Cooperative service interface with buffer and lock pool sharing, for enhancing message-dialog transfer between network provider and distributed system services

An Input Interface functions for a Cooperative Service Interface unit and enables data from a network to be placed in a designated input buffer of a Network Provider (NP) which can convey pointers to a Distributed System Service (DSS) unit's image buffer pool for access of the data by said DSS from memory. Sharing of buffer pools and lock pools lessen the overhead and latency which would normally burden such data transfers.

FIELD OF THE INVENTION 
The present disclosure relates to high-speed data commimication systems 
having interfaces to provide performance improvements for Network 
Providers and their Users. 
CROSS REFERENCES TO RELATED APPLICATIONS 
This application is related to co-pending application U.S. Ser. No. 
09/060,649 entitled "Output Interface method and System for enhanced Data 
Transfers via Cooperative Service Interface" and which is incorporated by 
reference. Also incorporated by reference are the following co-pending 
cases: 
U.S. Ser. No. 09/060,651 entitled "Network Data Path Interface Method and 
System for Enhanced Data Transmission; 
U.S. Ser. No. 09/060,647 entitled "Multiple Interface High Speed Data Com 
System and Method Utilizing Multiple Connection Library Interfaces With 
Buffer and Lock Pool Sharing"; 
U.S. Ser. No. 09/060,648 entitled "Connection Library Interface System and 
Method for Process Inter-Com mication Manager and Process 
Inter-Communication Element". 
BACKGROUND OF THE INVENTION 
In the data communication field involving computers and networking, there 
is a basic concept of the "dialog", which in computing circles, involves 
the exchange of human input and the immediate machine response that forms 
a "conversation" between an interactive computer and person using it. 
Another aspect of the "dialog" is the reference to the exchange of signals 
by computers communicating on a network. Dialogs can be used to carry data 
between different application processes, and can be used to carry data 
over computer networks. In computer networking, dialogs can be considered 
to provide data communication between application processes running on 
different systems or different hosts. Further, dialogs can carry data 
between application processes running on the same host. 
There is a generally recognized OSI (Open System Interconnection) standard 
for worldwide message transfer communications that defines a framework for 
implementing transfer protocols in 7 layers. Control is passed from one 
layer to the next, starting at the layer called "the Application Layer" in 
one station, proceeding to the bottom layer, over the channel to the next 
station, and back up the layers of a hierarchy which is generally 
recognized as having 7 layers. Most of all communication networks use the 
7-layer system. However, there are some non-OSI systems which incorporate 
two or three layers into one layer. 
The layers involved for network Users are generally designated from the 
lowest layer to the highest layer, as follows: 
1. The Physical Layers 
2. The Datalink Layers 
3. The Network Layers 
4. The Transport Layer; 
5. The Session Layer; 
6. The Presentation Layer; and 
7. The Application Layer. 
The Application Layer 7 (top layer) defines the language and syntax that 
programs use to communicate with other programs. It represents the purpose 
of communicating. For example, a program in a client workstation uses 
commands to request data from a program in a server. The common functions 
at this Application Layer level are that of opening, closing, reading and 
writing files, transferring files and e-mail, executing remote jobs, and 
obtaining directory information about network resources. 
The Presentation Layer 6 acts to negotiate and manage the way the data is 
represented and encoded between different computers. For example, it 
provides a common denominator between ASCII and the EBCDIC machines, as 
well as between different floating point and binary formats. This layer is 
also used for encryption and decryption. 
The Session Layer 5, coordinates communications in an orderly manner. It 
determines one-way or two-way communications, and manages the dialog 
between both parties, for example, making sure that the previous request 
has been fulfilled before the next request is sent. This Session Layer 
also marks significant parts of the transmitted data with checkpoints to 
allow for fast recovery in the event of a connection failure. Sometimes 
the services of this session layer are included in the Transport Layer 4. 
The Transport Layer 4, ensures end to end validity and integrity. The lower 
Data Link Layer (Layer 2) is only responsible for delivering packets from 
one node to another). Thus, if a packet should get lost in a router 
somewhere in the enterprise internet, the Transport Layer will detect this 
situation. This Transport Layer 4 ensures that if a 12MB file is sent, the 
full 12MB will be received. OSI transport services sometimes will include 
layers 1 through 4, and are collectively responsible for delivering a 
complete message or file from a sending station to a receiving station 
without error. 
