I need some advice on how to proceed with this design please:
I use BreezeJS internally on top of my Entity Framework Web API. So
all my data retrievals and saves are done in the Breeze style.
I now need to expose an API for external consumption which has a subset of
the calls I use internally.
Ideally I would like to consume the same API internally.
I do not want to tell the consumers that they have to
use BreezeJS on their client-side to consume my API (I am using
Swagger on top of it)
So, for now I have a separate set of API calls for the External API which go through different validation code and have a structure like:
Get(item)
Get(items)
List item
Post(item)
etc.
My question is: Am I going down the wrong track? Should I either be using BreezeJS on the ExternalAPI or stop using Breeze internally and consume the External API, OR should I perhaps wrap the ExternalAPI methods around Breeze and restrict the saving of the entity graph to the entity type that is being queried at the time only?
Related
Looking at data access for a multitenant SaaS database for a UI5 app I have two choices - JSON or OData. OData has some features of interest. However, I have concluded that I cannot use OData because of security issues.
In particular I am concerned that OData is a form of query language. As a very rough comparison this is like a SQL statement being composed at the client and sent to an ODBC server for processing. In a multitenant DB I will separate data between owners using, say, and org_id. If it were a SQL query I would have to include select data from table where org_id=this_tennant and .... If I can discover another tenants org_id then I can use an OData explorer to modify the query and pass into the OData source.
In a JSON data interface I would call a REST method that would mask how the data is accessed, and I would not need to expose secret details such as the org_id token. Granted the JSON / REST approach involves more work.
Or do I misunderstand OData ?
Another similar question was asked some time ago but some time has passed so I shall ask again.
The approach of OData is to define how RESTful APIs can be build. It adds a lot of concepts and conventions (e.g. entity types and sets, URL conventions, common query parameters, request format, batch support...) to plain REST and therefore provides you a standard for building your API.
However, it does not define where your data is coming from, but in most cases it will be database. Of course it would be possible to expose your database tables via an OData service in a generic way, but I would expect that the provider of the framework clearly describes how to handle and protect different tenants.
A more specific answer would require more information about the framework you will use.
I have a Web API using OData that I need to query. The client application is a SPA built with React/Redux, but it looks as if most data service libraries such as isomorphic-fetch do not support OData. Can BreezeJS be useful for me in this situation? Or OLingo's ODataJs? Any examples, tutorials, resources on using these or any other OData clients with Redux? AFAIK, I just need a the client library to query an OData source and support promises. And as far as the data I get back from the server, I just need simple json objects; no need for models that support binding.
I've seen discussions of Breeze + Angular/Backbone, but can it support Redux/React?
I doubt that either Breeze or ODataJS supports ES6, so if i had to wrap them in a ES6 module, would they still function properly?
Maybe it helps if you consider that OData isn't that far off from REST. If it's just about pulling the data from a OData service, you won't need much more than jQuery.getJSON and Breeze will work too. However, if you want to do it the fancy way, and want you app to introspect the meta-model and such, you should have a look at datajs or olingo.
my first question on StackOverflow, so apologies if not perfect right from the beginning ...
My question is actually two-fold:
Can I have the LightSwitch ApplicationData service (or any other internally defined Data Source) define ODATA actions on the service level or entity set/entity level? If yes, how do I do that? (I cannot find the route information in the application where I could override/add that.)
How would I consume these actions from the client side (via the built-in MS JS object model in msls or via screen/entity)? Even, if LightSwitch itself could not create/would not support actions, I would still like to know how to consume them from the client side, as we are exposing external ODATA data sources via LightSwitch to the client (and these ODATA source have actions defined).
I know I can use jaydata from the client side to consume that and execute actions on an ODATA source, but I would like to know if LightSwitch has built-in support for that.
Further information: we are using VS/LS 2013. And Silverlight is not an option, we only use the HTML client.
Thank you very much for your support and hints!
Regards, Ronald
There is nothing built-in to LightSwitch that lets you define custom OData actions on the service side or consume them from the client side. You'd need to use standard web functionality like ASP.NET's WebAPI and your favorite JavaScript OData library, like JayData.
I have been creating a basic OpenUI5 application, and aiming to implement SAP Gateway very soon.
I currently have a screen that populates an array with simple text-fields and a button. My aim is to send this array/table to a backend ABAP function module or class method. Can this be done? The table has the potential to be quite large.
You need to create a write capable oData service that accepts oData post requests from an UI5 application and writes data to a database table. During implementation of this oData service you may call any ABAP backend class methods of objects that you need to instantiate.
The most important point to realize is that the UI5 application is stateless. The application and all classes are instantiated for processing of the single request and die immediately after the request is processed.
I do not see any problem as long as you do not try to send gigabytes or hundreds of megabytes over the network.
Sending the data to a class method will not be possible as the ABAP methods of classes are not RFC enabled. For this purpose you can use only function modules.
Say I have the following model
I would like to present a unified front for these OData feeds to my clients.
Is there a nice way with OData to do this? Or should I just take IQueryables from the OData feeds and make a reflection endpoint on top of these?
If I use the reflection stuff on top of the OData that talks to the database (via Entity Framework) what kind of problems am I going to encounter?
I would not use the reflection provider over the client library, mainly because the client library LINQ provider doesn't support all the constructs used by the server. As a result some queries would simply not work at all (projections and expansions usually get broken).
Assuming you don't want to create any associations between the databases, you should be able to simply point the users at the right service. You can still expose something which looks like a unified endpoint without the need of having the same URL for all of them.
The main idea is that you unify the $metadata (if your model is static you can do this manually, if not you should be able to write some kind of "merge" tool pretty easily) and then provide a service document which points to the respective URLs for each entity set. In the WCF Data Services client, there's now support for these kind of services through entity set resolver: http://blogs.msdn.com/b/astoriateam/archive/2010/11/29/entity-set-resolver.aspx
The latest CTP with that support is here: http://blogs.msdn.com/b/astoriateam/archive/2011/06/30/announcing-wcf-data-services-june-2011-ctp-for-net4-amp-sl4.aspx
Not happy with the current accepted answer for this question, for me it's more of an anti-answer, of what not to do. My solution here applies as much today as it did in '11
To support a tenancy scenario, where each user/client data will always reside on the same Database, and the data schemas all match then all you need to do is change the connection string when the data context is instantiated.
Another term for this concept is Sharding, MS have some tools and APIs that can help, This is a simple enough walkthrough: Azure SQL Database Elastic database tools: Shard Elasticity but you can do this pretty easily from first principals.
If swapping out the connection string will work for your scenario we need to identify the mechanism that you will use to determine the connection string, there are two common solutions to this:
The simple way out is to use fixed host headers, a route or token in each request to the service, then you can hardcode the logic for determining the connection string without complicated mapping logic.
Use a master / header / mapping DB to store your configuration.
This database has a separate schema that's primary purpose is for retrieving the correct connection string for each request.
In most cases we combine this with the Authentication process, in which case
you keep the authentication in this central database, not in the individual databases.
In terms of the OData Controller, even with WCF Data Services, you just need to implement your logic for retrieving the connection string and use that when you instantiate your data context.
Of course, this doesn't help you if your client's data is spread across multiple databases, but it is a pretty common pattern for sclaing out large databases withough having to deploy a new farm of services for each database.