Service Location Working Group Pete St. Pierre INTERNET DRAFT Sun Microsystems 1 June 1998 Conversion of LDAP Schemas to and from SLP Templates draft-ietf-svrloc-template-conversion-03.txt Status of This Memo This document is a submission by the Service Location Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the srvloc@corp.home.net mailing list. Distribution of this memo is unlimited. This document is an Internet-Draft. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet- Drafts as reference material or to cite them other than as ``work in progress.'' To view the entire list of current Internet-Drafts, please check the ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). Abstract The Lightweight Directory Access Protocol (LDAP) and Service Location Protocol (SLP) are both useful mechanisms for locating service related information on a network. While they do perform similar functions, the way in which the information they provide is formatted is very different. This document describes a set of rules and mappings for translating between the ASN.1 based LDAP schema and an SLP Template as described in the "Service Template and service: Scheme" draft. St.Pierre Expires 1 December 1998 [Page i] Internet Draft Schemas and Templates 1 June 1998 Contents Status of This Memo i Abstract i 1. Motivation 1 2. ASN.1 and BER Encodings 1 3. ASN.1 Types and LDAP 2 4. URLs and Distinguished Names 3 5. Mapping from SLP Templates to LDAP Schemas 3 5.1. Data Type Mappings . . . . . . . . . . . . . . . . . . . 3 5.2. Integer . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.3. String . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.4. Boolean . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.5. Opaque . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.6. Enumerations . . . . . . . . . . . . . . . . . . . . . . 5 5.7. Multi-valued Attributes . . . . . . . . . . . . . . . . . 6 5.8. Optional Attributes . . . . . . . . . . . . . . . . . . . 6 5.9. Literal Attributes . . . . . . . . . . . . . . . . . . . 6 5.10. Explicit Matching . . . . . . . . . . . . . . . . . . . . 6 5.11. Template for Translation . . . . . . . . . . . . . . . . 6 5.12. Translated Schema . . . . . . . . . . . . . . . . . . . . 8 6. Mapping from Schemas to Templates 10 6.1. Data Type Mappings . . . . . . . . . . . . . . . . . . . 10 6.2. Integer . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.3. Case Ignore String, Case Exact String . . . . . . . . . . 11 6.4. Boolean . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.5. Octet String . . . . . . . . . . . . . . . . . . . . . . 11 6.6. Binary . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.7. Enumeration . . . . . . . . . . . . . . . . . . . . . . . 11 6.8. Rules for Other ASN.1 Primitive Types . . . . . . . . . . 12 6.9. Set Of . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.10. Real . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.11. Object Identifier . . . . . . . . . . . . . . . . . . . . 12 6.12. Sequence Of . . . . . . . . . . . . . . . . . . . . . . . 13 6.13. Schema to be Translated . . . . . . . . . . . . . . . . . 14 6.14. SLP Translation . . . . . . . . . . . . . . . . . . . . . 15 7. Notes on Matching Operators 16 St.Pierre Expires 1 December 1998 [Page ii] Internet Draft Schemas and Templates 1 June 1998 8. Acknowledgments 17 A. References 17 1. Motivation SLP templates[1] are intended to create a simple encoding of the syntactic and semantic conventions for individual service types, their attributes, and conventions. This can easily be generated, transmitted, read by humans and parsed by programs, as it is a string based syntax with required comments. On the other hand, directory schemas serve to formalize directory entry formulation for use with services like LDAP[2]. These directories serve to store information about many types of entities. Network services are an example of one such entity. The ability to register services across both SLP[3] and schema based directory services is a useful capability. In order to facilitate this, this document creates mappings between the SLP template grammar and the directory schemas. The simple notation and syntactic/semantic attribute capabilities of SLP will map well into directory schemas. This means that service templates will easily be converted into directory schemas. The reverse is not true. Only a certain restricted set of types, matching rules and encoding conventions used with LDAP will be directly mappable into service type templates. There are rules to cover the cases where mapping cannot be done directly. It is believed that the cases which are not supported are the exception rather than the rule. This document will outline the correct mappings for the four basic data types supported by SLP to the ASN.1/BER described in the X.209 specification[4]. This is the encoding used by the LDAP[2] directory schema. Likewise, rules and guidelines will be proposed to facilitate consistent mapping of ASN.1 based schemas to be translated in the SLP template grammar. 