The Network Layer 3 routes the messages to different networks. The 
node-to-node function of the Datalink Layer (Layer 2) is extended across 
the entire internetwork, because a routable protocol such as IP, IPX, SNA, 
etc., contains a "network address" in addition to a station address. If 
all the stations are contained within a single network segment, then the 
routing capability of this layer is not required. 
The Datalink Layer 2 is responsible for node-to-node validity and integrity 
of the transmission. The transmitted bits are divided into frames, for 
example, an Ethernet, or Token Ring frame for Local Area Networks (LANs). 
Layers 1 and 2 are required for every type of commication operation. 
The Physical Layer 1 is responsible for passing bits onto and receiving 
them from the connecting medium. This layer has no understanding of the 
meaning of the bits, but deals with the electrical and mechanical 
characteristics of the signals and the signaling methods. As an example, 
the Physical Layer 1 comprises the RTS (Request to Send) and the CTS 
(Clear to Send) signals in an RS-232 (a standard for serial transmission 
between computers and peripheral devices) environment, as well as TIM 
(Time Division Multiplexing) and FDM (Frequency Division Multiplexing) 
techniques for multiplexing data on a line. 
It will be seen that present-day comunication systems generally will have a 
high band-pass capability of data throughput for high speed network 
technologies which may occur at rates on the order of 100MB per second, to 
1 gigabit per second. 
However, sometimes the problems of delays or latency may be high. Latency 
is generally considered to be the time interval between the time a 
transaction issues and the time the transaction is reported as being 
completed. In certain systems having a high latency, the round-trip time 
for two clients communicating with each other to complete a data request 
can be on the order of milliseconds. 
The delays in communication due to "latency" will be seen to occur from 
conventional communication systems due partly to overhead in the 
communication layers, and generally is especially due to latency in the 
layers below the Transport Layer 4, i.e., Layers 3, 2 and 1. 
In high speed data communication systems, the Transport Layer 4 is still 
seen to impart substantial latency in communications. 
The present method and system describes the sequential operations for 
operating the Input Interface for a Cooperative Service Interface between 
Network Providers and their Users, such as DSSs (Distributed System 
Service) units which enhances the speed of dialog exchanges and this 
improves communication system performance. Further, the present Input 
Interface is used to supersede previously used sync Port Interfaces which 
had a number of latency problems. The sync Port Interfaces used an earlier 
Connection Block technology which had extra sublayers in the data path and 
had locking protocols which were not integrated so that each module had 
its own private lock which required considerable time to be spent in 
locking, unlocking and synchronization. 
SUMMARY OF THE INVENTION 
A Cooperative Services Interface is used to control message dialog 
transfers between a Distributed System Service (DSS) program and a Network 
Provider's layer of protocol. The Cooperative Services Interface involves 
a series of connections, connection rules, procedure headings and shared 
states implemented via a Connection Library (CL). 
The DSS operates at the Application Layer services of the OSI (Open Systems 
Interconnection Standards) while the Network Provider implements the 
Session, Transport, and Network Layers. 
An input channel in the I/O module places a request in a message queue for 
incoming data to be placed in a selected buffer in the Network Provider 
where the message's header is parsed for transmittal to the DSS. 
Image pointers in the DSS and the Network Provider provide access to 
messages in memory without having to actually move buffer data across the 
Cooperative Services Interface. 
Buffer sharing is implemented so that the Network Protocol Stack of the 
Network Provider has "input" buffers whereby ownership of these "input" 
buffers is logically transferred to the DSS when the DSS chooses to retain 
ownership of a buffer (holding a dialog message) delivered to the DSS. 
Sharing reduces need for data copying and enhances performance. Ownership 
of these shared buffers is returned to the original owner when the 
borrowing User is finished with the buffer. 
Additionally, a locking system is used whereby dialog locks are shared 
between the DSS and Network Provider making code easier to implement for 
increased performance.

GLOSSARY LIST 
1. Distributed System Services (DSS): One of a collection of services 
provided on Unisys Host computers to support communication across 
multi-host networks. DSSs can be services such as file handling, station 
transfer, and mail transfer. 
2. Cooperative Service Interface (Co-op): A systems level, 
connection-library based interface which allows the Distributed System 
Services (DSS) to communicate across the network with their peers. A 
system and method for using the services of a network provider to 
communicate with another instance of themselves somewhere else enabling 
communication to occur across a network. 
