Kestral Computing Pty Ltd Anthony (Tony) Julian Mayo Clinic. Kaiser Permanente. HL7 The Netherlands 5.1 CHAPTER 5 CONTENTS

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1 5. Query Chaper Chair Chaper Chair: and Edior: Chaper Chair Chaper Chair Chaper Chair Grahame Grieve Kesral Compuing Py Ld Anhony (Tony) Julian Mayo Clinic Doug Pra Siemens Medical Soluions Healh Services Corporaion Sco Roberson Kaiser Permanene Rene Spronk HL7 The Neherlands 5.1 CHAPTER 5 CONTENTS 5.1 CHAPTER 5 CONTENTS INTRODUCTION QUERY/RESPONSE MODEL EVOLUTION OF THE QUERY STANDARD QUERY DEVELOPMENT METHODOLOGY RESPONSE FORMAT QUERY SPECIFICATION FORMATS SUMMARY CHART OF QUERY/RESPONSE PAIRS QUERY/RESPONSE CONFORMANCE STATEMENT USING THE CONFORMANCE STATEMENT FORMAL SPECIFICATION OF THE CONFORMANCE STATEMENT CONFORMANCE STATEMENT TEMPLATES QUERY/RESPONSE MESSAGE PAIRS QBP/RSP QUERY BY PARAMETER/SEGMENT PATTERN RESPONSE (EVENTS VARY ) QBP/RTB QUERY BY PARAMETER/TABULAR RESPONSE (EVENTS VARY) QBP/RDY QUERY BY PARAMETER/DISPLAY RESPONSE (EVENTS VARY) QSB - CREATE SUBSCRIPTION (EVENT Q16) QVR - QUERY FOR PREVIOUS EVENTS (EVENT Q17) QCN/ACK - CANCEL QUERY/ACKNOWLEDGE MESSAGE (EVENT J01) QSX /ACK - CANCEL SUBSCRIPTION/ACKNOWLEDGE MESSAGE (EVENT J02) QUERY/RESPONSE MESSAGE SEGMENTS DSP - DISPLAY DATA SEGMENT QAK- QUERY ACKNOWLEDGMENT SEGMENT QID- QUERY IDENTIFICATION SEGMENT Healh Level Seven, Version All righs reserved. Page 5-1 Final Sandard. April 2007.

2 5.5.4 QPD QUERY PARAMETER DEFINITION QRI QUERY RESPONSE INSTANCE SEGMENT RCP RESPONSE CONTROL PARAMETER SEGMENT RDF - TABLE ROW DEFINITION SEGMENT RDT - TABLE ROW DATA SEGMENT AUXILIARY QUERY PROTOCOLS IMMEDIATE VS. DEFERRED RESPONSE QUERY CANCELLATION INTERACTIVE CONTINUATION OF RESPONSE MESSAGES BATCH MESSAGE AS A QUERY RESPONSE QUERY ERROR RESPONSE PUBLISH AND SUBSCRIBE INTRODUCTION DETAILS EXAMPLES ESTABLISHING A SUBSCRIPTION CANCELING A SUBSCRIPTION QUERY IMPLEMENTATION CONSIDERATIONS QUERY/RESPONSE MESSAGE EXAMPLES QUERY BY PARAMETER (QBP) / SEGMENT PATTERN RESPONSE (RSP) QUERY USING QSC VARIANT / SEGMENT PATTERN RESPONSE EXAMPLES QUERY BY PARAMETER (QBP) / TABULAR RESPONSE (RTB) QUERY USING QSC VARIANT / TABULAR RESPONSE (RTB) QUERY BY PARAMETER (QBP) / DISPLAY RESPONSE (RDY) QUERY USING QSC VARIANT (QBP) / DISPLAY RESPONSE (RDY) QUERY BY EXAMPLE (QBP) / TABULAR RESPONSE (RTB) SUPERCEDED QUERY/RESPONSE TRIGGER EVENTS AND MESSAGE PAIRS DISPLAY MESSAGE ORIGINAL MODE QUERIES ORIGINAL MODE DEFERRED ACCESS ENHANCED MODE QUERIES OTHER QUERY/RESPONSE MESSAGE SEGMENTS OTHER QUERY EXAMPLES OUTSTANDING ISSUES INTRODUCTION This chaper defines he rules ha apply o queries and o heir responses. I also defines he unsolicied display messages because heir message synax is query-like in naure. Version 2.4 of he sandard inroduces new models for query and response messages. The layou of his chaper is srucured such ha all informaion peraining o hose newly defined query/response message pairs, including auxiliary proocols, appears in secions and he previously defined queries appear in secion Ousanding issues appear in he final secion, 5.11 Page 5-2 April Healh Level Seven, Version All righs reserved. Final Sandard.

3 Topic Secion Reference Inroducion 5.2 Query/Response Model Evoluion of he Query Sandard Query Developmen Mehodology Response Formas Query Specificaion Formas Summary Char of Query/Response Pairs Query/Response Conformance Saemen 5.3 Query/Response Message Pairs Query/Response Message Segmens 5.5 Auxiliary Query Proocols 5.6 Publish and Subscribe 5.7 Query Implemenaion Consideraions 5.8 Query/Response Message Examples 5.9 Superceded Query/Response Trigger Evens and Message Pairs 5.10 Display Messages Original Mode Queries Enhanced Mode Queries Oher Query/Response Message Segmens Oher Query Examples Ousanding Issues 5.11 The Sandard embraces he mos common queries ha are likely o occur. These are defined by he funcional chapers. The following represens ypical examples of queries suppored by he Sandard: a) daa regarding a single paien, e.g., send all lab resuls for paien # b) daa regarding muliple paiens, e.g., send he lis of paiens whose aending physician is Dr. #123 c) daa ha is no paien relaed, e.g., send he age specific normal values for serum proein. d) daa wihin a specified ime range, e.g., send all serum glucose resuls, repored beween January 1, 1998 hrough December 31, 1999, for paien # The variey of poenial queries is almos unlimied. There was no aemp here o define a Sandard ha would cover every possible query. Chaper 5 discusses general ways query/response pairs are srucured. Funcional chapers discuss specific query/response pairs required for heir needs. The echnical commiees responsible for funcionally-specific chapers define deailed conen of he query/response segmen paerns wihin hose chapers. In paricular, here is no implicaion ha a specific sysem mus suppor generalized queries or Conformance Saemens o comply wih he Sandard. Raher, hese ransacions provide a forma, or a se of ools o suppor queries o he exen desired by he insiuion. The resources available and local policies will influence he ype of queries ha are implemened Query/response model A query wih is response should be hough of as a message pair. The following illusraion shows he hree generic models of message pairs: he declaraive, inerrogaive, and imperaive. Wihin each model, one Healh Level Seven, Version All righs reserved. Page 5-3 Final Sandard. April 2007.

