17 October 2023

Different types of caching in dotnetcore

 Different types of caching in dotnetcore

In .NET Core, you can implement different types of caching mechanisms based on your application's requirements. Here are several types of caching techniques available:

1. **In-Memory Caching:**

In-memory caching stores data in the application's memory. It's fast and suitable for small to medium-sized datasets.

- **Usage:** Use `Microsoft.Extensions.Caching.Memory` namespace.

- **Setup:** Add `services.AddMemoryCache()` in `Startup.cs`.

- **Example:** `IMemoryCache` interface is used for in-memory caching, as described in the previous response.

2. **Distributed Caching:**

Distributed caching stores data in a distributed cache server like Redis, SQL Server, or another server that supports distributed caching.

- **Usage:** Use `Microsoft.Extensions.Caching.Distributed` namespace.

- **Setup:** Add a distributed cache provider, such as Redis, and configure it in `Startup.cs`.

- **Example:** Using Redis as a distributed cache provider.

csharp

services.AddStackExchangeRedisCache(options =>

{

    options.Configuration = "localhost"; // Redis server connection string

    options.InstanceName = "SampleInstance"; // Redis instance name (optional)

});

3. **Response Caching Middleware:**

Response caching allows you to cache entire responses at the HTTP level, avoiding the execution of the entire pipeline for subsequent identical requests.

- **Usage:** Use `Microsoft.AspNetCore.ResponseCaching` middleware.

- **Setup:** Configure the middleware in `Startup.cs` in the `ConfigureServices` and `Configure` methods.

- **Example:**

```csharp

services.AddResponseCaching();

In your `Configure` method:

csharp

app.UseResponseCaching();

```

4. **Cache-Aside Pattern:**

Cache-Aside is a caching pattern where the application code is responsible for loading data into the cache on cache misses and reading data from the cache on cache hits.

- **Usage:** Implement your custom logic to load data into the cache.

- **Example:**

```csharp

public class CacheAsideService

{

    private readonly IMemoryCache _cache;

    private readonly IDataService _dataService;


    public CacheAsideService(IMemoryCache cache, IDataService dataService)

    {

        _cache = cache;

        _dataService = dataService;

    }

    public string GetData(int id)

    {

        if (!_cache.TryGetValue(id, out string data))

        {

            // Data not in cache, load it from the data service

            data = _dataService.GetData(id);

            // Store the data in cache

            _cache.Set(id, data, TimeSpan.FromMinutes(10)); // Cache for 10 minutes

        }

        return data;

    }

}

 5. **Lazy Loading / Memoization:**

Lazy loading or memoization is a technique where the result of an expensive operation is cached and returned when the same operation is called again with the same input.


- **Usage:** Implement caching logic within methods that perform expensive computations.

- **Example:**

```csharp

public class ExpensiveOperationService

{

    private readonly ConcurrentDictionary<int, string> _cache = new ConcurrentDictionary<int, string>();

    public string GetResult(int input)

    {

        return _cache.GetOrAdd(input, ComputeResult);

    }


    private string ComputeResult(int input)

    {

        // Expensive computation logic

        // ...

        return result;

    }

}

Each caching approach has its use cases, advantages, and trade-offs. The choice of caching technique depends on your application's requirements, scalability needs, and the nature of the data being cached. Consider the data size, expiration policies, and required response times when choosing the appropriate caching mechanism for your .NET Core application.

Versioning in Azure apim

  Versioning in Azure apim

In the context of API Management (APIM), versioning refers to the practice of managing different versions of APIs to ensure backward compatibility, allow for changes and updates, and provide a consistent experience for API consumers. API versioning is crucial when you need to make changes to your API without breaking existing applications or clients that depend on the API. Here are some common strategies for versioning APIs in API Management systems, including Azure API Management (APIM):

 1. URL Versioning:

   - **Example:** `https://api.example.com/v1/resource` or `https://api.example.com/v2/resource`

   - Version information is included directly in the URL.

   - Easy to implement and understand.

   - Clients must be aware of and specify the version they want to use.

