Re: [Suspected Spam]Re: [equinox-dev] [prov] Ruminations on IDirector vs

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Re: [Suspected Spam]Re: [equinox-dev] [prov] Ruminations on IDirector vs. ProvisioningHelper-like entity

From: James D Miles <jdmiles@xxxxxxxxxx>
Date: Thu, 16 Aug 2007 16:18:56 -0500
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I will have to get back to you on taking that.

Pascal Rapicault <Pascal_Rapicault@xxxxxxxxxx>

Pascal Rapicault <Pascal_Rapicault@xxxxxxxxxx>

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08/16/2007 03:58 PM

Please respond to
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Subject	[Suspected Spam]Re: [equinox-dev] [prov] Ruminations on IDirector vs. ProvisioningHelper-like entity

I'm a 100% with you for those two scenarios! The current implementation is silly 'cause the install and configure phases are merged. As a goal of this milestone, we want to introduce a "configure" phase (and maybe others based on what other provisioning story have defined) Do you want to take on this task (adding configure phase) to get yourself wet with the code? It will touch on a little bit of everything with being too crazy. PaScaL James D Miles <jdmiles@xxxxxx.c om> To Sent by: Equinox development mailing list equinox-dev-bounc <equinox-dev@xxxxxxxxxxx> es@xxxxxxxxxxx cc Subject 08/16/2007 04:50 Re: [equinox-dev] [prov] PM Ruminations on IDirector vs. ProvisioningHelper-like entity Please respond to Equinox development mailing list <equinox-dev@ecli pse.org> I am still working to get up to speed. I am still a little confused by the operations and phases so I may not be totally in sync on terms here. One of the options should be: We should be able to fetch and install (not configure) the new requirements in the background. The user does not necessarily need to know or care except as a general policy decision. If we have a broken download connection on a mobile device, we just restart on the artifact that did not finish. This scenario might not work for large downloads on a storage constrained device but even then should work for minor updates. Once every requirement is met (installed) the user can be prompted for when to configure. The configure phase should not take long at this point. It seems to me that this is also an argument for treating configure and install as separate operations and not treating everything as a phase of install. (Embedded image moved to file: pic12115.gif)Inactive hide details for "Tim Webb" <tim@xxxxxxxxxx>"Tim Webb" <tim@xxxxxxxxxx> "Tim Webb" <tim@trwe bb.com> (Embedded image moved to file: Sent by: pic21578.gif) equinox-d To ev-bounce (Embedded image moved to s@eclipse file: pic10629.gif) .org "Equinox development mailing list" <equinox-dev@xxxxxxxxxxx> 08/15/200 (Embedded image moved to file: 7 08:51 pic29525.gif) AM cc (Embedded image moved to file: pic16769.gif) Please respond to (Embedded image moved to file: Equinox development mailing list pic10176.gif) <equinox-dev@xxxxxxxxxxx> Subject (Embedded image moved to file: pic25365.gif) Re: [equinox-dev] [prov] Ruminations on IDirector vs. ProvisioningHelper-like entity (Embedded image moved to file: pic27181.gif) (Embedded image moved to file: pic30639.gif) More below... On 8/15/07, Jeff McAffer <Jeff_McAffer@xxxxxxxxxx> wrote: Some thoughts accumulated in reviewing this thread... - For clarity of discussion, we should ignore "proxy" objects unless they have some smarts, in which case they are not proxies. That is, if the Director is on the server and the Engine on the client, the fact that the server implementation may or may not need a local instance of Engine is immaterial. It may be an RMI proxy, something custom or the director may open a socket and stream commands directly to some port on the client. Doesn't matter. There is no Engine logic on the server. This is just distributed programming. My reference to the Engine was specifically due to what I saw in the current implementation where the Director instantiates an Engine. I was concerned that structuring it like this would mean that that single engine would need to be able to determine which response corresponds to which client's request. Should Director-level install / uninstall requests be assigned an identifier to allow for this correspondence? Having an identifier may also help in logging when you have multiple changes being requested to a system in parallel. All that said, I completely agree that the Director shouldn't need to know that an Engine is remote, local, or some other relayed style Engine. - With that in mind, the hybrid case Tim raises is interesting. The real question is not around client/server but around "how many directors are there". Either you have only one (doesn't matter where) or you have multiple cooperating in a hierarchy or mesh like structure. 1) If you have one then it is driving the policies and choices but needs to take into account multiple inputs to the profile definition. this is somewhat like our shared configurations today. There is a config and a parent config. We have hardcoded rules about the relationship between them (precedence etc). The "director" that is integrated into the Framework knows how to read these configs, merge them and implement the result. One could see the same thing happening in the hybrid case Tim described. 2) If you have multiple then we need some CooperatingDirector structure that defers some decisions to others and/or asks questions of others and merges results. For example, rather than just reading the profile data, a CooperatingDirector might ask its friend Directors for what they think is in the profile. Ultimately someone has to be in charge and be responsible for merging and making the final decisions/choices. It feels like policy choice as to whether that is done on the client or the server (in the hybrid case). Tim, you seem to have described something along these lines right? Perfect way to summarize the hybrid issue. One thing to remember is our discussion at the workshop around Governors. I recall that we were looking to defer alot of these sorts of policy decisions to the Governor. Using this approach you can do #1 from above where the Director (wherever it is) reads information from wherever is needed and merges/processed it according to a single Governor. The Governor itself may be here or there but it is driven by a set of policy files/preferences/settings etc. Is it fair