2. ASN.1 and BER Encodings ASN.1 defined schemas are assumed to be encoded using the Basic Encoding Rules(BER) defined in CCITT Recommendation X.209[4]. The X.209[4] specification contains details of the on-the-wire encoding of ASN.1 values. BER supports 4 types of encodings: Universal, Application, Context Specific and Private. All SLP types will map to Universal BER encoded values. St.Pierre Expires 1 December 1998 [Page 1] Internet Draft Schemas and Templates 1 June 1998 Within the scope of Universal types, there are both primitive encodings and constructed encodings. A primitive encoding is a data value encoding in which the content octets directly represent the value. Constructed encodings are data values encoding in which the content octets are the complete encoding of one or more other data values. [2] This document will deal primarily with mapping ASN.1 primitive encodings to SLP data types. 3. ASN.1 Types and LDAP Because of the simplicity of SLP data types, any SLP data type can be represented in ASN.1. This does not mean, however, that all LDAP servers may be able to handle all ASN.1 types we create. Specifically, most LDAP servers do not support ASN.1 enumerations. Also, not all LDAP servers are extensible. While some LDAP servers may allow for the definition of new ASN.1 syntax definitions, there is a base set of types that are common among most LDAP servers. These types are: Distinguished Name Case Ignore String Case Exact String Binary Integer Some LDAP implementations may also support an ASN.1 definition for telephone numbers. This syntax allows for searching without regard for hyphen and parenthesis use. SLP Type ASN.1 Type Common LDAP Type ---------------------------------------------- Integer Integer Integer String String Case Ignore String Boolean Boolean Case Ignore String Opaque Octet String Binary Because of the limitations of many LDAP servers. All SLP data types will be discussed in the context of the common LDAP data types listed above. When coverting from an SLP template to an LDAP schema, these are the preferred data types for translation. For completeness, alternate ASN.1 syntaxs are presented for each data type. It should St.Pierre Expires 1 December 1998 [Page 2] Internet Draft Schemas and Templates 1 June 1998 be noted that deployment of these types may not be supported by all LDAP implementations. 4. URLs and Distinguished Names SLP uses URLs to uniquely identify a service instance. These URLs must somehow be converted to unique handles or "Distinguished Names" for inclusion in an LDAP directory. This document proposes a mechanism for storing an SLP URL as a Relative Distinguished Name. 5. Mapping from SLP Templates to LDAP Schemas The first step in mapping a template is to create a Distinguished Dame (DN) for the entry. This DN is used to uniquely identify the record within the LDAP hierarchy. We do this in two steps, using the service URL. The first step is to create an DN. Since URLs are likely to contain characters that are not allowed in a DN, we must find a way to remove them. Also, the resulting DN must be unique across all peers in the LDAP name space. In order to meet these criteria, we take the URL and perform an MD5 [6] hash to obtain a unique bit string that represents the URL. This bit string is then represented as hex digits, and used for the value of the DN. Secondly, we create an attribute called "url". This attribute is of type Case Ignore String. In this attribute, we store the actual service URL. For example, the URL service:printer:lpr://www.printserv.net/public would be stored in an LDAP directory with the following two attributes. The value 6a1c0bfa0396f6be0bf73c4d1e8c45f1 is produced from the MD5 hash of the URL, so the attributes would