algorithmia-android

Java client for accessing Algorithmia's algorithm marketplace and data APIs from Android applications.

Note: because our java client depends on Apache HTTP Client, it is not compatible with the Android Runtime. In early versions of android, a legacy version of apache http client came pre-bundled, but was not updated over time. In recent android versions (6.0+) it was removed entirely. The algorithmia-android client uses native HttpURLConnection as its underlying client, as recommended by the Android documentation.

For API documentation, see the JavaDocs

Getting started

The Algorithmia Android client is published to Maven central and can be added as a dependency in Android Studio.

Note: Because our Java client depends on Apache HTTP Client, it is not compatible with the Android Runtime. In early versions of android, a legacy version of apache http client came pre-bundled, but was not updated over time. In recent android versions (6.0+) it was removed entirely. The algorithmia-android client uses native HttpURLConnection as its underlying client, as recommended by the Android documentation.

For API documentation, see the JavaDocs

To add the Algorithmia Android client, add the following line to your app/build.gradle file:

  compile "com.algorithmia:algorithmia-android:1.0.1"

Instantiate a client using your API Key:

AlgorithmiaClient client = Algorithmia.client(apiKey);

Note: The API key may be omitted only when making calls from algorithms running on the Algorithmia cluster

Android Threads

It is necessary to perform network operations (such as calling Algorithmia) on a background thread in Android, to avoid impacting UI performance. The standard way to acheive this in Android is to use an AsyncTask.

See Android documentation about UI vs. Background threads: Processes and Threads

/**
 * AsyncTask helper to make it easy to call Algorithmia in the background
 * @param <T> the type of the input to send to the algorithm
 */
public abstract class AlgorithmiaTask<T> extends AsyncTask<T, Void, AlgoResponse> {
    private static final String TAG = "AlgorithmiaTask";

    private String algoUrl;
    private AlgorithmiaClient client;
    private Algorithm algo;

    public AlgorithmiaTask(String api_key, String algoUrl) {
        super();

        this.algoUrl = algoUrl;
        this.client = Algorithmia.client(api_key);
        this.algo = client.algo(algoUrl);
    }

    @Override
    protected AlgoResponse doInBackground(T... inputs) {
        if(inputs.length == 1) {
            T input = inputs[0];
            // Call algorithmia
            try {
                AlgoResponse response = algo.pipe(input);
                return response;
            } catch(APIException e) {
                // Connection error
                Log.e(TAG, "Algorithmia API Exception", e);
                return null;
            }
        } else {
            // Too many inputs
            return null;
        }
    }
}

Calling Algorithms

The following examples of calling algorithms are organized by type of input/output which vary between algorithms.

Note: A single algorithm may have different input and output types, or accept multiple types of input, so consult the algorithm’s description for usage examples specific to that algorithm.

Text input/ouput

Call an algorithm with text input by simply passing a string into its pipe method. If the algorithm output is text, call the asString method on the response.

Algorithm algo = client.algo("algo://demo/Hello/0.1.1");
AlgoResponse response = algo.pipe("HAL 9000");
System.out.println(response.asString());
// -> Hello HAL 9000

Numeric input/output

import com.algorithmia.TypeToken;

Algorithm addOne = client.algo("docs/JavaAddOne");
AlgoResponse response = addOne.pipe(41);
Integer result = response.as(new TypeToken<Integer>(){});
// -> 42

JSON input/output

Call an algorithm with JSON input by simply passing in a type that can be serialized to JSON, including most plain old java objects and collection types. If the algorithm output is JSON, call the as method on the response with a TypeToken containing the type that it should be deserialized into:

import com.algorithmia.TypeToken;

Algorithm algo = client.algo("algo://WebPredict/ListAnagrams/0.1.0");
List<String> words = Arrays.asList(("transformer", "terraforms", "retransform");
AlgoResponse response = algo.pipe(words);
// WebPredict/ListAnagrams returns a JSON array of strings, so change to Java array
List<String> anagrams = response.as(new TypeToken<List<String>>(){});
// -> ["transformer", "retransform"]

If you already have serialized JSON, you can use pipeJson and call asJsonString on the response:

Algorithm algo = client.algo("algo://WebPredict/ListAnagrams/0.1.0");
String jsonWords = "[\"transformer\", \"terraforms\", \"retransform\"]";
AlgoResponse response = algo.pipeJson(jsonWords);
response.asJsonString();
// -> "[\"transformer\", \"retransform\"]"

Binary input/output

Call an algorithm with binary input by passing a byte[] into the pipe method. If the algorithm response is binary data, then call the as method on the response with a byte[] TypeToken to obtain the raw byte array.