4 sysem assumes he role of iniiaor and he oher sysem assumes he role of responder. HL7 queries follow he "inerrogaive" syle of messaging as described below. Server Even Acknowledgmen DECLARATIVE Clien (Daa Owner) Query Response INTERROGATIVE (Ineresed Pary) Operaional Reques Confirmaion IMPERATIVE Noe: All messaging in HL7 assumes a single basic paradigm using a poin-o-poin ransmission of an iniial message from a sender o a receiver, followed by a response or acknowledgemen message from he receiver back o he sender. The response/acknowledgmen message may be opional depending on several use cases ha will be discussed below. The poin-o-poin ransmission is defined independen of any paricular echnology or archiecure. The declaraive model is employed for disribuion or broadcas of unsolicied evens such as he ORU and RDS. Cliens (ineresed paries) ha desire informaion ha resides on a Server or daa owner may subscribe o be updaed when new informaion is available on he Server. The Server iniiaes a ransmission of even informaion. This ransmission may be o a single Clien, or may be a broadcas o muliple Cliens. Each Clien responds wih an acknowledgemen of receip. The inerrogaive model is employed for queries. A Clien iniiaes a query (a reques for daa) o he Server. The Server processes he query, responds wih a repor of success or failure of he query o he Clien, and furher responds by delivering informaion requesed by he query. The imperaive model is employed for remoe ineroperaion. A Clien iniiaes a reques for acion (such as an order) o he Server. The Server processes he reques and responds wih a repor of success or failure o he Clien. Noe: In HL7 v2.4, here is no formal assumpion of clien-server archiecure, or of a paricular publish and subscribe" archiecure. Thus he roles of he inercommunicaing applicaions may change according o he messaging needs. I.e. an applicaion may be a daa owner or Server for one se of messages (e.g., an order enry sysem creaing orders), and an ineresed pary or Clien for anoher se of messages (e.g., an order enry sysem receiving order saus messages from an ancillary deparmenal sysem). Page 5-4 April Healh Level Seven, Version All righs reserved. Final Sandard.

5 Furhermore, he "daa owning" sysem may be a middleware componen such as an "applicaion server" or a "messaging gaeway or rouer" ha disribues informaion from a server applicaion. In he discussions below, "Clien" and "Server" are used as shorhand synonyms for "requesing sysem/applicaion" and "responding sysem/applicaion" wihou implying he assumpion of a clien/server archiecure. Likewise, he suppor for "publish and subscribe" does no assume a paricular operaing sysem or archiecure, bu is defined a he applicaion level (level 7), in a echnology-neural form. The phrase daa owner is used o refer o he human insiuion ha operaes he Server program. One would say ha he daa owner defines he daa o be made available by he Server program Evoluion of he query sandard The Query Sandard, like he HL7 Sandard in general, has been evolving since is incepion in Version 2.1. Version 2.4 inroduces a new mehodology inended o supercede he previous generaion of queries. Original Mode Queries Originally, he parameers of an HL7 query were carried by he QRD and QRF segmens. Because hese segmens were inended o be used by all queries, he conen of hese segmens could only be loosely defined. Such "original mode queries" acually represen jus a saring poin for defining queries. In hese original mode queries, separae rigger evens were used o differeniae beween an immediae response and a deferred response. In addiion, some of he funcional chapers defined queries and responses wih separae rigger evens. Enhanced Mode Queries In HL7 V2.3, "enhanced mode queries" were inroduced ha aemped o provide for a much higher level of precision in queries. Four new ways of specifying a query were inroduced in Version 2.3. An Embedded Query Language query, which suppors free-form selec saemens, based on he query language of choice (e.g., SQL) a Virual Table reques query which suppors queries agains server daabase ables (virual or acual) based on specific selecion crieria a sored procedure reques, which enables an applicaion on one sysem o execue a sored procedure on anoher sysem, which is coded o exrac specific daa an even replay reques message, which is used o reques daa formaed as an even replay response Enhanced Mode inroduced hree new ways o pass daa o he responding sysem (e.g., a Server). 1) Passing values o specific parameers of a query. (Used by he sored procedure and even replay queries.) This is he mos common and sraighforward echnique for creaing queries. The drawback is ha he clien is ighly limied in he range of queries i can formulae. 2) Passing he query as a single complex query expression. (Used by he Virual Table query.) The query is defined by an expression-ree made up of he usual AND OR, <, >, Operaors can refer o column_names or variables defined by he Server. These Queries give he Clien significan flexibiliy in specifying heir query over he columns ha he Server has permied. The cos of his Clien flexibiliy is ha he Server mus evaluae he query expression, raher han simply plug parameer values ino an exising sored procedure. 3) Passing he query as a single sring in an exising daabase query language such as SQL. (Used by he EQL Exernal Query Language query.) An EQL query is represened as a sring formaed in he paricular synax of an exising query language. The Server will probably pass Healh Level Seven, Version All righs reserved. Page 5-5 Final Sandard. April 2007.

