#include <BESInterface.h>
Inheritance diagram for BESInterface:
Public Member Functions | |
virtual int | execute_request (const string &from) |
Executes the given request to generate a specified response object. | |
virtual void | dump (ostream &strm) const |
dumps information about this object | |
Static Public Member Functions | |
static void | add_init_callback (p_bes_init init) |
static void | add_end_callback (p_bes_end end) |
Protected Member Functions | |
virtual int | exception_manager (BESException &e) |
Manage any exceptions thrown during the whole process. | |
virtual void | initialize () |
Initialize the BES object. | |
virtual void | validate_data_request () |
Validate the incoming request information. | |
virtual void | build_data_request_plan () |
Build the data request plan. | |
virtual void | execute_data_request_plan () |
Execute the data request plan. | |
virtual void | invoke_aggregation () |
Aggregate the resulting response object. | |
virtual void | transmit_data () |
Transmit 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 | end_request () |
End the BES request. | |
virtual void | clean () |
Clean up after the request. | |
BESInterface () | |
BESInterface (ostream *strm) | |
virtual | ~BESInterface () |
Protected Attributes | |
BESDataHandlerInterface | _dhi |
BESTransmitter * | _transmitter |
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:
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().
BESInterface::BESInterface | ( | ) | [inline, protected] |
BESInterface::BESInterface | ( | ostream * | strm | ) | [protected] |
BESInterface::~BESInterface | ( | ) | [protected, virtual] |
void BESInterface::add_end_callback | ( | p_bes_end | end | ) | [static] |
void BESInterface::add_init_callback | ( | p_bes_init | init | ) | [static] |
void BESInterface::build_data_request_plan | ( | ) | [protected, 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.
Reimplemented in BESCgiInterface, and BESCmdInterface.
void BESInterface::clean | ( | ) | [protected, virtual] |
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.
strm | C++ i/o stream to dump the information to |
Implements BESObj.
Reimplemented in BESCgiInterface, and BESCmdInterface.
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
int BESInterface::exception_manager | ( | BESException & | 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.
e | BESException to be managed |
Reimplemented in BESApacheInterface.
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.
Reimplemented in BESCmdInterface.
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.
Reimplemented in BESCmdInterface.
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 BESApacheInterface, and BESCmdInterface.
void BESInterface::invoke_aggregation | ( | ) | [protected, virtual] |
void BESInterface::log_status | ( | ) | [protected, virtual] |
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.
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.
Reimplemented in BESCmdInterface.
void BESInterface::validate_data_request | ( | ) | [protected, virtual] |
Validate the incoming request information.
Reimplemented in BESApacheInterface, and BESCmdInterface.
BESDataHandlerInterface BESInterface::_dhi [protected] |
BESTransmitter* BESInterface::_transmitter [protected] |