Issue 18747: Observations in TimeExpressions (uml25-ftf) Source: Simula Research Laboratory (Mr. Bran Selic, selic(at)acm.org) Nature: Uncategorized Issue Severity: Summary: In section 8.4.4 dealing with TimeExpression and Duration (both of which are kinds of ValueSpecification) it currently says: "A TimeExpression or Duration is denoted by the textual representation of its expr, if it has one (see sub clause 8.3.5). The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. If a TimeExpression or Duration does not have an expr, then it is simply represented by its single associated Observation." It is not clear to me what is meant by "which may include the names of related Observations ". An Observation in the current time model is a kind of PackageableElement and not a value specification; i.e., it does not represent a value. The above text seems to suggest some kind of special case for Observation such that it should be treated as a value when its name appears in a TimeExpression or Duration. If so, what is the type of that value and where is it stored? (Note that Observation does not have an attribute for storing such a value.) What happens if the expression is one that computes the value of the Observation? Or, if the value of the Observation is needed to compute some other value? I suggested earlier that this problem can be easily resolved if we make Observation a kind of ValueSpecification, but this does mean a metamodel change. Resolution: Revised Text: Actions taken: June 2, 2013: received issue Discussion: End of Annotations:===== M-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:from:date:x-google-sender-auth:message-id :subject:to:content-type; bh=LJ3/1ZcpYy+X2UOiP6IxXGlF764+pgaVzeZbC6X35u8=; b=uOTuugFo5DoZORfluNCkwhH7pIAbkEA4h1ROg9Xvx1piObjEjGdfR40TGodTQyZGYa Z2wdOngoh+u5S+msfpQZHTFX9+TzvDs7SeYagBHt/YUnJzk1qnkiTiplWR8u7CCc2fDK 4vj6NF6KPRC8NSXfQ6idqyHNM8aVBKCyiRBNMsJwy3Vy0//YdbcQpPeOqLwfoK+ctemf /it3VjZagBKE3wg1DptDzvfuBBwoZmhGnCY+RuUuhVBoW4aOg6N5Sj+Fll9rIrMYY88i rI3xw7f1usyB4eEJlJwora1aZuFvwtzjiV9gloBQYUO2G0VxwYdZwiTSr4lxdO+jgx+y WEtg== X-Received: by 10.52.66.229 with SMTP id i5mr13419163vdt.131.1370205131329; Sun, 02 Jun 2013 13:32:11 -0700 (PDT) Sender: bran.selic@gmail.com From: Bran Selic Date: Sun, 2 Jun 2013 16:31:31 -0400 X-Google-Sender-Auth: RxSbwSzpKiHuAnvuHuU8Aq44I-8 Subject: Observations in TimeExpressions To: "uml25-ftf@omg.org" X-Virus-Scanned: amavisd-new at omg.org In section 8.4.4 dealing with TimeExpression and Duration (both of which are kinds of ValueSpecification) it currently says: "A TimeExpression or Duration is denoted by the textual representation of its expr, if it has one (see sub clause 8.3.5). The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. If a TimeExpression or Duration does not have an expr, then it is simply represented by its single associated Observation." It is not clear to me what is meant by "which may include the names of related Observations ". An Observation in the current time model is a kind of PackageableElement and not a value specification; i.e., it does not represent a value. The above text seems to suggest some kind of special case for Observation such that it should be treated as a value when its name appears in a TimeExpression or Duration. If so, what is the type of that value and where is it stored? (Note that Observation does not have an attribute for storing such a value.) What happens if the expression is one that computes the value of the Observation? Or, if the value of the Observation is needed to compute some other value? I suggested earlier that this problem can be easily resolved if we make Observation a kind of ValueSpecification, but this does mean a metamodel change. Bran From: "Rouquette, Nicolas F (313K)" To: Bran Selic , "uml25-ftf@omg.org" Subject: Re: Observations in TimeExpressions Thread-Topic: Observations in TimeExpressions Thread-Index: AQHOX9Bg0KZHiWx3+Ui5lOEmTTZteJki4qAA Date: Sun, 2 Jun 2013 20:38:26 +0000 Accept-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/14.3.4.130416 x-originating-ip: [128.149.137.114] X-Source-Sender: nicolas.f.rouquette@jpl.nasa.gov X-AUTH: Authorized X-Virus-Scanned: amavisd-new at omg.org