Changes between Initial Version and Version 1 of DRAFT_GAPI_AM_API_V2_DELTAS

Timestamp:

12/03/11 11:33:25 (12 years ago)

Author:

Aaron Helsinger

Comment:

--

DRAFT_GAPI_AM_API_V2_DELTAS

@@ +1 @@
+[[PageOutline]]
+
+= GENI AM API Changes from version 1 to version 2 =
+
+This page documents changes to the GENI Aggregate Manager API from [wiki:DRAFT_GAPI_AM_API_V1 version 1] to [wiki:DRAFT_GAPI_AM_API_V2 version 2]. It consists of the text describing the changes to the API which was used to define and adopt the changes to the API for version 2.
+ * [wiki:DRAFT_GAPI_AM_API_V1 Version 1 of the GENI Aggregate Manager API]
+ * [wiki:DRAFT_GAPI_AM_API_V2 Version 2 of the GENI Aggregate Manager API]
+ * [wiki:DRAFT_GAPI_AM_API_DRAFT Draft changes to the GENI Aggregate Manager API] for future versions. That is where this text originally was written.
+
+== Summary of Changes ==
+=== Change Set A: RSpecs are XML documents following GENI schemas ===
+
+'''Note''': At the GEC12 coding sprint, this change set was modified slightly from that which is widely implemented. This change
+ - removed the {{{default_ad_rspec}}} value from !GetVersion
+ - made the {{{rspec_version}}} argument to !ListResources required and renamed it {{{geni_rspec_version}}}
+ - renamed the other return values from !GetVersion to use the {{{geni_}}} naming prefix
+
+Other parts of this change set have been discussed and well behaved aggregates already implement them. The community has agreed to include this change in version 2 of this API.
+
+ * Specify that GENI RSpecs comply with GENI standard XML schemas as posted at http://www.geni.net/resources/rspec. GENI RSpec v3 is what was the ProtoGENI v2 schemas. RSpec and the ProtoGENI schemas are documented on [http://www.protogeni.net/trac/protogeni/wiki/RSpec the ProtoGENI wiki]. 
+ * Include additional options in !GetVersion and !ListResources to allow aggregates to support the GENI RSpecs in addition to their own native format.
+
+=== Change Set B: Flexible arguments and returns ===
+
+ * All methods take an ''options'' argument, which is a non null XML struct. No required options are added with this change - the struct may be empty.
+ * Method returns are modified to return at least 3 name/value pairs, with arbitrary additional such pairs. 
+  * {{{code}}} indicates success or error return. This itself is an XML-RPC struct, whose content is described below. 
+  * {{{value}}} is the return value as specified in AM API v1 or as modified by Change Set A (RSpec, etc), and 
+  * {{{output}}} is a human readable indication of the nature of the return or error. 
+  * Aggregates are free to use other additional name/value pairs in the return struct.
+
+== Adopted Change Details ==
+
+=== Change Set A ===
+
+'''Note''': At the GEC12 coding sprint, this change set was modified slightly from that which is widely implemented. This change
+ - removed the {{{default_ad_rspec}}} value from !GetVersion
+ - made the {{{rspec_version}}} argument to !ListResources required and renamed it {{{geni_rspec_version}}}
+ - renamed the other return values from !GetVersion to use the {{{geni_}}} naming prefix
+
+''Note: The change to GENI standard RSpec schemas originally referenced ProtoGENI v2 RSpec schemas, hosted at www.protogeni.net. These schemas have now been re-branded as GENI v3 RSpec schemas and are hosted at http://www.geni.net/resources/rspec/3.''' 
+
+''Note: Options in the geni_ namespace remain reserved, but not all GENI standard options need to be named with the geni_ prefix.''
+
+==== Part 1: Standardized XML-based GENI RSpecs ====
+At GEC10 [wiki:GEC10RSpec the GENI community agreed] that GENI RSpecs would be in what was the [http://www.protogeni.net/trac/protogeni/wiki/RSpec ProtoGENI v2 format] and is now known as GENI v3. Aggregates are free to use an alternate format internally, but must accept and produce compliant RSpecs on demand. Note that individual aggregates may use RSpec extensions to describe custom resources or properties of resources. For RSpec extension information, see the ProtoGENI [http://www.protogeni.net/trac/protogeni/wiki/RSpecExtensions2 wiki].
