libdap Updated for version 3.20.11
libdap4 is an implementation of OPeNDAP's DAP protocol.
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Common functions for DODS server filter programs. More...
#include <DODSFilter.h>
Public Types | |
enum | Response { Unknown_Response , DAS_Response , DDS_Response , DataDDS_Response , DDX_Response , DataDDX_Response , BLOB_Response , Version_Response } |
Public Member Functions | |
virtual void | dataset_constraint (DDS &dds, ConstraintEvaluator &eval, FILE *out, bool ce_eval=true) const |
virtual void | dataset_constraint (DDS &dds, ConstraintEvaluator &eval, ostream &out, bool ce_eval=true) const |
virtual void | dataset_constraint_ddx (DDS &dds, ConstraintEvaluator &eval, ostream &out, const string &boundary, const string &start, bool ce_eval=true) const |
DODSFilter () | |
DODSFilter (int argc, char *argv[]) throw (Error) | |
DODSFilter constructor. More... | |
virtual void | establish_timeout (FILE *stream) const |
virtual void | establish_timeout (ostream &stream) const |
virtual void | functional_constraint (BaseType &var, DDS &dds, ConstraintEvaluator &eval, FILE *out) const |
virtual void | functional_constraint (BaseType &var, DDS &dds, ConstraintEvaluator &eval, ostream &out) const |
virtual string | get_action () const |
virtual string | get_cache_dir () const |
Get the cache directory. More... | |
virtual string | get_ce () const |
Get the constraint expression. More... | |
virtual string | get_cgi_version () const |
virtual time_t | get_das_last_modified_time (const string &anc_location="") const |
virtual time_t | get_data_last_modified_time (const string &anc_location="") const |
virtual time_t | get_dataset_last_modified_time () const |
virtual string | get_dataset_name () const |
Get the dataset name. More... | |
virtual string | get_dataset_version () const |
Get the version information for the dataset. More... | |
virtual time_t | get_dds_last_modified_time (const string &anc_location="") const |
virtual time_t | get_request_if_modified_since () const |
virtual Response | get_response () const |
int | get_timeout () const |
virtual string | get_URL () const |
virtual bool | is_conditional () const |
Is this request conditional? More... | |
virtual void | print_usage () const |
Print usage information for a filter program. More... | |
virtual void | send_das (DAS &das, const string &anc_location="", bool with_mime_headers=true) const |
virtual void | send_das (FILE *out, DAS &das, const string &anc_location="", bool with_mime_headers=true) const |
Transmit a DAS. More... | |
virtual void | send_das (ostream &out, DAS &das, const string &anc_location="", bool with_mime_headers=true) const |
Transmit a DAS. More... | |
virtual void | send_data (DDS &dds, ConstraintEvaluator &eval, FILE *data_stream, const string &anc_location="", bool with_mime_headers=true) const |
Transmit data. More... | |
virtual void | send_data (DDS &dds, ConstraintEvaluator &eval, ostream &data_stream, const string &anc_location="", bool with_mime_headers=true) const |
Transmit data. More... | |
virtual void | send_data_ddx (DDS &dds, ConstraintEvaluator &eval, ostream &data_stream, const string &start, const string &boundary, const string &anc_location="", bool with_mime_headers=true) const |
Transmit data. More... | |
virtual void | send_dds (DDS &dds, ConstraintEvaluator &eval, bool constrained=false, const string &anc_location="", bool with_mime_headers=true) const |
virtual void | send_dds (FILE *out, DDS &dds, ConstraintEvaluator &eval, bool constrained=false, const string &anc_location="", bool with_mime_headers=true) const |
Transmit a DDS. More... | |
virtual void | send_dds (ostream &out, DDS &dds, ConstraintEvaluator &eval, bool constrained=false, const string &anc_location="", bool with_mime_headers=true) const |
Transmit a DDS. More... | |
virtual void | send_ddx (DDS &dds, ConstraintEvaluator &eval, FILE *out, bool with_mime_headers=true) const |
virtual void | send_ddx (DDS &dds, ConstraintEvaluator &eval, ostream &out, bool with_mime_headers=true) const |
virtual void | send_version_info () const |
Send version information back to the client program. More... | |
virtual void | set_ce (string _ce) |
virtual void | set_cgi_version (string version) |
virtual void | set_dataset_name (const string _dataset) |
virtual void | set_response (const string &r) |
void | set_timeout (int timeout=0) |
virtual void | set_URL (const string &url) |
Protected Member Functions | |
void | initialize () |
void | initialize (int argc, char *argv[]) |
virtual int | process_options (int argc, char *argv[]) |
Protected Attributes | |
string | d_action |
time_t | d_anc_das_lmt |
time_t | d_anc_dds_lmt |
string | d_anc_dir |
string | d_anc_file |
bool | d_bad_options |
string | d_cache_dir |
string | d_cgi_ver |
bool | d_comp |
bool | d_conditional_request |
string | d_dap2ce |
string | d_dataset |
time_t | d_if_modified_since |
string | d_program_name |
Response | d_response |
int | d_timeout |
string | d_url |
Common functions for DODS server filter programs.
