I wanted to implement some microservices and thought, what’s more micro than REST style functions, executing single functions using a functional language (functional everywhere!). So let’s take a dip into the world of Suave using F#.<\/p>\n
Suave is a lightweight, non-blocking, webserver which can run on Linux, OSX and Windows. It’s amazingly simple to get up and running and includes routing capabilities and more. Let’s try it out.<\/p>\n
Getting Started<\/strong><\/p>\n Create an F# application and the run Install-Package Suave via Package Manager Console<\/em>.<\/p>\n Now, this code (below) is taken from the Suave website.<\/p>\n Run your application and then from you favourite web browser, type in either http:\/\/localhost:8083\/hello<\/em> and\/or http:\/\/localhost:8083\/goodbye<\/em> and you should see “Hello GET” and\/or “Good bye GET”. From the code you can see the application also supports POST.<\/p>\n Let’s test this using Powershell’s Invoke-RestMethod. Typing Invoke-RestMethod -Uri http:\/\/localhost:8083\/hello -Method Post<\/em> and you will see “Hello POST”.<\/p>\n Passing arguments<\/strong><\/p>\n Obviously invoking a REST style method is great, but what about passing arguments to the service. We’re going to need to add the import open Suave.RequestErrors<\/em> to support errors. We can read parameters from the commands using HttpRequest queryParam<\/em><\/p>\n Disclaimer: This is literally my first attempt at such code, there may be a better way to achieve this, but I felt the code was worth recording anyway. So from our preferred web browser we can type http:\/\/localhost:8083\/math\/add?a=10&b=100<\/em> and you should see a: 10 b:100<\/em>.<\/p>\n Passing JSON to our service<\/strong><\/p>\n We can also pass data in the form of JSON. For example, we’re now going to pass JSON contain two integers to our new service. So first off add the following<\/p>\n Now we’ll create the data contracts for sending and receiving our data using, these will be serialized automatically for us through the function mapLson<\/em> which will see in use soon. Notice we’re also able to deal with specific types, such as integers in this case (instead of just strings everywhere).<\/p>\n Finally let’s see how we startup our server. Here we use the mapJson<\/em> to map our JSON request into the type Calc<\/em> from here we carry out some function (in this case addition) and the result is returned (type inference turns the result into a Result type).<\/p>\n Let’s test this using our Invoke-RestMethod<\/em> Powershell code. We can create the JSON body for this method in the following way.<\/p>\n References<\/strong><\/p>\n Suave Music Store <\/a> I wanted to implement some microservices and thought, what’s more micro than REST style functions, executing single functions using a functional language (functional everywhere!). So let’s take a dip into the world of Suave using F#. Suave is a lightweight, non-blocking, webserver which can run on Linux, OSX and Windows. It’s amazingly simple to get […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[6,119],"tags":[],"class_list":["post-3713","post","type-post","status-publish","format-standard","hentry","category-f","category-suave"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/3713","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/comments?post=3713"}],"version-history":[{"count":11,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/3713\/revisions"}],"predecessor-version":[{"id":3725,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/posts\/3713\/revisions\/3725"}],"wp:attachment":[{"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/media?parent=3713"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/categories?post=3713"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/putridparrot.com\/blog\/wp-json\/wp\/v2\/tags?post=3713"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}\r\nopen Suave\r\nopen Suave.Filters\r\nopen Suave.Operators\r\nopen Suave.Successful\r\n\r\n[<EntryPoint>]\r\nlet main argv = \r\n\r\n let app =\r\n choose\r\n [ GET >=> choose\r\n [ path "\/hello" >=> OK "Hello GET"\r\n path "\/goodbye" >=> OK "Good bye GET" ]\r\n POST >=> choose\r\n [ path "\/hello" >=> OK "Hello POST"\r\n path "\/goodbye" >=> OK "Good bye POST" ] ]\r\n\r\n startWebServer defaultConfig app\r\n\r\n 0 \/\/ return an integer exit code\r\n<\/pre>\n
\r\n let browse =\r\n request (fun r ->\r\n match r.queryParam "a" with\r\n | Choice1Of2 a -> \r\n match r.queryParam "b" with\r\n | Choice1Of2 b -> OK (sprintf "a: %s b: %s" a b)\r\n | Choice2Of2 msg -> BAD_REQUEST msg\r\n | Choice2Of2 msg -> BAD_REQUEST msg)\r\n\r\n let app =\r\n choose\r\n [ GET >=> choose\r\n [ path "\/math\/add" >=> browse ]\r\n ]\r\n\r\n startWebServer defaultConfig browse\r\n<\/pre>\n
\r\nopen Suave.Json\r\nopen System.Runtime.Serialization\r\n<\/pre>\n
\r\n[<DataContract>]\r\ntype Calc =\r\n { \r\n [<field: DataMember(Name = "a")>]\r\n a : int;\r\n [<field: DataMember(Name = "b")>]\r\n b : int;\r\n }\r\n\r\n[<DataContract>]\r\ntype Result =\r\n { \r\n [<field: DataMember(Name = "result")>]\r\n result : int;\r\n }\r\n<\/pre>\n\r\nstartWebServer defaultConfig (mapJson (fun (calc:Calc) -> { result = calc.a + calc.b }))\r\n<\/pre>\n\r\nInvoke-RestMethod -Uri http:\/\/localhost:8083\/ -Method Post -Body '{"a":10, "b":20}'\r\n<\/pre>\n
\nInvoke-RestMethod<\/a>
\nBuilding RESTful Web Services<\/a>
\nBuilding REST Api in Fsharp Using Suave<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"