+
+For more information:
+ * [http://www.geni.net/resources/rspec/3 Official GENI v3 RSpec schemas]
+ * [http://www.protogeni.net/trac/protogeni/wiki/RSpec GENI standard (was ProtoGENI v2) format]
+ * [http://www.protogeni.net/trac/protogeni/wiki/RSpecExtensions2 RSpec extension information]
+ * [http://www.protogeni.net/trac/protogeni/wiki/RSpecSchema2 RSpec schemas listing]
+
+Specific changes include:
+ * !ListResources: Return value of !ListResources remains an [http://www.xmlrpc.com/spec XML-RPC] string, but its format and meaning are now proscribed.
+
+ The return value is an RSpec matching the [http://www.protogeni.net/trac/protogeni/wiki/RSpec GENI standard] RSpec in text format if {{{geni_compressed}}} is unspecified or set to {{{false}}}. The return value will be a ZLib compressed and then base 64 encoded string representation of the RSpec if {{{geni_compressed}}} is specified and set to {{{true}}}.
+
+This RSpec will be a [http://www.geni.net/resources/rspec/3/ad.xsd advertisement RSpec] when invoked with no {{{geni_slice_urn}}} option, representing the resources available at this aggregate. When the client supplies the {{{geni_slice_urn}}} option, then the aggregate will return a [http://www.geni.net/resources/rspec/3/manifest.xsd manifest RSpec], representing all resources allocated to that slice by this aggregate. 
+
+ * !CreateSliver: rspec argument remains an [http://www.xmlrpc.com/spec XML-RPC] string, but its format and meaning are now proscribed.
+
+  `rspec`::
+    An RSpec matching the [http://www.protogeni.net/trac/protogeni/wiki/RSpec GENI standard] request RSpec [http://www.geni.net/resources/rspec/3/request.xsd schema] containing the resources that the caller is requesting for allocation to the slice specified in {{{slice_urn}}}. These are expected to be consistent with the resources returned by a previous invocation of [wiki:GAPI_AM_API#ListResources ListResources].
+
+ * !CreateSliver: return value remains an [http://www.xmlrpc.com/spec XML-RPC] string, but its format and meaning are now proscribed.
+
+ The return value is an RSpec matching the [http://www.protogeni.net/trac/protogeni/wiki/RSpec GENI standard] manifest RSpec [http://www.geni.net/resources/rspec/3/manifest.xsd schema] indicating the resources that were allocated to the slice. The result RSpec may contain additional information about the allocated resources.
+
+==== Part 2: New RSpec Version Options ====
+In order to allow aggregates to support both a native RSpec format (e.g. the standard !PlanetLab / SFA RSpecs) as well as the GENI-standard format (GENI v3, was ProtoGENI v2), we need new options to allow a client to request RSpecs in a particular format.
+
+Specifically, aggregates will advertise (in !GetVersion) the list of Advertisement and Request RSpec types they are willing to accept. And they will produce manifest RSpecs in a format matching the format of the !CreateSliver input request RSpec (e.g. return a GENI v3 manifest RSpec when given a GENI v3 request RSpec, and a native !PlanetLab manifest RSpec when given a !PlanetLab request RSpec).
+
+===== Contract details =====
+
+Aggregates advertise the {{{type}}} and {{{version}}} of RSpec formats that they support. If available, they specify the {{{schema}}}, {{{namespace}}} and {{{extensions}}} combination which is the authoritative definition of that format. Clients of the API should understand that combination in order to know how to understand the resources available at that aggregate. 
+
+If an aggregate advertises a particular {{{type}}}/{{{version}}} (optionally defined with a combination of {{{schema}}}, {{{namespace}}} and {{{extensions}}}) in the {{{geni_ad_rspec_versions}}} attribute of !GetVersion, then it promises to send a correct Advertisement RSpec in response to a !ListResources call which supplies an {{{geni_rspec_version}}} option containing that {{{type}}}/{{{version}}}. ({{{geni_rspec_version}}} is a {{{struct}}} with 2 members, {{{type}}} and {{{version}}}. {{{type}}} and {{{version}}} are ''case-insensitive'' strings, matching those in {{{geni_ad_rspec_versions}}}).