3. Connection Library (CL): This is method of connecting two code files 
together at run time so that they can use each other's services. The 
Connection Library is a collection of one or more connection library 
elements and a library template. The "Library Template" is a structure 
that is built by the compiler and maintained by the Master Control Program 
(MCP) that determines what the procedures and functions and items that you 
are trying to import from the library. This involves a multiplicity of 
Connection Library elements. A Connection Library (or Server Library) 
permits access to another program's exported procedures and data. 
Connection Libraries allow one or more instances of two-way access, to the 
other program, and from the other program to the Library. Server Libraries 
allow only once instance of one-way access. 
4. The Port File: A port file is an interface that allows programs to talk 
to their peers on the same system or other systems and which is based on 
the file interface. The "file interface" is used for disks, tapes, and 
card readers and all the traditional peripheral types and the port file 
provides adaptation of that interface for interprocess communication. 
5. Sync Port Connection Block (CB): This was an older version of the 
cooperative interface which did not permit lock sharing or buffer sharing. 
Connection Block later evolved into more versatile operations as 
Connection Libraries and likewise the co-op interface was the evolution of 
improvements to the Sync Port Interface. The Sync Port Interface uses 
connection blocks while the more highly developed co-op interface uses 
Connection Libraries whereby the new co-op interface used buffer sharing, 
lock sharing and fault management. 
6. Provider: Provider is just a system or operation or a piece of software 
that provides a service. It could be looked at as a collection of software 
that provides a service. 
7. Process Intercommunication Element-Connection Library (PIE-CL): This is 
the interface used by the port interface software to talk to the Network 
Provider. 
8. Process Intercommunication Element-Connection Block (PIE-CB): This is an 
interface used by the port interface software to talk to the Network 
Provider using an earlier form of technology designated as the connection 
block technology. The old PIE-CB technology did not provide for lock 
sharing and buffer sharing but the new PIE-CL (Connection Library) does 
provide lock sharing and buffer sharing. 
9. Scatter Consolation: This is code put into NP Support software to make a 
machine which does not have hardware scatter capabilities appear to have 
scatter capabilities. Scatter is the operation of taking data coming in 
off an I/O bus and putting it into multiple different areas in the local 
memory, that is to say, it is scattered around. 
10. Distributed Application Supervisor (DAS): This is a unit that has a 
function of determining what software should be loaded into the channel 
adapter, into the integrated communications processor (ICP) etc. It also 
is used to manage exceptions that it may notice, for example, such as 
software that is running in the ICP, which may detect some error and then 
the DAS must determine how to handle the error. 
11. Network Support: A process which controls when Network Providers and 
DSSs are initiated and terminated and which routes network-related 
operator entered coamands and their responses. 
11a. NP Support: Network Processor Support. The software which allows 
Network Provider access to the Input and Output Queues, which contains 
Nultiqueue Simulation software, and which multiplexes and demultiplexes 
data across the single input and output queues used in the earlier method 
of implementation of functions for a network data path interface. 
12. Multiple Queue: There are I/O queues between the host memory and 
channel adapter card. The present system can define up to 16 queues in its 
I/O architecture which is an advantage over the earlier use of only two 
queues which involved one queue for input and one queue for output. 
Putting in multiple queues, gave each module a direct queue so that there 
was no need for multiplexing over one queue and then de-multiplexing on 
the other end. Thus, now each receiver would have its own queue. 
12a. MQ simulation software is in NP Support which "simulates" Multiple 
Queues on systems where the hardware does not support multiple queues. 
13. Connection Block (CB): This is a method of connecting two code files 
together at run time so that they can use each other's services. It is 
similar to a file or a task or a job or a database or any of these types 
of abstract objects that are used in a given program. A CB is a less 
robust implementation of a Connection Library (CL). 
14. Supervisor CB/CL: This involves the supervisor connection 
block/connection library and this is the interface object that the NP 
Support uses to talk to the distributed application supervisor (DAS). 
15. Physical I/O: The Physical I/O system is part of the Master Control 
Program of the Unisys computer system hierarchy. This involves the 
software that talks to the hardware controllers. For example, it operates 
so as to indicate that it wants sector 35 off disk 22 and seeks 57 bytes 
from that location. 
