1. A method of implementing Yunten's Dual-Server Web Application Program Architecture (YWAPA) implemented on a set of hardware processors as a means for building target interactive web application systems, wherein the method comprising implementing parts a, b, and c of said YWAPA: (a) a target interactive application program which runs on a network machine wherein said target program is a Document-Free Interactive Web Application Program (DFWAP) which does not internally store, access, generate, process or serve browser-executed dialogue documents such as Hypertext Markup Language (HTML) documents and communicates with a user through execution of, by a web browser or by a generic user interface engine at a client machine, external dialogue documents pre-stored at a document-only HTTP server; wherein, to simplify application-program development process and to overcome shortcomings of HTTP protocol, a DFWAP substitutes for “implicit application behavior structure hidden in and behind cryptic browser pages and page hyperlinks” of HTTP request-response based prior-art application program development practice, an “explicit DFWAP Functional Behavior Structure (FBS) with links to dialogue pages which contain no hyperlinks back into said application program structure” whereby hiding internals of web pages behind said front-end functional behavior and truly separating web-page content from specification of application program behavior; wherein recursive application of grammar rules of YWAM's notational Web Programming Language (WPL) is a means for developing said FBS whereas a DFWAP comprises said program behavior structure further developed to implement functionality specified in said structure; wherein a DFWAP directly controls the execution sequence of dialogue documents at a browser by reversing document-to-program hyperlink convention of prior art as program-to-document links embedded in its execution paths and by commanding the browser to retrieve and execute the dialogue documents it encounters in its execution paths hence provides for enforcing human-engineered and/or mission-specific document sequencing; whereas a browser retrieves said documents from said HTTP server which does nothing else for a DFWAP but serves no other than HTML-code and JAVASCRIPT containing documents and supporting static resource files whereas this server is a DFWAP's only source for unprocessed interactive dialogue documents, wherein: (i) for application-to-user data flow, a DFWAP modifies all dialogue documents not at a server-machine at server-machine's expense but at a client machine via document modification requests it sends through its websocket connections; (ii) for user-to-application data flow, the method provides for transmitting to a DFWAP any browser-recognizable user action, event, data, or object generated at a client machine; (iii) wherein the method extends granularity of browser-program interaction beyond method/page invocations to program-statement/page-element level of interactivity; wherein the method employs per-window websocket connections whereas all documents loaded into a window are automatically bound to the window's websocket connection whereby each document need not explicitly set up its own connection; wherein, a websocket connection process is initiated by a DFWAP's connection request to a browser document but not by a browser document, and said request identifies to a browser a dynamically-generated URI for a server endpoint as a target endpoint for websocket protocol, whereby the method relieves a programmer from managing connection endpoint URI path strings in application source code and in browser-document JAVASCRIPT code; wherein //DC functions in a DFWAP facilitate document-level web-application-program concurrency, and, plurality of Parallel Interactive Document Objects (PIDO's) further facilitate intra-document concurrency; wherein a dialogue document of a DFWAP communicates only with its user and with its DFWAP and communicates with the rest of the WEB through its DFWAP, and a DFWAP can also be called by prior-art technologies as a means for enforcing dialogue document sequencing; wherein the only HTTP request a DFWAP accepts from a web browser running at a client machine is an “upgrade” to websocket connection request and it accepts this message only to be able to connect to a HTTP-based browser; whereas a user interface engine which uses a protocol different than HTTP substitutes for said “upgrade” request a connection request consistent with the protocol it uses; and furthermore, because a DFWAP eliminates document-to-program link convention of HTTP based prior art, no executable application program object in a DFWAP can be accessed and put into execution via a browser document hyperlink; (b) an application program server for instantiating said target DFWAP which also is a DFWAP operative on said network machine wherein, once instantiated, a target DWAP interacts with its user on its own but not through said server; wherein said server continuously listens on a preselected non-standardized TCP listening port for client connection requests and interprets each connection request as a request for connecting to a new instance of a DFWAP; wherein said client is a generic user interface engine which in this embodiment is a web browser; wherein the only HTTP request the server accepts is an “upgrade” to websocket connection request which the server interprets as above; whereas a user interface engine which does not use HTTP protocol substitutes for said “upgrade” request a simple TCP connection request; wherein the server receives said “upgrade” request from a standards-based platform-independent stand-alone Application Instantiation Page (AIP) which the browser retrieves from said HTTP server upon a user's request or upon encountering a hyperlink to said AIP; wherein, contrary to what the keyword “upgrade” of said incoming HTTP request implies, no HTTP communication between this server and the requestor exists prior to said upgrade request; wherein upon receiving said “upgrade” request the server first executes a step of establishing a websocket connection to said AIP, next the server minimally further executes a step of instantiating and executing the target DFWAP as a process or a thread connected to the endpoint of the connection to said AIP; and (c) a set of dialogue documents served by said HTTP server including an HTML-standards-based platform-independent stand-alone “.html” DFWAP instantiation page called Application Instantiation Page (AIP) that provides for a browser-user's hyperlink access to user interface of said otherwise hyperlink-inaccessible target DFWAP of item “a” above, said AIP containing Application Message Processor (AMP) functionality, wherein when retrieved at a client machine by a browser via its hyperlink and executed, first the AIP establishes a persistent TCP socket connection to a pre-established non-standardized listening port of said server of item “b” above which in response executes a step of instantiating and executing the target DFWAP of item “a” above as a process or a thread connected to the endpoint of said TCP connection to said AIP, and next, said target DFWAP constructs its client-machine user interface and its websocket connection to this interface via a //DC function call that activates DSWAP protocol which, by using said connection to said AIP, interacts with AMP of said AIP in setting up said interface and websocket connection to said interface; whereas above disclosed method is also a means for transforming an existing pre-web interactive application program into a web-browser-accessible interactive web application program, and, DFWAP functions developed by above disclosed method for controlling browser-document sequencing can also be embedded in execution paths of HTTP request-response based servers that upgrade to websocket communications.