When a DODS server receives a request from a DODS client, the server CGI script dispatches the request to one of several `‘filter’' programs. Each filter is responsible for returning a different aspect of the dataset information: one is for data, one is for the dataset DDS, one is for the dataset DAS, and a fourth is for a usage message describing the server itself. Some installations may have additional optional filters.
The filter program receives a data request from the dispatch script. It receives its operating parameters from the command line, like any UNIX command, and it returns its output to standard output, which the httpd server packages up into a reply to the client.
This class contains some common functions for the filter programs used to make up the DODS data servers. The filter programs do not have to be called by a CGI program, but that is the normal mechanism by which they are invoked.
Add a test to make sure that the required arguments are given.
We need to rethink the ancillary file/directory stuff. I don't think it's ever been used...
Definition at line 78 of file DODSFilter.h.
Types of responses DODSFilter know about.
Definition at line 82 of file DODSFilter.h.
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Make an empty instance. Use the set_*() methods to load with needed values. You must call at least set_dataset_name() or be requesting version information.
Definition at line 129 of file DODSFilter.h.
libdap::DODSFilter::DODSFilter | ( | int | argc, |
char * | argv[] | ||
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throw | ( | Error | |
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DODSFilter constructor.
Create an instance of DODSFilter using the command line arguments passed by the CGI (or other) program. The default constructor is private; this and the copy constructor (which is just the default copy constructor) are the only way to create an instance of DODSFilter.
These are the valid options:
The name of the file on which the filter is to operate. Usually this would be the file whose data has been requested. In fact, this class can be specialized and any meaning can be associated to this string. It could be the name of a database, for example.
-o
responseSpecifies the type of response desired. The response is a string and must be one of DAS
, DDS
, DataDDS
or Version
. Note that Version
returns version information in the body of the response and is useful for debugging, et cetera. Each response returns version information in an HTTP header for internal use by a client.
-c
Send compressed data. Data are compressed using the deflate program.
-e
expressionThis option specifies a non-blank constraint expression used to subsample a dataset.
-v
cgi-versionSet the CGI/Server version to cgi-version
. This is a way for the caller to set version information passed back to the client either as the response to a version request of in the response headers.
-d
ancdirSpecifies that ancillary data be sought in the ancdir directory. ancdir must end in '/'.
-f
ancfileSpecifies that ancillary data may be found in a file called ancfile.
-r
cache directorySpecify a directory to use if/when files are to be cached. Not all handlers support caching and each uses its own rules tailored to a specific file or data type.
-t
timeoutSpecifies a a timeout value in seconds. If the server runs longer than timeout seconds, an Error is returned to the client explaining that the request has timed out.
-l
timeIndicates that the request is a conditional request; send a complete response if and only if the data has changed since time. If it has not changed since time, then send a 304 (Not Modified) response. The time parameter is the Last-Modified
time from an If-Modified-Since condition GET request. It is given in seconds since the start of the Unix epoch (Midnight, 1 Jan 1970).
Definition at line 170 of file DODSFilter.cc.
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Definition at line 187 of file DODSFilter.cc.