+
+If an Aggregate advertises a particular {{{type}}}/{{{version}}} (optionally defined with a combination of {{{schema}}}, {{{namespace}}} and {{{extensions}}}) in the {{{geni_request_rspec_versions}}} attribute of !GetVersion then it promises to correctly honor a !CreateSliver call containing a request RSpec in the given format, and then to return a Manifest RSpec in the corresponding format (i.e. a GENI format request is answered with a GENI format manifest). The aggregate also promises to send a correctly formatted Manifest RSpec in response to a !ListResources call which supplies a valid {{{geni_slice_urn}}} option and an {{{geni_rspec_version}}} option containing that supported {{{type}}}/{{{version}}}.
+
+===== New !GetVersion required attributes =====
+
+Return the version of the GENI Aggregate API and RSpecs supported by this aggregate.
+
+{{{
+struct GetVersion()
+}}}
+
+The result is an [http://www.xmlrpc.com/spec XML-RPC] struct with at least the following members:
+
+{{{
+{
+  int geni_api;
+  array geni_request_rspec_versions of {
+    string type;
+    string version;
+    string schema;
+    string namespace;
+    array extensions of string;
+  };
+  array geni_ad_rspec_versions of {
+    string type;
+    string version;
+    string schema;
+    string namespace;
+    array extensions of string;
+  };
+}
+}}}
+
+ `geni_api`::
+    An integer indicating the revision of the Aggregate Manager API that an aggregate supports. This document describes API version 2 (two).
+
+ `geni_request_rspec_versions`::
+   An array of data structures indicating the RSpec types accepted by this AM in a request.
+
+ `geni_ad_rspec_versions`::
+   An array of data structures indicating what types of RSpec advertisements may be produced by this AM in !ListResources.
+
+Elements used within {{{geni_request_rspec_versions}}} and {{{geni_ad_rspec_versions}}}:
+ `type`, `version`::
+   Two ''case-insensitive'' strings which together comprise the type of RSpec. The RSpec `type` should be one of "geni", "protogeni", "sfa", "orca", "openflow", or "orbit" and `version` should be a type-specific version identifier as specified by the appropriate control framework. The "geni" type is reserved for GENI standard format RSpecs, following the schemas hosted at www.geni.net.
+
+ `schema`::
+   An optional URL pointing to a schema which can be used to verify the given type of RSpec.
+
+ `namespace`::
+   An optional XML namespace which the RSpec of the given type belongs to.
+
+ `extensions`::
+   An array of aggregate-specific strings denoting which extensions are supported. In the case of ProtoGENI, these are XML namespaces which denote the extension as a whole.
+
+Implementations can add additional members to the struct as desired. Implementations should choose an appropriate prefix to avoid conflicts, but avoid {{{geni_}}} which should be reserved for common options.
+
+This operation is similar to ProtoGENI's [http://www.protogeni.net/trac/protogeni/wiki/ComponentManagerAPIV2#GetVersion GetVersion] operation. The [http://svn.planet-lab.org/attachment/wiki/WikiStart/sfa.pdf SFA] specification does not include this operation other than through this method.
+
+===== New !ListResources Option =====
+!ListResources will take an additional ''required'' option, {{{geni_rspec_version}}}, allowing a user to request an Advertisement or Manifest Rspec in a particular format. This struct must contain a {{{type}}} and {{{version}}} matching one of this Aggregate's advertised {{{geni_ad_rspec_versions}}}.
+
+Specifics:
+
+Return information about available resources or resources allocated to a slice.
+
+{{{
+string ListResources(string credentials[], struct options)
+}}}
+
+....
+
+ `options`::
+    An [http://www.xmlrpc.com/spec XML-RPC] struct containing members indicating the set of resources the caller is interested in or the format of the result. In addition to the members specified below, callers can pass additional members that specific aggregate manager implementations might honor. Implementations should choose an appropriate prefix to avoid conflicts, but avoid {{{geni_}}} which should be reserved for common options.
+
+The following members are available for use in the options parameter. All aggregate managers are required to implement these options.