6 his sring expression direcly o an exising daabase engine o evaluae he query, which will have o parse his expression o recover he query. The drawback of his echnique is ha differen daabase engines use differen query languages, and so he exac query sring which he Clien consrucs will depend on he Server s query language. Also in Version 2.3, he use of he rigger even was moving closer o he definiion se forh in chaper 2. Each offered query had is own rigger even. In Version each response had is own rigger even. Version 2.4 Queries Users of 2.3 queries encounered some somewha arbirary limiaions suggesed by he 2.3 sandard. A close reading of he 2.3 virual able query wording made i appear ha he only way a query could be specified by a QSC selecion expression was if i reurned abular (RDT) resuls, and i seemed ha queryby-parameer queries could no reurn abular resuls. Versions of he HL7 sandard afer more cleanly separae how a query is specified from how he daa is reurned, and hey emphasize he exisence of a Conformance Saemen. HL7 coninues o suppor he semanics of he Sored Procedure/Even Replay queries and he Virual Table queries, bu formulaes he synax more clearly using a single new query, he Query By Parameer (QBP). The QBP query is inended o unify he semanics of he sored-procedure, even-replay and virual-able queries wihin he framework of a precise conformance saemen. The sandard recognizes he coninued use of he Original Mode queries (QRD/QRF), bu uses a new query formalism o explain heir semanics more clearly. The bulk of he new maerial afer Version consiss of defining a forma for Conformance Saemens, and giving examples of query design and use. Noe: Version 2.5 inroduces a new, use-case-based mechanism for conformance in Secion 2.12 of Chaper 2. Query implemeners are encouraged o review and, where appropriae, adop he profiling srucures oulined in ha secion. Curren Conformance Saemen srucures are reained in Chaper 5 pending revision o he new srucures in he nex version of he Sandard. Compaibiliy wih pas versions For backward compaibiliy, boh he original and enhanced queries remain in he sandard, bu heir descripion has been relegaed o a for backward compaibiliy only secion. The main par of his chaper is a complee and consisen explanaion of he recommended approach o HL7 queries in Version 2.4. As in versions of HL7 prior o 2.4, he deailed domain conen of he query and response messages is defined by he echnical commiees responsible for he funcionally-specific chapers; he basic forms and mehodology for queries and responses are defined in his chaper. Secions and discuss Response Formas and Query Specificaion Formas Query developmen mehodology Typically, an individual HL7 conforman query would evolve as follows: An insiuion, or daa owner, decides ha i would like o make informaion available via a query. I decides precisely wha daa will be made available and how i will be offered. Knowing is own daa, he daa owner will define is query o reurn one of hree represenaions of he daa: Page 5-6 April Healh Level Seven, Version All righs reserved. Final Sandard.

7 1) As radiional HL7 segmens. (See secion , Segmen paern response..) 2) As rows and columns of daa from a precisely defined Virual Table. (See secion , Tabular response. ) 3) As rows of human readable ex ready o oupu o a screen or priner. (See secion , Display response. ) Nex, he daa owner specifies exacly which inpu variables he Clien can use o conrol he daa ha he Server agrees o reurn. The complee specificaion of wha daa are available, how he daa will be reurned, and wha variables can be valued or consrained in a Query is called he Conformance Saemen. The Conformance Saemen concep is criical o he proper usage of he query/response pair. In he absence of a Conformance Saemen, he Clien would be unaware of he exisence of he query, le alone how o use i or wha o expec from i. The daa owner adverises he exisence of, and suppor for, a query by publishing a Conformance Saemen. The Conformance Saemen has he following broad srucure: Inroducion including ile, rigger evens, mode, characerisics and purpose Query Grammar Response Grammar Inpu Specificaion and Commenary Response Conrol Oupu specificaions and Commenary Conformance saemen: A declaraion which ses forh he name of he query suppored by he Server, he logical srucure of he informaion ha can be queried, and he logical srucure of wha can be reurned. Secion 5.3 will explain he conformance saemen in deail. The nex secion elaboraes on he hree syles of response daa (segmen paern, abular, and display) ha a daa owner may use o represen is daa. The inroducion of he Conformance Saemen concep is no inended o imply sysem cerificaion. I is inended o promoe well-specified queries. As in previous versions, suppor for queries is no required for HL7 conformance Response forma The firs decision a daa owner mus make in formulaing a query is o decide which syle of represening daa is mos appropriae for heir needs. Healh Level Seven, Version All righs reserved. Page 5-7 Final Sandard. April 2007.

8 HL7 recognizes hree main syles of represening responses o queries: abular, segmen paern, or display. Segmen paern and abular were previously known as record-oriened as described in earlier versions of his Sandard. Segmen paern responses consis of a se of HL7 segmens. Each query will define, in is conformance saemen, he precise grammar of HL7 segmens ha i will reurn. Tabular responses reurn daa as a se of rows, one RDT segmen per row. Display queries reurn daa in DSP segmens. An HL7 conforman sysem ineresed in supporing queries will choose one or more of hese syles before proceeding wih a deailed design. Tabular Segmen paern Display The responding sysem formas he daa in a relaional forma, as rows and columns. The responding sysem formas he daa on he basis of an applicaion-specific segmen-oriened (recordoriened) message. The responding sysem formas he daa in human readable forma for direc oupuing o a display device (in boh original and enhanced modes). These srucures suppor all original mode and enhanced mode responses, as well as he 2.4 queries Segmen paern response Segmen Paern daa responses reflec he radiional way of offering daa wihin HL7. The Server responds o queries by reurning a paern of HL7 segmens. For example, he core of a response o a query for Lab daa migh be defined by he following segmen grammar: {PID OBR [{OBX}] } For example, paien informaion will be reurned in he PID segmen and laboraory resuls in OBR and OBX segmens. In his syle, he message reurned by a Server is ofen a close approximaion o an exising unsolicied updae HL7 message. In creaing a Conformance Saemen for a segmen paern response, he daa owner mus decide on he exac segmen grammar i will reurn. The oupu specificaion of he Conformance Saemen for a segmen paern response will have a srucure very similar o he message definiion of a sandard HL7 ransacion. I mus define a grammar of segmens ha will be reurned, and, for each segmen, i should clarify, where necessary, he meaning of each field, he cardinaliy of he daa, and wheher he daa is opional or required Tabular response A daa owner may decide ha he bes model for he daa i wishes o offer is ha of a fairly convenional able of rows and columns. In his case, a daa owner adverises suppor for a sraighforward ( virual ) able of daa, wih specific columns of specific daa ypes. I furher indicaes which of he columns he Clien can consrain in is query. The response o a query will be in he form of a se of rows from he adverised able. The Virual Table is an absracion around a radiional daabase able. However, here are imporan differences beween a radiional daabase able and he Virual Table. The Virual Table need no be based Page 5-8 April Healh Level Seven, Version All righs reserved. Final Sandard.

