DCMTK: wlmscpfs: DICOM Basic Worklist Management SCP (based on data files)

DCMTK Version 3.6.9 OFFIS DICOM Toolkit

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wlmscpfs: DICOM Basic Worklist Management SCP (based on data files)

# SYNOPSIS

    wlmscpfs [options] port

# DESCRIPTION

The wlmscpfs application implements a Service Class Provider (SCP) for the Basic Worklist Management Service. The application will listen on a specified TCP/IP port for incoming association requests from a Worklist Management SCU. In case an association was acknowledged and a worklist query was received, the wlmscpfs application will query particular files in a certain directory (which can be specified through corresponding program options) on the file system for corresponding worklist information, and it will send this information back to the calling Worklist Management SCU. Aside from dealing with Worklist Management queries, the wlmscpfs application also supports the Verification Service Class as an SCP.

# PARAMETERS

    port  tcp/ip port number to listen on

# OPTIONS

## general options

      -h    --help
              print this help text and exit

            --version
              print version information and exit

            --arguments
              print expanded command line arguments

      -q    --quiet
              quiet mode, print no warnings and errors

      -v    --verbose
              verbose mode, print processing details

      -d    --debug
              debug mode, print debug information

      -ll   --log-level  [l]evel: string constant
              (fatal, error, warn, info, debug, trace)
              use level l for the logger

      -lc   --log-config  [f]ilename: string
              use config file f for the logger

## multi-process options

      -s    --single-process
              single process mode

            --fork
              fork child process for each association (default)

## input options

    general:

      -dfp  --data-files-path  [p]ath: string (default: .)
              path to worklist data files

    handling of worklist files:

      -efr  --enable-file-reject
              enable rejection of incomplete worklist files (default)

      -dfr  --disable-file-reject
              disable rejection of incomplete worklist files

## processing options

    returned character set:

      -cs0  --return-no-char-set
              return no specific character set (default)

      -cs1  --return-iso-ir-100
              return specific character set ISO IR 100

      -csk  --keep-char-set
              return character set provided in file

    other processing options:

      -nse  --no-sq-expansion
              disable expansion of empty sequences in C-FIND
              request messages

## network options

    preferred network transfer syntaxes:

      +x=   --prefer-uncompr
              prefer explicit VR local byte order (default)

      +xe   --prefer-little
              prefer explicit VR little endian TS

      +xb   --prefer-big
              prefer explicit VR big endian TS

      +xd   --prefer-deflated
              prefer deflated explicit VR little endian TS

      +xi   --implicit
              accept implicit VR little endian TS only

    network host access control (tcp wrapper):

      -ac   --access-full
              accept connections from any host (default)

      +ac   --access-control
              enforce host access control rules

    post-1993 value representations:

      +u    --enable-new-vr
              enable support for new VRs (UN/UT) (default)

      -u    --disable-new-vr
              disable support for new VRs, convert to OB

    deflate compression level (only with --prefer-deflated):

      +cl   --compression-level  [l]evel: integer (default: 6)
              0=uncompressed, 1=fastest, 9=best compression

    other network options:

      -ta   --acse-timeout  [s]econds: integer (default: 30)
              timeout for ACSE messages

      -td   --dimse-timeout  [s]econds: integer (default: unlimited)
              timeout for DIMSE messages

            --max-associations  [a]ssocs: integer (default: 50)
              limit maximum number of parallel associations

            --refuse
              refuse association

            --reject
              reject association if no implementation class UID

            --no-fail
              don't fail on an invalid query

            --sleep-before  [s]econds: integer
              sleep s seconds before find (default: 0)

            --sleep-after  [s]econds: integer
              sleep s seconds after find (default: 0)

            --sleep-during  [s]econds: integer
              sleep s seconds during find (default: 0)

      -pdu  --max-pdu  [n]umber of bytes: integer (4096..131072)
              set max receive pdu to n bytes (default: 16384)

      -dhl  --disable-host-lookup
              disable hostname lookup

## output options

    general:

      -rfp  --request-file-path  [p]ath: string
              path to store request files to

      -rff  --request-file-format  [f]ormat: string (default: #t.dump)
              request file name format

# NOTES

The semantic impacts of the above mentioned options is clear for the majority of options. Some particular options, however, are so specific that they need detailed descriptions which will be given in this passage.

