Plaza Kotlin API Library

The Plaza Kotlin SDK provides convenient access to the Plaza REST API from applications written in Kotlin.

The Plaza Kotlin SDK is similar to the Plaza Java SDK but with minor differences that make it more ergonomic for use in Kotlin, such as nullable values instead of Optional, Sequence instead of Stream, and suspend functions instead of CompletableFuture.

It is generated with Stainless.

MCP Server

Use the Plaza MCP Server to enable AI assistants to interact with this API, allowing them to explore endpoints, make test requests, and use documentation to help integrate this SDK into your application.

Note: You may need to set environment variables in your MCP client.

The REST API documentation can be found on docs.plaza.fyi. KDocs are available on javadoc.io.

Installation

Gradle

implementation("com.plazafyi:plaza-kotlin:0.1.0")

Maven

<dependency>
  <groupId>com.plazafyi</groupId>
  <artifactId>plaza-kotlin</artifactId>
  <version>0.1.0</version>
</dependency>

Requirements

This library requires Java 8 or later.

Usage

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient
import com.plazafyi.models.FeatureCollection
import com.plazafyi.models.elements.ElementQueryParams

// Configures using the `plaza.apiKey` and `plaza.baseUrl` system properties
// Or configures using the `PLAZA_API_KEY` and `PLAZA_BASE_URL` environment variables
val client: PlazaClient = PlazaOkHttpClient.fromEnv()

val params: ElementQueryParams = ElementQueryParams.builder()
    .near("48.8584,2.2945")
    .radius(500.0)
    .build()
val featureCollection: FeatureCollection = client.elements().query(params)

Client configuration

Configure the client using system properties or environment variables:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient

// Configures using the `plaza.apiKey` and `plaza.baseUrl` system properties
// Or configures using the `PLAZA_API_KEY` and `PLAZA_BASE_URL` environment variables
val client: PlazaClient = PlazaOkHttpClient.fromEnv()

Or manually:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient

val client: PlazaClient = PlazaOkHttpClient.builder()
    .apiKey("My API Key")
    .build()

Or using a combination of the two approaches:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient

val client: PlazaClient = PlazaOkHttpClient.builder()
    // Configures using the `plaza.apiKey` and `plaza.baseUrl` system properties
    // Or configures using the `PLAZA_API_KEY` and `PLAZA_BASE_URL` environment variables
    .fromEnv()
    .apiKey("My API Key")
    .build()

See this table for the available options:

Setter	System property	Environment variable	Required	Default value
`apiKey`	`plaza.apiKey`	`PLAZA_API_KEY`	true	-
`baseUrl`	`plaza.baseUrl`	`PLAZA_BASE_URL`	true	`"https://plaza.fyi"`

System properties take precedence over environment variables.

Tip

Don’t create more than one client in the same application. Each client has a connection pool and thread pools, which are more efficient to share between requests.

Modifying configuration

To temporarily use a modified client configuration, while reusing the same connection and thread pools, call withOptions() on any client or service:

import com.plazafyi.client.PlazaClient

val clientWithOptions: PlazaClient = client.withOptions {
    it.baseUrl("https://example.com")
    it.maxRetries(42)
}

The withOptions() method does not affect the original client or service.

Requests and responses

To send a request to the Plaza API, build an instance of some Params class and pass it to the corresponding client method. When the response is received, it will be deserialized into an instance of a Kotlin class.

For example, client.elements().query(...) should be called with an instance of ElementQueryParams, and it will return an instance of FeatureCollection.

Immutability

Each class in the SDK has an associated builder or factory method for constructing it.

Each class is immutable once constructed. If the class has an associated builder, then it has a toBuilder() method, which can be used to convert it back to a builder for making a modified copy.

Because each class is immutable, builder modification will never affect already built class instances.