that a Governer might be able to say "you must have software A, B and C with versions X, Y and Z respectively? Then the local director would be responsible for determining what modifications including potential software removal would be required to execute the constraints imposed by the Governer. In the Maya case, what the Governer states as the Profile's base requirements would be what we currently have in Maya as a Profile -- let's call it a Profile Template. Our data model in Maya also allows for software exclusion rules and again, this does seem to resonate better with the roles of a Governer than a Director. The Governer could tell the Director that software J can never be installed on a system. Now from a UI point of view having a Governer raises some interesting concerns as well. For example, if the Governer will never allow software J to be installed, could we optimize the UI and not show this to the user? Similarly, if the Governer dictates a range of software that can be consumed, can we filter out other versions from view? Ideally when running with full or partial governance we will still be able to leverage the same Director and Update UI for consistency from the user's perspective. More thoughts on the Governer below... - the goal of one round trip to figure out what to run is great. in the more cooperative hybrid cases though it is not clear how that is going to happen. If there are things to merge, someone has to do the merging. So either A has to tell B all things that might be needed to do the merging/computation or vice versa. Once the decisions are made, there will be further roundtrips to execute on the decisions. I should mention that one round trip to the governance? server would be preferred. There certainly may be many roundtrips to the distributed meta and artifact repositories in processing those operations. How optimized and how many requests are made may certainly be optimized by a custom meta repository but that's a second-level optimization at this point. - Tim, you mentioned " To accomplish this, we will need a way of describing the operations to be performed and then have a way to encode / decode them." Currently we seem to tell the the Engine a set of operands (pairs of IUs in old/new state) and a set of phases to run through. I'm not particularly happy with the vagueness around the use of IAdaptable in the API but modulo that, do you see anything different needed? Yes, I'm happy with the sort of data being modeled in the operands I saw. I do believe we will need to leverage those operands for other functions such as indicating product configuration priorities (which product is the primary one), but yes, the general idea of the operands seems to address the needs. While thinking through the Governer some more, here are some thoughts on what I could see us needing from this service. interface IGoverner { public ProfileConstraint[] getConstraintsForProfile(Profile profile, IProgressMonitor monitor) throws CoreException; public IStatus validateInstall(Profile profile, InstallableUnits[] installRoots, IProgressMonitor monitor); public IStatus validateUninstall(Profile profile, InstallableUnits[] uninstallRoots, IProgressMonitor monitor); public IStatus validateOperands(Profile profile, EngineOperation operation, IAdaptable operands, IProgressMonitor monitor); } The definition of ProfileConstraint is still a bit vague in my mind, but I could imagine functions that validate if a Profile is currently meeting the requirement, a way to get back information from the specific requirement type, and a way to use the requirements as a way for the IDirector to seed the creation of a new Profile. My first thought was that this would need to be a new ProfileConstraint object; however, upon reflection it may be that the Governer is simply returning a set of RequiredCapabilities to be used by the Director / Engine. Doing this will require leveraging RequiredCapabilities to have exclusion rules in addition to the current uses. One thought that comes to mind would be having the Governer's rules be installed as an InstallableUnit on the Profile. This would allow the Governer to be able to cache the rules applicable to a given Profile directly in the Profile, but more importantly, this would allow automatically injecting those rules into the Director / Engine flow without much (any) modification of the logic. Tim "Tim Webb" <tim@xxxxxxxxxx> ( Sent by: E equinox-dev-bounces@eclipse.o m rg To b "Equinox development mailing list" e <equinox-dev@xxxxxxxxxxx > d 08/14/2007 05:35 PM cc d (Embedded image moved to file: e pic32347.gif) d Subject i Please respond to Re: [equinox-dev] [prov] m Equinox development mailing Ruminations on IDirector vs. a list < ProvisioningHelper-like entity g equinox-dev@xxxxxxxxxxx> e m o (Embedded image moved to file: v pic29224.gif) e (Embedded image moved to file: d pic24976.gif) t o f i l e : p i c 0 8 8 3 6 . g i f ) Pascal, Thanks for the thoughts. This definitely gives me some further fodder for my investigation. Regarding the having an Engine that is used Server-side that relays to the client, I'm not sure how the current implementation would be used to accomplish that. Wouldn't the Engine need to be per-request in the case where a server is managing many systems? If so, the install and uninstall operations would need to be designated the corresponding Engine for the appropriate request. Or... Is there going to be a way to instantiate a different director per-request? If so, are we planning to expose an API for the "standard" Director that would allow specification of the corresponding Engine? Tim On 8/14/07, Pascal Rapicault < Pascal_Rapicault@xxxxxxxxxx> wrote: For the director / engine interaction here are some notes: - The Engine is API and one could decide to directly invoke it. - Currently the director is really simplistic and is far from being complete. Also this implementation is not opened and it is normal that you don't see what you are looking for. - When Jeff says no change to the director, he refers to the fact that the director could be reused on the server (maybe after some refactoring of the current code) but he does not exclude the presence of a "proxy director" on the client. For example one could imagine that on the server there would be a full blown director and an Engine. This Engine would be a proxy engine whose responsibility would be to send back actual commands to the engine running