HP 3000 Manuals

Information Access Server: Learning the Administrator Utility

B : How Access Server Works 

How Access Server Works 

To see how Access Server works, trace a request from Access PC to Access
Server and back.  Figure 1-2 illustrates the path this request will
follow.


          Figure 1-2.  Path between Access PC and Access Server 

For clarity, the process can be divided into three parts:

   *   PC user establishes communication from PC to host HP 3000.
   *   PC user gains access to Access Server.
   *   PC user requests specific information.

Assume that the PCs are properly configured for PC-to-host
communications, that the physical link is set up, and that Access Server
is properly installed and configured.

Establishing PC-to-Host Communications.     

   1.  A PC user selects and runs Access PC. This step places you in one
       of the blocks labeled Access PC in Figure 1-2.  (The load time may
       seem longer than for other software packages because Access PC is
       a very large PC application.)

   2.  Access PC displays the Main Menu screen.

   3.  At the Main Menu, the PC user chooses  Remote Tables .

   4.  If the PC user has not already connected to Access Server on the
       host HP 3000, the Remote Connection screen is provided
       automatically.  Here the PC user enters a valid user name and
       password for Access Server and, if needed, logon information to
       establish a session on the HP 3000.

   5.  If new logon information is provided, Access PC establishes a
       session by invoking a method file on the HP 3000.

   6.  To connect the PC user to Access Server, data communications
       routines send a sequence of commands to the HP 3000.  At this
       point, you have moved into the block labeled Access Server in
       Figure 1-2.  The commands sent to the HP 3000 do the following:

          *   Establish PC-to-host communications, during which the user
              is given a server process on the host HP 3000.

          *   The server process creates a son process associated with
              the PC user's host session.  The son process is called the
              Host Data Server Process (HDSP).

From here on, use Figure 1-2 to track the process as it moves back and
forth between the Access PC block and the Access Server block.

Gaining Access.     

   1.  HDSP checks the information you configured in the data dictionary.

       This is done by opening the databases (HDPDIC and HDPENV) that
       comprise the Information Access data dictionary, reading the
       information, and setting up the operating environment for the PC
       user.  As part of this process, HDSP performs an exchange of
       information with Access PC. A check is made to ensure that the
       user name and password (entered by the PC user at the Remote
       Connection screen in Access PC) identify a user you have
       configured.

   2.  If all goes well, Access PC is informed that this user may indeed
       use Access Server.

       At this point, the PC user sees the Remote Tables screen, which
       lists the names of the remote tables the user can access.

Requesting Information.   

   1.  From Access PC, the PC user selects one or more remote tables.

   2.  Access Server returns to Access PC the lists of item names within
       each table, one table at a time.

   3.  The PC user selects the items to be retrieved as columns in the
       remote table.

   4.  The PC user can now make any one of several requests to manipulate
       the data to be retrieved.  The user can perform queries and can
       ask to display, sort, summarize, generate reports from, and/or
       batch process the data.

   5.  Access Server retrieves the selected information, based on a
       combination of instructions:  those pre-configured by the DBA for
       the requested tables and items (data dictionary definitions), and
       those entered interactively by the PC user at the time of the
       request (Steps 1, 3, and 4).

Remote Data Sources 

Two remote HP 3000 systems are shown in Figure 1-2.

Remote HP 3000s.   

All remote HP 3000 systems must be one node away from the host.  The
configuration shown in Figure 1-2 is a valid configuration.  If, however,
REMOTE2 were linked not to the host but to REMOTE1, Access Server would
not be able to access data on REMOTE2.
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|                                                |
|     References in Information Access Server:   |
|       Database Administration:                 |
|        Chapter 1, Database Administration and  |
|                   Access Server                |
|        Chapter 2, Getting Started:             |
|                   What this Utility Lets You Do|
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MPE/iX 5.0 Documentation