Asynchronous execution

The default client is synchronous. To switch to asynchronous execution, call the async() method:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient
import com.plazafyi.models.FeatureCollection
import com.plazafyi.models.elements.ElementQueryParams

// Configures using the `plaza.apiKey` and `plaza.baseUrl` system properties
// Or configures using the `PLAZA_API_KEY` and `PLAZA_BASE_URL` environment variables
val client: PlazaClient = PlazaOkHttpClient.fromEnv()

val params: ElementQueryParams = ElementQueryParams.builder()
    .near("48.8584,2.2945")
    .radius(500.0)
    .build()
val featureCollection: FeatureCollection = client.async().elements().query(params)

Or create an asynchronous client from the beginning:

import com.plazafyi.client.PlazaClientAsync
import com.plazafyi.client.okhttp.PlazaOkHttpClientAsync
import com.plazafyi.models.FeatureCollection
import com.plazafyi.models.elements.ElementQueryParams

// Configures using the `plaza.apiKey` and `plaza.baseUrl` system properties
// Or configures using the `PLAZA_API_KEY` and `PLAZA_BASE_URL` environment variables
val client: PlazaClientAsync = PlazaOkHttpClientAsync.fromEnv()

val params: ElementQueryParams = ElementQueryParams.builder()
    .near("48.8584,2.2945")
    .radius(500.0)
    .build()
val featureCollection: FeatureCollection = client.elements().query(params)

The asynchronous client supports the same options as the synchronous one, except most methods are suspending.

Binary responses

The SDK defines methods that return binary responses, which are used for API responses that shouldn’t necessarily be parsed, like non-JSON data.

These methods return HttpResponse:

import com.plazafyi.core.http.HttpResponse
import com.plazafyi.models.tiles.TileGetParams

val params: TileGetParams = TileGetParams.builder()
    .z(0L)
    .x(0L)
    .y(0L)
    .build()
val tile: HttpResponse = client.tiles().get(params)

To save the response content to a file, use the Files.copy(...) method:

import java.nio.file.Files
import java.nio.file.Paths
import java.nio.file.StandardCopyOption

client.tiles().get(params).use {
    Files.copy(
        it.body(),
        Paths.get(path),
        StandardCopyOption.REPLACE_EXISTING
    )
}

Or transfer the response content to any OutputStream:

import java.nio.file.Files
import java.nio.file.Paths

client.tiles().get(params).use {
    it.body().transferTo(Files.newOutputStream(Paths.get(path)))
}

Raw responses

The SDK defines methods that deserialize responses into instances of Kotlin classes. However, these methods don’t provide access to the response headers, status code, or the raw response body.

To access this data, prefix any HTTP method call on a client or service with withRawResponse():

import com.plazafyi.core.http.Headers
import com.plazafyi.core.http.HttpResponseFor
import com.plazafyi.models.FeatureCollection
import com.plazafyi.models.elements.ElementQueryParams

val params: ElementQueryParams = ElementQueryParams.builder()
    .near("48.8584,2.2945")
    .radius(500.0)
    .build()
val featureCollection: HttpResponseFor<FeatureCollection> = client.elements().withRawResponse().query(params)

val statusCode: Int = featureCollection.statusCode()
val headers: Headers = featureCollection.headers()

You can still deserialize the response into an instance of a Kotlin class if needed:

import com.plazafyi.models.FeatureCollection

val parsedFeatureCollection: FeatureCollection = featureCollection.parse()

Error handling

The SDK throws custom unchecked exception types:

PlazaServiceException: Base class for HTTP errors. See this table for which exception subclass is thrown for each HTTP status code:

Status	Exception
400	`BadRequestException`
401	`UnauthorizedException`
403	`PermissionDeniedException`
404	`NotFoundException`
422	`UnprocessableEntityException`
429	`RateLimitException`
5xx	`InternalServerException`
others	`UnexpectedStatusCodeException`

PlazaIoException: I/O networking errors.
PlazaRetryableException: Generic error indicating a failure that could be retried by the client.
PlazaInvalidDataException: Failure to interpret successfully parsed data. For example, when accessing a property that’s supposed to be required, but the API unexpectedly omitted it from the response.
PlazaException: Base class for all exceptions. Most errors will result in one of the previously mentioned ones, but completely generic errors may be thrown using the base class.

Logging

The SDK uses the standard OkHttp logging interceptor.

Enable logging by setting the PLAZA_LOG environment variable to info:

export PLAZA_LOG=info

Or to debug for more verbose logging:

export PLAZA_LOG=debug

ProGuard and R8

Although the SDK uses reflection, it is still usable with ProGuard and R8 because plaza-kotlin-core is published with a configuration file containing keep rules.