The returned character set options are intended for situations in which the wlmscpfs application will return attribute values which are not composed of characters from the DICOM default character repertoire. In such cases, for example option --return-iso-ir-100 can be used to specify that a response to a modality's worklist management C-FIND request shall contain DICOM's Specific Character Set attribute (0008,0005) with a corresponding value, indicating the character repertoire from which the characters of returned attribute values were taken (in this example the repertoire ISO IR 100). Please note that the wlmscpfs application will not make sure that all returned values are actually made up of this character repertoire; the application expects this to be the case.

In general, the Specific Character Set attribute (0008,0005) will only be included in the C-FIND response if it contains any attributes that are affected by the character set, i.e. for value representations PN, LO, LT, SH, ST and UT.

Please note that a C-FIND request which is handled by this application may contain DICOM's Specific Character Set attribute (0008,0005), but this application will never use this attribute's value for matching. Besides, the question if DICOM's Specific Character Set attribute (0008,0005) will be contained in a C-FIND response which is returned by this application is always determined by the returned character set option which was specified when this application was started.

The options –enable-file-reject and –disable-file-reject can be used to enable or disable a file rejection mechanism which makes sure only complete worklist files will be used during the matching process. A worklist file is considered to be complete if it contains all necessary type 1 information which the SCP might have to return to an SCU in a C-FIND response message. Table K.6-1 in part 4 annex K of the DICOM standard lists all corresponding type 1 attributes (see column "Return Key Type").

## Writing Request Files

Providing option --request-file-path enables writing of the incoming C-FIND requests into text files. The option value provides the target directory where these files will be stored. All request files are stored in "dump" format as provided by the dcmdump tool and are raw, i.e. they are written as they arrive at wlmscpfs, without any tag processing applied by wlmscpfs.

Writing request files allows users to "interactively" prepare the worklist database (for wlmscpfs the worklist files served from the --data-file-path directory) by watching the request file directory. Once a request file appears, one needs some time to update worklist entries in the database. For that reason it makes sense to use --request-file-path in combination with option --sleep-before which lets users specify a certain amount of seconds that wlmscpfs should wait before actually starting to check the worklist database. Note that the request files written with --data-file-path are not automatically deleted by wlmscpfs.

If request files are enabled, wlmscpfs must automatically create file names within the given directory. By default, the format is <timestamp>.dump where <timestamp> is in the format YYYYMMDDhhmmssffffff where:

- YYYY is the current year
- MM is the current month
- DD is the current day
- hh are the current hours (in 24 hour format)
- mm are the current minutes
- ss are the current seconds and
- ffffff is the fraction of the current second

This should work as a default for most applications that would like to use request files and want to ensure unique file names. If it is desired to change this naming scheme, the option --request-file-format can be used. It permits one to specify the file naming pattern used by --request-file-path.

For flexibility, the following placeholders can be used in the pattern provided for --request-file-format:

- #a: calling application entity title of the peer SCU
- #c: called application entity title (AE title of worklist SCP application)
- #i: process id of the worklist SCP application process handling the request
- #p: patient ID if present, otherwise empty string
- #t: timestamp in the format YYYYMMDDhhmmssffffff

The default (i.e. the value if --request-file-format is not explicitly set) is #t.dump resulting in the timestamp format described above.

An example for such a user-defined format string would be "request_#i_#a_#c.txt". The #i makes most sense if wlmscpfs multi-process mode is enabled via --fork option in order to ensure that simultaneous request will not result in the same file name for both requests.

It should be noted that the #p placeholder uses the value of Patient ID (0010,0020) from the request as is, i.e. if the string contains non-ASCII characters, the file name computed by wlmscpfs might be broken and thus cannot be written successfully or will look broken once written. Also, an empty Patient ID is used as such, i.e. the #p will be replaced with an empty string.

## DICOM Conformance

The wlmscpfs application supports the following SOP Classes as an SCP:

    VerificationSOPClass                  1.2.840.10008.1.1
    FINDModalityWorklistInformationModel  1.2.840.10008.5.1.4.31

The wlmscpfs application will accept presentation contexts for all of the abovementioned supported SOP Classes using any of the transfer syntaxes:

    LittleEndianImplicitTransferSyntax    1.2.840.10008.1.2
    LittleEndianExplicitTransferSyntax    1.2.840.10008.1.2.1
    BigEndianExplicitTransferSyntax       1.2.840.10008.1.2.2

The default behavior of the wlmscpfs application is to prefer transfer syntaxes having an explicit encoding over the default implicit transfer syntax. If wlmscpfs is running on big-endian hardware it will prefer BigEndianExplicit to LittleEndianExplicit transfer syntax (and vice versa). This behavior can be changed with the --prefer options (see above).

