Oracle XML DB and Native Web Services

Transcription

1 Oracle XML DB and Native Web Services Ondřej Kupka December 3, 2012

2 Section Layout 1 Oracle XML DB Overview Core Ideas and Architecture Storing XML Data Example Structured Model and XML Schemas XML/SQL Duality 2 Oracle XML DB Repository 3 Oracle XML DB Native Web Services

3 Overview Overview and Architecture Oracle XML DB is a set of technologies for handling of XML data: Storing Generating Accessing Searching Validating Transforming Indexing The goal is to provide both XML and SQL access to the data (XML/SQL duality). XML data can be accessed using SQL, XML can be generated from relational data.

4 Core Ideas and Architecture Challenges and Ideas We have a RDBMS and we have XML data. That is a completely different thing. Relations and hierarchy is like apples and oranges. But we still have this RDBMS, so we should use it as much as possible. But we cannot say anything about a XML document s structure. Unless we know the schema, that is! Oracle XML DB: Abstract XMLType database object type, which basically behaves differently according to how much it knows about the data. The access is the same, but the storage is optimised when the structure is known.

5 Storing XML Data Storing XML Data XMLType XMLType is an abstract data type for native handling of XML data in the database. It is a database object type - tables of XMLType. It can be used as a column type. It can be passed into and out of PL/SQL procedures. It can use various storage models according to the situation.... Native XML operations (XMLType methods): extract() - extract a subset of nodes existsnode() - check if particular node exists in a XMLType instance schemavalidate() - validate the content of a XMLType instance against a schema transform() - XSLT

6 Storing XML Data XMLType Storage Model XMType tables and columns may be stored in these ways: 1 Structured storage (also object-relational, object-based persistence) 2 Unstructured storage (also CLOB, text-based persistence) 3 Binary XML (also post-parse persistence) 4 Hybrid of structured and unstructured

7 Storing XML Data Intermezzo - Data-Centric vs. Document-Centric The Interesting Part What are those various backend models good for? Well, it depends on how you approach your data and how you use it! Data-Centric Document-Centric XML schema-based data Little variation and little change over time Leads to Object-Relational approach, B-tree indices... Variable, free-form data Leads to CLOB or Binary XML, XMLIndex indices...

8 Storing XML Data Storage Models in Details - Structured Storage Pros Cons Queries fast - relational query performance Updates fast - only the part affected Space efficiency B-tree index Throughput Data flexibility - schema conformance Schema flexibility - one XMLType = single schema

9 Storing XML Data Storage Models in Details - XML Binary Storage Pros Cons Throughput - just encode/decode Queries - streaming XPath eval, multiple at once, fast access using XMLIntex Space efficiency Flexibility Full schema validation Not really any significant disadvantage

10 Storing XML Data Storage Models in Details - Unstructured Storage Pros Cons Throughput Flexibility Streams-based replication Queries slow - constructing DOM every time Updates slow - DOM, then the whole doc must be written back Space inefficient

11 Example Example Create and Insert Insert using SQL, PL/SQL, Java, C... Conventional and Direct-Path Load Mode CREATE TABLE mytable2 OF XMLType; CREATE DIRECTORY xmldir AS path_to_folder_containing_xml_file; INSERT INTO mytable2 VALUES (XMLType(bfilename( XMLDIR, file.xml ), nls_charset_id( AL32UTF8 ))); DECLARE res BOOLEAN; BEGIN res := DBMS_XDB.createResource( /home/user/..., bfilename( XMLDIR, file.xml ), nls_charset_id( AL32UTF8 )); END;/

12 Example Example Select SELECT XMLCast(XMLQuery( $p/<xpath> PASSING OBJECT_VALUE AS "p" RETURNING CONTENT) AS VARCHAR2(30)) "Reference" FROM table WHERE XMLExists( $p/<xpath condition> PASSING OBJECT_VALUE AS "p");

13 Structured Model and XML Schemas Structured Mode and XML Schemas Oracle decomposes XML into SQL objects according to the XML schema. Mapping of XML types into SQL types (complextype into SQL type) Element or attribute becomes a SQL attribute in that type Collections as tables or LOBs or out-of-line storage (REFs) Full utilisation or Oracle database Additional constrains not possible in a plain XML schema It is possible to annotate the XML schema to define storage model, override types mapping and name database objects. xdb:storevarrayastable="true" <xs:attribute name="itemid" type="xs:integer" xdb:sqlname="itemid" xdb:sqltype="number"/>

