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diff --git a/devel-docs/query/virtual-folder-in-depth.sgml b/devel-docs/query/virtual-folder-in-depth.sgml deleted file mode 100644 index d3e3e0504b..0000000000 --- a/devel-docs/query/virtual-folder-in-depth.sgml +++ /dev/null @@ -1,407 +0,0 @@ -<!doctype article PUBLIC "-//Davenport//DTD DocBook V3.0//EN" []> - -<!-- SGMLized by Bertrand <Bertrand.Guiheneuf@aful.org> --> - -<article id="index"> - <artheader> - <authorgroup> - <author> - <firstname>Giao</firstname> - <surname>Nguyen</surname> - </author> - </authorgroup> - - <title>An in-depth look at the virtual folder mechanism</title> - <abstract> - <para> - This document describes a different way of approaching mail - organization and how all things are possible in this brave new - world. This document does not describe physical storage issues - nor interface issues. - </para> - <para> - Historically mail has been organized into folders. These - folders usually mapped to a single storage medium. The - relationship between mail organization and storage medium was - one to one. There was one mail organization for every storage - medium. This scheme had its limitations. - </para> - <para> - Efforts at categorizations are only meaningful at the instance that - one categorized. To find any piece of data, regardless of how well - it was categorized, required some amount of searching. Therefore, any - attempts to nullify searching is doomed to fail. It's time to embrace - searching as a way of life. - </para> - <para> - These are the terms and their definitions. The example rules used are - based on the syntax for VM (http://www.wonderworks.com/vm/) by Kyle - Jones whose ideas form the basis for this. I'm only adding the - existence of summary files to aid in scaling. I currently use VM and - it's virtual-folder rules for my daily mail purposes. To date, my only - complaints are speed (it has no caches) and for the unitiated, it's - not very user-friendly. - </para> - <para> - Comments, questions, rants, etc. should be directed at Giao Nguyen - (grail@cafebabe.org) who will try to address issues in a timely - manner. - </para> - </abstract> - </artheader> - - <!-- Definitions --> - <sect1 id="definitions"> - <title>Definitions</title> - <sect2> - <title>Store</title> - <para> - A location where mail can be found. This may be a file (Berkeley - mbox), directory (MH), IMAP server, POP3 server, Exchange server, - Lotus Notes server, a stack of Post-Its by your monitor fed through - some OCR system. - </para> - </sect2> - - <sect2> - <title>Message</title> - <para> - An individual mail message. - </para> - </sect2> - <sect2> - <title>Vfolder</title> - <para> - A group of messages sharing some commonality. This is the result of a - query. The vfolder maybe contained in a store, but it is not necessary - that a store holds only one vfolder. There is always an implicit - vfolder rule which matches all messages. A store contains the vfolder - which is the result of the query (any). It's short for virtual folder - or maybe view folder. I dunno. - </para> - </sect2> - <sect2> - <title>Default-vfolder</title> - <para> - The vfolder defined by (any) applied to the store. This is not the - inbox. The inbox could easily be defined by a query. A default rule - for the inbox could be (new) but it doesn't have to be. Mine happens - to be (or (unread) (new)). - </para> - </sect2> - <sect2> - <title>Folder</title> - <para> - The classical mail folder approach: one message organization per - store. - </para> - </sect2> - <sect2> - <title>Query</title> - <para> - A search for messages. The result of this is a vfolder. There are two - kinds of queries: named queries and lambda queries. More on this - later. - </para> - </sect2> - <sect2> - <title>Summary file </title> - <para> - An external file that contains pointers to messages which are matches - for a named query. In addition to pointers, the summary file should - also contain signatures of the store for sanity checks. When the term - "index" is used as a verb, it means to build a summary file for a - given name-value pair. - </para> - </sect2> - </sect1> - - <!