ProGuard and R8 should automatically detect and use the published rules, but you can also manually copy the keep rules if necessary.

Jackson

The SDK depends on Jackson for JSON serialization/deserialization. It is compatible with version 2.13.4 or higher, but depends on version 2.18.2 by default.

The SDK throws an exception if it detects an incompatible Jackson version at runtime (e.g. if the default version was overridden in your Maven or Gradle config).

If the SDK threw an exception, but you’re certain the version is compatible, then disable the version check using the checkJacksonVersionCompatibility on PlazaOkHttpClient or PlazaOkHttpClientAsync.

Caution

We make no guarantee that the SDK works correctly when the Jackson version check is disabled.

Also note that there are bugs in older Jackson versions that can affect the SDK. We don’t work around all Jackson bugs (example) and expect users to upgrade Jackson for those instead.

Network options

Retries

The SDK automatically retries 2 times by default, with a short exponential backoff between requests.

Only the following error types are retried:

Connection errors (for example, due to a network connectivity problem)
408 Request Timeout
409 Conflict
429 Rate Limit
5xx Internal

The API may also explicitly instruct the SDK to retry or not retry a request.

To set a custom number of retries, configure the client using the maxRetries method:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient

val client: PlazaClient = PlazaOkHttpClient.builder()
    .fromEnv()
    .maxRetries(4)
    .build()

Timeouts

Requests time out after 1 minute by default.

To set a custom timeout, configure the method call using the timeout method:

import com.plazafyi.models.FeatureCollection

val featureCollection: FeatureCollection = client.elements().query(RequestOptions.builder().timeout(Duration.ofSeconds(30)).build())

Or configure the default for all method calls at the client level:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient
import java.time.Duration

val client: PlazaClient = PlazaOkHttpClient.builder()
    .fromEnv()
    .timeout(Duration.ofSeconds(30))
    .build()

Proxies

To route requests through a proxy, configure the client using the proxy method:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient
import java.net.InetSocketAddress
import java.net.Proxy

val client: PlazaClient = PlazaOkHttpClient.builder()
    .fromEnv()
    .proxy(Proxy(
      Proxy.Type.HTTP, InetSocketAddress(
        "https://example.com", 8080
      )
    ))
    .build()

Connection pooling

To customize the underlying OkHttp connection pool, configure the client using the maxIdleConnections and keepAliveDuration methods:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient
import java.time.Duration

val client: PlazaClient = PlazaOkHttpClient.builder()
    .fromEnv()
    // If `maxIdleConnections` is set, then `keepAliveDuration` must be set, and vice versa.
    .maxIdleConnections(10)
    .keepAliveDuration(Duration.ofMinutes(2))
    .build()

If both options are unset, OkHttp’s default connection pool settings are used.

HTTPS

Note

Most applications should not call these methods, and instead use the system defaults. The defaults include special optimizations that can be lost if the implementations are modified.

To configure how HTTPS connections are secured, configure the client using the sslSocketFactory, trustManager, and hostnameVerifier methods:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient

val client: PlazaClient = PlazaOkHttpClient.builder()
    .fromEnv()
    // If `sslSocketFactory` is set, then `trustManager` must be set, and vice versa.
    .sslSocketFactory(yourSSLSocketFactory)
    .trustManager(yourTrustManager)
    .hostnameVerifier(yourHostnameVerifier)
    .build()

Environments

The SDK sends requests to the production by default. To send requests to a different environment, configure the client like so:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient

val client: PlazaClient = PlazaOkHttpClient.builder()
    .fromEnv()
    .local()
    .build()

Custom HTTP client

The SDK consists of three artifacts:

plaza-kotlin-core
- Contains core SDK logic
- Does not depend on OkHttp
- Exposes PlazaClient, PlazaClientAsync, PlazaClientImpl, and PlazaClientAsyncImpl, all of which can work with any HTTP client
plaza-kotlin-client-okhttp
- Depends on OkHttp
- Exposes PlazaOkHttpClient and PlazaOkHttpClientAsync, which provide a way to construct PlazaClientImpl and PlazaClientAsyncImpl, respectively, using OkHttp
plaza-kotlin
- Depends on and exposes the APIs of both plaza-kotlin-core and plaza-kotlin-client-okhttp
- Does not have its own logic

This structure allows replacing the SDK’s default HTTP client without pulling in unnecessary dependencies.