2. **Query Parameter Versioning:

   - **Example:** `https://api.example.com/resource?version=v1` or `https://api.example.com/resource?version=v2`

   - Version information is passed as a query parameter.

   - Provides a cleaner URL but still requires client awareness of the version.

3. Header Versioning:

   - **Example:** Include a custom header like `Api-Version: v1` in the HTTP request.

   - Version information is included in the request header.

   - Keeps URLs clean, but clients still need to be aware of the version and set the appropriate header.

4. Accept Header Versioning:

   - **Example:** Include `Accept: application/vnd.example.v1+json` in the HTTP request header.

   - Version information is included in the `Accept` header.

   - Allows for version negotiation based on the `Accept` header value.

5. Resource-based Versioning:

   - Different versions of the API have different URIs for resources.

   - Entire URIs or parts of URIs change based on the version.

   - Provides clear separation but can lead to complex routing rules.

6. Semantic Versioning:

   - Use Semantic Versioning (SemVer) for APIs (Major.Minor.Patch) to indicate backward-compatible changes (Minor) and breaking changes (Major).

   - Clients can choose which version to use based on their compatibility requirements.

7. API Gateway Versioning:

   - Some API gateways, like Azure API Management, offer built-in versioning capabilities.

   - You can configure different versions of the API within the API gateway, associating each version with specific backend implementations.

Best Practices:

- Clearly document the versioning strategy used for your APIs.

- Avoid breaking changes in minor or patch versions; reserve major version increments for breaking changes.

- Provide versioning information in API documentation and responses.

- Plan for version deprecation and communicate it to API consumers well in advance.

- Consider versioning strategies in the context of your organization's development and release processes.

The choice of versioning strategy often depends on the specific use case, API consumers' requirements, and the capabilities provided by the API management platform being used.

Primary key vs Unique key in SQL Server

Primary key vs Unique key in SQL Server 

Both primary keys and unique keys in SQL Server are used to enforce the uniqueness of values in a column or a set of columns. However, there are important differences between them:

### Primary Key:

1. **Uniqueness:** A primary key ensures that the values in the specified column or columns are unique across all rows in the table.  

2. **Null Values:** A primary key column cannot contain NULL values. Every row must have a unique and non-null value in the primary key column(s).

3. **One per Table:** There can be only one primary key constraint in a table. It can consist of one or multiple columns.

4. **Clustered Index:** In SQL Server, the primary key constraint automatically creates a clustered index on the primary key column(s) if a clustered index does not already exist on the table.

5. **Foreign Key:** Primary key constraints are often used as the target of foreign key constraints in other tables. Foreign keys establish relationships between tables.

**Example of Primary Key:**

```sql

CREATE TABLE Employees (

    EmployeeID INT PRIMARY KEY,

    FirstName VARCHAR(50),

    LastName VARCHAR(50)

);

Unique Key:

1. **Uniqueness:** Like a primary key, a unique key ensures that the values in the specified column or columns are unique across all rows in the table.

2. **Null Values:** Unlike primary keys, unique key columns can contain NULL values. However, a unique key constraint will allow only one NULL value, meaning that you can have multiple NULLs in the column, but each non-null value must be unique.

3. **Multiple Unique Keys:** Unlike primary keys, you can have multiple unique key constraints in a table. Each unique key can consist of one or multiple columns.

4. **Non-Clustered Index:** Creating a unique key constraint creates a non-clustered index on the unique key column(s) if a clustered index does not already exist on the table.

5. **No Implicit Relationship:** Unique keys are not implicitly used as the target of foreign key constraints.

Example of Unique Key:

CREATE TABLE Customers (

    CustomerID INT UNIQUE,

    Email VARCHAR(255) UNIQUE,

    FirstName VARCHAR(50),

    LastName VARCHAR(50)

);

In summary, primary keys are used to uniquely identify records in a table and are often used as the target of foreign key constraints, while unique keys provide uniqueness but allow for multiple NULL values and do not establish relationships between tables implicitly. The choice between them depends on the specific requirements of your database schema.

Sql rank vs Dense_rank IN SQL SERVER

 Sql rank vs Dense_rank IN SQL SERVER

In SQL Server, `RANK()` and `DENSE_RANK()` are both window functions that are used to assign a rank to each row within a result set based on the values in one or more columns. However, they differ in how they handle duplicate values.

Here's a comparison of `RANK()` and `DENSE_RANK()` in SQL Server:

RANK():

- `RANK()` is a window function that assigns a unique rank to each distinct row within a result set based on the values in the specified column(s).

- If two or more rows have the same values, `RANK()` will assign the same rank to those rows and leave gaps in the ranking sequence for the next rank.

- The ranking values are not consecutive when there are ties.

**Example:**