9 on a single able or collecion of daa. I may represen a join or combinaion of daa among daabase ables (alhough he join or combinaion is no explicily exposed o he Clien). The concep of able, borrowed from he relaional daabase world, is used merely as a represenaional aid. The acual inernal daa srucure of he Server need no be relaional. Virual Tables may be used o presen daa elemens from inernal srucures ha are hierarchical, objec-oriened, or oherwise nonrelaional in naure. Virual Tables herefore insulae he user from he exac daa layou or represenaion in he daa source. Tha is o say, he requesor need no undersand he srucure of he ables, rows and columns of he daabase being queried bu only he srucure of he Virual Table represenaion. Likewise, he responder (daabase owner) does no have o expose he srucure of he real daabase. Neiher he owner nor he requesor needs o worry if he srucure of he daabase changes. The rows and columns of he Virual Table for a query are fully described in he Conformance Saemen for ha query. A virual able daa represenaion is appropriae when he informaion being offered is relaively simple. I would no be he appropriae represenaion for lab repors ha ypically involve a complex nesing of resuls ino secions. Daa carried by he ypical HL7 segmen or segmen group could be modeled as a virual able. For example, he ADT sysem migh offer a able consising of he fields of PID, NK1 and a single PV1 segmen. On he oher hand, i would be difficul o represen he visi hisory of a paien in a single virual able Display response A display message can be generaed where he updae informaion does no need o be capured by he receiving sysem s daabase, bu only displayed, eiher on a visual medium (such as a PC, worksaion or a CRT) or on prined medium. The display response does no acually represen a formal syle of daa organizaion. I represens a decision o reurn daa formaed for human, raher han for compuer, consumpion. The Server offers a prey-prined version of he daa in a forma ha is meaningful for human readers. Logically, he conen of he prey prined message migh be he complex daa carried by an HL7 segmen paern, or could be a simple record normally carried by a abular response Choosing among available response formas In pracice, i is easy o decide which syle of daa o offer. In general, segmen paern responses are able o carry complex daa srucures (e.g., an enire laboraory repor), while abular responses are ypically simple daa srucures. Therefore, abular response is inended as a simpler ool o accomplish a simpler ask. There is no need for he Clien o undersand, parse and process he deep srucure and relaionships implied by he segmen paern response. The Clien does no need a complex sae machine o do segmen level parsing. The rows all have he same srucure so only a simple sae machine is needed. If he query is defined by an HL7 echnical commiee, hen he decision is already made. If, on he oher hand, no query is ye defined bu he domain of he daa is well covered by HL7, hen i is probable ha here are exising HL7 segmens ha could carry he daa. A Z query may be consruced ou of he exising HL7 segmens. If he daa is sie specific, he sie can eiher creae is own Z segmens and offer a segmen paern response (which makes paricular sense if he overall daa is complex) or i can define is own Virual Table, offer a abular response and le he Clien process each record. Once i is known wha daa a Server is making available, hen he daa can be ordered or requesed. This is analogous o needing o refer o a caalog before ordering an iem by mail. Healh Level Seven, Version All righs reserved. Page 5-9 Final Sandard. April 2007.

10 5.2.5 Query specificaion formas The previous secion explained he hree represenaions for daa ha are reurned o a query clien. This secion discusses how he clien may represen a query for informaion. HL7 now recommends one primary way wih 3 basic varians for specifying a query. This query model wih is varians is inended o assis implemeners in ranslaing specific query needs from he ordinary prose of he business model ino an appropriae HL7 query paradigm. The paradigm seleced will depend upon he philosophy of he insiuion: wheher o allow relaive freedom o clien sysems in composing query expressions, or o conrol rigidly he fields and operaions o be offered. The following paragraphs compare and conras he feaures of each of he HL7 query varian models. The differences beween hem lie mainly in he processing hey require on he Server side. Query By Simple Parameer The firs varian is called he Simple Parameer query. In he simple parameer query, he inpu parameers are passed in order as successive fields of an HL7 segmen. The Server need only read hem from he corresponding HL7 fields, and plug hem ino an inernal funcion o evaluae he query. This is he mos basic form of he query in which he Server specifies a fixed lis of parameers in is Conformance Saemen. (For example, he Server may direc he querying sysem o specify a medical record number, a beginning dae, and an ending dae.) When invoking he query, he Clien passes a specific value for each parameer. This is analogous o invoking a sored procedure agains a daabase. The parameer definiion segmen (i.e., he QPD) can be seen as a generalizaion of he QRD and QRF segmens of he original mode query. Each field in he QRD and QRF corresponds o 1 parameer of he QPD insance. HL7 recommends ha queries defined by QRD and QRF segmens be recas as a version 2.4 Query By Parameer. The obvious implemenaion gain is ha he Server can simply map he inpu values o he parameers specified in he Conformance Saemen. An already known funcion or procedure is called o evaluae he query and selec daa o be reurned. The bulk of he work effor has already been invesed in he developmen of his predefined funcion or procedure. Query By Example Varian: The Query By Example (QBE) is an exension of Query By Parameer (QBP) in which search parameers are passed by sending hem in he segmen which naurally carries hem, insead of as fields of he QPD segmen. For example, if one waned o perform a find_candidaes query using QBE, one would send he demographics informaion on which o search in he PID and/or PD1 segmens, leaving blank hose fields in he segmen sen ha are no query parameers. If, for example, religion were no one of he query parameers, PID-17 would be lef blank when he PID was sen in he query. Parameers which do no occur naurally in an HL7 message, such as search algorihm, confidence level, ec., would coninue o be carried in he QPD segmen as hey are in he Query by Parameer. The exac segmens and fields available for use as query parameers would be specified in he Conformance Saemen for he query. Query using he QSC varian: Page 5-10 April The hird varian is known as he QSC varian because of is use of he QSC daa ype, which was used in he Virual Table query. The conformance saemen for he query will define all he variables ha he Clien may use in an expression. A runime, he Clien is able o define he Healh Level Seven, Version All righs reserved. Final Sandard.