If compiled with zlib support enabled (see --version output) and if option --prefer-deflated is used, also the following transfer syntax is accepted.

    DeflatedExplicitVRLittleEndianTransferSyntax  1.2.840.10008.1.2.1.99

The wlmscpfs application does not support extended negotiation.

Currently, the wlmscpfs application supports the following attributes as matching keys:

    (0008,0020) StudyDate
    (0008,0030) StudyTime
    (0008,0050) AccessionNumber
    (0008,0090) ReferringPhysicianName
    (0010,0010) PatientName
    (0010,0020) PatientID
    (0010,0021) IssuerOfPatientID
    (0010,0030) PatientBirthDate
    (0010,0040) PatientSex
    (0010,2297) Responsible Person
    (0010,2298) Responsible Person Role
    (0032,1032) RequestingPhysician
    (0038,0010) AdmissionID
    (0040,0100) ScheduledProcedureStepSequence
      (0008,0060) > Modality
      (0040,0001) > ScheduledStationAETitle
      (0040,0002) > ScheduledProcedureStepStartDate
      (0040,0003) > ScheduledProcedureStepStartTime
      (0040,0006) > ScheduledPerformingPhysicianName
    (0040,1001) RequestedProcedureID
    (0040,1003) RequestedProcedurePriority

As return keys the following attributes are currently supported by wlmscpfs:

    (0008,0020) StudyDate
    (0008,0030) StudyTime
    (0008,0050) AccessionNumber
    (0008,0080) InstitutionName
    (0008,0081) InstitutionAddress
    (0008,1040) InstitutionalDepartmentName
    (0008,0090) ReferringPhysicianName
    (0008,1080) AdmittingDiagnosesDescription
    (0008,1110) ReferencedStudySequence
      (0008,1150) > ReferencedSOPClassUID
      (0008,1155) > ReferencedSOPInstanceUID
    (0008,1120) ReferencedPatientSequence
      (0008,1150) > ReferencedSOPClassUID
      (0008,1155) > ReferencedSOPInstanceUID
    (0010,0010) PatientName
    (0010,0020) PatientID
    (0010,0021) IssuerOfPatientID
    (0010,0030) PatientBirthDate
    (0010,0040) PatientSex
    (0010,1000) OtherPatientIDs (retired)
    (0010,1001) OtherPatientNames
    (0010,1020) PatientSize
    (0010,1030) PatientWeight
    (0010,1040) PatientAddress
    (0010,1080) MilitaryRank
    (0010,2000) MedicalAlerts
    (0010,2110) ContrastAllergies
    (0010,2160) EthnicGroup
    (0010,21a0) SmokingStatus
    (0010,21b0) AdditionalPatientHistory
    (0010,21c0) PregnancyStatus
    (0010,21d0) LastMenstrualDate
    (0010,2297) ResponsiblePerson
    (0010,2298) ResponsiblePersonRole
    (0010,4000) PatientComments
    (0020,000d) StudyInstanceUID
    (0032,1032) RequestingPhysician
    (0032,1033) RequestingService
    (0032,1060) RequestedProcedureDescription
    (0032,1064) RequestedProcedureCodeSequence
      (0008,0100) > CodeValue
      (0008,0102) > CodingSchemeDesignator
      (0008,0103) > CodingSchemeVersion
      (0008,0104) > CodeMeaning
    (0038,0010) AdmissionID
    (0038,0011) IssuerOfAdmissionID
    (0038,0050) SpecialNeeds
    (0038,0300) CurrentPatientLocation
    (0038,0500) PatientState
    (0040,0100) ScheduledProcedureStepSequence
      (0008,0060) > Modality
      (0032,1070) > RequestedContrastAgent
      (0040,0001) > ScheduledStationAETitle
      (0040,0002) > ScheduledProcedureStepStartDate
      (0040,0003) > ScheduledProcedureStepStartTime
      (0040,0004) > ScheduledProcedureStepEndDate
      (0040,0005) > ScheduledProcedureStepEndTime
      (0040,0006) > ScheduledPerformingPhysicianName
      (0040,0007) > ScheduledProcedureStepDescription
      (0040,0008) > ScheduledProtocolCodeSequence
        (0008,0100) > > CodeValue
        (0008,0102) > > CodingSchemeDesignator
        (0008,0103) > > CodingSchemeVersion
        (0008,0104) > > CodeMeaning
      (0040,0009) > ScheduledProcedureStepID
      (0040,0010) > ScheduledStationName
      (0040,0011) > ScheduledProcedureStepLocation
      (0040,0012) > PreMedication
      (0040,0020) > ScheduledProcedureStepStatus
      (0040,0400) > CommentsOnTheScheduledProcedureStep
    (0040,1001) RequestedProcedureID
    (0040,1002) ReasonForTheRequestedProcedure
    (0040,1003) RequestedProcedurePriority
    (0040,1004) PatientTransportArrangements
    (0040,1005) RequestedProcedureLocation
    (0040,1008) ConfidentialityCode
    (0040,1009) ReportingPriority
    (0040,1010) NamesOfIntendedRecipientsOfResults
    (0040,1400) RequestedProcedureComments
    (0040,2001) ReasonForTheImagingServiceRequest
    (0040,2004) IssueDateOfImagingServiceRequest
    (0040,2005) IssueTimeOfImagingServiceRequest
    (0040,2008) OrderEnteredBy
    (0040,2009) OrderEnterersLocation
    (0040,2010) OrderCallbackPhoneNumber
    (0040,2016) PlacerOrderNumberImagingServiceRequest
    (0040,2017) FillerOrderNumberImagingServiceRequest
    (0040,2400) ImagingServiceRequestComments
    (0040,3001) ConfidentialityConstraintOnPatientDataDescription