Customized `OkHttpClient`

Tip

Try the available network options before replacing the default client.

To use a customized OkHttpClient:

Replace your plaza-kotlin dependency with plaza-kotlin-core
Copy plaza-kotlin-client-okhttp’s OkHttpClient class into your code and customize it
Construct PlazaClientImpl or PlazaClientAsyncImpl, similarly to PlazaOkHttpClient or PlazaOkHttpClientAsync, using your customized client

Completely custom HTTP client

To use a completely custom HTTP client:

Replace your plaza-kotlin dependency with plaza-kotlin-core
Write a class that implements the HttpClient interface
Construct PlazaClientImpl or PlazaClientAsyncImpl, similarly to PlazaOkHttpClient or PlazaOkHttpClientAsync, using your new client class

Undocumented API functionality

The SDK is typed for convenient usage of the documented API. However, it also supports working with undocumented or not yet supported parts of the API.

Parameters

To set undocumented parameters, call the putAdditionalHeader, putAdditionalQueryParam, or putAdditionalBodyProperty methods on any Params class:

import com.plazafyi.core.JsonValue
import com.plazafyi.models.elements.ElementQueryParams

val params: ElementQueryParams = ElementQueryParams.builder()
    .putAdditionalHeader("Secret-Header", "42")
    .putAdditionalQueryParam("secret_query_param", "42")
    .putAdditionalBodyProperty("secretProperty", JsonValue.from("42"))
    .build()

These can be accessed on the built object later using the _additionalHeaders(), _additionalQueryParams(), and _additionalBodyProperties() methods.

To set a documented parameter or property to an undocumented or not yet supported value, pass a JsonValue object to its setter:

import com.plazafyi.models.elements.ElementQueryParams

val params: ElementQueryParams = ElementQueryParams.builder()
    .near("48.8584,2.2945")
    .radius(500.0)
    .build()

The most straightforward way to create a JsonValue is using its from(...) method:

import com.plazafyi.core.JsonValue

// Create primitive JSON values
val nullValue: JsonValue = JsonValue.from(null)
val booleanValue: JsonValue = JsonValue.from(true)
val numberValue: JsonValue = JsonValue.from(42)
val stringValue: JsonValue = JsonValue.from("Hello World!")

// Create a JSON array value equivalent to `["Hello", "World"]`
val arrayValue: JsonValue = JsonValue.from(listOf(
  "Hello", "World"
))

// Create a JSON object value equivalent to `{ "a": 1, "b": 2 }`
val objectValue: JsonValue = JsonValue.from(mapOf(
  "a" to 1, "b" to 2
))

// Create an arbitrarily nested JSON equivalent to:
// {
//   "a": [1, 2],
//   "b": [3, 4]
// }
val complexValue: JsonValue = JsonValue.from(mapOf(
  "a" to listOf(
    1, 2
  ), "b" to listOf(
    3, 4
  )
))

Normally a Builder class’s build method will throw IllegalStateException if any required parameter or property is unset.

To forcibly omit a required parameter or property, pass JsonMissing:

import com.plazafyi.core.JsonMissing
import com.plazafyi.models.elements.ElementQueryParams
import com.plazafyi.models.elements.ElementRetrieveParams

val params: ElementQueryParams = ElementRetrieveParams.builder()
    .type(JsonMissing.of())
    .build()

Response properties

To access undocumented response properties, call the _additionalProperties() method:

import com.plazafyi.core.JsonBoolean
import com.plazafyi.core.JsonNull
import com.plazafyi.core.JsonNumber
import com.plazafyi.core.JsonValue

val additionalProperties: Map<String, JsonValue> = client.elements().query(params)._additionalProperties()
val secretPropertyValue: JsonValue = additionalProperties.get("secretProperty")

val result = when (secretPropertyValue) {
    is JsonNull -> "It's null!"
    is JsonBoolean -> "It's a boolean!"
    is JsonNumber -> "It's a number!"
    // Other types include `JsonMissing`, `JsonString`, `JsonArray`, and `JsonObject`
    else -> "It's something else!"
}