11 exac search crieria by consrucing a ree of operaor/operand nodes ha consrain he available inpu parameers. To evaluae he query, he Server mus be willing o analyze and inerpre he query expression a runime. The Server may ranslae he inpu expression ino is local daa access language, or perhaps i will inerpre he reques iself, and evaluae he expression for each iem of he virual able. The clien s Complex Expression is analogous o an SQL selecion saemen agains a relaional daabase. This varian is mos like he Virual Table Query (VQQ). There are a number of facors o consider in deermining which varian o offer. In he Complex Expression (QSC) varian, he Clien may selec any or all of he variables offered and may specify any permissible operaors and values for each variable. By conras, in he Simple Parameer varian or he Query By Example varian, he Clien mus provide values for exacly he se of variables offered. The Simple Parameer varian is easy o parse and process because i has posiional fields; i.e., he parameers are in a predefined and fixed order. Likewise, he Query By Example varian lends iself o simple processing, since parameers will occur in known posiions in defined segmens. The Complex Expression varian, on he oher hand, requires more involved parsing and processing because of is flexibiliy and he opionaliy of is elemens. Thus, while he Complex Expression varian offers more funcionaliy o he Clien, i is more burdensome for he Server o process. Conversely, he Simple Parameer and Query By Example varians offer less funcionaliy o he Clien bu are generally easier for he Server o implemen; hey are ofen based on exising sored procedures on he Server's sysem Expressing he same daa using he varians The following is an example of a query saed in all hree varian forms. This example is presened o illusrae he uiliy of each forma for he purpose of offering a query. Which forma o use depends upon he level of processing complexiy o be implemened on he Server and he degree of specificaion flexibiliy required by he Clien. The purpose of he query is o allow a simple inquiry upon an adminisraive daabase. Suppose a paien informaion reques is submied by he Clien. The Server is o respond wih demographic informaion: paien's dae of birh, sex, and ZIP code Expression as simple parameers As we have seen, his varian requires an exac parameer specificaion. The clien sysem ransmis a QBP query message in he following forma: MSH ^~\& FEH.IVR HUHA.CSC HUHA.DEMO QBP^Z58^QBP_Q13 1 D 2.4 QPD Z58^Pa Parm Qry 2 Q RCP I The names of he inpu and oupu fields are no specified in he query message, bu by he Conformance Saemen, idenified by QPD-1-message query name. The MSH-9.2-rigger even and he QPD-1-message query name are his query's only disinguishing elemens. The requesing sysem mus refer o his query's Conformance Saemen o learn more abou he inpu and oupu fields. Healh Level Seven, Version All righs reserved. Page 5-11 Final Sandard. April 2007.

12 Expression as query by example Jus as in he Simple Parameer varian, he Query By Example requires an exac parameer specificaion. The disincion in a Query By Example is ha segmens oher han QPD are used o ransmi he parameers. The segmens offered should be already-exising segmens ha he Server can parse easily. The clien sysem ransmis a Query By Example in he following forma. MSH ^~\& FEH.IVR HUHA.CSC HUHA.DEMO QBP^Z58^QBP_Q13 1 D 2.4 QPD Z58^Pa Parm Qry 2 Q502 PID RCP I Parameers used in his query are specified in he Conformance Saemen Expression as a complex expression In conras, he Complex Expression varian allows flexible inpu specificaions. This allows more choices for he Clien sysem, bu can require more complex processing capabiliy on he par of he Server Sysem. If he above Simple Parameer varian were o be saed as a Complex Expression, i migh look like his. MSH ^~\& FEH.IVR HUHA.CSC HUHA.DEMO QBP^Q13^QBP_Q13 1 D 2.4 QPD Z999^Pa Sel Qry 1 RCP I Noe he explici saemen of he inpu field name in QPD-3-user parameers. Also, noe ha his query migh be used o specify and reques oher fields, depending upon he specificaion of wha is permied by he server sysem's Conformance Saemen. Query Modaliies Simple Parameer Varian Complex Expression Varian The Server specifies parameers and he Clien passes specific values o he parameers when he query is invoked The Server offers variables which can be used by he Clien who passes a consraining expression (subjec o any limiaions specified by he Conformance Saemen) over hose variables when invoking he query Using he new modaliies shown in he able, he variey and number of queries is almos unlimied. There is no implicaion ha a specific Server mus suppor all of hese poenial generalized queries o comply wih he Sandard. Raher, hese ransacions provide a forma, or a se of ools, o suppor queries o he exen desired by he insiuion. The resources available and local policies will influence he ypes of queries ha are implemened Summary char of query/response pairs The following char delineaes he query/response messages defined in chaper 5: Descripion Query Response Response ype Defining segmen(s) Sec Ref Cancel query QCN Page 5-12 April Healh Level Seven, Version All righs reserved. Final Sandard.

