[Glass] GsDevKit Server Blocks for Thin Client appications ... pre-announcement
Mariano Martinez Peck via Glass
glass at lists.gemtalksystems.com
Thu Apr 30 10:26:29 PDT 2015
Hi Pierre,
Do you want to do a super killer example of using Roassal and ServerBlocks?
As you may known, since in Smalltalk you cannot delete an object (compared
to relational DBs where you do delete rows), removing all references to an
object so that is GCed, sometimes is not a walk in park. Ben was tired of
using the Pharo Explorer for that, and he did this:
http://smalltalkhub.com/#!/~BenComan/PointerDetective
If that is valuable in Pharo, imagine in GemStone. And now, with the
serverBlocks, that would be very easy.
Just see today's email of Otto saying he couldn't GC an object.
To find pointers to an object in GemStone:
SystemRepository findReferencePathToObject: 123456789 asObject
yeah...maybe I should try it myself :)
On Wed, Apr 29, 2015 at 7:42 PM, Pierre CHANSON <chans.pierre at gmail.com>
wrote:
> Thanks again Dale !
>
> here are three small examples using these blocks in the roassal workspace
> of tODE: https://vimeo.com/126435220
>
> I highlight here the server blocks in red.
>
> The first one is a Mondrian view of the class Collection (server side)
> with all it's subclasses.
> The classes are processed in the block and stocked statically on the
> variable "classes".
>
>
> --------------------------------------------------------------------------------------------------------------------------------------
> | b classes |
> classes := shell onServerDo:[Collection withAllSubclasses collect: [ :c |
> c name -> {(c superClass name). ((c instVarNamed: #methDicts asString)
> numElements)}]].
>
> b := RTMondrian new.
> b shape circle.
> b nodes: classes.
> b edges connectFrom: [:e | classes detect: [ :c | c name = e value first ]
> ifNone:[ nil ]] .
>
> b shape bezierLineFollowing: [:e | classes detect: [ :c | c name = e value
> first ] ifNone:[ nil ]];
> color: (Color blue alpha: 0.2).
>
>
> b normalizer
> normalizeSize: [:e | e value second ] using: #sqrt;
> normalizeColor: [:e | e value second ] using: (Array with: Color green
> with: Color red) using: #sqrt.
> b layout cluster.
> b build.
> b view open
>
> --------------------------------------------------------------------------------------------------------------------------------------
>
> The second script use the RTExploraBuilder to do the same process, but
> this time the builder call dynamically the server on clics (we are using
> the oop of objects).
>
>
> --------------------------------------------------------------------------------------------------------------------------------------
> | builder |
> builder := RTExploraBuilder new.
> builder shape circle
> size: 30;
> color: (Color blue alpha: 0.5);
> if: [ :cls |
> (shell onServerDo: [ (Object _objectForOop: (cls value))
> subclasses size]) = 0 ] fillColor: (Color red alpha: 0.5).
> builder
> layout: [RTClusterLayout new horizontalGap: 80];
> onClickExplore: [ :cls |
> shell onServerDo: [ ((Object _objectForOop: (cls value))
> subclasses collect: [:c | c asString -> c asOop]) asArray ]
> ];
> withPopup: [:cls | cls key];
> dragChildren;
> node: (shell onServerDo: [Collection asString -> Collection asOop]
> );
> open.
>
> --------------------------------------------------------------------------------------------------------------------------------------
>
>
> The last script is about users. This need the last version of Roassal. We
> present some selection menus, a button and a radar Chart. Created with the
> RTMenuBuilder the button add a new user on the server with the
> characteristics selected in the other menus and present the characteristics
> of the added users on a Kiviat chart on the view.
>
>
> --------------------------------------------------------------------------------------------------------------------------------------
> |nameMenus privilegeMenus groupMenus|
> v := RTView new.
>
> kiv := RTKiviatBuilder new view: v.
> n := RTMultiLinearColorForIdentity new objects: (kiv objects).