+
+{{{
+{
+  boolean geni_available;
+  boolean geni_compressed;
+  string geni_slice_urn;
+  struct geni_rspec_version {
+    string type;
+    string version;
+  };
+}
+}}}
+
+....
+
+ `geni_rspec_version`::
+    An [http://www.xmlrpc.com/spec XML-RPC] struct indicating the type and version of Advertisement or Manifest RSpec to return. The struct contains 2 members, {{{type}}} and {{{version}}}. {{{type}}} and {{{version}}} are ''case-insensitive'' strings, matching those in {{{geni_ad_rspec_versions}}} as returned by !GetVersion at this aggregate. This option is ''required'', and aggregates are expected to return a geni_code {{{1}}} ('Bad Arguments') if it is missing.
+
+    The returned Rspec will be an Advertisement RSpec when no {{{geni_slice_urn}}} option is supplied. When a valid {{{geni_slice_urn}}} option is supplied, the returned RSpec will be a Manifest RSpec of the type corresponding to {{{geni_rspec_version}}}, but in manifest format.
+
+    If the aggregate cannot support the requested {{{type}}}/{{{version}}} (that pair is not listed in {{{geni_ad_rspec_versions}}}), then the aggregate returns an error 13 (UNSUPPORTED).
+
+===== New !CreateSliver behavior =====
+If an Aggregate advertises a {{{type}}}/{{{version}}} pair in its {{{geni_request_rspec_versions}}} as returned by !GetVersion, then it promises to correctly honor a !CreateSliver call containing a request RSpec in the given format, and then to return a Manifest RSpec in the corresponding format (ie a GENI v3 standard request is answered with a GENI v3 manifest).
+
+=== Change Set B ===
+
+==== Part 1: Additional options argument ====
+Adding support for additional functionality in the AM API is currently difficult. Many possible areas of innovation are variations on existing functions. This change adds flexibility in arguments to support such innovation.
+
+Under this proposal, each method will take an argument which is a set of name-value pairs (an XML-RPC struct, aka a property list). This argument is required for all methods except !GetVersion (where it is optional), but may be empty (non NULL but containing no name/value pairs). Aggregates may support new entries in this 'options' argument to allow new non-standardized functionality.
+
+Specifically, this change adds a final {{{struct options}}} argument to each of !GetVersion, !CreateSliver, !SliverStatus, !RenewSliver, !DeleteSliver,  and Shutdown. !ListResources already has that argument. The argument is optional for !GetVersion, but required for all other functions.
+
+Aggregates are compliant with this API change by accepting this argument; only for !ListResources are they required to handle any specific options. Similarly, clients are required to supply this argument to talk to compatible aggregates, but are only required to supply any particular options for !ListResources.
+
+In !GetVersion, this argument remains optional. Clients that only talk AM API v1 will get an error invoking most functions, when they leave off the {{{options}}} argument. Experimenters can then call !GetVersion (without the {{{options}}} argument). AM API v2 compliant Aggregates shall include the {{{geni_api}}} argument as a top-level entry in the return struct, specifying {{{2}}} to indicate to clients that this AM speaks version 2 of the AM API.  This allows experimenters to understand that they need to upgrade their client, or might instruct a clever client tool to automatically switch to version 2 syntax.
+
+Aggregates should not ''require'' any new options to any method - they should always have a reasonable default for any such option. Clients must always be able to work with any aggregate by simply supplying the options required by this API.
+
+Aggregates are encouraged to document any new options which they accept in any method, to bootstrap coordination with clients, and provide documentation for human experimenters. This API does not specify how aggregates provide that documentation. One way to provide partial documentation, is to implement [http://xmlrpc-c.sourceforge.net/introspection.html XML-RPC introspection]. Through the use of method help, aggregates can provide human readable text describing options. Alternatively or additionally, aggregates may document options as part of their return from !GetVersion. This allows clients to either avoid communicating with an aggregate for which the client does not understand how to provide those options, or to tailor the client's request to provide those extra options. 
+
+==== Part 2: Richer return values ====
+In AM API v1, method failures come back sometimes as XML-RPC Faults, sometimes as ''False'', and is occasionally inconsistent across aggregates. Failures typically do not indicate how the Experimenter should modify their request for it to succeed, or if this is a server error. This proposed change expands and formalizes the return structures, to support semantically richer returns, allowing Experimenters better insight into both successes and failures, and how to respond.
