The .NET Haystack client library is built to ease communicating with Haystack compatible libraries. The NuGet package ProjectHaystack.Client can be found on nuget.org.

There are two main functions:

• Athentication
• Conversion between haystack text and managed models

The Haystack authentication officially supports https://project-haystack.org/doc/Auth#scram and unofficially others (like basic authentication) all through a handshake mechanism that tells the client what methods are supported.

See the Clients chapter for more information about the authentication selection.

As of version 2.0 older clients have been removed in favor of a single modern interface. If you have a high dependency on the old clients you should use the 1.x version of the library.

The HaystackClient is a modular client that uses the HttpClient implementation for communication and an IAuthenticator for the authentication method.

It can be used to do "raw" requests to the server, but it can also be used to automatically convert between queries and results into the managed classes. For conversion it relies on the HZincWriter and HZincReader classes.

This chapter describes some usage examples of the library. More examples can be found in the Examples library.

var user = "someuser";
var pass = "somepassword";
var uri = new Uri("https://someserver/api/");
var auth = new AutodetectAuthenticator(user, pass);
var client = new HaystackClient(auth, uri);

client.OpenAsync();

One of the simplest calls is the call of the "about" page which contains some basic information about the server. This call requires no content, so it simply sends an empty grid.

HaystackDictionary result = await client.AboutAsync();

It is possible to do a raw call to the server if you do mainly want to use the authentication mechanism, but not the conversion. This can be useful if you do conversion elsewhere, or if you want to get specific data types from the server, like json:

string result = await client.PostStringAsync("about", string.Empty, "text/zinc", "application/json");

When sending more complex requests, like an Axon query in SkySpark you can build and send a grid with a specific operation.

var axon = "someaxon";
var grid = new HaystackGrid()
	.AddColumn("expr")
	.AddRow(new HaystackString(axon));
HaystackGrid[] result = await client.EvalAllAsync(grid);

As the AutodetectAuthenticator adds a little bit of overhead and complexity and doesn't cover all cases, it may be useful to use a specific authentication method provided in the library or one that you created.

var auth = new ScramAuthenticator(user, pass);
var client = new HaystackClient(auth, uri);

Other examples of authenticators are BasicAuthenticator and NonHaystackBasicAuthenticator.

The HaystackClient creates its own static default HttpClient, but you can also provide your own for more control over the communication. The default authentication uses cookies, so if you provide your own client, you need to provide it a cookie container to be able to authenticate properly.

var handler = new HttpClientHandler() { UseCookies = false, AllowAutoRedirect = false };
var httpClient = new HttpClient(handler);
var client = new HaystackClient(httpClient, auth, uri);

If you have questions you can ask them on the Project Haystack Forum. If you have issues or suggestions for the library you can create a new issue in the repository. If you want to contribute, just create your fork and create a pull request on the main repository.

Originally the library is a .NET Framework port from the Java Toolkit with the exception of a dependency on TimeZoneConverter.

Over time it has been modified to .NET 5.0, dropping support for the old functional origins and providing native .NET features like asynchronous functions and enumerators.