13 Descripion Query Response Response ype Defining segmen(s) Sec Ref Embedded query language query EQQ Enhanced mode (superceded) EQL Query By Parameer QBP QPD 5.4.1, 5.4.2, Query, original Mode QRY Original mode (superceded) Even Replay Query RQQ Enhanced mode (superceded) Sored procedure reques SPQ Enhanced mode (superceded) Virual Table query VQQ Enhanced mode (superceded) QRD/QRF ERQ SPR VTQ Display response RDY Display DSP Enhanced display response EDR Enhanced mode (superceded) Even replay response ERP Enhanced mode (superceded) Response Segmen Paern DSP , ERQ , RSP Segmen paern Response abular RTB abular RDF/RDT Tabular Daa Response TBR abular RDF/RDT Unsolicied display message UDM Display (superceded) URD/URS The following char delineaes he query/response messages defined in he funcional chapers: Descripion Query Response Response ype Defining segmen(s) Sec Ref ADT response QRY^A19 ADR^A19 Original mode QRD/QRF Allocae idenifiers QBP^Q24 RSP^K24 Segmen paern QBP Ancillary RPT (display) (for backward compaibiliy only) ARD Original mode 7 Find candidaes QBP^Q22 RSP^K22 Segmen paern QBP Ge corresponding idenifiers Ge person demographics Order saus query/ Order saus response Pharmacy adminisraion informaion QBP^Q23 RSP^K23 Segmen paern QBP QBP^Q21 RSP^K21 Segmen paern QBP OSQ^Q06 OSR^Q06 Original mode QRD/QRF QRY^Q27 RAR^RAR Original mode QRD/QRF Maser files query MFQ Original mode Maser files query response MFR Original mode 8.43 Personnel informaion QBP^Qnn RSP^Knn Segmen paern QBP Pharmacy dispense QRY^Q28 RDR^RDR Original mode QRD/QRF Healh Level Seven, Version All righs reserved. Page 5-13 Final Sandard. April 2007.

14 Descripion Query Response Response ype Defining segmen(s) Sec Ref informaion Pharmacy dose informaion Pharmacy encoded order informaion Pharmacy prescripion order response Reques clinical informaion Resuls of observaion, query for Reurn Clinical Informaion QRY^Q30 RGR/RGR Original mode QRD/QRF QRY^Q29 RER^RER Original mode QRD/QRF QRY^Q26 ROR^ROR Original mode QRD/QRF RQC^I05 Original mode QRD/QRF QRY^R02 ORF^R04 Original mode QRD/QRF RCI^I05 Original mode QRD/QRF Reurn Clinical Lis RCL^I06 Original mode QRD/QRF Reurn paien referral RRI Original mode 11.5 Reurn paien referral RRI Original mode 11.5 Schedule query SQM Original mode Schedule query response SQR Original mode Query for vaccinaion record Vaccinaion query record response Vaccinaion query response wih muliple PID maches VXQ^V01 Original mode VXR^V03 Original mode VXX^V02 Original mode QUERY/RESPONSE CONFORMANCE STATEMENT The inroducion of he Query/Response Conformance Saemen concep is no inended o imply sysem cerificaion. I is inended o promoe he definiion and implemenaion of well-specified queries. As in previous versions, suppor for queries is no required for HL7 conformance. In he inroducion, he daa owner describes he daa being made available and he purpose of he query. He specifies he exac coded value Query which he Clien mus used o invoke his query. The Query Grammar defines he exac segmens he Clien may send. For each field of hose segmens, he conformance saemen will define how he Server will inerpre clien values. (For example, he paien name field is inerpreed as a regular expression mach.) The Response Grammar defines he exac paern of segmens ha he Server will reurn. Each Segmen Paern Response will specify is own paern of segmens. (For example, lab daa queries will reurn paerns of OBR and OBX, while demographic queries migh respond wih paerns of PID, PV1 segmens.) When a daa owner defines a abular response query, he response grammar migh simply be a lis of RDT segmens ha carry rows of daa. The user selecs columns from a Virual Table o define he oupu for he Query By Parameer/Tabular Response (QBP/RTB). Noe ha in he case of an HL7-defined query, a specific secion of he HL7 Sandard will define a Conformance Saemen. By conras, in he case of a sie defined query, he Conformance Saemen is wrien by analyss and programmers of he Server applicaion/sysem, and is available o he analyss and programmers of he Clien applicaion/sysem. Page 5-14 April Healh Level Seven, Version All righs reserved. Final Sandard.

15 Alhough he Conformance Saemen is a new consruc wih Version 2.4, i may also be used wih he previous generaion queries. Noe: Version 2.5 inroduces a new, use-case-based mechanism for conformance in Chaper 2. Query implemeners are encouraged o review and, where appropriae, adop he profiling srucures oulined in ha chaper. Curren Conformance Saemen srucures are reained in Chaper 5 pending revision o he new srucures in he nex version of he Sandard Using he conformance saemen Criical o he proper usage of he new query/response pairs is he Conformance Saemen concep. In he absence of a Conformance Saemen, he Clien migh no be aware of he exisence of a query, or migh no know how o use i or wha o expec from i. The Server adverises he exisence of, and suppor for, a query by publishing a Conformance Saemen. The Conformance Saemen idenifies he query, specifies wha iems can be queried and describes wha he response will look like. Conformance Saemen: A declaraion which ses forh he name of he query suppored by he Server, he logical srucure of he informaion ha can be queried, and he logical srucure of wha can be reurned. A number of examples of Conformance Saemens can be found in secion Query wih abular response example The user wishes o know he ideniy of he paien whose medical record number is MSH ^~\& PCR GenHosp MPI QBP^Q40^QBP_Q P 2.4 QPD Q40^WhoAmI^HL7nnnn Q ^^^MPI^MR RCP I RDF PaienLis^CX^20~Paien^XPN^48~Moher smaiden^xpn^48~dob^t S^26~Sex^IS^1~Race^CE^80 The MPI sysem reurns he following RTB message MSH ^~\& MPI GenHosp PCR RTB^R40^RTB_R40 ACK9901 P 2.4 MSA AA 8699 QAK Q0001 OK Q40^WhoAmI^HL7nnnn 1 QPD Q28^WhoAmI^HL7nnnn Q ^^^MPI^MR RDF PaienLis^CX^20~Paien^XPN^48~Moher smaiden^xpn^48~dob^t S^26~Sex^IS^1~Race^CE^80 RDT ^^^MPI^MR Everyman^Adam M Healh Level Seven, Version All righs reserved. Page 5-15 Final Sandard. April 2007.