+
+Allowing aggregates to return more information, on both errors and success, will allow for a richer client-server communication. It would also allow aggregates to give clients hints on how to use successful returns, or otherwise innovate within the bounds of the AM API.
+
+This change will modify all methods to return an XML-RPC struct (aka property list) on any application layer success, failure, and even on an error or for most exceptions. Note that a malformed XML-RPC request should still raise an XML-RPC Fault, and other Faults dictated by the XML-RPC specification should still be raised. This struct will contain the return value from the previous revision of the AM API as an entry, as modified by other changes adopted for API version 2. This struct will have 3 defined entries, and aggregates are free to include other entries to give more information to clients. 
+
+The three required entries in the return structure are {{{code}}}, {{{value}}}, and {{{output}}}. 
+
+ * {{{code}}}: An XML-RPC struct containing 3 sub elements. For details on this (adopted) proposal, see: https://openflow.stanford.edu/display/FOAM/AM+return+code+proposal
+
+In summary however:
+
+{{{
+code {
+  geni_code: XML-RPC integer, registered in an XML document off the GENI AM API page
+  am_type: Optional: XML-RPC string, case insensitive, types in a registry (XML document) linked off the GENI AM API page
+  am_code: Optional: XML-RPC integer
+}
+}}}
+
+Integers above are allowed to be negative.
+
+{{{am_type}}} and {{{am_code}}} are optional: AMs need not supply them and clients should not have to use them to understand the nature of the response.
+They serve to further specify the nature of the return as indicated by {{{geni_code}}}
+
+Success is indicated by {{{geni_code}}} value of {{{0}}}
+
+Error codes and AM types are in an XML document off the GENI AM API page
+
+ * {{{value}}}: On success, this is required. Optional on failure or error. Object representing the successful return value. This will be the object previously returned by the function (for example the manifest RSpec for !CreateSliver, or the struct for !SliverStatus). The value is not defined on error, though aggregates are free to use it.
+  * For !GetVersion, the {{{value}}} is an XML-RPC struct
+  * For !ListResources, the {{{value}}} is an RSpec
+  * For !CreateSliver, the {{{value}}} is an RSpec
+  * For !RenewSliver, the {{{value}}} is a boolean
+  * For !DeleteSliver, the {{{value}}} is a boolean
+  * For !SliverStatus, the {{{value}}} is an XML-RPC struct
+  * For Shutdown, the {{{value}}} is a boolean
+ * {{{output}}}: On failure or error, this is required. Optional on success. This is a String with a human readable message explaining the result. Specifically, this might include an error string, a stacktrace, or other useful messages to help the Experimenter resolve or report the failure or error. It is not defined on success, though aggregates are free to use it.
+
+Aggregates are encouraged to use {{{code}}} values and {{{output}}} messages that help experimenters and tools distinguish between bad input, other experimenter error, temporary server errors, or server bugs. 
+
+GENI standard error codes will be documented on the GENI AM API Wiki page.
+
+Aggregates are similarly encouraged to provide hints on how to fix bad requests using the {{{value}}} entry to experimenters on error or failures. For example, a failed !RenewSliver call that failed because you are not allowed to renew your sliver that far in the future, might return a new date string in the {{{value}}} field that would be allowed. Similarly, a failed !CreateSliver call might return a modified request RSpec in the {{{value}}} field.
+
+Aggregates should avoid raising an error (XML-RPC Fault) for application layer errors or any other cases where the XML-RPC specification does not require a Fault, but rather should attempt to return this struct, providing any error messages and stack traces in the {{{output}}} field or other additional fields. Where the XML-RPC standard prescribes specific Faults, those will remain XML-RPC Faults.
+
+Aggregates are free to add additional return values to support aggregate or resource specific functionality, or to innovate within the bounds of the AM API. Aggregates are encouraged to document any such new return values which they return, to bootstrap coordination with clients, and provide documentation for human experimenters. One way to provide partial documentation, is to implement [http://xmlrpc-c.sourceforge.net/introspection.html XML-RPC introspection]. Through the use of method help, aggregates can provide human readable text describing return values. Alternatively or additionally, aggregates may document return values as part of their return from !GetVersion. We have not specified the format for advertising those extra return values in !GetVersion.
