Aug 02, 2017 As part of the series of posts announced at this initial blog post (.NET Application Architecture Guidance) that explores each of the architecture areas currently covered by our team, this current blog post focuses on “Microservices and Docker containers: Architecture, Patterns and Development guidance”. MYSQL primary key strategy for microservices architecture. We are currently using auto-generated primary keys and we would like to switch to an approach which is more suitable for microservices-based applications: either we are going to use business defined primary key (a tax code for persons) or global unique identifiers.

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These keys look like -JiGh31GA20JabpZBfa, so not numeric. If you wanted to make a numeric only ID, you would make that a parameter of the object to avoid overwriting the generated key. The keys (the paths of the new data) are guaranteed to be unique, so there's no point in overwriting them with a numeric key. By convention, a shadow primary key is created for the owned type and it will be mapped to the same table as the owner by using table splitting. This allows to use owned types similarly to how complex types are used in EF6 in the traditional.NET Framework. While creating a single service may be easy, the end state for a microservices initiative is a potentially large number of services used in aggregate to deliver a functional application. The right way to start is to define the overall application functionality and then identify the individual services required—and the best place to do that is. For some services, a relational database is the best choice. Other services might need a NoSQL database such as MongoDB, which is good at storing complex, unstructured data, or Neo4J, which is designed to efficiently store and query graph data. Use a (single) database that is shared by multiple services. The second, using Flask-Migrate (assuming you’re also using Flask-SQLAlchemy) is more idiomatic. This will allow you to version control your database schema using a tool that was built exactly for that purpose, and will automatically generate both upgrade and downgrade operations to each version.

This section outlines how to create a simple microservice that performs create, read, update, and delete (CRUD) operations on a data source.

Designing a simple CRUD microservice

From a design point of view, this type of containerized microservice is very simple. Perhaps the problem to solve is simple, or perhaps the implementation is only a proof of concept.

Figure 6-4. Internal design for simple CRUD microservices

An example of this kind of simple], as shown in the ConfigureServices method in an earlier code example.

However, for production environments, you might want to explore additional ways on how to store secrets like the connection strings. An excellent way to manage application secrets is using Azure Key Vault.

Azure Key Vault helps to store and safeguard cryptographic keys and secrets used by your cloud applications and services. A secret is anything you want to keep strict control of, like API keys, connection strings, passwords, etc. and strict control includes usage logging, setting expiration, managing access, among others.

Azure Key Vault allows a very detailed control level of the application secrets usage without the need to let anyone know them. The secrets can even be rotated for enhanced security without disrupting development or operations.

Applications have to be registered in the organization's Active Directory, so they can use the Key Vault.

You can check the Key Vault Concepts documentation for more details.

Implementing versioning in ASP.NET Web APIs

As business requirements change, new collections of resources may be added, the relationships between resources might change, and the structure of the data in resources might be amended. Updating a Web API to handle new requirements is a relatively straightforward process, but you must consider the effects that such changes will have on client applications consuming the Web API. Although the developer designing and implementing a Web API has full control over that API, the developer does not have the same degree of control over client applications that might be built by third party organizations operating remotely.

Versioning enables a Web API to indicate the features and resources that it exposes. A client application can then submit requests to a specific version of a feature or resource. There are several approaches to implement versioning:

• URI versioning

• Query string versioning

• Header versioning

Query string and URI versioning are the simplest to implement. Header versioning is a good approach. However, header versioning not as explicit and straightforward as URI versioning. Because URL versioning is the simplest and most explicit, the eShopOnContainers sample application uses URI versioning.

With URI versioning, as in the eShopOnContainers sample application, each time you modify the Web API or change the schema of resources, you add a version number to the URI for each resource. Existing URIs should continue to operate as before, returning resources that conform to the schema that matches the requested version.

As shown in the following code example, the version can be set by using the Route attribute in the Web API controller, which makes the version explicit in the URI (v1 in this case).

Generate Numeric Key For Db In Microservice Architecture Software

This versioning mechanism is simple and depends on the server routing the request to the appropriate endpoint. Pes 2017 serial license key generator.exe. However, for a more sophisticated versioning and the best method when using REST, you should use hypermedia and implement HATEOAS (Hypertext as the Engine of Application State).