14 Structured Model and XML Schemas XML Schemas Registration You have to register your XML schemas before they can be used to validate objects. You need 1 The XML schema document 2 A string to be used as a identifier, typically an URL BEGIN DBMS_XMLSCHEMA.registerSchema( SCHEMAURL => SCHEMADOC => XDBURIType( /src/schemas/xsd/file.xsd ).getclob(), LOCAL => TRUE, GENTYPES => TRUE, GENTABLES => TRUE); # USUALLY YOU DON T WANT THIS!!! END;

15 XML/SQL Duality XML/SQL Duality The same data can be exposed as either rows in a table, being manipulated with SQL, or as nodes in a XML document and manipulated using DOM, XSLT... Oracle supports SQL/XML standard. This allows you address XML content anywhere in your SQL. It uses XPath or XQuery to identify nodes to operate on. XPath rewrite optimizes stuff.

16 XML/SQL Duality XMLTable Result of XMLQuery may include multiple elements without the root node, so-called XML fragments. XMLTable can turn such a fragment into multiple rows to perform joins and similar. SELECT vt.column_value FROM table t, XMLTable( <XPath> PASSING t.object_value) vt WHERE XMLExists( $t/<xpath> PASSING OBJECT_VALUE AS "t"); COLUMN_VALUE <e>...</e> <e>...</e> <e>...</e> 3 rows selected.

17 XML/SQL Duality Relational Views It is very simple, just create a view (CREATE OR REPLACE VIEW) using virtual tables! Completely transparent to the view user

18 XML/SQL Duality Generating XML Data from Relational Data SQL/XML functions to construct XML XMLElement XMLAttributes XMLForest Use in the SELECT clause - SELECT XMLElement(XMLAttributes(...)) DBURIType Simple way - convert table name into element, multiple ROW s containing columns as elements

19 Section Layout 1 Oracle XML DB Overview Core Ideas and Architecture Storing XML Data Example Structured Model and XML Schemas XML/SQL Duality 2 Oracle XML DB Repository 3 Oracle XML DB Native Web Services

20 Oracle XML DB Repository It is an interface to your XML documents which imitates folder/file hierarchy. Data accessible using FTP, WebDAV, HTTP(S). It is based on so-called resources. A resource is usually an XML document. It has corresponding metadata file attached to it, holding ACL.

21 Accessing Repository from SQL RESOURCE VIEW PATH VIEW Columns: RES, ANY PATH, RESID Columns: PATH, RES, LINK, RESID SELECT path(1) path, depth(1) depth FROM PATH_VIEW WHERE under_path(res, 3, /sys, 1) = 1;

22 Section Layout 1 Oracle XML DB Overview Core Ideas and Architecture Storing XML Data Example Structured Model and XML Schemas XML/SQL Duality 2 Oracle XML DB Repository 3 Oracle XML DB Native Web Services

23 Oracle XML DB Native Web Services You can enable web access for your XML DB in form of servlets. Log in as SYS. Use either xdbconfig or following. User needs XDB WEBSERVICES. WSDL generated automatically. DECLARE SERVLET_NAME VARCHAR2(32) :=... ; BEGIN DBMS_XDB.deleteServletMapping(SERVLET_NAME); DBMS_XDB.deleteServlet(SERVLET_NAME); DBMS_XDB.addServlet(NAME => SERVLET_NAME, LANGUAGE => C, DISPNAME => Web Service, DESCRIPT => Servlet for queries over the web, SCHEMA => XDB ); DBMS_XDB.addServletSecRole(SERVNAME => SERVLET_NAME, ROLENAME => XDB_WEBSERVICES, ROLELINK => XDB_WEBSERVICES ); DBMS_XDB.addServletMapping(PATTERN => /wsv/*, NAME => SERVLET_NAME); END; /

24 Query Over The Web <?xml version="1.0"?> <env:envelope xmlns:env=" "> <env:body> <query xmlns=" <query_text type="sql"> <![CDATA[SELECT * FROM employees WHERE salary = :e]]> </query_text> <bind name="e">50</bind> <pretty_print>true</pretty_print> </query> </env:body> </env:envelope>

25 PL/SQP Over The Web You can use it, but it is a mess. You basically encode the parameters for the function into a SOAP request and do kind of RPC, receiving the return value as XML again.

26 Thank you!