+
+For comparison, Orca functions return property lists internally. The ProtoGENI CMV2 API returns a struct with exactly these 3 values. ProtoGENI however uses a different range of return codes, and largely does not define the {{{value}}} slot on errors.
+
+For example, !SliverStatus could return on success:
+{{{
+{
+  code: {
+       geni_code: 0
+        },
+  value: 
+{
+  geni_urn: <sliver URN>
+  geni_status: ready
+  geni_resources: [ { geni_urn: <resource URN>
+                      geni_status: ready
+                      geni_error: ''},
+                    { geni_urn: <resource URN>
+                      geni_status: ready
+                      geni_error: ''}
+                  ]
+}
+
+  output: <none>
+}
+}}}
+
+On failure, !DeleteSliver might return:
+{{{
+{
+  code: {
+        geni_code: 12
+        }
+  value: False
+  output: 'No such slice here'
+}
+}}}
+(That code and output are merely examples.)
+
+An exception:
+At the top level, !GetVersion adds a required entry: 'geni_api'=2. This allows v1 clients to determine that they are indeed talking to a
+GENI AM, but since the version is 2, that is why other function calls will fail with an XML-RPC Fault.
+
+==== Supporting multiple API versions ====
+Aggregates are free to support multiple versions of the API. They do so by providing different URLs for each version of the API that they support.
+Aggregates should have a 'default' URL (the one typically advertised). That version runs whichever version of the API the server chooses (could be the latest, could be something else.)
+Each server implementing the API must include all methods, including !GetVersion.
+
+This change modifies !GetVersion to include a new required member:
+{{{
+geni_api_versions: an XML-RPC struct containing 1+ entries of:
+  Name: Integer - supported GENI AM API version
+  Value: String - URL to the XML-RPC server implementing that version of the GENI AM API
+}}}
+
+For example
+{{{
+geni_api_versions: {
+  1: <URL>,
+  2: <Local URL>,
+   ...
+}
+}}}
+
+Where the entries indicate versions of the API supported, and URLs are absolute URLs where that version of the API is supported. (As per Change Set B above, this new member is a sub-structure to the {{{value}}} member.)
+
+==== Changes Summary: New Method Signatures ====
+When taken together, the new method signatures would be:
+
+{{{
+struct GetVersion(options=None)
+Success Return:
+{ 
+  geni_api = 2
+  code = {
+       geni_code = 0
+         }
+  value
+      {
+        geni_api=2,
+        geni_api_versions {
+             2: <local URL>,
+             <other versions and URLs as supported>
+             }
+        geni_request_rspec_versions [{
+          type=GENI
+          version=3
+          schema=...
+          namespace=....
+          extensions []},
+          <other version structs>]
+        geni_ad_rspec_versions [{type, version, schema, namespace, extensions},]
+      }
+  output = <None>
+}
+
+struct ListResources(string credentials[], struct options)
+Success Return:
+{
+   code= {geni_code=0}
+   value= <GENI v3 Ad or Manifest RSpec string>
+   output = <None>
+}
+
+struct CreateSliver(string slice_urn,
+                    string credentials[],
+                    <GENIv3 request RSpec schema compliant XML string> rspec,
+                    struct users[],
+                    struct options)
+Success Return:
+{
+   code={geni_code=0}
+   value= <GENI v3 Manifest RSpec string>
+   output = <None>
+}
+
+struct DeleteSliver(string slice_urn, string credentials[], struct options)
+Success Return:
+{
+   code={geni_code=0}
+   value= boolean
+   output = <None>
+}
+
+struct SliverStatus(string slice_urn, string credentials[], struct options)
+Success Return:
+{
+   code={geni_code=0}
+   value= struct (as defined in v1)
+   output = <None>
+}
+
+struct RenewSliver(string slice_urn,
+                    string credentials[],
+                    string expiration_time, struct options)
+Success Return:
+{
+   code={geni_code=0}
+   value= boolean
+   output = <None>
+}
+
+struct Shutdown(string slice_urn, string credentials[], struct options)
+Success Return:
+{
+   code={geni_code=0}
+   value= boolean
+   output = <None>
+}
+}}}