Bran, Is there a level of indirection missing in the description? Instead of: The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. I wonder if it is instead: The representation is of a formula for computing the time or duration value, which may include constants and names of the events of the related Observations. - Nicolas. From: Bran Selic Date: Sunday, June 2, 2013 1:31 PM To: "uml25-ftf@omg.org" Subject: Observations in TimeExpressions In section 8.4.4 dealing with TimeExpression and Duration (both of which are kinds of ValueSpecification) it currently says: "A TimeExpression or Duration is denoted by the textual representation of its expr, if it has one (see sub clause 8.3.5). The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. If a TimeExpression or Duration does not have an expr, then it is simply represented by its single associated Observation." It is not clear to me what is meant by "which may include the names of related Observations ". An Observation in the current time model is a kind of PackageableElement and not a value specification; i.e., it does not represent a value. The above text seems to suggest some kind of special case for Observation such that it should be treated as a value when its name appears in a TimeExpression or Duration. If so, what is the type of that value and where is it stored? (Note that Observation does not have an attribute for storing such a value.) What happens if the expression is one that computes the value of the Observation? Or, if the value of the Observation is needed to compute some other value? I suggested earlier that this problem can be easily resolved if we make Observation a kind of ValueSpecification, but this does mean a metamodel change. Bran DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type; bh=bwgAHg7P+lM0lVQEZHYpdZoooERdmqwRvo/srI2ZLSg=; b=VOf9XoPX/TN9IFPsMdhwaU+CJuURDKJZdYgYmdFW6tR2ViNElXZlL0jP3F1teTg8ah BgI9EFKOuQtaCVcfd4jJw5jrGFVGYu6h93CoGw3JzN8OFf780xrkwmSB5TnxSJENxtpg jivgGrUcr0+vdYC020wWtNad/9QzkvPEXxLejCZ7rRNZAdyLK2j918HIoVCA++/k+O1d 82VM3TzSXEkAP2hlRlcfUJHhl9r5HkB5V3wm0UJph2h9+apK/3B1xf3+N4z35pWcPS8D TX1/F7N/vGrH+h0QkL1uh1QfzIW1f1ZzPxaNKxm525wTCV1jyJAJZEAta4XFw1zWaaQn idfg== X-Received: by 10.52.110.133 with SMTP id ia5mr13491175vdb.129.1370206799227; Sun, 02 Jun 2013 13:59:59 -0700 (PDT) Sender: bran.selic@gmail.com From: Bran Selic Date: Sun, 2 Jun 2013 16:59:19 -0400 X-Google-Sender-Auth: vX6FjClT72SyNu9tmT5MxWKp1vU Subject: Re: Observations in TimeExpressions To: "Rouquette, Nicolas F (313K)" Cc: "uml25-ftf@omg.org" X-Virus-Scanned: amavisd-new at omg.org Nicolas, I don't see how that helps. Neither events nor event occurrences are elements that represent time values. Of course, these things may have associated time values, but then the expressions should refer to those associated time values rather than the events of observations. On Sun, Jun 2, 2013 at 4:38 PM, Rouquette, Nicolas F (313K) wrote: Bran, Is there a level of indirection missing in the description? Instead of: The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. I wonder if it is instead: The representation is of a formula for computing the time or duration value, which may include constants and names of the events of the related Observations. - Nicolas. From: Bran Selic Date: Sunday, June 2, 2013 1:31 PM To: "uml25-ftf@omg.org" Subject: Observations in TimeExpressions In section 8.4.4 dealing with TimeExpression and Duration (both of which are kinds of ValueSpecification) it currently says: "A TimeExpression or Duration is denoted by the textual representation of its expr, if it has one (see sub clause 8.3.5). The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. If a TimeExpression or Duration does not have an expr, then it is simply represented by its single associated Observation." It is not clear to me what is meant by "which may include the names of related Observations ". An Observation in the current time model is a kind of PackageableElement and not a value specification; i.e., it does not represent a value. The above text seems to suggest some kind of special case for Observation such that it should be treated as a value when its name appears in a TimeExpression