1. Web Service Calls from Within PL/SQL The Bare Necessities

2. UTL_HTTP  The UTL_HTTP package can be used to access data on the internet over HTTP.  If the package fetches data from a Web site using HTTPS (secure), then it requires Oracle Wallet Manager (OWM) to set up an Oracle wallet.  Necessary Procedures:  BEGIN_REQUEST  SET_AUTHENTICATION (if password protected)  GET_RESPONSE  READ_TEXT

3. HTTPS calls 1. Get certificates for website (you will need the URL, username, and password). *Demonstration 2. Store the certificates in an Oracle Wallet (using OWM). 3. Set the Wallet in your procedure using UTL_HTTP.SET_WALLET(wallet.path, wallet.password);

4. UTL_HTTP.BEGIN_REQUEST  UTL_HTTP.BEGIN_REQUEST (url IN VARCHAR2, method IN VARCHAR2 DEFAULT 'GET‘);  If url has illegal or reserved characters (like spaces) use UTL_URL package  If you desire to post to the website, then put ‘POST’ as the method. If you desire to receive information from the website, then use ‘GET’.  Returns request

5. UTL_HTTP.SET_AUTHENTICATION  UTL_HTTP.SET_AUTHENTICATION(request, username, password);  The request is the returned value after BEGIN_REQUEST.  Obtain username and password from web service provider.

6. UTL_HTTP.GET_RESPONSE  UTL_HTTP.GET_RESPONSE(request);  Returns response.  The request will be ended when this function returns (regardless of exception) so there is no need for END_REQUEST.

7. UTL_HTTP.READ_TEXT  UTTL_HTTP.READ_TEXT(response, response_txt, length);  Response is the result of GET_RESPONSE.  Response_txt is the out variable set as VARCHAR2.  Length is the maximum length you desire the response_txt.

8. Need to query the response_txt?  Your response may be a string of XML or JSON code. So what if you need to store that data in an ORACLE relational database?

9. XML  ORACLE needs to know that you desire to query XML not a VARCHAR2 string.  To change your data type to XMLTYPE do:  L_xml := XMLTYPE.CREATEXML(l_response_txt);  L_xml is a local variable of XMLTYPE  ORACLE also needs to query from a table:  To store your data into a table may I suggest a GTT:  CREATE GLOBAL TEMPORARY TABLE xml_gtt OF XMLTYPE;  INSERT INTO xml_gtt VALUES (l_xml);

10. XML (continued…)  You can now query this data in this way (*assuming your xml data is well formed):  SELECT xtab.column1, xtab.column2, xtab.columnN FROM xml_gtt x,xmltable('/path1/path2/path3' passing x.sys_nc_rowinfo$ columns column1 VARCHAR2(100) path 'xmldata1',column2 VARCHAR2(100) path 'xmldata2',columnN VARCHAR2(20) path 'xmldataN') xtab;  SYS_NC_ROWINFO$ is the default column name of the gtt.  Example…

11. JSON  Unlike querying XML, ORACLE can query a VARCHAR2 string of well- formed JSON.  To store your data into a table may I suggest a GTT:  CREATE GLOBAL TEMPORARY TABLE json_gtt OF VARCHAR2;  INSERT INTO json_gtt VALUES (response_txt);  If desired you can put a constraint on your GTT that checks if your JSON data is well-formed:  CONSTRAINT ensure_json CHECK (response_txt IS JSON)

12. JSON (continued…)  You can now query this data in a similar way as the XML data:  SELECT jtab.column1, jtab.column2, jtab.columnN FROM json_gtt j,json_table(j.sys_nc_rowinfo$, '$.path1.path2.path3' COLUMNS( column1 NUMBER path 'jsondata1',column2 VARCHAR2(100) path 'jsondata2',columnN VARCHAR2(20) path 'jsondataN‘)) jtab;  SYS_NC_ROWINFO$ is the default column name of the gtt.