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• Read Data

Read Data

Read data by providing SQL query through the specified channel.

Prerequisites

Read channels are created and started in the organization.

Request Format

POST https://{apigw-address}/data-federation/v2.0/channels/read/{channelId}

Request Parameters (Header)

Name	Mandatory/Optional	Data Type	Description
Content-Type	Mandatory	String	Content or file type. The default value is application/json.
Authorization	Mandatory	String	Access Token, by the format of Bearer xxx. How to get the Access Token >>

Request Parameters (URI)

Name	Location (Path/Query)	Mandatory/Optional	Data Type	Description
orgId	Query	Mandatory	String	Your organization ID. How to get the orgId>>
channelId	Path	Mandatory	String	Channel ID

Request Parameters (Body)

Name	Mandatory/Optional	Data Type	Description
sqlQuery	Mandatory	String	SQL query for getting data from storage systems.
queue	Optional	String	Specify the priority of the data query job. Options are Hot, Warm, and Cold. The Hot queue has the highest priority, the Warm queue has the medium priority, and the Cold queue has the lowest priority.
itemFormat	Optional	String	Reserved parameter for specifying the format of returned JSON. This field is currently inactive.

Response Parameters

Name	Data Type	Description
data	List<Object>	Data that is returned by the SQL query. For more information, see Returned Data Struct

Returned Data Struct

Name	Data Type	Description
columns	String	Column name.
metadata	String	Meta data.
queryState	String	Data querying state.
rows	List<Object>	Rows of data. For more information, see Data Row Struct

Data Row Struct

Name	Data Type	Description
COLUMN_NAME	String	Column name.
DATA_TYPE	String	Data type.
IS_NULLABLE	String	Data type.

Error Code

Sample

Request Sample

url: https://{apigw-address}/data-federation/v2.0/channels/read/{channelId}&orgId={}

method: POST

requestBody:
{
  "sqlQuery": "show schemas"
}

Return Sample

{
    "msg": "OK",
    "code": 0,
    "data": {
        "metadata": ["VARCHAR"],
        "columns": ["SCHEMA_NAME"],
        "queryState": "COMPLETED",
        "rows": []
    }
}

Java SDK Sample

import com.alibaba.fastjson.JSONObject;
import com.envision.apim.poseidon.config.PConfig;
import com.envision.apim.poseidon.core.Poseidon;
import com.envision.apim.poseidon.request.PoseidonRequest;
import com.google.common.net.HttpHeaders;
import org.apache.commons.codec.binary.Hex;
import org.junit.Test;

import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Sample {

  private static String accessKey = "AccessKey of your APP";
  private static String secretKey = "SecretKey of your APP";
  private static String orgId = "yourOrgId";
  private static String channelId = "yourChannelId";
  private static String url = "https://{domain_url}";
  private static String token = "";

    private static class Request extends PoseidonRequest {

        public void setQueryParam(String key, Object value) {
            queryEncodeParams().put(key, value);
        }

        public void setMethod(String method) {
            this.method = method;
        }

        public void setBodyParams(String key, Object value) {
            bodyParams().put(key, value);
        }

        private String method;

        @Override
        public String baseUri() {
            return "";
        }

        @Override
        public String method() {
            return method;
        }
    }

    public static String getToken() {
        Request request = new Request();
        request.setMethod("POST");
        long timestamp = System.currentTimeMillis();
        String temp = accessKey + timestamp + secretKey;
        request.bodyParams().put("encryption", string2Sha256(temp).toLowerCase());
        request.bodyParams().put("timestamp", timestamp);
        request.bodyParams().put("appKey", accessKey);
        try {
            JSONObject response = Poseidon.config(PConfig.init().appKey(accessKey).appSecret(secretKey).debug())
                    .url(url + "/apim-token-service/v2.0/token/get")
                    .getResponse(request, JSONObject.class);
            return response.getJSONObject("data").getString("accessToken");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    private static String string2Sha256(String str) {
        MessageDigest messageDigest;
        String encodeStr = "";
        try {
            messageDigest = MessageDigest.getInstance("SHA-256");
            byte[] hash = messageDigest.digest(str.getBytes(StandardCharsets.UTF_8));
            encodeStr = Hex.encodeHexString(hash);
        } catch (NoSuchAlgorithmException e) {

        }
        return encodeStr;
    }

    @Test
    public void ReadData() {
        token = getToken();
        Request request = new Request();
        request.setQueryParam("orgId", orgId);
        request.setMethod("POST");
        request.headerParams().put(HttpHeaders.AUTHORIZATION, "Bearer " + token);
        request.headerParams().put(HttpHeaders.CONTENT_TYPE, "application/json");
        request.setBodyParams("sqlQuery", "show schemas");
        request.setBodyParams("queue", null);
        request.setBodyParams("itemFormat", null);
        JSONObject response = Poseidon.config(PConfig.init().appKey(accessKey).appSecret(secretKey))
                .url(url + "/data-federation/v2.0/channels/read/" + channelId)
                .getResponse(request, JSONObject.class);
        System.out.println(response);
    }
}