look like: DN = 6a1c0bfa0396f6be0bf73c4d1e8c45f1 url = service:printer:lpr://www.printserv.net/public 5.1. Data Type Mappings SLP supports four data types. Each of these data types can be mapped into a specific ASN.1 type. In this way, translation of data types can be described easily. All SLP data types are encoded as strings in the protocol. St.Pierre Expires 1 December 1998 [Page 3] Internet Draft Schemas and Templates 1 June 1998 Complexity is added when the SLP data type is expressed as an enumeration. This section describes the translation of each data type to its corresponding ASN.1 type. A discussion of proper enumeration handling follows these mappings. 5.2. Integer Both SLP templates and ASN.1 support Integers, so there is a one to one mapping between an SLP Integer attribute and an ASN.1 Integer attribute. On the wire encoding of these two is very different, though. In SLP, all integers are encoded as strings. An integer value of 17869 would be represented by a 5 byte string containing the values of the characters '1', '7', '8', '6', and '9' in the character set specified in the request or response packet. The ASN.1 Integer type is encoded in BER according to the rules in section 8 of the X.209 specification. The encoding of an ASN.1 integer value is primitive. The content octets shall consist of one or more octets. The rules ensure that an integer value is always encoded in the smallest possible number of octets. 5.3. String SLP strings are encoded as described in section 20.5 of the SLP protocol specification [3]. All value strings are considered case insensitive for matching operations. These strings are mapped to the ASN.1 DisplayString syntax. LDAP servers may or may not support the DisplayString syntax. The preferred representation of an SLP String is Case Ignore String. 5.4. Boolean Boolean attributes may have one of two possible values. In SLP, these values are represented as strings, TRUE and FALSE. In SLP's string encoding of a boolean value, case does not matter. ASN.1 supports a Universal, primitive type of boolean. X.209 specifies that the Contents field of a FALSE boolean value be encoded as a single octet with a value of zero. A boolean whose value is TRUE shall be encoded as a single octet whose value shall be any non-zero value, at the sender's option. St.Pierre Expires 1 December 1998 [Page 4] Internet Draft Schemas and Templates 1 June 1998 Many LDAP servers do not support a data type of Boolean. For this reason, it is recommended that the SLP boolean type be translated to a Case Ignore String. The value stored in this string should be either "true" or "false". 5.5. Opaque SLP values that are encoded as Opaque are really a series of octets. While SLP uses the construct of :, this maps very nicely to the tag/length/value BER encoding of the ASN.1 Octet String. The field of the SLP encoding will not match the field of the BER encoding, as radix-64 encoding results in a 4 to 3 expansion of the original data. Likewise, data presented in radix-64 notation must be converted back to the original byte stream to be encoded in the Contents field of the BER encoding. LDAP servers most commonly support the Binary data type instead of the more generic Octet String. For compatibility across LDAP implementations, SLP Opaque values should be stored using the LDAP data type of Binary. As with Octet Strings, the Binary type should store the original byte stream, not the radix-64 notation used within the SLP protocol. 5.6. Enumerations The SLP template grammar provides for the definition of enumerations. Enumerations are defined by listing all possible values for the attribute following any help text provided for that attribute. While the template syntax allows for creation of enumerations, the SLP protocol does not strictly enforce enumerations. These enumerations are still treated as text strings within the protocol, and values outside the scope of the enumeration defined may be present. The template enumeration is intended as a guideline to client side applications as to what values may be expected. An ASN.1 enumeration commonly maps a text string to a numerical value. In the BER encoding, the numerical value is passed as an integer across the wire. The receiving side must then translate the the value to the associated string as defined in the ASN.1 description. LDAP servers do not commonly support generic ASN.1 