> kiv shape circle color: [ :value | n rtValue: value kiviatNode named];
> size: 10.
>
>
> kiv addMetric: [ :v | v second size] max: 5 title: 'groups'.
> kiv addMetric: [ :v | v third size] max: 5 title: 'privileges'.
> kiv addMetric: [ :v | v first size] max: 10 title: 'name'.
>
>
> kiv activatePolygons.
> kiv build.
>
> b := RTMenuBuilder new view: v.
>
> nameMenus := Array with: ('Henri'->[:m |]) with: ('Bob'->[:m |]) with:
> ('Robert'->[:m |]).
> groupMenus := Array with: ('Subscribers'->[:m |])
> with:('Publishers'->[:m |]).
> privilegeMenus := Array with: ('ObsoleteStatistics'->[:m |])
> with:('UserPassword'->[:m |]) with:('SessionAccess'->[:m |]).
>
>
> b menu: 'add User' callback: [
> |name groups privileges |
>
> name := (nameMenus detect: [ :m | m selected ]) name.
> groups := (groupMenus select: [:m | m selected]) collect: [:g | g
> name].
> privileges := (privilegeMenus select: [:m | m selected]) collect:
> [:p | p name].
> shell onServerDo: [
> AllUsers addNewUserWithId: name password: ''
> defaultObjectSecurityPolicy: nil privileges: privileges inGroups: groups .
> System commitTransaction.].
> kiv addDynamicObject: (Array with: (name) with: (groups) with:
> (privileges))
> ].
>
> nameMenus := b menu: 'user' subcheckmenus: nameMenus background:
> (Color red alpha: 0.3).
> RTMenuGroup on: nameMenus.
> nameMenus first selected: true.
>
>
> groupMenus := b menu: 'groups' subcheckmenus: groupMenus background:
> (Color blue alpha: 0.3).
> groupMenus first selected: true.
>
>
> privilegeMenus := b menu: 'privileges' subcheckmenus: privilegeMenus
> background: (Color green alpha: 0.3).
>
> privilegeMenus first selected: true.
>
> b view open.
>
> --------------------------------------------------------------------------------------------------------------------------------------
>
> Pierre
>
>
>
>
> 2015-04-23 19:58 GMT+02:00 Mariano Martinez Peck via Glass <
> glass at lists.gemtalksystems.com>:
>
>>
>>
>> On Wed, Apr 22, 2015 at 1:53 AM, Richard Sargent <
>> richard.sargent at gemtalksystems.com> wrote:
>>
>>> Mariano,
>>>
>>> Depending on what you mean by "execute stuff on server Y", 3.2 includes
>>> something called GsExternalSession. It it capable of executing Smalltalk
>>> specified in Block on a separate session against the same stone or a
>>> different one.
>>>
>>> It doesn't support copying object graphs, but if your definition of
>>> execute stuff has limited requirements for exchanging data, it could be
>>> what you are looking for.
>>> See the 3.2 documentation for details.
>>>
>>
>> Good to know too. Thanks Richard.
>>
>>
>>> On Apr 21, 2015 7:01 PM, "Mariano Martinez Peck via Glass" <
>>> glass at lists.gemtalksystems.com> wrote:
>>>
>>>>
>>>>
>>>> On Thu, Apr 16, 2015 at 2:23 AM, Dale Henrichs via Glass <
>>>> glass at lists.gemtalksystems.com> wrote:
>>>>
>>>>> A GsDevKit Server Block[1] is a block that is written in-line in
>>>>> client Smalltalk, but is executed in GemStone. For example the following
>>>>> expression is executed in a standard Pharo workspace:
>>>>>
>>>>> | shell x y |
>>>>> shell := TDShell forSessionNamed: 'devKit'.
>>>>> x := 3.
>>>>> y := 4.
>>>>> shell onServerDo: [ x + y ].