```sql

SELECT 

    RANK() OVER (ORDER BY ColumnName) AS Rank

FROM 

    TableName;

# DENSE_RANK():

- `DENSE_RANK()` is also a window function that assigns a unique rank to each distinct row within a result set based on the values in the specified column(s).

- If two or more rows have the same values, `DENSE_RANK()` will assign the same rank to those rows but will not leave gaps in the ranking sequence.

 It produces consecutive ranking values, even when there are ties.

**Example:**

```sql

SELECT 

    DENSE_RANK() OVER (ORDER BY ColumnName) AS DenseRank

FROM 

    TableName;

In summary, if you want consecutive ranking values without any gaps, you should use `DENSE_RANK()`. If you don't mind having gaps in the ranking sequence for tied values, you can use `RANK()`. The choice between them depends on your specific use case and the behavior you want for tied values in your ranking results.

Magic table in sql server

 Magic table in sql server

In SQL Server, there is no specific concept called a "magic table." However, the term "magic table" is commonly used to refer to the special tables that are used in triggers to access the data that was modified by the triggering action (such as an INSERT, UPDATE, DELETE statement). These special tables are known as inserted and deleted tables.

Here's how they work:

1. **Inserted Table:**

   - In the context of an `INSERT` or `UPDATE` trigger, the `inserted` table contains the new rows that were inserted or the updated rows after the modification.

   - For example, in an `INSERT` trigger, you can access the newly inserted rows from the `inserted` table to perform further actions based on the inserted data.

   ```sql

   CREATE TRIGGER trgAfterInsert

   ON TableName

   AFTER INSERT

   AS

   BEGIN

       -- Inserted table contains newly inserted rows

       SELECT * FROM inserted;

   END

   ```

2. **Deleted Table:**

   - In the context of a `DELETE` or `UPDATE` trigger, the `deleted` table contains the old rows that were deleted or the rows before they were updated.

   - For example, in a `DELETE` trigger, you can access the deleted rows from the `deleted` table to perform actions before the rows are deleted permanently.


   ```sql

   CREATE TRIGGER trgAfterDelete

   ON TableName

   AFTER DELETE

   AS

   BEGIN

       -- Deleted table contains rows that were deleted

       SELECT * FROM deleted;

