1. OPeNDAP Developer’s Workshop Feb 21-23 2007 OPeNDAP 4 Data Server – Hyrax James Gallagher and Nathan Potter 21 Feb 2007

2. OPeNDAP Developer’s Workshop Feb 21-23 2007 But first… These are Hyrax “Despite the unexceptional appearance of modern hyraxes, the order has a remarkable prehistoric lineage and hyraxes may be the closest living relatives of the elephant.” WikiPedia.

3. OPeNDAP Developer’s Workshop Feb 21-23 2007 Overview Goals of the Hyrax Project Introduction to customization Discussion topic

4. OPeNDAP Developer’s Workshop Feb 21-23 2007 Goals of the Hyrax Project Integrate THREDDS catalogs with DAP Improve security of our data server Reduce work to maintain the server Reuse the existing server software Integrate work with/for Earth System Grid (ESG) back into the OPeNDAP software Improve the server’s performance

5. OPeNDAP Developer’s Workshop Feb 21-23 2007 Integrate THREDDS Requirements: –Standard representation for catalogs –Separation of the logical from the physical data organization –A no-hands mode » Fully automatic catalogs –Graceful transition from custom to automatic catalogs –Full THREDDS features – not stripped down –Must use Unidata’s THREDDS software Hyrax 1.0.2 has met these.

6. OPeNDAP Developer’s Workshop Feb 21-23 2007 Improve the Server’s Security The original data server design was hard to make ‘hack proof’ –Common Gateway Interface (CGI) –Data handlers were run as a subprocess in a protected shell –Main CGI modules written in Perl As the server grew in complexity, these became more pressing issues. Improvements –Perl/CGI » Java/Servlet –Subprocess/shell » Specialized IPC

7. OPeNDAP Developer’s Workshop Feb 21-23 2007 Reduce Maintenance and Reuse Existing Software The Perl software was becoming unwieldy – Reimplementation was needed whether in Perl, Java, … Considerable effort has gone into writing our data handlers for netCDF, …, and we could not rewrite them. Additional code for the handlers had to be minimal (for the most complex handler - asciival, it’s size increased by 21%, format handlers were just half that value)

8. OPeNDAP Developer’s Workshop Feb 21-23 2007 Integrate ESG Work ESG II had developed a flexible server for the DAP –Its capabilities far out stripped the CGI server –Several extensions to OPeNDAP software were needed The changes/extensions to the OPeNDAP software were merged back into our copies of the code and both projects resumed working from the same version of the software.

9. OPeNDAP Developer’s Workshop Feb 21-23 2007 Improve Performance The new server architecture eliminates basic design problems. –Fewer subprocess created, issues with Perl, … Response handlers in the BES pass binary objects, not the objects’ network representation Better use of HTTP (e.g., persistent connections now supported)

10. OPeNDAP Developer’s Workshop Feb 21-23 2007 Recap: Goals of Hyrax A higher performance server Provides true THREDDS catalogs A high level of data-handling code reused A more secure design A more maintainable design that can evolve gracefully

11. OPeNDAP Developer’s Workshop Feb 21-23 2007 Introduction to Customization The OPeNDAP Data Server was designed to be extended. Hyrax - can be Extended by: –Writing a handlers for the front end –Writing a handlers for the back end –Directly access the back end

12. OPeNDAP Developer’s Workshop Feb 21-23 2007 Hyrax Architecture OLFS Java Servlet Engine BES Unix Daemon BES Commands XML- encapsulated object File system with data files, SQL Database, … DAP2 THREDDS HTML Optional THREDDS catalogs

13. OPeNDAP Developer’s Workshop Feb 21-23 2007 Adding a new BES Handler Add support for a new data format or data source (relational data base) Build a gateway to another data system (such as a WCS server) Support new response types (such as netCDF 3 files) Add new commands Patrick West will talk about this next.

14. OPeNDAP Developer’s Workshop Feb 21-23 2007 Direct access to the BES Use this to build a connection-oriented system Build new front end systems And more… Jose Garcia will talk about this following Patrick.

15. OPeNDAP Developer’s Workshop Feb 21-23 2007 Adding a new OLFS Handler OLFS –Dispatch activity abstracted –Dispatch figures out what they want –Uses a handler to figure out how to do it

16. OPeNDAP Developer’s Workshop Feb 21-23 2007 Inside OLFS DispatchDispatchHandler

17. OPeNDAP Developer’s Workshop Feb 21-23 2007 Inside OLFS Dispatch GET POST DispatchHandler Network Interface

18. OPeNDAP Developer’s Workshop Feb 21-23 2007 Inside OLFS Dispatch GET POST DispatchHandler Network InterfaceUniform Dispatch Interface

19. OPeNDAP Developer’s Workshop Feb 21-23 2007 Inside OLFS Dispatch GET POST DispatchHandler HttpDispatchHandler ThreddsDispatchHandler SoapDispatchHandler Network InterfaceUniform Dispatch Interface

20. OPeNDAP Developer’s Workshop Feb 21-23 2007 Inside OLFS Dispatch GET POST DAS DDS catalog SOAP DispatchHandler HttpDispatchHandler ThreddsDispatchHandler SoapDispatchHandler Network InterfaceUniform Dispatch Interface

21. OPeNDAP Developer’s Workshop Feb 21-23 2007 Inside OLFS Dispatch GET POST DAS DDS catalog SOAP DispatchHandler HttpDispatchHandler ThreddsDispatchHandler SoapDispatchHandler Network InterfaceUniform Dispatch InterfaceVarious sources of information BES Crawlable…

22. OPeNDAP Developer’s Workshop Feb 21-23 2007 Summary BES Handler: Add support for a new data format, response type, commands or to build a gateway OLFS Handler: Build support for a new network protocol while (re)using the existing software and/or interact with a new data source Use the BES directly: Build new front–ends (web portals, LAN-based systems)

23. OPeNDAP Developer’s Workshop Feb 21-23 2007 Recap: Hyrax Architecture OLFS Java Servlet Engine BES Unix Daemon BES Commands XML- encapsulated object File system with data files, SQL Database, … DAP2 THREDDS HTML Optional THREDDS catalogs

24. OPeNDAP Developer’s Workshop Feb 21-23 2007 Discussion Topic: How Could Hyrax Support the WCS Protocol? A BES Handler could be written to support new response formats (i.e., the well-known binary formats) A BES command set could be written for operations unique to WCS An OLFS DispatchHandler could be built to use the new BES commands