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1.1     ! root        1: % run this through LaTeX with the appropriate wrapper
        !             2: 
        !             3: \chapter      {Defining New Services}\label{services}
        !             4: There are several components which are manipulated when a service is invoked.
        !             5: Briefly,
        !             6: let us consider how to define a new service.
        !             7: There are three databases to be managed:
        !             8: \begin{describe}
        !             9: \item[isoentities:] which maintains the mappings between application-entity
        !            10:        information and presentation addresses
        !            11:        (described in Chapter~\ref{isoentities});
        !            12: 
        !            13: \item[isobjects:] which maintains the mappings between object descriptors and
        !            14:        object identifiers
        !            15:        (described in Chapter~\ref{isobjects});
        !            16:        and,
        !            17: 
        !            18: \item[isoservices:] which maintains the mappings between textual descriptions
        !            19:        of services, service selectors, and local programs
        !            20:        (described in Chapter~\ref{isoservices} of \voltwo/).
        !            21: \end{describe}
        !            22: 
        !            23: For the remainder of this chapter,
        !            24: consider any fictitious service
        !            25: with suffix \verb"servicestore"
        !            26: (e.g., for the host \verb"gremlin",
        !            27: the service might be known as \verb"gremlin-servicestore"),
        !            28: and with an application context name of \verb*"local service".
        !            29: 
        !            30: There are many ways in which the mappings can be performed.
        !            31: Two approaches are described in this chapter.
        !            32: If you wish to use a different variation,
        !            33: then presumably you know enough about what you are doing not to need
        !            34: additional documentation here!
        !            35: 
        !            36: \section      {Standard Services}\label{service:standard}
        !            37: The ``standard'' approach is  the simplest and most straight-forward mapping
        !            38: strategy.
        !            39: 
        !            40: First,
        !            41: the abstract syntax {\em presentation context information\/} (PCI) of
        !            42: the service,
        !            43: along with the {\em application context\/} of the service should be defined.
        !            44: These are object identifiers (as described in Section~\ref{psap:oid} on
        !            45: page~\pageref{psap:oid}).
        !            46: The object identifier tree \verb"1.17.2" has been usurped for
        !            47: defining local services using {\em The ISO Development Environment}.
        !            48: Choose \verb"n",
        !            49: where \verb"n" is the lowest unassigned number in the \verb"1.17.2.n" subtree,
        !            50: for use by the service
        !            51: (\verb"n" should be an integer greater than \verb"0").
        !            52: Now edit the \man isobjects(5) file thusly:
        !            53: \begin{quote}\small\begin{verbatim}
        !            54: "local service pci"    1.17.2.n.1
        !            55: "local service"        1.17.2.n.2
        !            56: \end{verbatim}\end{quote}
        !            57: 
        !            58: Next,
        !            59: the template for the {\em application-entity information\/} and
        !            60: {\em presentation address\/} of the service should be defined.
        !            61: These are used for outgoing connections.
        !            62: The application-entity information portion is currently an object identifier,
        !            63: from the \verb"1.17.4.1" subtree.
        !            64: The presentation address portion is a presentation selector,
        !            65: a session selector, a transport selector, and a set of network addresses.
        !            66: Currently, the convention is to use empty presentation and session selectors,
        !            67: a unique transport selector,
        !            68: and a simple default template for the network addresses
        !            69: (the templates will be filled-in during connection establishment).
        !            70: The choice of a transport selector is troublesome;
        !            71: for the present,
        !            72: a 16--bit binary selector space is suggested.
        !            73: Choose \verb"p",
        !            74: where \verb"p" is the lowest unassigned TSAP ID between \verb"1024" and
        !            75: \verb"2047" inclusive.
        !            76: Now edit the \man isoentities(5) file thusly:
        !            77: \begin{quote}\small\begin{verbatim}
        !            78: default servicestore    1.17.4.1.n  ""  ""  #p/
        !            79: \end{verbatim}\end{quote}
        !            80: 
        !            81: Finally,
        !            82: the program on the local system implementing the service should be defined.
        !            83: This is used for incoming connections.
        !            84: Given the strategy used for allocating presentation addresses above,
        !            85: one need only map between a transport selector and a program.
        !            86: Edit the \man isoservices(5) thusly:
        !            87: \begin{quote}\small\begin{verbatim}
        !            88: "tsap/servicestore"    #p  program arg1 arg2 ... argN
        !            89: \end{verbatim}\end{quote}
        !            90: 
        !            91: \section      {GOSIP Services}\label{service:gosip}
        !            92: The U.S.~Government OSI Profile\cite{US.GOSIP} specifies a somewhat different
        !            93: mapping strategy.
        !            94: Rather than list the differences,
        !            95: the entire process is described here.
        !            96: 
        !            97: First,
        !            98: the abstract syntax {\em presentation context information\/} (PCI) of the
        !            99: service,
        !           100: along with the {\em application context\/} of the service should be defined.
