BESInterface Class Reference

Entry point into BES, building responses to given requests. More...

#include <BESInterface.h>

Inheritance diagram for BESInterface:

Inheritance graph
[legend]
Collaboration diagram for BESInterface:

Collaboration graph
[legend]
List of all members.

Public Member Functions

virtual void dump (ostream &strm) const
 dumps information about this object
virtual int execute_request (const string &from)
 Executes the given request to generate a specified response object.
virtual int finish_with_error (int status)

Static Public Member Functions

static void add_end_callback (p_bes_end end)
static void add_init_callback (p_bes_init init)

Protected Member Functions

 BESInterface (ostream *strm)
virtual void build_data_request_plan ()=0
 Build the data request plan.
virtual void clean ()
 Clean up after the request.
virtual void end_request ()
 End the BES request.
virtual int exception_manager (BESError &e)
 Manage any exceptions thrown during the whole process.
virtual void execute_data_request_plan ()
 Execute the data request plan.
virtual int finish (int status)
virtual void initialize ()
 Initialize the BES object.
virtual void invoke_aggregation ()
 Aggregate the resulting response object.
virtual void log_status ()
 Log the status of the request.
virtual void report_request ()
 Report the request and status of the request to BESReporterList::TheList().
virtual void transmit_data ()
 Transmit the resulting response object.
virtual void validate_data_request ()
 Validate the incoming request information.
virtual ~BESInterface ()

Protected Attributes

BESDataHandlerInterface_dhi
BESTransmitter_transmitter

Detailed Description

Entry point into BES, building responses to given requests.

BESInterface is an abstract class providing the entry point into the retrieval of information using the BES framework. There are eight steps to retrieving a response to a given request:

  1. initialize the BES environment
  2. validate the incoming information to make sure that all information is available to perform the query
  3. build the request plan to retrieve the information. A response can be generated for multiple files using multiple server types (cedar, cdf, netcdf, etc...)
  4. execute the request plan and build the response object
  5. transmit the response object
  6. log the status of the request
  7. send out report information that can be reported on by any number of reporters registered with the system.
  8. end the request

The way in which the response is generated is as follows. A BESResponseHandler is found that knows how to build the requested response object. The built-in response handlers are for the response objects das, dds, ddx, data, help, version. These response handlers are added to a response handler list during initialization. Additional response handlers can be added to this list. For example, in Cedar, response handlers are registered to build flat, tab, info, and stream responses.

To build the response objects a user can make many requests. For example, a das object can be built using as many different files as is requested, say for file1,file2,file3,file4. And each of these files could be of a different data type. For example, file1 and file3 could be cedar files, file2 could be cdf file and file4 could be a netcdf file.

The structure that holds all of the requested information is the BESDataHandlerInterface. It holds on to a list of containers, each of which has the data type (cedar, cdf, nph, etc...) and the file to be read. The BESDataHandlerInterface is built in the build request method.

The response handlers know how to build the specified response object, such as DAS, DDS, help, status, version, etc...

For each container in the BESDataHandlerInterface find the request handler (BESRequestHandler) for the containers data type. Each request handler registers functions that know how to fill in a certain type of response (DAS, DDS, etc...). Find that function and invoke it. So, for example, there is a CedarRequestHandler class that registers functions that knows how to fill in the different response objects from cedar files.

Once the response object is filled it is transmitted using a specified BESTransmitter.

The status is then logged (default is to not log any status. It is up to derived classes of BESInterface to implement the log_status method.)

The request and status are then reported. The default action is to pass off the reporting to BESReporterList::TheList(), which has a list of registered reporters and passes off the information to each of those reporters. For example, if the Cedar project wants to report on any cedar access then it can register a reporter with BESReporterList::TheList().

See also:
BESGlobalInit

BESKeys

BESResponseHandler

BESRequestHandler

BESTransmitter

BESLog

BESReporter

Definition at line 123 of file BESInterface.h.


Constructor & Destructor Documentation

BESInterface::BESInterface ( ostream *  strm  )  [protected]

Definition at line 69 of file BESInterface.cc.

BESInterface::~BESInterface (  )  [protected, virtual]

Definition at line 80 of file BESInterface.cc.


Member Function Documentation

void BESInterface::add_end_callback ( p_bes_end  end  )  [static]

Definition at line 464 of file BESInterface.cc.

void BESInterface::add_init_callback ( p_bes_init  init  )  [static]

Definition at line 282 of file BESInterface.cc.

virtual void BESInterface::build_data_request_plan (  )  [protected, pure virtual]

Build the data request plan.