-- Queries --> - <sect1> - <title>Queries</title> - <para> - Named queries are analogous to classical mail folders. Because named - queries maybe reused, summary files are kept as caches to reduce - the overall cost of viewing a vfolder. Summary files are superior to - folders in that they allow for the same messages to appear in multiple - vfolders without message duplications. Duplications of messages - defeats attempts at tagging a message with additional user information - like annotations. Named queries will define folders. - </para> - <para> - Lambda queries are similar to named queries except that they have no - name. These are created on the fly by the user to filter out or - include certain messages. - </para> - <para> - All queries can be layered on top of each other. A lambda query can be - layered on a named query and a named query can be layered on a lambda - query. The possibilities are endless. - </para> - <para> - The layerings can be done as boolean operations (and, or, not). Short - circuiting should be used. - </para> - <para> - Examples: - <programlisting> -(and (author "Giao") - (unread)) - </programlisting> - The (unread) query should only be evaluated on the results of (author - "Giao"). - <programlisting> -(or (author "Giao") - (unread)) - </programlisting> - Both of these queries should be evaluated. Any matches are added to the - resulting vfolder. - </para> - </sect1> - - <!-- Summary files --> - <sect1> - <title>Summary files</title> - <para> - Summary files are only meaningful when applied to the context of the - default-vfolder of a store. - </para> - <para> - Summary files should be generated for queries of the form: - <programlisting> -(function "constant value") - </programlisting> - Summary files should never be generated for queries of the form: - <programlisting> - (function (function1)) - - (and (function "value") - (another-function "another value")) - </programlisting> - Given a query of the form: - <programlisting> - (and (function "value") - (another-function "another value")) - </programlisting> - The system should use one summary file for (function "value") and - another summary file for (another-function "another value"). I will - call the prior form the "plain form". - </para> - <para> - It should be noted that the signature of the store should be based on - the assumption that new data may have been added to the store since - the application generated the summary file. Signatures generated on - the entirety of the store will most likely be meaningless for things - like POP/IMAP servers. - </para> - </sect1> - - <!-- Incremental Indexing --> - <sect1> - <title>Incremental indexing</title> - <para> - When new messages are detected, all known queries should be evaluated - on the new messages. vfolders should be notified of new messages that - are positive matches for their queries. The indexes generated by this - process should be merged into the current indexes for the vfolder. - </para> - </sect1> - - <!-- Can I have multiple stores --> - <sect1> - <title>Can I have multiple stores?</title> - <para> - I don't see why not. Again, the inbox is a vfolder so you can get a - unified inbox consisting of all new mail sent to all your stores or - your can get inboxes for each store or any combination your heart - desire. You get your cake, eat it, and someone else cleans the dishes! - </para> - </sect1> - - <!-- Why all this? --> - <sect1> - <title>Why all this?</title> - <para> - Consider the dynamic nature of the following query: - <programlisting> -(and (author "Giao") - (sent-after (today-midnight))) - </programlisting> - today-midnight would be a function that is evaluated at run-time to - calculate the appropriate object. - </para> - </sect1> - - <!-- Scenarios of usage and their solutions --> - <sect1> - <title>Scenarios of usage and their solutions</title> - <sect2> - <title>Mesage alterations</title> - <para> - This is a fuzzy area that should be left to the UI to handle. Messages - are altered. Read status are altered when a new message is read for - example. How do we handle this if our query is for unread messages? - Upon viewing the state would change. - </para> - <para> - One idea is to not evaluate the queries unless we're changing between - vfolder views. This assumes that one can only view a particular - vfolder at a time. For multi-vfolder viewing, a message change should - propagate through the vfolder system. Certain effects (as in our - example) would not be intuitive. - </para> - <para> - It would not be a clean solution to make special cases but they may be - necessary where certain defined fields are ignored when they are - changed. Some combination of the above rules can be used. I don't - think it's an easy solution. - </para> - </sect2> - <sect2> - <title>Message inclusion and exclusion</title> - <para> - Messages are included and excluded also with queries. The final query - will have the form of: - <programlisting> - (and (author "Giao") - (criteria value) - (not (criteria other-value))) - </programlisting> - Userland criterias may be a label of some sort. These may be userland - labels or Message-IDs. What are the performance issues involved in - this? With short circuiting, it's not a major problem. - </para> - <para> - The