To access a property’s raw JSON value, which may be undocumented, call its _ prefixed method:

import com.plazafyi.core.JsonField

val field: JsonField<Any> = client.elements().query(params)._field()

if (field.isMissing()) {
  // The property is absent from the JSON response
} else if (field.isNull()) {
  // The property was set to literal null
} else {
  // Check if value was provided as a string
  // Other methods include `asNumber()`, `asBoolean()`, etc.
  val jsonString: String? = field.asString();

  // Try to deserialize into a custom type
  val myObject: MyClass = field.asUnknown()!!.convert(MyClass::class.java)
}

Response validation

In rare cases, the API may return a response that doesn’t match the expected type. For example, the SDK may expect a property to contain a String, but the API could return something else.

By default, the SDK will not throw an exception in this case. It will throw PlazaInvalidDataException only if you directly access the property.

If you would prefer to check that the response is completely well-typed upfront, then either call validate():

import com.plazafyi.models.FeatureCollection

val featureCollection: FeatureCollection = client.elements().query(params).validate()

Or configure the method call to validate the response using the responseValidation method:

import com.plazafyi.models.FeatureCollection

val featureCollection: FeatureCollection = client.elements().query(RequestOptions.builder().responseValidation(true).build())

Or configure the default for all method calls at the client level:

import com.plazafyi.client.PlazaClient
import com.plazafyi.client.okhttp.PlazaOkHttpClient

val client: PlazaClient = PlazaOkHttpClient.builder()
    .fromEnv()
    .responseValidation(true)
    .build()

FAQ

Why don’t you use plain `enum` classes?

Kotlin enum classes are not trivially forwards compatible. Using them in the SDK could cause runtime exceptions if the API is updated to respond with a new enum value.

Why do you represent fields using `JsonField<T>` instead of just plain `T`?

Using JsonField<T> enables a few features:

Allowing usage of undocumented API functionality
Lazily validating the API response against the expected shape
Representing absent vs explicitly null values

Why don’t you use `data` classes?

It is not backwards compatible to add new fields to a data class and we don’t want to introduce a breaking change every time we add a field to a class.

Why don’t you use checked exceptions?

Checked exceptions are widely considered a mistake in the Java programming language. In fact, they were omitted from Kotlin for this reason.

Checked exceptions:

Are verbose to handle
Encourage error handling at the wrong level of abstraction, where nothing can be done about the error
Are tedious to propagate due to the function coloring problem
Don’t play well with lambdas (also due to the function coloring problem)

Semantic versioning

This package generally follows SemVer conventions, though certain backwards-incompatible changes may be released as minor versions:

Changes to library internals which are technically public but not intended or documented for external use. (Please open a GitHub issue to let us know if you are relying on such internals.)
Changes that we do not expect to impact the vast majority of users in practice.

We take backwards-compatibility seriously and work hard to ensure you can rely on a smooth upgrade experience.

We are keen for your feedback; please open an issue with questions, bugs, or suggestions.

Plaza Kotlin API Library

Plaza Kotlin API Library

MCP Server

Installation

Gradle

Maven

Requirements

Usage

Client configuration

Modifying configuration

Requests and responses

Immutability

Asynchronous execution

Binary responses

Raw responses

Error handling

Logging

ProGuard and R8

Jackson

Network options

Retries

Timeouts

Proxies

Connection pooling

HTTPS

Environments

Custom HTTP client

Customized OkHttpClient

Completely custom HTTP client

Undocumented API functionality

Parameters

Response properties

Response validation

FAQ

Why don’t you use plain enum classes?

Why do you represent fields using JsonField<T> instead of just plain T?

Why don’t you use data classes?

Why don’t you use checked exceptions?

Semantic versioning

What can I help you with?

Suggestions

Customized `OkHttpClient`

Why don’t you use plain `enum` classes?

Why do you represent fields using `JsonField<T>` instead of just plain `T`?

Why don’t you use `data` classes?