The attribute (0008,0005) SpecificCharacterSet is a special case and its support by wlmscpfs is discussed in the NOTES section above.

## Access Control

When compiled on Unix platforms with TCP wrapper support, host-based access control can be enabled with the --access-control command line option. In this case the access control rules defined in the system's host access control tables for wlmscpfs are enforced. The default locations of the host access control tables are /etc/hosts.allow and /etc/hosts.deny. Further details are described in hosts_access(5).

# LOGGING

The level of logging output of the various command line tools and underlying libraries can be specified by the user. By default, only errors and warnings are written to the standard error stream. Using option --verbose also informational messages like processing details are reported. Option --debug can be used to get more details on the internal activity, e.g. for debugging purposes. Other logging levels can be selected using option --log-level. In --quiet mode only fatal errors are reported. In such very severe error events, the application will usually terminate. For more details on the different logging levels, see documentation of module "oflog".

In case the logging output should be written to file (optionally with logfile rotation), to syslog (Unix) or the event log (Windows) option --log-config can be used. This configuration file also allows for directing only certain messages to a particular output stream and for filtering certain messages based on the module or application where they are generated. An example configuration file is provided in <etcdir>/logger.cfg.

# COMMAND LINE

All command line tools use the following notation for parameters: square brackets enclose optional values (0-1), three trailing dots indicate that multiple values are allowed (1-n), a combination of both means 0 to n values.

Command line options are distinguished from parameters by a leading '+' or '-' sign, respectively. Usually, order and position of command line options are arbitrary (i.e. they can appear anywhere). However, if options are mutually exclusive the rightmost appearance is used. This behavior conforms to the standard evaluation rules of common Unix shells.

In addition, one or more command files can be specified using an '@' sign as a prefix to the filename (e.g. @command.txt). Such a command argument is replaced by the content of the corresponding text file (multiple whitespaces are treated as a single separator unless they appear between two quotation marks) prior to any further evaluation. Please note that a command file cannot contain another command file. This simple but effective approach allows one to summarize common combinations of options/parameters and avoids longish and confusing command lines (an example is provided in file <datadir>/dumppat.txt).

# ENVIRONMENT

The wlmscpfs utility will attempt to load DICOM data dictionaries specified in the DCMDICTPATH environment variable. By default, i.e. if the DCMDICTPATH environment variable is not set, the file <datadir>/dicom.dic will be loaded unless the dictionary is built into the application (default for Windows).

The default behavior should be preferred and the DCMDICTPATH environment variable only used when alternative data dictionaries are required. The DCMDICTPATH environment variable has the same format as the Unix shell PATH variable in that a colon (":") separates entries. On Windows systems, a semicolon (";") is used as a separator. The data dictionary code will attempt to load each file specified in the DCMDICTPATH environment variable. It is an error if no data dictionary can be loaded.

# COPYRIGHT

Copyright (C) 1996-2024 by OFFIS e.V., Escherweg 2, 26121 Oldenburg, Germany.

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