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Definition at line 859 of file DODSFilter.cc.
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Definition at line 868 of file DODSFilter.cc.
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Definition at line 893 of file DODSFilter.cc.
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Use values of this instance to establish a timeout alarm for the server. If the timeout value is zero, do nothing.
Definition at line 628 of file DODSFilter.cc.
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Definition at line 641 of file DODSFilter.cc.
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Definition at line 825 of file DODSFilter.cc.
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Definition at line 836 of file DODSFilter.cc.
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Get the string name of the response to be returned.
Definition at line 458 of file DODSFilter.cc.
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Get the cache directory.
The cache_dir
is used to hold the cached .dds and .das files. By default, this returns an empty string (store cache files in current directory.
Definition at line 594 of file DODSFilter.cc.
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Get the constraint expression.
Return the entire constraint expression in a string. This includes both the projection and selection clauses, but not the question mark.
Definition at line 350 of file DODSFilter.cc.
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Return the version information passed to the instance when it was created. This string is passed to the DODSFilter ctor using the -v option.
Definition at line 338 of file DODSFilter.cc.
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Get the last modified time for the dataset's DAS. This time, given in seconds since the epoch (1 Jan 1970 00:00:00 GMT), is the greater of the datasets's and any ancillary DAS' last modified time.
anc_location | A directory to search for ancillary files (in addition to the CWD). |
Definition at line 499 of file DODSFilter.cc.
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Get the last modified time to be used for a particular data request. This method should look at both the constraint expression and any ancillary files for this dataset. The implementation provided here returns the latest time returned by the get_dataset
...(), get_das
...() and get_dds
...() methods and does not currently check the CE.
anc_location | A directory to search for ancillary files (in addition to the CWD). |
Definition at line 551 of file DODSFilter.cc.
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Get the dataset's last modified time. This returns the time at which the dataset was last modified as defined by UNIX's notion of modification. This does not take into account the modification of an ancillary DAS or DDS. Time is given in seconds since the epoch (1 Jan 1970 00:00:00 GMT).
This method perform a simple check on the file named by the dataset given when the DODSFilter instance was created. If the dataset is not a filter, this method returns the current time. Servers which provide access to non-file-based data should subclass DODSFilter and supply a more suitable version of this method.
From the stat(2) man page: ``Traditionally, st_mtime
is changed by mknod(2), utime(2), and write(2). The st_mtime
is not changed for changes in owner, group, hard link count, or mode.''
Definition at line 484 of file DODSFilter.cc.
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Get the dataset name.
The `‘dataset name’' is the filename or other string that the filter program will use to access the data. In some cases this will indicate a disk file containing the data. In others, it may represent a database query or some other exotic data access method.
Definition at line 370 of file DODSFilter.cc.
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Get the version information for the dataset.
To read version information that is specific to a certain dataset, override this method with an implementation that does what you want. By default, this returns an empty string.
Definition at line 409 of file DODSFilter.cc.
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Get the last modified time for the dataset's DDS. This time, given in seconds since the epoch (1 Jan 1970 00:00:00 GMT), is the greater of the datasets's and any ancillary DDS' last modified time.
Definition at line 522 of file DODSFilter.cc.
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Get the value of a conditional request's If-Modified-Since header. This value is used to determine if the request should get a full response or a Not Modified (304) response. The time is given in seconds since the Unix epoch (midnight, 1 Jan 1970). If no time was given with the request, this methods returns -1.
Definition at line 582 of file DODSFilter.cc.
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Get the enum name of the response to be returned.
Definition at line 452 of file DODSFilter.cc.
int libdap::DODSFilter::get_timeout | ( | ) | const |
Get the server's timeout value.
Definition at line 611 of file DODSFilter.cc.
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Get the URL. This returns the URL, minus the constraint originally sent to the server.
Definition at line 385 of file DODSFilter.cc.
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Called when initializing a DODSFilter that's not going to be passed a command line arguments.
Definition at line 194 of file DODSFilter.cc.
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Initialize. Specializations can call this once an empty DODSFilter has been created using the default constructor. Using a method such as this provides a way to specialize the process_options() method and then have that specialization called by the subclass' constructor.