enumerations. For this reason, the preferred conversion for enumerated SLP values is Case Ignore String. LDAP servers will not however be able to St.Pierre Expires 1 December 1998 [Page 5] Internet Draft Schemas and Templates 1 June 1998 perform value checking to assure stored values are in a legal range. Applications should always verify values before making use of them. 5.7. Multi-valued Attributes Multi-valued attributes are defined in an SLP template using the 'M' flag. This flag indicates that an attribute may have more than one value. All values for a given attribute must be of the same encoding type. The ASN.1 syntax for SET OF is commonly used to define multi-valued ASN.1 objects that must be of the same type. Commonly, LDAP servers assume values may be multi-valued. In these cases, no additional configuration is necessary. 5.8. Optional Attributes SLP uses the 'O' flag to indicate an attribute may or may not be present. These optional attributes are defined using the "May" clause in an ASN.1 definition. All other attributes must be defined as a "Must" 5.9. Literal Attributes ASN.1 does not have a mechanism to indicate that the values of an attribute may not be translated from one language to another. 5.10. Explicit Matching The SLP template syntax uses a flag of 'X' to indicate that an attribute must match exactly with a query made by a client. There is, however, no mechanism to prevent clients from using the sub-string operator with explicit matching attributes. Common practice would be to map this to the ASN.1 matching syntax of "MATCHES EXACTLY". 5.11. Template for Translation The template included below is derived from the printer service scheme described in [5]. All translations assume the use of ASN.1 data types supported by all LDAP servers. type = printer version = 0.0 St.Pierre Expires 1 December 1998 [Page 6] Internet Draft Schemas and Templates 1 June 1998 language = en description = The printer service template describes the attributes supported by network printing devices. Devices may be either directly connected to a network, or connected to a printer spooler that understands the a network queuing protocol such as IPP, lpr or the Salutation Architecture. url-syntax = The URL syntax is specific to the printing protocol being employed description = STRING # This attribute is a free form string that can contain any # site-specific descriptive information about this printer. security-mechanisms-supported = STRING L M none # This attribute indicates the security mechanisms supported tls, ssl, http-basic, http-digest, none operator = STRING L M # A person, or persons responsible for maintaining a # printer on a day-to-day basis, including such tasks # as filling empty media trays, emptying full output # trays, replacing toner cartridges, clearing simple # paper jams, etc. location-address = STRING O # Physical/Postal address for this device. Useful for # nailing down a group of printers in a very large corporate # network. For example: 960 Main Street, San Jose, CA 95130 priority-queue = BOOLEAN O FALSE # TRUE indicates this printer or print queue is a priority # queuing device. number-up = INTEGER O 1 # This job attribute specifies the number of source # page-images to impose upon a single side of an instance # of a selected medium. 1, 2, 4 paper-output = STRING M L O standard # This attribute describes the mode in which pages output St.Pierre Expires 1 December 1998 [Page 7] Internet Draft Schemas and Templates 1 June 1998 # are arranged. standard, noncollated sort, collated sort, stack, unknown 5.12. Translated Schema This translated schema uses the template attributes primarily as comments in the beginning of the schema definition. Since all Objects must support a cannonical name (cn), we use the URL as the value for an object cn. This maps well, as a cn identifies a particular object and a URL identifies a particular resource. -- The printer service template describes the attributes -- supported by network printing devices. Devices may be either -- directly connected to a network, or connected to a printer -- spooler that understands the a network queuing protocol such as -- IPP, lpr or the Salutation Architecture. printer OBJECT-CLASS SUBCLASS OF top MUST CONTAIN { dn, url, description, security-mechanisms-supported } MAY CONTAIN { operator, location-address, priority-queue, number-up, paper-output } dn OBJECT-TYPE