16. Logical I/O (LIO): Logical I/O is also part of the Master Control 
Program (MCP) and involves the file interface code. Whenever writing is 
done to a file or read from a file in a program, the system is actually 
calling the MCP module called Logical I/O. The Port File interface code is 
also a subpart of logical I/O. It has its own module but provides Logical 
I/O functions for the Port Files. The regular Logical I/O operates with 
disks, tapes, printers, card punches and other peripherals. 
17. Gather Simulation: This is provided by code in the physical I/O. Gather 
is an output operation whereby the I/O management module goes to the 
memory and gets certain messages or data from one location and then from 
another location and from another location and puts it together in order 
to pass it on to a particular peripheral such as a tape. 
Contrarily, "Scatter" operates the other direction, for example, the IOM 
will indicate that it has a stream of bits from a particular tape and it 
is then going to put some of this information here in one place, some of 
it here in another place and some of it in another or third place and that 
is the "scatter" operation. 
18. Network Processor: Examples of these units are Channel Adapters, 
Integrated Communication Processor (ICP), Emulated Integrated 
Communication Processor (KICP), DICPs and Network Interface Cards. An 
integrated communication processor is often called a Data Link Processor 
(DLP) and, in particular, ICP is a Data Link Processor that has a Network 
Interface Card (NIC) associated with it. Channel Adapters also have 
Network Interface Cards. 
18a. An emulated ICP is a portion of software that "pretends" to be the 
Network Interface Card on a system that operates on the basis of emulating 
the I/O mainframe system, such as was done in the Unisys Micro-A or Unisys 
A-7 and other systems. These systems do not supply any specialized I/O 
hardware but rather provide software that emulates that specialized 
hardware. Thus an emulated ICP is a portion of software that pretends to 
be and operate as if it were ICP/DLP. 
18b. Direct Integrated Communication Processor (DICP): The DICPs are also 
actually known as "channel adapters" and they are the units that replace 
the datalink processors (DLP) in the new I/O architecture. Thus a direct 
integrated couuunication processor is a channel adapter that does 
networking operations. 
19. Interfaces--Cooperative System Services: They involve (i) an input data 
path for dialogs associated with the Connection Library between the 
Network Provider and the DSS; (ii) an output data path for dialogs 
associated with the Connection Library between the DSS and the Network 
Provider. 
20. Channel Adapters (CA): A channel adapter is a device that enables 
hardware using two different types of communication channels to 
communicate. 
21. Path Sub-System (PSS): This is the peer of NP Support that runs in the 
integrated communication processor (ICP), the emulated integrated 
communication processor (EICP) or the direct integrated coemunication 
processor (DICP). This is the unit that the NP support talks its QSP 
protocol to. 
22. Protocol Stack Extension Logic (PSEL): This is part of the network 
provider involving its protocol stack that runs in the integrated 
communication processor (ICP). 
23. COMS: This represents a communications management system. It is a 
Unisys message control system that supports processing for a network on 
the Unisys ClearPath NX server. It is described in the reference: Unisys A 
Series Communication Management System (CNS) operations guide, May 1989, 
Doc. 1154523.380. 
24. Protocol Specific Handler (PSH): This is software which talks to items 
such as communication processors in order to get terminal access. 
25. Network Selector Module (NSM): This is part of Ports Module in the 
Master Control Program (MCP). Its purpose is to take a User's File Open 
Request, a port file, and determine which Network Provider should be used. 
The Network Selector Module 9 (FIG. 3A) selects a Network Provider 20 to 
use for a specific instance of the port interface. 
26. Library Template: A structure built by the compiler and maintained by 
the MCP to determine the procedures, functions and items to be imported 
from the Connection Library. 
27. Pipe: A pipe is a path (input or output) between a Network Provider and 
the Channel Adapter/Integrated Communications Processor (CA/ICP), which is 
associated with a specific end point. A pipe can be associated with a 
connection end point on the ICP/CA for output or to a specific entity end 
point (upper layer protocol) in the Network Provider for input. The use of 
pipe is defined by the Network Provider and the CA/ICP and the QSP IDs 
which are used to uniquely identify each pipe. QSP refers to the Queue 
Service Provider. A pipe may or may not map directly to a specific queue. 
28. Queue: A queue number identifies a specific I/O queue relative to a 
particular ICP/CA (Integrated Communications Processor/Channel Adapter). 
Each queue is an independent list of I/O requests. Within each queue, 
requests are ordered. There is no ordering of requests in different 
queues. The ICP/CA is given one request at a time (the one at the head of 
the list) from each queue. 
