{% include JB/setup %}
Session api is a high level api for zeppelin. There's no zeppelin concept (note, paragraph) in this api. The most important thing is a ZSession which represent a running interpreter process. It is pretty to create a ZSession and its api is very straightforward, we can see a concret examples below.
It is very easy to create a ZSession, you need to provide ClientConfig, interpreter and also you can customize your ZSession by specificy its interpreter properties.
After you can create ZSession, you need to start it before running any code. ZSession's lifecycle is under your control, you need to call stop method expclitly, otherwise the interpreter processs will keep running.
{% highlight java %} ZSession session = null; try { ClientConfig clientConfig = new ClientConfig(“http://localhost:8080”); Map<String, String> intpProperties = new HashMap<>(); intpProperties.put(“spark.master”, “local[*]”);
session = ZSession.builder() .setClientConfig(clientConfig) .setInterpreter(“spark”) .setIntpProperties(intpProperties) .build();
session.start(); System.out.println("Spark Web UI: " + session.getWeburl());
// scala (single result) ExecuteResult result = session.execute(“println(sc.version)”); System.out.println("Spark Version: " + result.getResults().get(0).getData());
// scala (multiple result) result = session.execute(“println(sc.version)\n” + “val df = spark.createDataFrame(Seq((1,"a"), (2,"b")))\n” + “z.show(df)”);
// The first result is text output System.out.println("Result 1: type: " + result.getResults().get(0).getType() + ", data: " + result.getResults().get(0).getData() ); // The second result is table output System.out.println("Result 2: type: " + result.getResults().get(1).getType() + ", data: " + result.getResults().get(1).getData() ); System.out.println(“Spark Job Urls:\n” + StringUtils.join(result.getJobUrls(), “\n”));
// error output result = session.execute(“1/0”); System.out.println("Result status: " + result.getStatus() + ", data: " + result.getResults().get(0).getData());
// pyspark result = session.execute(“pyspark”, “df = spark.createDataFrame([(1,‘a’),(2,‘b’)])\n” + “df.registerTempTable(‘df’)\n” + “df.show()”); System.out.println("PySpark dataframe: " + result.getResults().get(0).getData());
// matplotlib result = session.execute(“ipyspark”, “%matplotlib inline\n” + “import matplotlib.pyplot as plt\n” + “plt.plot([1,2,3,4])\n” + “plt.ylabel(‘some numbers’)\n” + “plt.show()”); System.out.println("Matplotlib result, type: " + result.getResults().get(0).getType() + ", data: " + result.getResults().get(0).getData());
// sparkr result = session.execute(“r”, “df <- as.DataFrame(faithful)\nhead(df)”); System.out.println("Sparkr dataframe: " + result.getResults().get(0).getData());
// spark sql result = session.execute(“sql”, “select * from df”); System.out.println("Spark Sql dataframe: " + result.getResults().get(0).getData());
// spark invalid sql result = session.execute(“sql”, “select * from unknown_table”); System.out.println("Result status: " + result.getStatus() + ", data: " + result.getResults().get(0).getData()); } catch (Exception e) { e.printStackTrace(); } finally { if (session != null) { try { session.stop(); } catch (Exception e) { e.printStackTrace(); } } } {% endhighlight %}
Here's a list of apis of ZSession.
{% highlight java %} public void start() throws Exception
public void start(MessageHandler messageHandler) throws Exception
public void stop() throws Exception
public ExecuteResult execute(String code) throws Exception
public ExecuteResult execute(String subInterpreter, Map<String, String> localProperties, String code, StatementMessageHandler messageHandler) throws Exception
public ExecuteResult submit(String code) throws Exception
public ExecuteResult submit(String subInterpreter, Map<String, String> localProperties, String code, StatementMessageHandler messageHandler) throws Exception
public void cancel(String statementId) throws Exception
public ExecuteResult queryStatement(String statementId) throws Exception
public ExecuteResult waitUntilFinished(String statementId) throws Exception
{% endhighlight %}
For more detailed usage of session api, you can check the examples in module zeppelin-client-examples