>>>>>
>>>>
>>>>
>>>> Dale,
>>>>
>>>> I know (because I already asked a few months/years ago) that from a
>>>> stone X you can do a remote login on stone Y and execute stuff in Y. But
>>>> now I wonder....could server blocks also work for gemstone-gemstone? (my
>>>> gut feelings tell me that yes) I mean, could I run the above code from
>>>> GemStone itself? That would automatically resolve all the remote login
>>>> stuff and the ston serialization.
>>>>
>>>> Thanks in advance,
>>>>
>>>>
>>>>
>>>>> and the `[3 + 4 ]` block is executed in GemStone using the `devKit`
>>>>> session description to log into the stone. The temp vars x and y referenced
>>>>> in the server block and defined in Pharo are shipped across the wire to
>>>>> GemStone along with block source where the block source is compiled and
>>>>> executed. The result is then shipped back across the wire and returned as
>>>>> the result of #onServerDo: message in Pharo. Pharo execution can continue
>>>>> on using the result. STON[2] is used to serialize the objects that are
>>>>> shipped across the wire.
>>>>>
>>>>> For any of you familiar with underpinnings of GemTools, Jade or tODE,
>>>>> this is not necessarily ground-breaking technology, however, exposing this
>>>>> capability to developers just may be.
>>>>>
>>>>> It has been a long standing crime that developers in the Pharo
>>>>> community choose to use MongoDB and MySQL over GemStone, but frankly the
>>>>> problem is that (until now) we have not had a simple client-based solution
>>>>> for adding GemStone-based persistence for native Pharo applications - the
>>>>> pharo developers have not really had a choice.
>>>>>
>>>>> Being able to embed server blocks in client code certainly qualifies
>>>>> as simple. Solution(?), well that remains to be seen, but I am optimistic.
>>>>>
>>>>> As a more concrete example, here's Pharo workspace code that uses
>>>>> NeoCSV running in Pharo to load stone objects in a Dictionary in GemStone:
>>>>>
>>>>> 'NeoCSVBenchmark.csv' asFileReference
>>>>> readStreamDo: [ :stream |
>>>>> | reader converter buffer bufCnt numRecords records |
>>>>> converter := [ :string | NeoNumberParser parse: string ].
>>>>> reader := NeoCSVReader on: (ZnBufferedReadStream on: stream).
>>>>> reader
>>>>> recordClass: NeoCSVTestObject;
>>>>> addIntegerField: #'x:';
>>>>> addIntegerField: #'y:';
>>>>> addIntegerField: #'z:'.
>>>>> buffer := Array new: 1000.
>>>>> bufCnt := 0.
>>>>> [ reader atEnd ]
>>>>> whileFalse: [
>>>>> bufCnt := bufCnt + 1.
>>>>> buffer at: bufCnt put: reader next.
>>>>> bufCnt = buffer size
>>>>> ifTrue: [
>>>>> numRecords := bufCnt.
>>>>> records := buffer.
>>>>> DevKitShell
>>>>> onServerDo: [
>>>>> 1 to: numRecords do: [ :index |
>>>>> | record |
>>>>> record := records at: index.
>>>>> NeoCSVDictionary at: record x put: record ].
>>>>> System commitTransaction.
>>>>> nil ].
>>>>> bufCnt := 0 ] ] ].
>>>>> DevKitShell onServerDo: [ System commitTransaction ]
>>>>>
>>>>> The code ships 1000 instances of NeoCSVTestObject at a pop to
>>>>> GemStone. Using the above technique, one can easily arrange to store some
>>>>> pretty large object graphs in GemStone ... Efficient queries based on
>>>>> standard Smalltalk can be written on the client and transparently performed
>>>>> in GemStone (see the GsDevKitServerBlocks doc[1] for the complete example).
>>>>>
>>>>> Server blocks do not duplicate the functionality GemBuilder for
>>>>> Smalltalk[6][7] which provides transparent replication and maintenance of
>>>>> objects between the client and server. With server blocks you end up with
>>>>> disconnected copies of server objects.