Additional resources

• Scott Hanselman. ASP.NET Core RESTful Web API versioning made easy
  https://www.hanselman.com/blog/ASPNETCoreRESTfulWebAPIVersioningMadeEasy.aspx

• Versioning a RESTful web API
  https://docs.microsoft.com/azure/architecture/best-practices/api-design#versioning-a-restful-web-api

• Roy Fielding. Versioning, Hypermedia, and REST
  https://www.infoq.com/articles/roy-fielding-on-versioning

Generating Swagger description metadata from your ASP.NET Core Web API

Swagger is a commonly used open source framework backed by a large ecosystem of tools that helps you design, build, document, and consume your RESTful APIs. It is becoming the standard for the APIs description metadata domain. You should include Swagger description metadata with any kind of microservice, eitherll cover in some detail in this guide but there's also the option to use NSwag, which can generate Typescript and C# API clients, as well as C# controllers, from a Swagger or OpenAPI specification and even by scanning the .dll that contains the controllers, using NSwagStudio.

How to automate API Swagger metadata generation with the Swashbuckle NuGet package

Generating Swagger metadata manually (in a JSON or YAML file) can be tedious work. However, you can automate API discovery of ASP.NET Web API services by using the Swashbuckle NuGet package to dynamically generate Swagger API metadata.

Swashbuckle automatically generates Swagger metadata for your ASP.NET Web API projects. It supports ASP.NET Core Web API projects and the traditional ASP.NET Web API and any other flavor, such as Azure API App, Azure Mobile App, Azure Service Fabric microservices based on ASP.NET. It also supports plain Web API deployed on containers, as in for the reference application.

Swashbuckle combines API Explorer and Swagger or swagger-ui to provide a rich discovery and documentation experience for your API consumers. In addition to its Swagger metadata generator engine, Swashbuckle also contains an embedded version of swagger-ui, which it will automatically serve up once Swashbuckle is installed.

This means you can complement your API with a nice discovery UI to help developers to use your API. It requires a very small amount of code and maintenance because it is automatically generated, allowing you to focus on building your API. The result for the API Explorer looks like Figure 6-8.

Figure 6-8. Swashbuckle API Explorer based on Swagger metadata—eShopOnContainers catalog microservice

The Swashbuckle generated Swagger UI API documentation includes all published actions. The API explorer is not the most important thing here. Once you have a Web API that can describe itself in Swagger metadata, your API can be used seamlessly from Swagger-based tools, including client proxy-class code generators that can target many platforms. For example, as mentioned, AutoRest automatically generates .NET client classes. But additional tools like swagger-codegen are also available, which allow code generation of API client libraries, server stubs, and documentation automatically.

Currently, Swashbuckle consists of five internal NuGet packages under the high-level meta- package Swashbuckle.AspNetCore for ASP.NET Core applications. Ip desktop softphone mac download.

After you have installed these NuGet packages in your Web API project, you need to configure Swagger in the Startup class, as in the following simplified code:

Once this is done, you can start your application and browse the following Swagger JSON and UI endpoints using URLs like these:

Generate Numeric Key For Db In Microservice Architecture 2017

You previously saw the generated UI created by Swashbuckle for a URL like http://<your-root-url>/swagger. In Figure 6-9 you can also see how you can test any API method.

Figure 6-9. Swashbuckle UI testing the Catalog/Items API method

The Swagger UI API detail shows a sample of the response and can be used to execute the real API, which is great for developer discovery. Figure 6-10 shows the Swagger JSON metadata generated from the eShopOnContainers microservice (which is what the tools use underneath) when you request http://<your-root-url>/swagger/v1/swagger.json using Postman.

Figure 6-10. Swagger JSON metadata

It is that simple. And because it is automatically generated, the Swagger metadata will grow when you add more functionality to your API.

Additional resources

• ASP.NET Web API Help Pages using Swagger
  https://docs.microsoft.com/aspnet/core/tutorials/web-api-help-pages-using-swagger

• Get started with Swashbuckle and ASP.NET Core
  https://docs.microsoft.com/aspnet/core/tutorials/getting-started-with-swashbuckle

• Get started with NSwag and ASP.NET Core
  https://docs.microsoft.com/aspnet/core/tutorials/getting-started-with-nswag