   END

   ```

By using these `inserted` and `deleted` tables, you can effectively access the data being modified by the triggering SQL statement within the body of the trigger. These tables are sometimes colloquially referred to as "magic tables" due to their special and implicit nature within triggers.

16 October 2023

Add multiple client in Azure APIM

 Add multiple client in Azure APIM

In Azure API Management (APIM), adding multiple clients, also known as applications or subscriptions, allows different entities (such as developers or applications) to access your APIs securely. Here are the steps to add multiple clients in APIM:

### 1. **Sign in to the Azure Portal:**

   - Go to [Azure Portal](https://portal.azure.com/).

### 2. **Select your API Management Service:**

   - Navigate to your APIM instance from the Azure Portal.

### 3. **Add a New Application:**

   - In your APIM instance, go to the "Security" section.

   - Click on "Add" to create a new application.

### 4. **Fill in Application Details:**

   - Provide a unique client ID for the application. This is typically generated by the system.

   - You can set a display name for the application to identify it easily.

   - Optionally, configure other settings like product subscriptions, policies, etc.

   - Save your changes.

### 5. **Generate Client Secrets or Certificates (if necessary):**

   - Depending on your security requirements, generate client secrets or upload certificates for authentication.

   - Client secrets are typically used with confidential clients, such as server-side applications.

   - Certificates provide an additional layer of security and are used for authentication in similar scenarios.

### 6. **Configure API Access:**

   - In the application settings, configure the specific APIs, operations, or products that this application can access.

   - You can define rate limits, quotas, and policies for each application separately.

### 7. **Retrieve Client ID and Client Secret:**

   - After saving the application details, make sure to note down the generated Client ID and Client Secret. These are essential for authenticating the client application.

### 8. **Securely Store Client Secrets:**

   - If you're using client secrets, ensure that you securely store them. For security reasons, the client secret is only shown once during the creation process. Make sure to save it in a secure location.

### 9. **Implement Authentication in Client Applications:**

   - In your client applications, implement authentication using the Client ID and Client Secret or other methods like client certificates, depending on what you configured in APIM.

   - Make sure to include the necessary authentication headers or tokens in API requests made by the client applications.

By following these steps, you can add multiple clients in Azure API Management, allowing different applications or users to securely access your APIs based on the defined policies and configurations.

When to choose azure function and logic app

 When to choose azure function and logic app

Azure Functions and Logic Apps are both serverless computing options in Azure, but they serve different purposes and are designed for different scenarios. Here's a breakdown of when to choose Azure Functions and Logic Apps based on your specific requirements:

### Choose Azure Functions When:

1. **Event-Driven Tasks:**

   - Use Azure Functions when you need to execute code in response to events. For example, handling HTTP requests, reacting to messages in a queue, or responding to changes in a database.

2. **Microservices Architecture:**

   - Azure Functions are suitable for building microservices, where each function can handle a specific task or process, and these functions can be orchestrated to create complex applications.

3. **Stateless and Short-Lived Operations:**

   - Functions are stateless, meaning they don't maintain state between executions. They are designed for short-lived operations. Use them when your tasks can be executed quickly without requiring long-running processes.

4. **Flexible Language Support:**

   - Azure Functions support multiple programming languages such as C#, Python, JavaScript, and PowerShell. You can choose the language that best fits your expertise and requirements.

5. **HTTP APIs and Webhooks:**

   - Functions are great for building HTTP APIs and handling webhooks. They can easily handle incoming HTTP requests and return responses.

6. **Integration with Other Azure Services:**

   - Azure Functions can integrate seamlessly with other Azure services, such as Azure Storage, Azure Cosmos DB, Azure Service Bus, and Azure Event Hubs.

### Choose Logic Apps When:

1. **Workflow Orchestration:**

   - Use Logic Apps when you need to orchestrate workflows with multiple steps involving various services and APIs. Logic Apps provide a visual designer for creating complex workflows.

2. **Integration with SaaS Applications:**

   - Logic Apps are designed for integrating with Software as a Service (SaaS) applications. They have built-in connectors for popular services like Salesforce, Office 365, Twitter, and more.

3. **Non-Developer Friendly:**

   - Logic Apps are suitable for business users and non-developers who need to create workflows without writing code. The visual designer makes it easy to create and modify workflows.

4. **Built-In Connectors:**

   - Logic Apps come with a wide range of built-in connectors for various services and APIs. You can easily connect to external systems without writing custom code.

5. **Long-Running and Stateful Workflows:**

   - Logic Apps support long-running workflows and can maintain state between steps, making them suitable for processes that require multiple stages and extended periods of execution.

6. **B2B Integrations:**

   - Logic Apps are well-suited for Business-to-Business (B2B) integrations, allowing you to exchange data and automate processes with partners and suppliers.

In summary, choose **Azure Functions** when you need lightweight, event-driven, and stateless functions with flexibility in language choice. Choose **Logic Apps** when you require complex workflow orchestration, integration with SaaS applications, visual design capabilities, and support for long-running and stateful processes. Often, these services can complement each other within a larger application architecture, providing the right tool for the specific task at hand.

Implementing OAuth validation in a Web API

 I mplementing OAuth validation in a Web API Implementing OAuth validation in a Web API using C# typically involves several key steps to sec...