        !           101: These are object identifiers (as described in Section~\ref{psap:oid} on
        !           102: page~\pageref{psap:oid}).
        !           103: As previously described,
        !           104: the object identifier tree \verb"1.17.2" is used to define local services.
        !           105: Choose \verb"n",
        !           106: where \verb"n" is the lowest unassigned number in the \verb"1.17.2.n" subtree,
        !           107: for use by the service
        !           108: (\verb"n" should be an integer greater than \verb"0").
        !           109: Now edit the \man isobjects(5) file thusly:
        !           110: \begin{quote}\small\begin{verbatim}
        !           111: "local service pci"    1.17.2.n.1
        !           112: "local service"        1.17.2.n.2
        !           113: \end{verbatim}\end{quote}
        !           114: 
        !           115: Next,
        !           116: the template for the {\em application-entity information\/} and
        !           117: {\em presentation address\/} of the service should be defined.
        !           118: These are used for outgoing connections.
        !           119: The application-entity information portion is currently an object identifier,
        !           120: from the \verb"1.17.4.1" subtree.
        !           121: The presentation address portion is a presentation selector,
        !           122: a session selector, a transport selector, and a set of network addresses.
        !           123: Currently, the convention is to use a unique presentation selector,
        !           124: along with standard values for the session and transport selectors,
        !           125: and a simple default template for the network addresses
        !           126: (the templates will be filled-in during connection establishment).
        !           127: The choice of the selectors is mandated by GOSIP:
        !           128: a 16--bit binary selector space is used.
        !           129: Choose \verb"p",
        !           130: where \verb"p" is the lowest unassigned PSAP ID between \verb"1024" and
        !           131: \verb"2047" inclusive.
        !           132: Now edit the \man isoentities(5) file thusly:
        !           133: \begin{quote}\small\begin{verbatim}
        !           134: default servicestore    1.17.4.1.n    #p/#1/#1/
        !           135: \end{verbatim}\end{quote}
        !           136: 
        !           137: Finally,
        !           138: the program on the local system implementing the service should be defined.
        !           139: This is used for incoming connections.
        !           140: Given the strategy used for allocating presentation addresses above,
        !           141: one need only map between a presentation selector and a program.
        !           142: Edit the \man isoservices(5) thusly:
        !           143: \begin{quote}\small\begin{verbatim}
        !           144: "psap/servicestore"    #p  program arg1 arg2 ... argN
        !           145: \end{verbatim}\end{quote}
        !           146: 
        !           147: This strategy is less efficient than the first approach as it requires the
        !           148: \man tsapd(8c) daemon to parse more information from the remote peer prior to
        !           149: invoking the program which implements desired application context.
        !           150: 
        !           151: \section      {Static Servers}\label{static:services}
        !           152: In Section~\ref{acs:server},
        !           153: two different server disciplines,
        !           154: the dynamic and the static approaches,
        !           155: were described.
        !           156: Thus far,
        !           157: this chapter has described the dynamic approach.
        !           158: The distinguishing mechanism of this discipline is that the entry in the
        !           159: \man isoentities(5) file specifies \verb"default" for the host portion of the
        !           160: service, e.g.,
        !           161: \begin{quote}\small\begin{verbatim}
        !           162: default servicestore    1.17.4.1.n    #p/#1/#1/
        !           163: \end{verbatim}\end{quote}
        !           164: 
        !           165: To implement the static server discipline,
        !           166: as described in Section~\ref{acs:server},
        !           167: one defines the service for a particular host and specifies the non-standard
        !           168: network (sub)address that the service exists on.
        !           169: For example:
        !           170: \begin{quote}\small\begin{verbatim}
        !           171: gremlin imagestore    1.17.4.1.n \
        !           172:                       #p/#1/#1/Internet=gremlin+17000
        !           173: \end{verbatim}\end{quote}
        !           174: Indicates that the service \verb"gremlin-imagestore" is available only by
        !           175: using the TCP network service to the host \verb"gremlin" and then using TCP
        !           176: port \verb"17000".
        !           177: Similar definitions may be made for hosts using an X.25 service.
        !           178: Further,
        !           179: as is the case with any entry in the \man isoentities(5) file,
        !           180: multiple network address may be present for a single service.
        !           181: In these cases,
        !           182: the server listens on all of these addresses.
        !           183: 
        !           184: After making a suitable definition in the \man isoentities(5) file,
        !           185: the server program must be started
        !           186: (either by hand or automatically from some system startup file,
        !           187: e.g., \file{/etc/rc.local}) without any arguments.
        !           188: The server program,
        !           189: using the \verb"isodeserver" routine described on page~\pageref{isodeserver}
        !           190: will then perform the appropriate actions to start listening on the desired
        !           191: addresses.

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