criterias and values are determined by the UI. The vfolder - mechanism isn't concerned with such issues. - </para> - <para> - Messages can be included and excluded at will. The idea is often - called "arbitrary inclusion/exclusion". This can be done by - Message-IDs or other fields. It's been noted that Message-IDs are not - unique. - </para> - <para> - I propose that any given vfolder is allocated an inclusion label and an - exclusion label. These should be randomly generated. This should be - part of the vfolder description. It should be noted that the vfolder - description has not been drafted yet. - </para> - <para> - The result is such that the rules for a given named query is: - <programlisting> - (and (user-query) - (label inclusion-label) - (not exclusion-label)) - </programlisting> - </para> - </sect2> - <sect2> - <title>Query scheduling</title> - <para> - Consider the following extremely dynamic queries: - <programlisting> - A: - (and (author "Giao") - (sent-after (today-midnight))) - - B: - (and (sent-after (today-midnight)) - (author "Giao")) - - C: - (or (author "Giao") - (sent-after (today-midnight))) - </programlisting> - Query A would be significantly faster because (author "Giao") is not - dynamic. A summary file could be generated for this query. Query B is - slow and can be optimized if there was a query compiler of some - sort. Query C demonstrates a query in which there is no good - optimization which can be applied. These come with a certain amount of - baggage. - </para> - <para> - It seems then that for boolean 'and' operations, plain forms should be - moved forward and other queries should be moved such that they are - evaluated later. I would expect that the majority of queries would be - of the plain form. - </para> - <para> - First is that the summary file is tied to the query and the store - where the query originates from. Second, a hashing function for - strings needs to be calculated for the query so that the query and the - summary file can be associated. This hashing function could be similar - to the hashing function described in Rob Pike's "The Practice of - Programming". (FIXME: Stick page number here) - </para> - </sect2> - <sect2> - <title>Archives</title> - <para> - Many people are concerned that archives won't be preserved, archives - aren't supported, and many other archive related issues. This is the - short version. - </para> - <para> - Archives are just that, archives. Archives are stores. Take your - vfolder, export it to a store. You are done. If you load up the store - again, then the default-vfolder of that store is the view of the - vfolder, except the query is different. - </para> - <para> - The point to vfolder is not to do away with classical folder - representation but to move the queries to the front where it would - make data management easier for people who don't think in terms of - files but in terms of queries because ordinary people don't think in - terms of files. - </para> - </sect2> - </sect1> - - <!-- Miscellany --> - <sect1> - <title>Miscellany</title> - <sect2> - <title>Annotations</title> - <para> - There should be a scheme to add annotations to messages. Common mail - user agents have used a tag in the message header to mark messages as - read/unread for example. Extending on this we have the ability to add - our own data to a message to add meaning to it. If we have a good - scheme for doing this, new possibilities are opened. - </para> - <sect3> - <title>Keywords</title> - <para> - When sending a message, a message could have certain keywords attached - to it. While this can be done with the subject line, the subject line - has a tendency to be munged by other mail applications. One popular - example is the "[rR]e:" prefix. Using the subject line also breaks the - "contract" with other mail user agents. Using keywords in another - field in the message header allows the sender to assist the recipient - in organizing data automatically. Note that the sender can only - provide hints as the sender is unlikely to know the organization - schemes of the recipient. - </para> - </sect3> - </sect2> - <sect2> - <title>Scope</title> - <para> - Let us assume that we have multiple stores. Does a query work on a - given store? Or does it work on all stores? Or is it configurable such - that a query can work on a user-selected list of stores? - </para> - </sect2> - </sect1> - - <!-- Alternatives to the above --> - <sect1> - <title>Alternatives to the above</title> - <para> - Jim Meyer (purp@selequa.com) is putting some notes on where - annotations needs to be located. They'll be located here as well as - any contributions I may have to them. - </para> - </sect1> -</article> |