...) and reference all of them from the website and then call the one I need depending on what data I need to retrieve.
But I mean for me, the above solutions are not really ideal because if I have the first solution, I will have a ton of methods all in one class (no abstraction whatsoever) and in the second solution, I will have to reference about 10 different web services from the website (one for articles, one for categories, etc.)
At school they told us to use the web service (or web services) to access the class library, and then retrieve the data from the class library using the Webmethods, but both solutions I mentioned earlier on seem a bit dodgy.
Is there a better way of how I might go about in implementing this structure?
In your example you suggested one service for Articles and one service for Categories. That may of course be just an example, but in that case it would not make sense to separate them, because it would be quite likely and common to have queries and/or routines which make use of both Category data and Article data.
With that in mind, it usually makes the most sense to group routines by the degree to which they are related to one another. If you can separate all your possible routines into, say, three clean groups with little to no overlap, then it makes sense to have three services. If you cannot cleanly separate any of your routines, you should limit yourself to one web service.
But regarding your statement "No abstraction" being a downside of one web service - that isn't necessarily true. You can always create layers of abstraction behind the web service, so that the service class itself is simply a facade with many thin method calls that reach into bulkier logic elsewhere.
In the end, the only approach which truly matters because it's the only approach which works is this: take the simplest approach possible, only build what you need to build in as few layers as you can; only add complexity when you reach a problem which cannot be solved in a better way than by adding that complexity. It is always easier to add complexity than to take it away.
I would put all the webmethods into the same class. The webmethods should only be wrappers around you business classes plus whatever input validation and authorisation you need.
Since web services are generally used by mahcines and not humans there is no pressing need for a hierarchy. It can become a burden to manage the URLs and web server if you create a webmethod class per business class.
If you are planning on using the HTML page that browsers automatically generate to call your web services as your main user interface you need to be a little bit careful. For example you won't be able to rely on SOAP headers if you need to authenticate requests.
Why not use ADO.Net Data Service?