SYNTAX Distinguished Name DESCRIPTION "The DN of the printer being described" url OBJECT-TYPE SYNTAX Case Ignore String DESCRIPTION "The URL of the printer being described" description OBJECT-TYPE SYNTAX Case Ignore String DESCRIPTION "This attribute is a free form string that can contain Any site-specific descriptive information about this St.Pierre Expires 1 December 1998 [Page 8] Internet Draft Schemas and Templates 1 June 1998 printer." security-mechanisms-supported OBJECT-TYPE SYNTAX Case Ignore String DESCRIPTION "This attribute indicates the security mechanisms supported. These values are: tls ssl http-basic http-digest none" operator OBJECT-TYPE SYNTAX SET OF Case Ignore String DESCRIPTION "A person, or persons responsible for maintaining a printer on a day-to-day basis, including such tasks as filling empty media trays, emptying full output trays, replacing toner cartridges, clearing simple paper jams, etc." location-address OBJECT-TYPE SYNTAX Case Ignore String DESCRIPTION "Physical/Postal address for this device. Useful for nailing down a group of printers in a very large corporate network. For example: 960 Main Street, San Jose, CA 95130" priority-queue OBJECT-TYPE SYNTAX Case Ignore String DESCRIPTION "TRUE indicates this printer or print queue is a priority queuing device." number-up OBJECT-TYPE SYNTAX INTEGER DESCRIPTION "This job attribute specifies the number of source page-images to impose upon a single side of an instance of a selected medium." paper-output OBJECT-TYPE SYNTAX Case Ignore String DESCRIPTION "This attribute describes the mode in which pages output are arranged. These values are: standard St.Pierre Expires 1 December 1998 [Page 9] Internet Draft Schemas and Templates 1 June 1998 noncollated sort collated sort stack unknown" 6. Mapping from Schemas to Templates ASN.1 employs a much richer set of data types than provided by SLP. The table below show the mapping of selected ASN.1 data type to their nearest SLP equivalent. Because of the complexity and flexibility of ASN.1, a complete list cannot be provided. As sample of some ASN.1 encodings and their mappings to SLP: ASN.1 type SLP type --------------------------------------- Integer Integer Case Exact String String Case Ignore String String Boolean Boolean Octet String Opaque Binary Opaque Enumeration String Set Of 'M' flag Real String Object Identifier String Sequence Of Multiple Attributes 6.1. Data Type Mappings ASN.1 supports a much larger range of values. As such, a subset will be selected for mapping SLP values. ASN.1 uses BER encoding as described in CCITT Recommendation X.209[2]. BER encodings are based on tuples containing a Type, Length and Contents. 6.2. Integer Both SLP templates and ASN.1 support Integers, so there is a one to one mapping between an SLP Integer attribute and an ASN.1 Integer attribute. Details on the encoding of integers is summarized in the SLP template to ASN.1 section above, as well as being explained in detail in RFC2165[3] and the X.209[2] specification. St.Pierre Expires 1 December 1998 [Page 10] Internet Draft Schemas and Templates 1 June 1998 6.3. Case Ignore String, Case Exact String Strings are supported between both SLP and ASN.1. SLP encoding of the strings must conform to the rules for handling special characters, as outlined in RFC 2165 [3]. 6.4. Boolean Boolean values are supported by both SLP and ASN.1, though on wire encodings will vary. X.209[2] specifies zero and non-zero encoding for booleans, where SLP encodes booleans using the strings TRUE and FALSE. 6.5. Octet String An ASN.1 octet string should be mapped to an Opaque in an SLP template. An octet string is a sequence of bytes, whereas an Opaque is a sequence of bytes that has been encoded using radix64. 6.6. Binary An ASN.1 Binary should be mapped to an Opaque in an SLP template. A binary value is a sequence of bytes, whereas an Opaque is a sequence of bytes that has been encoded using radix64. 