Introducing Fog: A Library for Interacting with Azure from F#

Fog is a library that makes it easier to use F# to interact with Windows Azure through the Windows Azure SDK for .NET. It provides functions for many of the common activities related to table storage, blob storage, and queue storage as well as service bus queues and topics. Provided functions include both course and fined-grained approaches that remove boiler plate code and make it easier to use various functional patterns and techniques. The course grained functions currently use config settings with specific names to allow most operations to only require a single function call.

The syntax of Fog is pretty straight forward. The following examples use the course grained approach. To see how to use the fined-grained functions, which match almost one to one with the Azure SDK for .NET methods, see the Fog integration tests.

Blob Storage

With Fog all you have to do to interact with Azure blob storage is to add the connection string information in the config with a name of "BlobStorageConnectionString". Once that is done, you can use syntax like the following:

UploadBlob "testcontainer" "testblob" "This is a test" |> ignore 
DeleteBlob "testcontainer" "testblob"

or

UploadBlob "testcontainer" "testblob" testBytes |> ignore 

DownloadBlob<byte[]> "testcontainer" "testblob"

Table Storage

The simplest way to interact with Azure table storage is to add the connection string information in the config with a name of "TableStorageConnectionString". Once that is done, you can use syntax like the following:

[<DataServiceKey("PartitionKey", "RowKey")>] 

type TestClass() = 
    let mutable partitionKey = "" 
    let mutable rowKey = "" 
    let mutable name = "" 
    member x.PartitionKey with get() = partitionKey and set v = partitionKey <- v 

    member x.RowKey with get() = rowKey and set v = rowKey <- v 

    member x.Name with get() = name and set v = name <- v 

let originalClass = 
    TestClass(PartitionKey = "tprt", RowKey = Guid.NewGuid().ToString(), Name = "test") 
CreateEntity "testtable" originalClass |> ignore 

let newClass = originalClass 
newClass.Name <- "test2" 

UpdateEntity "testtable" newClass |> ignore 

DeleteEntity "testtable" newClass 

Queue Storage

For queue storage, add the connection string configuration value with setting name "QueueStorageConnectionString".

AddMessage "testqueue" "This is a test message" |> ignore 

let result = GetMessages "testqueue" 20 5 
for m in result do 
    DeleteMessage "testqueue" m 

Service Bus

There are a few service bus related config entries. Here's the list of expected names: ServiceBusIssuer, ServiceBusKey, ServiceBusScheme, ServiceBusNamespace, ServiceBusServicePath

To send a message do this:

type TestRecord = { Name : string } 
let testRecord = { Name = "test" } 

SendMessage "testQueue" testRecord 

To receive a message, pass the queue name, a function to handle successful message retrieval, and another function to handle errors.

HandleMessages "testQueue" 
    <| fun m -> printfn "%s" m.GetBody<TestRecord>().Name

    <| fun ex m -> raise ex 

To use topics in a pub/sub type of scenario, use something like the following to subscribe:

Subscribe "topictest2" "AllTopics4" 
    <| fun m -> printfn "%s" m.GetBody<TestRecord>().Name 

    <| fun ex m -> raise ex 

Message publishing can be accomplished like this:

Publish "topictest2" testRecord 

A few other handy functions include Unsubscribe and DeleteTopic:

Unsubscribe "topictest2" "AllTopics4" 
DeleteTopic "topictest2"

How to get it

The easiest way to get Fog is to install the Fog NuGet package. You can also find the full source as well as integration tests on the Fog GitHub site.