16 Example of Conformance Saemen wih abular response Conformance Saemen Query Saemen ID (Query ID=Z99): Type: Query : Query Trigger (= MSH-9): Query Mode: Response Trigger (= MSH-9): Query Characerisics: Purpose: Response Characerisics: Based on Segmen Paern: Z99 Query (or Publish) Who Am I QBP^Z99^QBP_Q13 Boh RSP^Z84^RSP_K11 Reurns response sored by PaienLas unless oherwise specified. Find he ideniy of he paien for specified medical record number(s) Reurns response sored by PaienLas unless oherwise specified. QBP^Z99^QBP_Q13 Query Grammar: QBP Message Saus Secion Reference MSH Message Header Segmen [{SFT}] Sofware Segmen QPD Query Parameer Definiion [ RDF ] Table Row Definiion Segmen RCP Response Conrol Parameer [ DSC ] Coninuaion Poiner RSP^Z84^RSP_K11 Response Grammar: RTB Message Saus Secion Reference MSH Message Header Segmen [{SFT}] Sofware Segmen MSA Message Acknowledgemen [ ERR ] Error QAK Query Acknowledgemen QPD Query Parameer Definiion [ --- ROW_DEFINITION begin RDF Table Row Definiion Segmen [ { RDT } ] Table Row Daa Segmen ] --- ROW_DEFINITION end [ DSC ] Coninuaion Poiner Page 5-16 April Healh Level Seven, Version All righs reserved. Final Sandard.

17 QPD Inpu Parameer Specificaion Seq (Query ID=Z99) 1 MessageQuer y Key/ Search S o r LEN TYPE O p 60 CE R 2 QueryTag 32 ST R R e p Mach Op TBL Segmen Service Idenifier Code Elemen 3 PaienLis S Y 20 CX O PID-3 PID-3 Paien Idenifier Lis QPD Inpu Parameer Descripion and Commenary Inpu Parameer (Query ID=Z99) MessageQueryNa me Comp. DT CE Descripion Mus be valued Z99^WhoAmI^HL7nnnn. QueryTag ST Unique o each query message insance. PaienLis CX Componens: <ID (ST)> ^ <check digi (ST)> ^ <code idenifying he check digi scheme employed (ID)> ^ < assigning auhoriy (HD)> ^ <idenifier ype code (IS)> ^ < assigning faciliy (HD)> The combinaion of values for PaienID, and PaienIDAssigningAuhoriy, are inended o idenify a unique enry on he PATIENT_MASTER able. The PaienIDTypeCode is useful for furher filering or o supply uniqueness in he even ha he assigning auhoriy may have more han one coding sysem. (The PATIENT_MASTER able conains a consrain ha prevens muliple paiens from being idenified by he same combinaion of field values.) This PATIENT_MASTER enry will be searched agains on he PHARMACY_DISPENSE_TRANSACTION able o rerieve he rows fulfilling he query condiions. If his field is no valued, all values for his field are considered o be a mach. ID ST If his field, PID.3.1, is no valued, all values for his field are considered o be a mach. Assigning Auhoriy Idenifier Type Code HD IS If his field, PID.3.4, is no valued, all values for his field are considered o be a mach. If his field, PID.3.5, is no valued, all values for his field are considered o be a mach. RCP Response Conrol Parameer Descripion and Commenary Seq (Query ID=Z99) Componen LEN DT Descripion 1 Query Prioriy 1 ID (D)eferred or (I)mmediae. Defaul is I. 2 Quaniy Limied Reques 10 C Q Quaniy N M Number of unis (specified by he following componen) ha will be reurned in each incremen of he response. If no value is given, he enire response will be reurned in a single incremen. Unis C CHaracers, LInes, PaGes, or Healh Level Seven, Version All righs reserved. Page 5-17 Final Sandard. April 2007.

18 Seq (Query ID=Z99) Componen 3 Response Modaliy 60 C E 6 Sor-by 256 S RT Sor-by Sequenc ing Oupu Specificaion and Commenary: Virual Table Col (Query ID=Z99) Key/ Search S o r LEN TYPE O p LEN DT Descripion Rep E ST RecorDs. Defaul is LI. Real ime or Bach. Defaul is R. Segmen field name of an oupu column by which he response may be sored. Mus conain a Y in he Sor column of he oupu specificaion able. ID As specified in HL7 Table Sequencing. Defaul is Ascending. Mach Op TBL Segmen Service Idenifier Code Elemen PaienLis S Y 20 CX O PID.3 PID-3: Paien Idenifier Lis Paien 48 XPN PID.5 PID-5 Paien Moher smaiden 48 XPN PID.6 PID-6 Moher s Maiden DOB 26 TS PID.7 PID-7 Dae/Tim e of Birh Sex 1 IS PID.8 PID-8 Sex Race 80 CE PID.10 PID-10 Race Formal specificaion of he conformance saemen The Conformance Saemen conains he following informaion: Conformance Saemen ID: The unique idenifier applying o his query's Conformance Saemen. This value is ransmied as he firs componen of QPD-1-Message query name. For sies implemening he Conformance SIG s Implemenaion Guide, his value shall also be ransmied in MSH-21-Conformance saemen ID. Formal Query : idenifies a unique query or publicaion, e.g., PharmacyDispenseHisory. Query Trigger: idenifies he rigger even for he query. Noe ha more han one conformance saemen may map o he same generic rigger even (Q10 hrough Q15). If a non-generic rigger even is used, i should correspond o exacly one Conformance Saemen. Page 5-18 April Healh Level Seven, Version All righs reserved. Final Sandard.

