OllamaHelper (VB.NET) Documentation

Overview

The VB.NET implementation of OllamaHelper provides core functionality for interacting with the Ollama API.

Installation

            
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Basic Usage

            
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Imports Helpers

' Initialize the helper
Dim helper = New OllamaHelper(
    endpoint:="http://localhost:11434",
    model:="llama2",
    temperature:=0.7F,
    maxTokens:=2000
)

' Get completion
Dim response = Await helper.GetCompletion("What is AI?")

' Stream response
Await For Each token In helper.GetCompletionStream("Tell me a story")
    Console.Write(token)
Next
        

Core Features

Model Management

            
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' List models
Dim models = Await helper.ListModels()

' Get model info
Dim info = Await helper.GetModelInfo("llama2")

' Set model parameters
helper.SetTemperature(0.8F)
helper.SetMaxTokens(1000)
        

Chat Functions

            
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' Single message
Dim response = Await helper.Chat("Hello!")

' Conversation
Dim conversation = New List(Of ChatMessage) From {
    New ChatMessage With {.Role = "user", .Content = "Hi"},
    New ChatMessage With {.Role = "assistant", .Content = "Hello!"}
}
Dim reply = Await helper.ChatWithHistory(conversation)
        

Streaming

            
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' Stream chat response
Await For Each token In helper.StreamChat("Tell me a joke")
    Console.Write(token)
Next

' Stream with history
Await For Each token In helper.StreamChatWithHistory(conversation)
    Console.Write(token)
Next
        

Error Handling

            
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Try
    Dim response = Await helper.GetCompletion(prompt)
Catch ex As OllamaException
    Console.WriteLine($"Ollama error: {ex.Message}")
Catch ex As HttpRequestException
    Console.WriteLine($"Network error: {ex.Message}")
End Try
        

Advanced Usage

Custom Configuration

            
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Dim config = New OllamaConfig With {
    .Temperature = 0.7F,
    .MaxTokens = 2000,
    .TopP = 0.9F,
    .FrequencyPenalty = 0.1F,
    .PresencePenalty = 0.1F
}

Dim helper = New OllamaHelper("http://localhost:11434", "llama2", config)
        

Batch Processing

            
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Public Async Function ProcessBatch(prompts As IEnumerable(Of String)) As Task(Of IEnumerable(Of String))
    Dim tasks = prompts.Select(Function(p) helper.GetCompletion(p))
    Return Await Task.WhenAll(tasks)
End Function
        

Best Practices

1. Connection Management

            
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Public Class ManagedOllamaHelper
    Implements IDisposable

    Private ReadOnly _helper As OllamaHelper
    Private _disposed As Boolean

    Public Sub New()
        _helper = New OllamaHelper()
    End Sub

    Public Sub Dispose() Implements IDisposable.Dispose
        If Not _disposed Then
            ' Clean up resources
            _disposed = True
        End If
    End Sub
End Class
        

2. Rate Limiting

            
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Public Class RateLimitedOllamaHelper
    Private ReadOnly _helper As OllamaHelper
    Private ReadOnly _semaphore As SemaphoreSlim

    Public Sub New(Optional maxConcurrent As Integer = 5)
        _helper = New OllamaHelper()
        _semaphore = New SemaphoreSlim(maxConcurrent)
    End Sub

    Public Async Function GetCompletionWithRateLimit(prompt As String) As Task(Of String)
        Await _semaphore.WaitAsync()
        Try
            Return Await _helper.GetCompletion(prompt)
        Finally
            _semaphore.Release()
        End Try
    End Function
End Class
        

3. Retry Logic

            
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Public Async Function GetCompletionWithRetry(prompt As String, Optional maxRetries As Integer = 3) As Task(Of String)
    For i As Integer = 0 To maxRetries - 1
        Try
            Return Await _helper.GetCompletion(prompt)
        Catch ex As OllamaException
            If i = maxRetries - 1 Then Throw
            Await Task.Delay(1000 * (i + 1))
        End Try
    Next
    Throw New Exception("Max retries exceeded")
End Function
        

Performance Optimization

1. Caching

            
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Public Class CachedOllamaHelper
    Private ReadOnly _helper As OllamaHelper
    Private ReadOnly _cache As MemoryCache

    Public Sub New()
        _helper = New OllamaHelper()
        _cache = New MemoryCache(New MemoryCacheOptions())
    End Sub

    Public Async Function GetCachedCompletion(prompt As String) As Task(Of String)
        Dim key = ComputeHash(prompt)
        Dim cached As String = Nothing
        If _cache.TryGetValue(key, cached) Then
            Return cached
        End If

        Dim response = Await _helper.GetCompletion(prompt)
        _cache.Set(key, response, TimeSpan.FromHours(1))
        Return response
    End Function
End Class
        

2. Connection Pooling

            
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Public Class PooledOllamaHelper
    Private ReadOnly _pool As ConcurrentBag(Of OllamaHelper)
    Private ReadOnly _poolSize As Integer

    Public Sub New(Optional poolSize As Integer = 5)
        _poolSize = poolSize
        _pool = New ConcurrentBag(Of OllamaHelper)()
        For i As Integer = 0 To poolSize - 1
            _pool.Add(New OllamaHelper())
        Next
    End Sub

    Public Async Function GetCompletion(prompt As String) As Task(Of String)
        Dim helper As OllamaHelper = Nothing
        If Not _pool.TryTake(helper) Then
            helper = New OllamaHelper()
        End If

        Try
            Return Await helper.GetCompletion(prompt)
        Finally
            _pool.Add(helper)
        End Try
    End Function
End Class
        

Testing

            
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Public Class OllamaHelperTests
    Private _helper As OllamaHelper
    Private _mockFactory As Mock(Of IHttpClientFactory)

    
    Public Sub Setup()
        _mockFactory = New Mock(Of IHttpClientFactory)()
        _helper = New OllamaHelper(
            "http://localhost:11434",
            "llama2",
            httpClientFactory:=_mockFactory.Object
        )
    End Sub

    
    Public Async Function GetCompletion_ValidPrompt_ReturnsResponse() As Task
        ' Arrange
        Dim prompt = "Test prompt"

        ' Act
        Dim response = Await _helper.GetCompletion(prompt)

        ' Assert
        Assert.IsNotNull(response)
    End Function
End Class