Appendix: User Defined Routines in Informix

Transcription

1 Appendix: User Defined Routines in Informix Implementation of user defined routines SPL: stored procedure language SQL like syntax for procedural programming UDRs can be defined and registered directly in SQL C routines C functions are compiled into libraries that are bound to the database process Registration in SQL Data type mapping Java routines Java VM is dynamically embedded into database process UDR accesses database through JDBC UDRs can be registered and called from SQL C Routine Java Routine SPL Routine External Routine User-Defined Routine Functions Procedures 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 1 Architecture of Informix Internet Foundation Java Environment Java VM Java UDR SQL query Result Set Informix Database Server JDBC Driver C/C++ Java SPL Language Manager Client SQL processor Disk access Database 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 2 1

2 Implementing a Java UDR in Informix // 1. Defining the Java function public class getpricelist { public static String getpricelist( String name ) throws SQLException { try { // here JDBC calls can be made, http accesses, RMI calls etc. } catch (Exception e) { throw new SQLException( e.tostring() ); } }...} // 2. Defining the result type public class PriceList implements SQLData { /* * JDBC 2.0 style SQL/Java object mapping */ public String name; public String product_desc; double unit_price;... } 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 3 Example cntd. // 3. Defining functions to map from and to SQL types public void writesql ( SQLOutput stream ) throws SQLException { /* Writes this object to the given SQL output data stream and maps the outgoing Java data to SQL types. */ ((SQLUDTOutput)stream).writeString( dist_name, 20 ); ((SQLUDTOutput)stream).writeString( product_desc, 20 ); stream.writedouble ( unit_price ); // 4. Registering the function and the type in SQL create function getpricelist (name varchar) returns lvarchar with ( class='jvp' ) external name 'thisjar:javaudrs.getpricelist.getpricelist' language java end function; grant execute on function getpricelist( name varchar ) to public; create opaque type price_list ( internallength=64, alignment=8 ) execute procedure sqlj.setudtextname( 'price_list', 'PriceList' ) // 5. using the UDR in SQL select getpricelist('table' ) price_list from manufact; 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 4 2

3 Global Serializability Serializability in federated database Federation of autonomous local DBMS (LDBS) Coexistence of global and local transactions Global database system coordinates global transactions Problem Global serializability can only be achieved when local schedules are known (indirect conflicts) Example LDBS1: R G1 (a) W G2 (a) G1 -> G2 LDBS2: R T1 (c) W G1 (c) R G2 (b) W T1 (b) G2->T1->G1 local transaction T1 MDBS global transaction G global subtransactions g1 g2 g3 local Transaction T2 G 2 G 1 LDBS 1 LDBS 2 LDBS 3 LDBS1 a b c LDBS2 T , Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 5 Ticket Method Idea Introduce direct conflicts between subtransactions of global transactions that execute on the same LDBS Modification of LDBS: introduce a special object ticket Every subtransaction of a global transaction must read this special object and write a time stamp to it (method taketicket()) Time stamps reflect the local serialization (write conflicts for taketicket()) MDBS generates from the tickets dependency graph Global transaction is correctly serialized, if the tickets have the same serialization Variants optimistic: tickets are drawn at the end of the subtransaction of a global transaction (different serializations will be frequent) Pessimistic: tickets are drawn at the start of the subtransaction of a global transaction (write conflicts frequent) 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 6 3

4 Appendix: Tuxedo Transaction Monitor Transaction Monitor product of BEA Systems Typical example of an X/Open compliant TM Main System Components System /T Administration Application development Implementation of TM, XA, XA+, XATMI System /D SQL-DBMS (RM) for system /T Workstation Interface to clients on remote nodes Tuxedo /Q Persistent message queues JOLT Java development and runtime environment 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 7 Specific Tuxedo Concepts Uses queues for process communication Multiple servers can be bound to a single queue Supports multiple message paradigms Request/reply Queue-based Event-based (publish/subscribe) Conversational Provides FML Buffers Typed buffers for data exchange with remote nodes Call: tpcall(char* svc, char* idata, ) Supports multiple data types: STRING, CARRAY, C-structures, FML (field manipulation language - tagged data), XML Content-based routing ATMI BEAs X/Open DTP compliant application to TM interface 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 8 4

5 Tuxedo Architecture Overview 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 9 Important Tuxedo Components Bulletin Board Manages all configuration information Servers, routing, load balancing, Workstation Listeners Receives connection requests from clients Uses one or more workstation handlers to handle the requests Manages the pool of workstation handlers Workstation Handlers Manages requests from one or more workstations and the Tuxedo server Multiplexes communication WLS and WLH allows to manage 1000s of workstations Bridges Allow to send and receive requests between multiple server machines Vendor specific solution User Log Logging all messages 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 10 5

6 Single Maching Configuration 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 11 Multiple Machine Configuration 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 12 6

7 Handling of Workstations 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 13 Architecture of a Message Queuing System (Tuxedo) 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 14 7

8 Architecture of a Message Queuing System Processing steps 1-3: sending message to queue and receiving requests (transaction 1, automatically invoced by function tpenqueue) 4-7: processing of the request by the server (transaction 2) 8-10: receiving the reply by the client System services TMQUEUE, TMQUEUEFORWARD, QUEUE SERVER GROUP Use also the XATMI functions Must be configured and administered by the system administrator XATMI API Extended with transactional enqueuing and dequeuing functions: tpenqueue(), tpdequeue() 2002, Karl Aberer, EPFL - SSC, Laboratoire de systèmes d'informations rèpartis 15 8