>>>>>
>>>>> Because of this disconnect, I think the best way to architect an
>>>>> application using server blocks, is to plan on "executing all business
>>>>> logic" on the server --- If you are using an MVC pattern, the M would
>>>>> primarily be managed on the server while the VC would be managed on the
>>>>> client.
>>>>>
>>>>> As an application evolves, the code can migrate back and forth between
>>>>> client and server as needed.
>>>>>
>>>>> Most of the server blocks code leverages tODE and has been in use for
>>>>> several years. The code that spelunks in the block structure and extracts
>>>>> the _value_ of temp variables is only a couple of days old and has some
>>>>> pretty rough edges (notice the odd placement of temp variables and
>>>>> declarations in the above example).
>>>>>
>>>>> The server-side debugger and inspectors, etc. will use tODE (at least
>>>>> for now) ... in the server blocks doc[1] I demonstrate an
>>>>> #exportClassToServer: to illustrate the potential to share code in weird
>>>>> and wonderful ways between the client and server.
>>>>>
>>>>> If you have the interest/opportunity to take this code for a spin, let
>>>>> me know. I have written instructions[5] for installing the experimental
>>>>> Roassal Visualization code[4] (GemStone and Pharo3.0 or Pharo4.0) for
>>>>> Pierre Chanson and those instructions can be used for doing work with
>>>>> GsDevKit
>>>>> Server Blocks. There are a handful of obvious things that need to be
>>>>> done:
>>>>> - connection pools
>>>>> - coordinated client/server debuggers
>>>>> - client-side exception handlers for server errors
>>>>> - more???
>>>>> and if folks express interest in start to do exploratory work with
>>>>> server blocks, then I will make time to provide support.
>>>>>
>>>>> I am hoping to have something to announce by Smalltalks in November,so
>>>>> it would be useful if some experienced GemStoners tried things out before
>>>>> then...
>>>>>
>>>>> I do have to finish up the documentation for GsDevKitHome 1.0.0 and
>>>>> tODE 0.1.0 and I'm also committed to doing some work on the 3.3 GemStone
>>>>> release, so we'll see how that goes:)
>>>>>
>>>>> I also think that server blocks can be very useful for the "develop in
>>>>> Pharo, deploy in GemSstone" crowd, since it will be possible to write
>>>>> "pharo-based scripts" to perform server-side tasks ...
>>>>>
>>>>> Questions or comments?
>>>>>
>>>>> Dale
>>>>>
>>>>> [1]
>>>>> https://github.com/GsDevKit/gsDevKitHome/blob/dev/docs/articles/gsDevKitServerBlocks.md
>>>>> #gsdevkit-server-blocks
>>>>> [2] https://github.com/GsDevKit/ston#ston---smalltalk-object-notation
>>>>> [3] https://vimeo.com/123261640
>>>>> [4]
>>>>> https://github.com/GsDevKit/gsDevKitHome/tree/dev/projects/roassal#roassal-visualization
>>>>> [5]
>>>>> https://github.com/GsDevKit/gsDevKitHome/blob/dev/projects/roassal/devBootstrap.md
>>>>> [6] http://gemtalksystems.com/products/gbs-vw/
>>>>> [7] http://gemtalksystems.com/products/gbs-va/
>>>>>
>>>>> _______________________________________________
>>>>> Glass mailing list
>>>>> Glass at lists.gemtalksystems.com
>>>>> http://lists.gemtalksystems.com/mailman/listinfo/glass
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Mariano
>>>> http://marianopeck.wordpress.com
>>>>
>>>> _______________________________________________
>>>> Glass mailing list
>>>> Glass at lists.gemtalksystems.com
>>>> http://lists.gemtalksystems.com/mailman/listinfo/glass
>>>>
>>>>
>>
>>
>> --
>> Mariano
>> http://marianopeck.wordpress.com
>>
>> _______________________________________________
>> Glass mailing list
>> Glass at lists.gemtalksystems.com
>> http://lists.gemtalksystems.com/mailman/listinfo/glass
>>
>>
>
--
Mariano
http://marianopeck.wordpress.com
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