This class and any class that specializes it should call this method in its constructor. Note that when this method is called, the object is not fully constructed.
argc | The argument count |
argv | The vector of char * argument strings. |
Definition at line 235 of file DODSFilter.cc.
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Is this request conditional?
Definition at line 308 of file DODSFilter.cc.
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Print usage information for a filter program.
This message is printed when the filter program is incorrectly invoked by the dispatch CGI. This is an error in the server installation or the CGI implementation, so the error message is written to stderr instead of stdout. A server's stderr messages show up in the httpd log file. In addition, an error object is sent back to the client program telling them that the server is broken.
Definition at line 665 of file DODSFilter.cc.
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Processing the command line options passed to the filter is handled by this method so that specializations can change the options easily.
argc | The argument count |
argv | The vector of char * argument strings. |
Definition at line 264 of file DODSFilter.cc.
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Definition at line 734 of file DODSFilter.cc.
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Transmit a DAS.
This function formats and prints an ASCII representation of a DAS on stdout. This has the effect of sending the DAS object back to the client program.
out | The output FILE to which the DAS is to be sent. |
das | The DAS object to be sent. |
anc_location | The directory in which the external DAS file resides. |
with_mime_headers | If true (the default) send MIME headers. |
Definition at line 696 of file DODSFilter.cc.
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Transmit a DAS.
This function formats and prints an ASCII representation of a DAS on stdout. This has the effect of sending the DAS object back to the client program.
out | The output stream to which the DAS is to be sent. |
das | The DAS object to be sent. |
anc_location | The directory in which the external DAS file resides. |
with_mime_headers | If true (the default) send MIME headers. |
Definition at line 716 of file DODSFilter.cc.
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Transmit data.
Send the data in the DDS object back to the client program. The data is encoded using a Marshaller, and enclosed in a MIME document which is all sent to data_stream
. If this is being called from a CGI, data_stream
is probably stdout
and writing to it has the effect of sending the response back to the client.
dds | A DDS object containing the data to be sent. |
eval | A reference to the ConstraintEvaluator to use. |
data_stream | Write the response to this FILE. |
anc_location | A directory to search for ancillary files (in addition to the CWD). This is used in a call to get_data_last_modified_time(). |
with_mime_headers | If true, include the MIME headers in the response. Defaults to true. |
Definition at line 950 of file DODSFilter.cc.
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Transmit data.
Send the data in the DDS object back to the client program. The data is encoded using a Marshaller, and enclosed in a MIME document which is all sent to data_stream
. If this is being called from a CGI, data_stream
is probably stdout
and writing to it has the effect of sending the response back to the client.
dds | A DDS object containing the data to be sent. |
eval | A reference to the ConstraintEvaluator to use. |
data_stream | Write the response to this stream. |
anc_location | A directory to search for ancillary files (in addition to the CWD). This is used in a call to get_data_last_modified_time(). |
with_mime_headers | If true, include the MIME headers in the response. Defaults to true. |
Definition at line 976 of file DODSFilter.cc.
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Transmit data.
Send the data in the DDS object back to the client program. The data is encoded using a Marshaller, and enclosed in a MIME document which is all sent to data_stream
. If this is being called from a CGI, data_stream
is probably stdout
and writing to it has the effect of sending the response back to the client.
dds | A DDS object containing the data to be sent. |
eval | A reference to the ConstraintEvaluator to use. |
data_stream | Write the response to this stream. |
start | |
boundary | |
anc_location | A directory to search for ancillary files (in addition to the CWD). This is used in a call to get_data_last_modified_time(). |
with_mime_headers | If true, include the MIME headers in the response. Defaults to true. |
Definition at line 1118 of file DODSFilter.cc.
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Definition at line 815 of file DODSFilter.cc.
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Transmit a DDS.
