Pathway/iTS Web Client Programming Manual (G06.24+)

Introduction to Pathway/iTS Web Clients
Compaq NonStop Pathway/iTS Web Client Programming Manual—520270-001
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Router Process
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The Transform class, which provides methods to implement the SCREEN COBOL
TRANSFORM statement
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The Program Unit class, which provides methods for setting attributes for a program
unit—for example, the currency symbol and the decimal-point character
•
Special-register classes, which define the Java equivalents of the SCREEN COBOL
special registers
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Exception classes, which provide handling for SCREEN COBOL exceptions
•
User conversion classes, which define the Java equivalent of the standard user
conversion routines in PATHTCPL
The classes and methods in the Java import package are described in detail in Section 6,
Java Import Package Reference.
Router Process
The Java client, working with a standard web browser, communicates with existing
Pathway servers by sending connection requests to a Pathway/iTS router process
residing on a NonStop Himalaya system. The router processes listen and distribute
connection requests for servicing. Each router process is configured with a TCP/IP port
used to associate an application with connection requests.
The router processes support converted web clients that use the HTTP or the raw sockets
protocol and user-written intelligent device support (IDS) requesters that use the raw
sockets protocol. The router processes distribute connection requests from web clients
or intelligent devices to started TERM objects within the TCPs in such a way that the
connection load is optimally balanced among all the TCPs in the Pathway environment.
When all the TERM objects in all the configured TCPs are in use, the router queues
new connection requests until a TERM object is available. The router also queues the
TERM objects that are ready for a connection until a connection request arrives.
Terminal Control Process (TCP)
In support of web clients, the TCPs perform link management and line handling, as they
do for SCREEN COBOL terminal requesters. Within a TCP, each TERM object that
handles a web client is configured with its FILE attribute pointing to a router process.
Each such TERM object sends a message to the router process indicating that it is
available to service a connection. When a client requests a connection, the request is
sent to the router and the router passes the client information to the TCP. The TCP then
establishes a socket connection to the client, verifies access rights, and passes control to
the gateway thread.
The combination of the router and TCP processes provides general load balancing for
gateway threads. TERM objects within multiple TCP processes are associated with a
given router process. This enables the router process to identify the gateway thread that
Note. Although the Pathway/iTS router processes, described in the following subsection,
support both HTTP and raw sockets protocols, the Java import package requires the use of the
HTTP protocol.