It is the responsibility of the derived class to build the request plan. In other words, the container list must be filled in and the action set in the BESDataHandlerInterface structure.

See also:
BESDataHandlerInterface

Implemented in BESBasicInterface, and BESXMLInterface.

Referenced by execute_request().

void BESInterface::clean (  )  [protected, virtual]

Clean up after the request.

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 500 of file BESInterface.cc.

References _dhi, and BESDataHandlerInterface::clean().

Referenced by BESBasicInterface::clean().

Here is the call graph for this function:

void BESInterface::dump ( ostream &  strm  )  const [virtual]

dumps information about this object

Displays the pointer value of this instance along with information about BESDataHandlerInterface, the BESTransmitter being used, and the number of initialization and termimation callbacks.

Parameters:
strm C++ i/o stream to dump the information to

Implements BESObj.

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 533 of file BESInterface.cc.

References _dhi, _transmitter, BESTransmitter::dump(), BESDataHandlerInterface::dump(), BESIndent::Indent(), BESIndent::LMarg(), and BESIndent::UnIndent().

Referenced by BESBasicInterface::dump().

Here is the call graph for this function:

void BESInterface::end_request (  )  [protected, virtual]

End the BES request.

This method allows developers to add callbacks at the end of a request, to do any cleanup or do any extra work at the end of a request

Definition at line 475 of file BESInterface.cc.

References _dhi, BESDEBUG, BESDataHandlerInterface::container, BESDataHandlerInterface::data, DATA_REQUEST, BESDataHandlerInterface::first_container(), BESDataHandlerInterface::next_container(), and BESContainer::release().

Referenced by finish().

Here is the call graph for this function:

int BESInterface::exception_manager ( BESError e  )  [protected, virtual]

Manage any exceptions thrown during the whole process.

Specific responses are generated given a specific Exception caught. If additional exceptions are thrown within derived systems then implement those in the derived exception_manager methods. This is a catch-all manager and should be called once derived methods have caught their exceptions.

Parameters:
e BESError to be managed
Returns:
status after exception is handled
See also:
BESError

Definition at line 519 of file BESInterface.cc.

References _dhi, BESExceptionManager::handle_exception(), and BESExceptionManager::TheEHM().

Referenced by execute_request(), finish(), and finish_with_error().

Here is the call graph for this function:

void BESInterface::execute_data_request_plan (  )  [protected, virtual]

Execute the data request plan.

Given the information in the BESDataHandlerInterface, execute the request. To do this we simply find the response handler given the action in the BESDataHandlerInterface and tell it to execute.

If no BESResponseHandler can be found given the action then an exception is thrown.

See also:
BESDataHandlerInterface

BESResponseHandler

BESResponseObject

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 338 of file BESInterface.cc.

References _dhi, BESDataHandlerInterface::action, BESDEBUG, BESDataHandlerInterface::data, DATA_REQUEST, BESResponseHandler::execute(), invoke_aggregation(), BESDataHandlerInterface::response_handler, and transmit_data().

Referenced by BESBasicInterface::execute_data_request_plan(), and execute_request().

Here is the call graph for this function:

int BESInterface::execute_request ( const string &  from  )  [virtual]

Executes the given request to generate a specified response object.

Execute the request by: 1. initializing BES 2. validating the request, make sure all elements are present 3. build the request plan (ie filling in the BESDataHandlerInterface) 4. execute the request plan using the BESDataHandlerInterface 5. transmit the resulting response object 6. log the status of the execution 7. notify the reporters of the request 8. end the request, which allows developers to add callbacks to notify them of the end of the request

If an exception is thrown in any of these steps the exception is handed over to the exception manager in order to generate the proper response. Control is returned back to the calling method if an exception is thrown and it is the responsibility of the calling method to call finish_with_error in order to transmit the error message back to the client.

Returns:
status of the execution of the request, 0 if okay, !0 otherwise
See also:
initialize()

validate_data_request()

build_data_request_plan()

execute_data_request_plan()

finish_no_error()

finish_with_error()

transmit_data()

log_status()

report_request()

end_request()

exception_manager()

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 117 of file BESInterface.cc.

References _dhi, build_data_request_plan(), BESDataHandlerInterface::data, DATA_REQUEST, exception_manager(), execute_data_request_plan(), BESDataHandlerInterface::executed, finish(), initialize(), REQUEST_FROM, SERVER_PID, BESDataHandlerInterface::set_output_stream(), BESLog::TheLog(), and validate_data_request().

Referenced by BESBasicInterface::execute_request().

Here is the call graph for this function:

int BESInterface::finish ( int  status  )  [protected, virtual]

Definition at line 177 of file BESInterface.cc.