29. Queue Service Provider (QSP): This is a unit that provides the queue 
service to a requester. It is basically a protocol that puts everything 
into one queue and takes it all back off. That protocol is called QSP 
protocol (Queue Service Provider). 
30. Pipe ID: A field in the QSP protocol which identifies the logical pipe. 
It is used for multi-queue simulation. 
31. Dialog: A dialog or dialogs are operations which carry data between 
different applications processes. Dialogs can be logically set to carry 
data over a computer network. In a computer network, dialogs provide data 
comuncation between application processes running on different end systems 
or hosts. Dialogs can also carry data between application processes 
running on the same host. Dialogs are implemented by the use of the 
various functional layers for exazple, Application, Presentation Session, 
Transport, Network, Link and Physical, which are used in data 
communication networks to provide various services and also reliability. 
Each layer will have its own particular protocol and range of fundamental 
instructions in order to provide services. Dialog operations and 
particular features may sometime include the scatter support and gather 
support. 
32. Connection Library Element: This is one element of the Connection 
Library which may involve multiple elements. It provides much like the 
FILE object in a program (which is the actual file on disk), but rather it 
is an OBJECT in the program that allows access to an actual file on the 
disk. 
33. Network Provider: A software operation which implements the 
Presentation, Session, Transport and Network Layer portions of the 
relevant protocol stack in the MCP environment. 
34. Lock: An object which can be used to ensure that only one entity is 
accessing a shared resource or object at any given time. 
35. PIE-CL: Process Inter-communication Element-Connection Library. 
36. PIE-CB: Process Inter-communication Element-Connection Block. 
37. PIN-CL: Processor Inter-communication Manager Connection Library. 
38. PIN-CB: Processor Inter-communication Manager Connection Block. 
39. Open Sequence: is a protocol dependent exchange of messages which 
establishes a dialog. 
40. Interface Name: This is a library attribute defined in Unisys 
Corporation's published document 8600 0494 entitled "ClearPath HMP NX and 
A Series Task Management Programming Guide". 
41. E-Mode: The operator set for Unisys Corporation's A-Series computers. 
42. E-Mode Environment: The operating environment of a machine which 
supports E-Mode and runs the Master Control Program (MCP). 
43. EIO File Object: A file system-based mechanism used to associate an 
instance of Network Processor Support (FIG. 3B, element 35) with a Network 
Processor (Glossary Item 18). 
44. Link Library: A function call of the (Master Control Program) which 
creates a binding link between two Connection Libraries (CL's). 
45. Data Path CL (20m, FIG. 3B): The Connection Library object used by the 
Network Provider to talk to Network Processor Support and Physical I/O or 
vice-versa. 
GENERAL OVERVIEW 
FIG. 3(A) is an overview of a specialized high speed datacom system where a 
User terminal 8 utilizes the interconnecting bus 60 to connect to a first 
computer system 3 and a second computer system 3p which is basically a 
duplicate copy of the first network. 
There are different categories of elements involved in FIG. 3A which can be 
summarized as follows: 
(a) Network Providers designated NP, which may involve the TCP/IP protocol, 
or other protocols. 
(b) The users of the Network Providers, such as the DSs (Distributed System 
Services), COMS (Communication Management System), and PSHs (Protocol 
Specific Handlers) which interface terminal-related protocols to the COMS 
program defined in the Glossary. 
(c) Master Control Programn (MCP), which is the main operating system of 
which one portion includes the Network Selector. 
(d) The Network Support items, such as the interface to the Network 
Selector, the DSS Router interface, and the network software installation 
and configuration. 
Referring to FIG. 3A, it will be seen that each computer system 3 and 3p is 
composed of correspondingly similar modules which can be described below 
for examle, in connection with the network 3, of FIG. 3A. 
The User terminal 8 will comiicate with the low-level kernel 28 of comuter 
system 3 which is in communication with the network data path 30 which 
communicates with the network's protocol stack 20 (Network Provider). The 
network's protocol stack 20 has a communication line 21 to the DAS 22, 
(Distributed Application Supervisor) which has two communication lines to 
the low-level kernel 28, these communication lines being shown as 23s and 
23i. The network's protocol stack communicates to a Connection Library 18u 
which connects to the Ports module 18. The Ports module 18 is in 
communication with the Port Interface 14 which is in commication with the 
User program 10p. The subject of the present disclosure is the Cooperative 
Service Interface 12 shown connected in the computer system 3 between the 
network's protocol stack 20 (Network Provider) and the service module 10s, 
generally designated as Distributed System Service (DSS) 10s or 10p 
(network 3p) in FIG. 3. 