6.7. Enumeration SLP templates support the concept of enumerations through the listing of values in the attribute definition. This is similar to the ASN.1 definition of enumerations, though encodings vary. In SLP enumerated values are passed between client and server as strings. BER encodes the ASN.1 enumeration by passing the number of the elements position in the enumeration. This requires both sides to have knowledge of the specific enumeration prior to decoding an enumerations value. Example: color-supported = STRING M none # This attribute specifies whether the Printer supports # color and, if so, what type. none, highlight, three color, four color, monochromatic In this example, 'none' would have a value of 1, 'highlight' would be 2, 'three color' would be 3, etc. St.Pierre Expires 1 December 1998 [Page 11] Internet Draft Schemas and Templates 1 June 1998 6.8. Rules for Other ASN.1 Primitive Types It is not reasonable to think that all ASN.1 data types can be accurately represented using the very basic data types defined in ASN.1. As such, data types that do not map directly to SLP data types should be defined as either a String, or as Opaque. ASN.1 types that may only contain valid characters for Strings, as defined in X.209[2] should be encoded as strings. If a value may contain illegal string values, the SLP Opaque type should be used. In either case, the first line of the help text is used to indicate the original ASN.1 data type. 6.9. Set Of Sets can be accommodated in an SLP template by specifying the attribute is multivalued. The flag 'M' is used to indicate an attribute Can have multiple values. All values must be of the same type. As such, a multivalued attribute of type string could have values of "one, 2, three", but the value 2 would be returned as a string, not an integer. Likewise, a multivalued integer could not have a value of "1, 2, three", as all values would need to be converted to strings, which are illegal for an attribute of type integer. 6.10. Real There is no direct mapping between floating point numbers and any SLP data types. As such, attributes are defined as type String. Comments are added to the attribute help text indicating the value was originally an ASN.1 real. For example: weight = STRING # ASN.1: Real # The objects weight in pounds. 6.11. Object Identifier Object identifiers(OIDs) are commonly used in the ASN.1 world to identify object and attributes. OIDs are a numerical representation of an elements place in the naming hierarchy. Each element at a particular level of a hierarchy has a unique number assigned within that level of the hierarchy. A sample OID would be the naming tree for SNMP MIBs. St.Pierre Expires 1 December 1998 [Page 12] Internet Draft Schemas and Templates 1 June 1998 iso(1) org(3) dod(6) internet(1) mgmt(2) mib(1) would be written as the string 1.3.6.1.2.1 Because this representation reduces down to a string of dot separated numbers, this maps easily to the SLP String type. The help text for this element should indicate it is an ASN.1 OID identifier = STRING # ASN.1: OID # The object identifier for this SNMP agent. 6.12. Sequence Of The ASN.1 construct 'Sequence Of' is probably the least intuitive to map to an SLP template. SLP attributes can only contain values of like type. By definition, this is an ASN.1 SET OF. ASN.1 sequences are made of multiple values of different types. For example, an attribute named 'Engine' may be defined as: engine OBJECT-TYPE SYNTAX SEQUENCE OF { name DisplayString, status INTEGER { unknown(1) running(2) shutdown(3) } } DESCRIPTION "Engine description." In order to map this to an SLP template, we can create multiple attributes and rely on the ordering for association. The above translates as: engine-name = STRING M # The name of one of this craft's engines. engine-status = STRING M unknown # The state of this crafts engines. unknown, running, shutdown St.Pierre Expires 1 December 1998 [Page 13] Internet Draft Schemas and Templates 1 June 1998 To do this, we are relying on an assumption stated in the service: Scheme Draft [1] that all values of a multivalued attribute retain their order. When new values are added, they are added to the end of the list of values. As such, if we had: engine-name = right, left engine-status = running, shutdown We would assume that the engine named right is running and the engine named left is shutdown. 