or Duration. If so, what is the type of that value and where is it stored? (Note that Observation does not have an attribute for storing such a value.) What happens if the expression is one that computes the value of the Observation? Or, if the value of the Observation is needed to compute some other value? I suggested earlier that this problem can be easily resolved if we make Observation a kind of ValueSpecification, but this does mean a metamodel change. Bran From: "Rouquette, Nicolas F (313K)" To: Bran Selic CC: "uml25-ftf@omg.org" Subject: Re: Observations in TimeExpressions Thread-Topic: Observations in TimeExpressions Thread-Index: AQHOX9Bg0KZHiWx3+Ui5lOEmTTZteJki4qAAgAB7MYD//51PgA== Date: Sun, 2 Jun 2013 22:06:06 +0000 Accept-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: user-agent: Microsoft-MacOutlook/14.3.4.130416 x-originating-ip: [128.149.137.114] X-Source-Sender: nicolas.f.rouquette@jpl.nasa.gov X-AUTH: Authorized X-Virus-Scanned: amavisd-new at omg.org Bran, The level of indirection I refer to is about the semantics of the "event" property, which depends on what kind of element it is referring to. If TimeObservation::event refers to. An Event . it signifies the time when the event happens A MessageEnd . it signifies the time of the sending or receiving the MessageEnd::message If DurationObservation::event refers to. A Message . it signifies the duration between sending / receiving the message A GeneralOrdering . it signifies the duration between the before/after occurrences An InteractionFragment . it signifies the duration of the execution of the InteractionFragment A Behavior . it signifies the duration of the execution of the Behavior The above is just my own personal interpretation of UML. I can't claim that it is what the metamodel was intended for. It just happens to be a logically reasonable interpretation of what it is today. - Nicolas. From: Bran Selic Date: Sunday, June 2, 2013 1:59 PM To: JPL Cc: "uml25-ftf@omg.org" Subject: Re: Observations in TimeExpressions Nicolas, I don't see how that helps. Neither events nor event occurrences are elements that represent time values. Of course, these things may have associated time values, but then the expressions should refer to those associated time values rather than the events of observations. On Sun, Jun 2, 2013 at 4:38 PM, Rouquette, Nicolas F (313K) wrote: Bran, Is there a level of indirection missing in the description? Instead of: The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. I wonder if it is instead: The representation is of a formula for computing the time or duration value, which may include constants and names of the events of the related Observations. - Nicolas. From: Bran Selic Date: Sunday, June 2, 2013 1:31 PM To: "uml25-ftf@omg.org" Subject: Observations in TimeExpressions In section 8.4.4 dealing with TimeExpression and Duration (both of which are kinds of ValueSpecification) it currently says: "A TimeExpression or Duration is denoted by the textual representation of its expr, if it has one (see sub clause 8.3.5). The representation is of a formula for computing the time or duration value, which may include the names of related Observations and constants. If a TimeExpression or Duration does not have an expr, then it is simply represented by its single associated Observation." It is not clear to me what is meant by "which may include the names of related Observations ". An Observation in the current time model is a kind of PackageableElement and not a value specification; i.e., it does not represent a value. The above text seems to suggest some kind of special case for Observation such that it should be treated as a value when its name appears in a TimeExpression or Duration. If so, what is the type of that value and where is it stored? (Note that Observation does not have an attribute for storing such a value.) What happens if the expression is one that computes the value of the Observation? Or, if the value of the Observation is needed to compute some other value? I suggested earlier that this problem can be easily resolved if we make Observation a kind of ValueSpecification, but this does mean a metamodel change. Bran