Tuesday, March 03, 2009 by rain
17 .6 realizes distributed computation
Last when make up in this in,The distributed computation that we will realize PowerBuilder in network environment.In our program test room,Have two machines,They run Win95.As client computer,One serves as a server.If the condition allows,The machine that recommends better with a function moving NT serves as a server,Such meetings run the ground betterer.
...Tuesday, March 03, 2009 by rain
17 .5 founds Server interface
So far,We had established Server warehouse,In moving object of the NVO in Clients library to Server library,Define and initialization Transport object,Receive the interface that goes down to need to define a moving Server.Press in button press in column window palette pushbutton,The choice is built.
...Tuesday, March 03, 2009 by rain
17 .4 moves NVO in Server
So far till,This is program of a stand-alone only,Still do not have distributed move.Receive go we will NVO moves in another PB library,The program that forms service end to move.
...Tuesday, March 03, 2009 by rain
17 .3 founds Connection Object
Now,We had defined NVO,The acting target that makes it,Have a look how to be defined next again with initialization it links object Connection Object.As different as Transaction object,The system does not make this target automatically to use a program,And need already was defined by hand oneself.
...Tuesday, March 03, 2009 by rain
17 .2 Nonvisual Object and Proxy Object
The first pace,What what we do is the discount computational module generates a blame to be able to inspect object NVO.
Click user object pushbutton,By NEW,The Custom pushbutton in choosing Class casing next,The system appears window of an user object.There is a word to be in the caption column that we can notice the window:Inherited From Nonvisual Object,The object that it shows to we found is NVO.Then we define a function for NVO.The User Object Functions in opening Declare bill of fare,By NEW pushbutton,Opened function to define the window so (graph 17-2) .This function name is GetDiscount,It needs to a parameter is Custom Name (user name) ,The type is.String.
Tuesday, March 03, 2009 by rain
17 .1 establishs distributed program
In on a few chapters,We introduced PowerBuilder distributed calculative basic idea,Be in next paragraphic in,We will make a simple distributed program.The applied process that one the next has existed in light of us,Next make it distributed the program that run.
...Tuesday, March 03, 2009 by rain
16 .Flow of work of 3 distributed PowerBuilder
Below,The working flow that we review distributed PowerBuilder with example.Have two client computer suppose,A server.In each client computer,Have a client respectively end application process is moving.In the server,A service carries applied process to provide a service for program of these two clients.
...Tuesday, March 03, 2009 by rain
16 .2 calls the parameter of function remotely
Client program when calling long-range NVO,The parameter that may use function.These function parameter can be any simple data types (Simple Data Types) ,Include structure, array to wait,Cite means (By Reference) the direct perhaps way that pass a cost (By Value) OK.The parameter that PowerBuilder also supports NVO boy or girl friend.
...Tuesday, March 03, 2009 by rain
16 .1 fictitious machine
In this one chapter,The working mechanism that we describe distributed PowerBuilder in detail.
PowerBuilder is carried in the service is to use what fictitious engine model will come true.Every time when a client computer and server are linked,The memory that the server becomes independent one piece for open up of this client computer,The fictitious machine that forms an independence.
...Tuesday, March 03, 2009 by rain
15 .3 representatives object
If we have a program,It has a lot of processing boy or girl friends,These processing objects just are " knowledge " true owner.The business that we should do is in how putting these targets to different machine,Realize distributed computation.How to accomplish this?In PowerBuilder,Normally the practice is,First NVO of these object make it,Come out the interface abstraction of NVO next,Make it is additional a kind of special target,We call it the representative (Proxy) .The exterior interface just the same of representative and NVO,If a NVO has three public function,With a communal variable,So,Its representative also has three communal case. Number and a communal variable.Notice,We mention public function and variable only,If be them,be illicit some,Won't appear in the representative.Because of this,To realize distributed computation,We should build a such distributed object models:Applied process should need distributed calculative content forms one or more blame to be able to look a boy or girl friend,Namely NVO,The interface target that makes NVO according to NVO next,Act as agent namely object,Next,The NVO that we run true implementation program is put to server end,Put acting target in the client implement on end,This core with respect to model of PB distributed object.Next,Make us relatively detailed object of ground description representative.
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