19 The use of Q for HL7-sandard query rigger evens is convenional; anoher leer may be used if he supply of Q riggers is exhaused. The assignmen of a rigger even, while mandaory, is inended o faciliae processing raher han o idenify a query uniquely. A query is uniquely idenified by he value ransmied in QPD-1-Message query name. This value mus be he same in boh he query and response messages, even hough he rigger even for he query differs from he rigger even for he response. Response Trigger: idenifies he unique rigger even for he response. Noe ha more han one conformance saemen may map o he same generic rigger even (K10 hrough K15). If a nongeneric rigger even is used, i should correspond o exacly one Conformance Saemen. The use of K for HL7-sandard response rigger evens is convenional; anoher leer may be used if he supply of K riggers is exhaused. Query Prioriy: Specifies if he query is immediae, deferred or selecable Query Characerisics: Narraive describing general feaure of he query Purpose: Describes inen of query Query Grammar: defines he logical srucure of wha can be sen by he Clien. The srucure of his par of he Conformance Saemen is very similar in appearance o a message synax. Response Grammar: defines he logical srucure of wha can be reurned by he Server. The srucure of his par of he Conformance Saemen is very similar in appearance o a message synax wih 2 addiional columns: Commen and Suppor Indicaor Daa Model: he logical srucure of he informaion ha can be queried. I can be hough of as a se of rows or a lis of iems having he same forma as he Virual Table srucure described in he nex secion. This works for boh abular and segmen paern queries. A display query can be considered as orhogonal o he abular and segmen paern queries and follows he same inpu srucure. This is no always included in he Conformance Saemen. Inpu Parameer Specificaion and Commenary: Cies he allowable parameers ha can be passed o he recipien. The srucure of his par of he Conformance Saemen is very similar in appearance o an HL7 Segmen Aribue Table wih several addiional columns: Col, Key/Search, Sor, MachOp, Segmen, and Service Idenifier Code. A QPD Inpu Parameers able and corresponding explanaion able is always provided. These ables discuss all he fields of he QPD segmen, including QPD-1-Message query name and QPD-2-Query ag. If he query is a Query By Example, addiional inpu parameers and explanaion ables are provided for all he fields ha may be populaed in he example segmens. Response Conrol: Specifies execuion dae and ime, resricions on amoun of daa, and query modaliy. This is no always included in he Conformance Saemen. Oupu Specificaion and Commenary: Used for abular and display response. For he abular response, i specifies he column names ha will be reurned. The srucure of his par of he Conformance Saemen is very similar in appearance o an Aribue Table wih several addiional columns: Col, Key/Search, Sor, MachOp, Segmen, and Service Idenifier Code. For he display response, i describes he forma of he daa ha will be reurned. Healh Level Seven, Version All righs reserved. Page 5-19 Final Sandard. April 2007.

20 Noe ha in he case of an HL7-defined query, a specific secion of he HL7 sandard will define a Conformance Saemen. The exisence of a sandard Conformance Saemen for any given query does no mean ha a sysem mus implemen his paricular query o be conforman o he HL7 Sandard. However, sysems ha do implemen he query mus follow he specificaions as given in he Conformance Saemen. Sies ha wish o offer queries no specified by he Sandard may creae heir own Conformance Saemens. By conras o an HL7-sandard query, in he case of a sie defined query, he Conformance Saemen is wrien by he Server, and is available o he analyss and programmers of he Clien sysem o enable hem o know he exac behavior of he Server. Alhough he Conformance saemen is a new consruc wih version 2.4, i may also be used wih he previous generaion queries. Inpu Parameer Specificaion and Inpu Descripion and Commenary are always included for he QPD segmen. When he Query By Example varian is used, hey are provided for he QBE as well. An Oupu Specificaion and Commenary showing a Virual Table is provided for queries ha accommodae a abular response. For Conformance Saemens published in he HL7 Sandard, each able includes he Conformance Saemen ID in parenheses in he upper lef-hand cell. This allows he able o be impored auomaically ino he HL7 daabase Seps for developing a conformance saemen 1) Before composing he Conformance Saemen, express he query in ordinary English senences. 2) Transform he query ino a mahemaical or pseudo-language saemen. A synax such as SQL provides a useful mechanism. 3) From he pseudo-saemen, exrac he parameers and he operaions upon he parameers. 4) Adverise he parameers in he Conformance Saemen. 5) Wihin he Conformance Saemen, explain he operaions ha will be performed upon he parameers: relaional conjuncions, equaliy/inequaliy, ec. Use examples o aid he user in undersanding how he query migh be invoked in specific insances Conformance Saemen inroducion The Conformance Saemen begins wih a able ha summarizes he characerisics and idenifying informaion abou he query o which he Conformance Saemen applies. Page 5-20 April Healh Level Seven, Version All righs reserved. Final Sandard.

21 Conformance Saemen Query Saemen ID (Query ID=Znn): Type: Query : Query Trigger (= MSH-9): Query Mode: Response Trigger (= MSH-9): Query Characerisics: Purpose: Response Characerisics: Based on Segmen Paern: Query Saemen ID: The unique idenifier applying o his Conformance Saemen. This value is ransmied as he firs componen of QPD-1-Message query name. Type: Usually Query, excep for publish-and subscribe Conformance Saemens (see Secion ) for which he value should be Publish. Query : The name corresponding o he idenifier in Query Saemen ID. This value is ransmied as he second componen of QPD-1-Message query name. Query Trigger (= MSH-9): The exac value ha he Clien will ransmi in he MSH-9-Message ype field of he query message. Query Mode: Wheher he query may be sen in Real ime (including Bolus) or in Bach; see Secion The value Boh indicaes ha boh real-ime/bolus and bach modes are accepable. Response Trigger (= MSH-9): The exac value ha he Server will ransmi in he MSH-9-Message ype field of he response message. Query Characerisics: Paricular feaures of his query. This is free ex inended o help he query implemenor in selecing among queries. Purpose: The end resul ha his query is inended o accomplish. Free ex. Response Characerisics: Paricular feaures of his response. This is free ex inended o help he query implemenor in selecing among queries. Based on Segmen Paern: For queries ha reurn a segmen paern response, his is he (non-query response) message ype upon which he segmen paern is based Query grammar The Conformance Saemen shows a query grammar. This is a brief model of he segmens used in he query message. QBP^Znn^QBP_Qnn Query Grammar: QBP Message Saus Secion Reference MSH Message Header Segmen [{SFT}] Sofware Segmen Healh Level Seven, Version All righs reserved. Page 5-21 Final Sandard. April 2007.