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https://github.com/propensive/telekinesis

A lightweight URI representation and HTTP client
https://github.com/propensive/telekinesis

http http-client rest scala

Last synced: 3 months ago
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A lightweight URI representation and HTTP client

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# Telekinesis



__A lightweight HTTP client and server for the Loom generation__



__Telekinesis__ is a lightweight HTTP client for sending and HTTP requests.



## Features



- immutable API optimized for Scala 3 and lightweight concurrency with Loom

- Simple and flexible request handling

- HTTP server can be run standalone or wrap a servlet container

- typesafe representations of HTTP request and response headers and MIME types

- transparent typeclass-based request body query parameter serialization and deserialization

- optional pattern-matching on requests

- fast streaming without complexity

- safe parameter and header access

- typesafe representation of URLs



## Availability



## Getting Started



Here is an example of a simple HTTP request:



```scala

import telekinesis.*



val response = url"http://example.com/test".query(flag = t"yes", param = t"7").get().as[Text]

```



### Sending an HTTP request



An HTTP request may be sent by calling one of the HTTP methods—`get`, `post`, `put`, `options`, `head`, `trace`,

`delete`, `connect` or `patch`—on the `Http` object. As a minimum, these methods all take a URL as their first

parameter. This may be provided as a `Url` (see below) or a `Text`, or any type which has a contextual

`ToLocation` instance which can convert it into URL string. This may be useful for integration with alternitave

URL representations.



If the request is successful, a response will be returned synchronously as an `HttpResponse` instance.

`HttpResponse` provides the methods `status` (the HTTP status code), `headers` (a map of HTTP response headers),

and `body` which will be a representation of the response body, in bytes.



The easiest way to access the body is by converting it to another type, using a contextual reader. That can be

achieved by calling `as` with an appropriate type, for example,

```scala

url"https://example.com/service".get().as[Text]

```

or with a suitable JSON library such as [Jacinta](https://propensive.com/opensource/jacinta/),

```scala

import jacinta.*

url"http://example.com/file".post(content).as[Json]

```



### Request and response bodies



The type of `body` is `Body`, defined as an alias for, `Unit | IArray[Byte] | LazyList[IArray[Byte]]`, a union

type corresponding to the cases of an empty response, a response of known length, and a streamed response,

respectively.



This type is commonly used for both requests and responses.



### Error handling



HTTP requests may fail for a variety of reasons. These will be thrown as `HttpError`s only when the `as` method

is invoked (an `HttpResponse` is always returned from `get` or `post`, even in the event of a failure status).

An `HttpError` contains a `status` field of the HTTP status code.



Some HTTP requests will fail, but will still send a useful response body which can be read and interpreted like

any other, albeit from the `HttpError` instance.



Here is an example of an HTTP error being handled:



```scala

try uri.get().as[Text]

catch

  case error@HttpError(HttpStatus.NotFound, _) =>

    t"The page was not found. The server responded with: ${error.as[Text]}"

  case HttpError(_, _) =>

    t"The request failed"

```



## Status



Telekinesis is classified as __fledgling__. For reference, Soundness projects are

categorized into one of the following five stability levels:



- _embryonic_: for experimental or demonstrative purposes only, without any guarantees of longevity

- _fledgling_: of proven utility, seeking contributions, but liable to significant redesigns

- _maturescent_: major design decisions broady settled, seeking probatory adoption and refinement

- _dependable_: production-ready, subject to controlled ongoing maintenance and enhancement; tagged as version `1.0.0` or later

- _adamantine_: proven, reliable and production-ready, with no further breaking changes ever anticipated



Projects at any stability level, even _embryonic_ projects, can still be used,

as long as caution is taken to avoid a mismatch between the project's stability

level and the required stability and maintainability of your own project.



Telekinesis is designed to be _small_. Its entire source code currently consists

of 640 lines of code.



## Building



Telekinesis will ultimately be built by Fury, when it is published. In the

meantime, two possibilities are offered, however they are acknowledged to be

fragile, inadequately tested, and unsuitable for anything more than

experimentation. They are provided only for the necessity of providing _some_

answer to the question, "how can I try Telekinesis?".



1. *Copy the sources into your own project*

   

   Read the `fury` file in the repository root to understand Telekinesis's build

   structure, dependencies and source location; the file format should be short

   and quite intuitive. Copy the sources into a source directory in your own

   project, then repeat (recursively) for each of the dependencies.



   The sources are compiled against the latest nightly release of Scala 3.

   There should be no problem to compile the project together with all of its

   dependencies in a single compilation.



2. *Build with [Wrath](https://github.com/propensive/wrath/)*



   Wrath is a bootstrapping script for building Telekinesis and other projects in

   the absence of a fully-featured build tool. It is designed to read the `fury`

   file in the project directory, and produce a collection of JAR files which can

   be added to a classpath, by compiling the project and all of its dependencies,

   including the Scala compiler itself.

   

   Download the latest version of

   [`wrath`](https://github.com/propensive/wrath/releases/latest), make it

   executable, and add it to your path, for example by copying it to

   `/usr/local/bin/`.



   Clone this repository inside an empty directory, so that the build can

   safely make clones of repositories it depends on as _peers_ of `telekinesis`.

   Run `wrath -F` in the repository root. This will download and compile the

   latest version of Scala, as well as all of Telekinesis's dependencies.



   If the build was successful, the compiled JAR files can be found in the

   `.wrath/dist` directory.



## Contributing



Contributors to Telekinesis are welcome and encouraged. New contributors may like

to look for issues marked

[beginner](https://github.com/propensive/telekinesis/labels/beginner).



We suggest that all contributors read the [Contributing

Guide](/contributing.md) to make the process of contributing to Telekinesis

easier.



Please __do not__ contact project maintainers privately with questions unless

there is a good reason to keep them private. While it can be tempting to

repsond to such questions, private answers cannot be shared with a wider

audience, and it can result in duplication of effort.



## Author



Telekinesis was designed and developed by Jon Pretty, and commercial support and

training on all aspects of Scala 3 is available from [Propensive

OÜ](https://propensive.com/).



## Name



The library provides a way of handling URIs, performing "action at a distance",

or _telekinesis_; specifically the processing of a request on a remote server.

A man called Uri was also famed for his ability to perform telekinesis with

spoons.



In general, Soundness project names are always chosen with some rationale,

however it is usually frivolous. Each name is chosen for more for its

_uniqueness_ and _intrigue_ than its concision or catchiness, and there is no

bias towards names with positive or "nice" meanings—since many of the libraries

perform some quite unpleasant tasks.



Names should be English words, though many are obscure or archaic, and it

should be noted how willingly English adopts foreign words. Names are generally

of Greek or Latin origin, and have often arrived in English via a romance

language.



## Logo



The logo shows the characters `://`, which form part of every URL.



## License



Telekinesis is copyright © 2024 Jon Pretty & Propensive OÜ, and

is made available under the [Apache 2.0 License](/license.md).