6.13. Schema to be Translated In general, ASN.1 provides a much more general set of data types than provided for by SLP. For this reason, it is more complex to convert LDAP schemas to templates for SLP. The following schema represents an example of a schema for an exported filesystem. The section presents it as in ASN.1 and the following section shows the SLP template translation. -- abstraction of a fstab entry (a "mount") -- these lookups would likely be performed by an -- an automounter type application mount OBJECT-CLASS SUBCLASS OF top MUST CONTAIN { -- the mount host mountHost, -- the mount point mountDirectory. -- the mount type mountType } MAY CONTAIN { -- mount options mountOption, -- dump frequency mountDumpFrequency, -- passno mountPassNo } St.Pierre Expires 1 December 1998 [Page 14] Internet Draft Schemas and Templates 1 June 1998 mountHost OBJECT-TYPE SYNTAX Case Ignore String DESCRIPTION "The mount host" mountDirectory SYNTAX Case Ignore String DESCRIPTION "The filesystem to mount" mountType OBJECT-TYPE SYNTAX INTEGER { ufs(1) hsfs(2) nfs(3) rfs(4) } DESCRIPTION "The type of the filesystem being mounted" mountOption OBJECT-TYPE SYNTAX SET OF Case Ignore String DESCRIPTION "mount options for this filesystem" mountDumpFrequency OBJECT-TYPE SYNTAX INTEGER (0..9) DESCRIPTION "How often to dump this filesystem" mountPassNo OBJECT-TYPE SYNTAX Integer DESCRIPTION "Boot time mount pass number" 6.14. SLP Translation type = mount version = 1.0 language = en description = "This would describe a remote filesystem access protocol" url-syntax = St.Pierre Expires 1 December 1998 [Page 15] Internet Draft Schemas and Templates 1 June 1998 filesystem = 1*[ DIGIT / ALPHA ] urlpath = "/" filesystem mountHost = STRING L # The mount host mountDirectory = STRING L # The filesystem to mount mountType = STRING L ufs # The type of the filesystem being mounted ufs, hsfs, nfs, rfs mountOption = STRING M O L # mount options for this filesystem mountDumpFrequency = INTEGER O 0 # How often to dump this filesystem 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 mountPassNo = INTEGER O # Boot time mount pass number 7. Notes on Matching Operators The SLP template grammar does not describe the matching properties of attributes, but ASN.1 does. If choosing to add matching properties to an SLP template when converting it to an ASN.1 based schema, the following rules should be kept in mind. LDAP and SLP support the same matching operations, though using slightly different matching semantics. In addition to greaterOrEqual and lessOrEqual, SLP provides for a simple less or greater match. LDAP Search Operators SLP Search Operators and (&) & or (|) | not (!) != equalityMatch (=) == substrings greaterOrEqual (>=) >= lessOrEqual (<=) <= present (=*) St.Pierre Expires 1 December 1998 [Page 16] Internet Draft Schemas and Templates 1 June 1998 ASN.1 provides for three varieties of substring value matching, namely initial, any, and final. In specifying the match capability of an attribute, ASN.1 specifies that a value may match the leading part, any part, or the final part of a string value. Using the SLP search semantics, this is accomplished through the substring (*) operator. Searching for initial, any or final is handled through specific placement of the operator. The following example, taken from RFC2165 illustrates this: initial: "bob*" matches "bob", "bobcat", and "bob and sue" final: "*bob" matches "bob", "bigbob", and "sue and bob" any: "*bob*" matches "bob", "bobcat", "bigbob", and "a bob I know" 8. Acknowledgments Thanks to Jonathan Wood for the suggestion to use MD5 hashes to avoid character escape problems between URLs and DNs. A. References [1]E. Guttman, C. Perkins, J. Kempf "Service Templates and service: Schemes", Work in Progress, March, 1987 draft-ietf-svrloc-service-scheme-09.txt [2]W. Yeong, T. Howes, S. Kille, "Lightweight Directory Access Protocol", RFC1777. 03/28/1995. [3]J. Veizades, E. Guttman, C. Perkins, and S. Kaplan. "Service Location Protocol", RFC 2165. June 1997. [4]CCITT Recommendation X.209, "Specification of Basic Encoding Rules for Abstract Syntax Notation One (ASN.1), 1988 [5]P. St. Pierre, "Definition of printer: URLs for use with Service Location", Work in Progress, March, 1998 draft-ietf-svrloc-printer-scheme-02.txt [6]Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, MIT Laboratory for Computer Science and RSA Data Security, Inc., St.Pierre Expires 1 December 1998 [Page 17] Internet Draft Schemas and Templates 1 June 1998 Full Copyright Statement Copyright (C) The Internet Society (1997). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Authors' Address Questions about this memo can be directed to: Pete St. Pierre Sun Microsystems 901 San Antonio Avenue Palo Alto, CA 94303 USA Phone: +1 415 786-5790 email: Pete.StPierre@Eng.Sun.COM St.Pierre Expires 1 December 1998 [Page 18]