This function formats and prints an ASCII representation of a DDS on stdout. When called by a CGI program, this has the effect of sending a DDS object back to the client program. Either an entire DDS or a constrained DDS may be sent.
out | The output FILE to which the DAS is to be sent. |
dds | The DDS to send back to a client. |
eval | A reference to the ConstraintEvaluator to use. |
constrained | If this argument is true, evaluate the current constraint expression and send the ‘constrained DDS’ back to the client. |
anc_location | The directory in which the external DAS file resides. |
with_mime_headers | If true (the default) send MIME headers. |
Definition at line 757 of file DODSFilter.cc.
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Transmit a DDS.
This function formats and prints an ASCII representation of a DDS on stdout. When called by a CGI program, this has the effect of sending a DDS object back to the client program. Either an entire DDS or a constrained DDS may be sent.
out | The output stream to which the DAS is to be sent. |
dds | The DDS to send back to a client. |
eval | A reference to the ConstraintEvaluator to use. |
constrained | If this argument is true, evaluate the current constraint expression and send the ‘constrained DDS’ back to the client. |
anc_location | The directory in which the external DAS file resides. |
with_mime_headers | If true (the default) send MIME headers. |
Definition at line 784 of file DODSFilter.cc.
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Send the DDX response. The DDX never contains data, instead it holds a reference to a Blob response which is used to get the data values. The DDS and DAS objects are built using code that already exists in the servers.
dds | The dataset's DDS with attributes in the variables. |
eval | A reference to the ConstraintEvaluator to use. |
out | Destination |
with_mime_headers | If true, include the MIME headers in the response. Defaults to true. |
Definition at line 1051 of file DODSFilter.cc.
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Send the DDX response. The DDX never contains data, instead it holds a reference to a Blob response which is used to get the data values. The DDS and DAS objects are built using code that already exists in the servers.
dds | The dataset's DDS with attributes in the variables. |
eval | A reference to the ConstraintEvaluator to use. |
out | Destination |
with_mime_headers | If true, include the MIME headers in the response. Defaults to true. |
Definition at line 1070 of file DODSFilter.cc.
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Send version information back to the client program.
This function formats and sends to stdout version information from the httpd server, the server dispatch scripts, the DODS core software, and (optionally) the dataset.
Definition at line 679 of file DODSFilter.cc.
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Definition at line 356 of file DODSFilter.cc.
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Set the CGI/Server version number. Servers use this when answering requests for version information. The version ‘number’ should include both the name of the server (e.g., ff_dods
) as well as the version number. Since this information is typically divined by configure, it's up to the executable to poke the correct value in using this method.
Note that the -v switch that this class understands is deprecated since it is usually called by Perl code. It makes more sense to have the actual C++ software set the version string.
version | A version string for this server. |
Definition at line 327 of file DODSFilter.cc.
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Definition at line 376 of file DODSFilter.cc.
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Set the response to be returned. Valid response names are "DAS", "DDS", "DataDDS, "Version".
r | The name of the object. |
InternalErr | Thrown if the response is not one of the valid names. |
Definition at line 420 of file DODSFilter.cc.
void libdap::DODSFilter::set_timeout | ( | int | t = 0 | ) |
Set the server's timeout value. A value of zero (the default) means no timeout.
t | Server timeout in seconds. Default is zero (no timeout). |
Definition at line 604 of file DODSFilter.cc.
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Set the URL. Set the URL sent to the server.
url | The URL, minus the constraint. |
Definition at line 393 of file DODSFilter.cc.
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Definition at line 108 of file DODSFilter.h.
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Definition at line 112 of file DODSFilter.h.
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Definition at line 113 of file DODSFilter.h.
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Definition at line 102 of file DODSFilter.h.
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Definition at line 103 of file DODSFilter.h.
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Definition at line 95 of file DODSFilter.h.
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Definition at line 104 of file DODSFilter.h.
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Definition at line 101 of file DODSFilter.h.
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Definition at line 94 of file DODSFilter.h.
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Definition at line 96 of file DODSFilter.h.
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Definition at line 100 of file DODSFilter.h.
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Definition at line 99 of file DODSFilter.h.
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Definition at line 114 of file DODSFilter.h.
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Definition at line 98 of file DODSFilter.h.
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Definition at line 107 of file DODSFilter.h.
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Definition at line 110 of file DODSFilter.h.
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Definition at line 105 of file DODSFilter.h.