import com.algorithmia.TypeToken;
import org.apache.commons.io.FileUtils;

URL url = new URL("https://stopthehitch.files.wordpress.com/2013/06/arnold-schwarzenegger-1920x1080.jpg");
byte[] input = IOUtils.toByteArray(url.openConnection().getInputStream());
// Call SmartThumbnail algorithm passing in byte array as input
AlgoResponse response = client.algo("opencv/SmartThumbnail/0.1").pipe(input);
byte[] buffer = response.as(new TypeToken<byte[]>(){});
// -> [byte array]

Error Handling

API errors will result in the call to pipe throwing APIException. Errors that occur durring algorithm execution will result in AlgorithmException when attempting to read the response.

Algorithm algo = client.algo("util/whoopsWrongAlgo")
try {
    AlgoResponse response = algo.pipe("Hello, world!");
    String output = response.asString();
    algoOutput.setText(output)
} catch (AlgorithmException e) {
    AlgoFailure failure = (AlgoFailure) response;
    algoOutput.setText("Algorithm Error: " + failure.error);
}

Request Options

The client exposes options that can configure algorithm requests. This includes support for changing the timeout or indicating that the API should include stdout in the response:

// setTimeout takes long class, set to 10 minutes
long lg = 600L;
Algorithm algo = client.algo("algo://demo/Hello/0.1.1")
                         .setTimeout(lg, TimeUnit.MINUTES)
                         .setStdout(true);
AlgoResponse response = algo.pipe("HAL 9000");
response.asJsonString();
// -> "Hello Hal 9000"

Note: setStdout(true) is ignored if you do not have access to the algorithm source.

Working with Data

The Algorithmia Android client also provides a way to manage both Algorithmia hosted data and data from Dropbox or S3 accounts that you've connected to you Algorithmia account.

This client provides a DataFile type (generally created by client.file(uri)) and a DataDir type (generally created by client.dir(uri)) that provide methods for managing your data.

Create directories

Create directories by instantiating a DataDirectory object and calling create():

DataDirectory robots = client.dir("data://.my/robots");
robots.create();

DataDirectory dbxRobots = client.dir("dropbox://robots");
dbxRobots.create();

Upload files to a directory

Upload files by calling put on a DataFile object, or by calling putFile on a DataDirectory object.

DataDirectory robots = client.dir("data://.my/robots");

// Upload local file - for example this path and file could be from sdcard.
robots.putFile(new File("/path/to/Optimus_Prime.png"));
// Write a text file
robots.file("Optimus_Prime.txt").put("Leader of the Autobots");
// Write a binary file
robots.file("Optimus_Prime.key").put(new byte[] { (byte)0xe0, 0x4f, (byte)0xd0, 0x20 });

Download contents of file

Download files by calling getString, getBytes, or getFile on a DataFile object:

DataDirectory robots = client.dir("data://.my/robots");

// Download file and get the file handle
File OPFile = robots.file("Optimus_Prime.txt").getFile();

// Get the file's contents as a string
String OPText = robots.file("Optimus_Prime.txt").getString();

// Get the file's contents as a byte array
byte[] OPBytes = robots.file("Optimus_Prime.png").getBytes();

Delete files and directories

Delete files and directories by calling delete on their respective DataFile or DataDirectory object. DataDirectories take an optional force parameter that indicates whether the directory should be deleted if it contains files or other directories.

client.file("data://.my/robots/Optimus_Prime.txt").delete();
client.dir("data://.my/robots").delete(false);

List directory contents

Iterate over the contents of a directory using the iterator returned by calling files, or dirs on a DataDirectory object:

// List top level directories
DataDirectory myRoot = client.dir("data://.my");
for(DataDirectory dir : myRoot.dirs()) {
    System.out.println("Directory " + dir.toString() + " at URL " + dir.getUrl());
}

// List files in the 'robots' directory
DataDirectory robots = client.dir("data://.my/robots");
for(DataFile file : robots.files()) {
    System.out.println("File " + file.toString() + " at URL: " + file.getUrl());
}

Manage directory permissions

Directory permissions may be set when creating a directory, or may be updated on already existing directories.

DataDirectory fooLimited = client.dir("data://.my/fooLimited");

// Create the directory as private
fooLimited.create(DataAcl.PRIVATE);

// Update a directory to be public
fooLimited.updatePermissions(DataAcl.PUBLIC);

// Check a directory's permissions
if (fooLimited.getPermissions().getReadPermissions() == DataAclType.PRIVATE) {
    System.out.println("fooLimited is private");
}