node-oracledb/examples/cqn2.js

127 lines
3.7 KiB
JavaScript

/* Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved. */
/******************************************************************************
*
* You may not use the identified files except in compliance with the Apache
* License, Version 2.0 (the "License.")
*
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0.
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*
* See the License for the specific language governing permissions and
* limitations under the License.
*
* NAME
* cqn2.js
*
* DESCRIPTION
* Shows object-level Continuous Query Notification (formerly known
* as Database Change Notification), allowing a method to be invoked
* when an object changes. Notification are grouped into intervals.
*
* The user must have been granted CHANGE NOTIFICATION.
* The node-oracledb host must be resolvable by the database host.
*
* Run this script and when the subscription has been created, run
* these statements in a SQL*Plus session:
* INSERT INTO CQNTABLE VALUES (1);
* COMMIT;
*
* This example requires node-oracledb 2.3 or later.
*
* This example uses Node 8's async/await syntax.
*
*****************************************************************************/
const oracledb = require("oracledb");
const dbConfig = require('./dbconfig.js');
// dbConfig.events = true; // CQN needs events mode, which is true by default in 4.0
const interval = setInterval(function() {
console.log("waiting...");
}, 5000);
function myCallback(message)
{
// message.type is one of the oracledb.SUBSCR_EVENT_TYPE_* values
console.log("Message type:", message.type);
if (message.type == oracledb.SUBSCR_EVENT_TYPE_DEREG) {
clearInterval(interval);
console.log("Deregistration has taken place...");
return;
}
console.log("Message database name:", message.dbName);
console.log("Message transaction id:", message.txId);
for (let i = 0; i < message.tables.length; i++) {
const table = message.tables[i];
console.log("--> Table Name:", table.name);
// Note table.operation and row.operation are masks of
// oracledb.CQN_OPCODE_* values
console.log("--> Table Operation:", table.operation);
if (table.rows) {
for (let j = 0; j < table.rows.length; j++) {
const row = table.rows[j];
console.log("--> --> Row Rowid:", row.rowid);
console.log("--> --> Row Operation:", row.operation);
console.log(Array(61).join("-"));
}
}
console.log(Array(61).join("="));
}
}
const options = {
callback : myCallback,
sql: "SELECT * FROM cqntable",
// Stop after 60 seconds
timeout : 60,
// Return ROWIDs in the notification message
qos : oracledb.SUBSCR_QOS_ROWIDS,
// Group notifications in batches covering 10 second
// intervals, and send a summary
groupingClass : oracledb.SUBSCR_GROUPING_CLASS_TIME,
groupingValue : 10,
groupingType : oracledb.SUBSCR_GROUPING_TYPE_SUMMARY
};
async function runTest() {
let connection;
try {
connection = await oracledb.getConnection(dbConfig);
await connection.subscribe('mysub', options);
console.log("Subscription created...");
} catch (err) {
console.error(err);
clearInterval(interval);
} finally {
if (connection) {
try {
await connection.close();
} catch (err) {
console.error(err);
}
}
}
}
process
.on('SIGTERM', function() {
console.log("\nTerminating");
process.exit(0);
})
.on('SIGINT', function() {
console.log("\nTerminating");
process.exit(0);
});
runTest();