References _dhi, end_request(), BESDataHandlerInterface::error_info, exception_manager(), BESError::get_message(), log_status(), BESInfo::print(), report_request(), BESLog::TheLog(), and transmit_data().

Referenced by execute_request(), and finish_with_error().

Here is the call graph for this function:

int BESInterface::finish_with_error ( int  status  )  [virtual]

Definition at line 268 of file BESInterface.cc.

References _dhi, BESDataHandlerInterface::error_info, exception_manager(), and finish().

Here is the call graph for this function:

void BESInterface::initialize (  )  [protected, virtual]

Initialize the BES object.

This method must be called by all derived classes as it will initialize the environment

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 293 of file BESInterface.cc.

References _dhi, BESDEBUG, BESDataHandlerInterface::data, and DATA_REQUEST.

Referenced by execute_request(), and BESBasicInterface::initialize().

void BESInterface::invoke_aggregation (  )  [protected, virtual]

Aggregate the resulting response object.

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 365 of file BESInterface.cc.

References _dhi, AGG_CMD, AGG_HANDLER, BESAggregationServer::aggregate(), BESDEBUG, BESDataHandlerInterface::data, BESAggFactory::find_handler(), and BESAggFactory::TheFactory().

Referenced by execute_data_request_plan(), and BESBasicInterface::invoke_aggregation().

Here is the call graph for this function:

void BESInterface::log_status (  )  [protected, virtual]

Log the status of the request.

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 437 of file BESInterface.cc.

Referenced by finish().

void BESInterface::report_request (  )  [protected, virtual]

Report the request and status of the request to BESReporterList::TheList().

If interested in reporting the request and status of the request then one must register a BESReporter with BESReporterList::TheList().

If no BESReporter objects are registered then nothing happens.

See also:
BESReporterList

BESReporter

Reimplemented in BESXMLInterface.

Definition at line 453 of file BESInterface.cc.

References _dhi, BESDEBUG, BESDataHandlerInterface::data, DATA_REQUEST, BESReporterList::report(), and BESReporterList::TheList().

Referenced by finish(), and BESXMLInterface::report_request().

Here is the call graph for this function:

void BESInterface::transmit_data (  )  [protected, virtual]

Transmit the resulting response object.

The derived classes are responsible for specifying a transmitter object for use in transmitting the response object. Again, the BESResponseHandler knows how to transmit itself.

If no response handler or no response object or no transmitter is specified then do nothing here.

See also:
BESResponseHandler

BESResponseObject

BESTransmitter

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 401 of file BESInterface.cc.

References _dhi, _transmitter, BESDEBUG, BESDataHandlerInterface::data, DATA_REQUEST, BESDataHandlerInterface::error_info, BESInfo::print(), BESDataHandlerInterface::response_handler, BESResponseHandler::transmit(), and BESInfo::transmit().

Referenced by execute_data_request_plan(), finish(), and BESBasicInterface::transmit_data().

Here is the call graph for this function:

void BESInterface::validate_data_request (  )  [protected, virtual]

Validate the incoming request information.

Reimplemented in BESBasicInterface, and BESXMLInterface.

Definition at line 320 of file BESInterface.cc.

Referenced by execute_request(), and BESBasicInterface::validate_data_request().


Member Data Documentation

BESDataHandlerInterface* BESInterface::_dhi [protected]

Definition at line 136 of file BESInterface.h.

Referenced by BESXMLInterface::BESXMLInterface(), BESXMLInterface::build_data_request_plan(), BESBasicInterface::build_data_request_plan(), BESXMLInterface::clean(), clean(), BESBasicInterface::clean(), dump(), end_request(), exception_manager(), BESXMLInterface::execute_data_request_plan(), execute_data_request_plan(), BESBasicInterface::execute_data_request_plan(), execute_request(), finish(), finish_with_error(), initialize(), invoke_aggregation(), BESBasicInterface::invoke_aggregation(), BESXMLInterface::log_status(), BESBasicInterface::log_status(), BESXMLInterface::report_request(), report_request(), BESXMLInterface::transmit_data(), transmit_data(), and BESBasicInterface::transmit_data().

BESTransmitter* BESInterface::_transmitter [protected]

Definition at line 137 of file BESInterface.h.

Referenced by BESBasicInterface::build_data_request_plan(), dump(), BESBasicInterface::initialize(), BESXMLInterface::transmit_data(), and transmit_data().


The documentation for this class was generated from the following files:
Generated on Thu Feb 11 09:16:25 2010 for OPeNDAP Hyrax Back End Server (BES) by  doxygen 1.4.7