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# Package: Kernel-HTTP

## Class: HTTPClient

### Introduction

**Environment: `container`**

HTTPClient is a HTTP client library.

It has the following attributes:

* `host` the host of the request
* `port` the port of the request
* `url` the url of the request
* `timeout` the timeout of the request
* `contents` the contents of the request
* `contentType` the content type of the request
* `method` the http request method.

It has the following methods:

* `queryAt:put:` Add key equals value as an HTTP query parameter to the current request.
* `headerAt:put:` Add key equals value as an HTTP header to the current request.
* `execute` execute the request
* `get` execute a get request
* `put` execute a put request
* `post` execute a post request
* `delete` execute a delete request
* `head` execute a head request

You can use it to make HTTP requests to a server.

for example, for a HTTP get:

```smalltalk
httpClient := HTTPClient new.
httpClient url: 'http://www.example.com'.
result := httpClient get.
```

and for a HTTP post:

```smalltalk
httpClient := HTTPClient new.
httpClient url: 'http://www.example.com/api'.
httpClient
 contents:
 { ('key1' -> 'key1').
   ('key2' -> 2) } asJson.
result := httpClient post.
```

The result is a Dictionary which has three keys:

* `status` The http status code.
* `headers` The http headers.
* `response` The http response body. It wil be parsed as JSON if possible, otherwise it will be a string.

For example, you can check the status code like this:

```smalltalk
result := httpClient get.
" If the HTTP status code differs from 200, exit the current block. "
(result at: 'status') = 200 ifFalse: [ ^ nil ].
```

Sometimes, the http request may raise an error for a failure request, we can catch error like this:

```smalltalk
error := nil.
[ httpClient get ] onErrorDo: [ :ex | error := ex ].
" If error is not nil, it means the http request failed. "
error ifNotNil: [
  " The error is an APIError object, we can check the error code like this: "
  error code = 'http-request-error'.
  "we can terminate the execution by caret operator.  "
  ^ nil ].
```

### Instance Method

#### Category: accessing - request

* **`contentType`** - Get the contentType of the HTTPClient.
* **`contentType:`** - Set the contentType of the HTTPClient.
* **`contents`** - Get the contents of the HTTPClient.
* **`contents:`** - Set the contents of the HTTPClient.
* **`headerAt:put:`** - Set key equals value in the HTTP header of the current request.

  For example:

  ```smalltalk
  self headerAt: 'x-conversation-id' put: UUIDGenerator next.
  ```
* **`host`** - Get the host of the HTTPClient.
* **`host:`** - Set the host of the HTTPClient.
* **`method`** - Get the method of the HTTPClient.
* **`method:`** - Set the method of the HTTPClient.
* **`port`** - Get the port of the HTTPClient.
* **`port:`** - Set the port of the HTTPClient.
* **`queryAt:put:`** - Add key equals value as an HTTP query parameter to the current request.

  If a key is already present, its corresponding value will be replaced.

  For example:

  ```smalltalk
  self queryAt: 'id' put: '12'.
  ```
* **`timeout`** - Get the timeout of the HTTPClient.
* **`timeout:`** - Set the timeout of the HTTPClient.
* **`url`** - Get the url of the HTTPClient.
* **`url:`** - Set the url of the HTTPClient.

#### Category: operations

* **`delete`** - Execute an HTTP DELETE the request set up and return the response #contents.
* **`execute`** - Execute the currently set up request to generate a response. Return the #contents of the response, if any.
* **`get`** - Execute an HTTP GET the request set up and return the response #contents.
* **`head`** - Execute a HTTP HEAD on the request set up and return nil.
* **`post`** - Execute an HTTP POST the request set up and return the response #contents.
* **`put`** - Execute an HTTP PUT the request set up and return the response #contents.

## Class: UUIDGenerator

### Introduction

**Environment: `container`**

The UUIDGenerator generates UUIDs, this can be used by following the syntax below

```smalltalk
"Return a new UUID string."
UUIDGenerator next
```

### Class Method

#### Category: accessing

* **`next`** - returns a new UUID string.