on the client. Therefore the flow would go as follow: - the proxy director on the client is invoked for installation - it contacts the director on the server which generates the list of instructions, - the list of instructions is given to the server engine which streams those to the engine - this client engine receives the instructions and executes them. In this case the communication client / server is an implementation detail of your client. - In the previous description, the proxy director could be aware of a local director to fallback on when running in disconnected mode. - Other pieces of the agent infrastructure are expected to be pluggable such as local stores, registries, etc. HTH PaScaL "Tim Webb" <tim@xxxxxxxxxx > Sent by: To equinox-dev-bounc "Equinox development mailing list" es@xxxxxxxxxxx < equinox-dev@xxxxxxxxxxx > cc Maya development mailing list 08/14/2007 02:55 < maya-dev@xxxxxxxxxxx> PM Subject [equinox-dev] [prov] Ruminations on IDirector vs. Please respond to ProvisioningHelper-like entity Equinox development mailing list <equinox-dev@ecli pse.org> Bare with me -- a few issues to get through... Currently the IDirector interface has two methods : install and uninstall. In looking through the code of ProvisioningHelper and IDirector (SimpleDirector) I'm not sure as to the right way to describe to the user the series of operations that would be performed in installing software X prior to actually initiating the installation. I could duplicate similar code to what is found in SimpleDirector using the ProfileInstallRegistry and DependencyExpander to determine what would be required -- however, this seems to be duplicating a significant amount of logic. Would it make sense to add to IDirector a call that would expand a given set of installRoots to the series of ProvisioningOperands that would be required? Such as... interface IDirector { .... public IStatus describeInstall(InstallableUnit[] installRoots, Profile profile, ProvisioningOperandCollection operands, IProgressMonitor monitor); public IStatus describeUninstall(InstallableUnit[] uninstallRoots, Profile profile, ProvisioningOperandCollection operands, IProgressMonitor monitor); } Separately, who would be responsible for determining an upgrade vs. install operation? The current implementations of SimpleDirector and NewSimpleDirector seem to assume that the software is an install. Is it safe to assume that with time the default IDirector implementation will be able to handle determining when an Update should be performed instead of an Install? As it turns out, in potentially using the Director server-side in Maya, we need to be able to return the operations that need to be performed back to the client. In addition, we may wish to show to the user what the impact of performing a given operation would be prior to actually having the user &n bsp; perform it. In discussions with Jeff I understand that it is preferred to leave the current director implementation in-tact without requiring each way it is consumed to implement a new director. Given this desire, we're going to want to find a way to encode the operations to be performed into an XML description to deliver back to the client. To accomplish this, we will need a way of describing the operations to be performed and then have a way to encode / decode them. Approaching the issue another way, in the best case usage, the Maya provisioning client connects to the server exactly once. It requests the instructions to be used in ensuring it has the right software. If we were to attempt to switch the IDirector to be behind an RPC-type facade, we will need at least two connections to the server -- one to get the list of InstallRoots and a second to tell the Director to install. Currently, we couldn't do this since the IDirector assumes it knows where the engine is -- passing the engine in as a parameter would help allowing the director to be remote from the executing engine. Next, in some situations the user in a Maya installation may wish to install software locally. Depending on the policy / governance configuration, I could imagine this operation being performed without contacting the server - requiring a functioning local director, however, for some deployments you may need to contact the server to determine if you are allowed to perform the requested task. In this mode, having the IDirector as an RPC may be required. The exact policy might even be based on what the requested install actually entails. Assuming all of this is makes some sense, how would you avoid having to reimpement the IDirector implementation? One option would be to have a GovernanceAwareProxyDirector (I know, horrible name), that would be able to decide if it just defers to the standard local Director implementation or leverages the server-side Director to determine the operations to be performed. When it contacts the server-side director, it might receive back a serialized form of the provisioning operands. Using this list of operands, it could then directly contact the local engine or potentially call the standard simple director assuming it had another function such as: interface IDirector { .... public IStatus executeOperands(IAdaptable operands, IProgressMonitor monitor); } Now I don't suggest adding such an operation is an ideal solution -- but I am curious if we want to expose to someone other than the director direct access to the engine. If not, then I'm struggling a bit in how to best balance the needs of a hybrid deployment where you sometimes use a local director and then occasionally have to call out to a remote director. As I write this all out, the more I feel that the entity running on the server is potentially not a standard Director but is Director-like. I like the idea of keeping a local director always running even when deferring some operations to a server-side component to augment the processing. The benefit to always having the client-side director is that it can ensure consistency of the local system for instance when there is software installed locally that is not tracked by the central server -- the server-side resolution would check software within it's domain are correctly configured for the client including executing various policy decisions but the client-side director would handle resolution to determine if the software not known to the central server is still valid. Phew. 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