FIG. 3A involves a service networking operation, where for example, there 
are two peer computer systems 3 and 3p. One computer system such as 
computer system 3 will have a User terminal 8 which connects to it, and 
also connects to the second computer system 3p. 
For example, the User terminal 8 may have a payroll application program, 
while the databases for this may reside in computer system 3 or computer 
system 3p. 
The low-level kernel 28 and 28p are software interfaces which connect to 
the computer networks. In the User terminal 8, there could be an 
equivalent interface called the Network Interface Card. 
Each of the computers contain multiple protocol engines, each of which 
supports a protocol, such as TCP/IP, UDP (User Datagram Protocol) and 
other internet protocols. 
The Ports 18 and 18p are file interface-based software which allows 
programs to send messages to other programs across the network, so that 
programs can talk to other programs. The software in the Port Interfaces 
14 and 14p, are basically placed in the MCP or Master Control Program, and 
they operate as system software within the MCP (40 of FIG. 2). The User 
programs 10c1 and Service 10c of FIG. 3B could be in a PC, or a UNIX 
machine, or a Unisys 2200, or a Microsoft NT platform. 
FIG. 3B illustrates a generic architecture for a computer system, such as 
for UNIX platforms, where User Program 10c1 correlates to 10p of FIG. 3A; 
and 10c of FIG. 3B correlates to 10s (Service) of FIG. 3A. The interfaces 
12a, 12b of FIG. 3B correlate Port I/F 14 of FIG. 3A and the Protocol 
Stack 20 of FIG. 3B correlates to Network Provider 20 of FIG. 3A. The 
interface 20n of FIG. 3B correlates to the I/O interface 40 of FIG. 2 
while the Network Interface Card 50N of FIG. 3B correlates to the Network 
Processor 50 of FIG. 2 which can connect to bus 60 of FIG. 3A. 
The operations of FIG. 3A function such that the computer system 3 could 
become a sender and send a message to computer system 3p which could 
become a receiver, after which the computer system 3p becomes a sender and 
sends back an answer to computer system 3 as the receiver. 
In FIG. 3A, each of the computer systems 3 and 3p will have a DSS Router 11 
and Network Processor Support Module 35. Further, a Port 18 associated 
with port interface 14, assigned to communication with a Network Provider 
20 by the Network Selector Module 9. 
It should be understood that the FIG. 3A computer system 3 and the system 
3p may be a long distance apart, such as in different cities or different 
countries. 
The Port Interfaces 14 and 14p are part of the I/O subsystem, and are 
described in the Unisys I/O Subsystem Programming Guide, Document number 
86000056, published June 1995. 
As seen in FIG. 1, the present method and system involves the transfer of 
dialog messages between a Distributed System Service (DSS) 10 and a 
Network Provider 20. 
The DSS can generally be any software program, but typically is an 
implementation of the "Application Layer" (Layer 7) which defines the 
language and syntax that a program uses to communicate with another 
program as part of the OSI (Open Systems Interconnection Standards). The 
Application Layer may involve services such as FTP (File Transfer 
Protocol), FTAM (File Transfer and Management) and messaging protocols 
such as mail, Telnet and other terminal access protocols. 
The Network Provider 20 of FIG. 1 is also often referred to as Network 
Transport Protocol Implementation such that the Network Provider (NP) is 
an implementation of the hierarchical layers (6,5,4,3) "below" the 
Application Layer 7. The Network Provider thus implements the protocol 
stack for the lower layers such as TCP/IP, UDP/IP, BNA or the OSI 
presentation layer down. 
The Network Provider 20 encompasses the Presentation (Layer 6), the Session 
(Layer 5), and the Transport (Layer 4), and the Datalink (Layer 2) is 
implemented in the Network Processor in the Network Interface Card 50 of 
FIG. 2. The Network (Layer 3) is typically implemented in the Network 
Provider, but also may be implemented in the Network Processor. 
The present disclosure for the Cooperative Service Interface 12 and its 
method of operation will be seen in the broad view of FIG. 3A, as the 
interface between the service module 10s, also called "DSS" (Distributed 
System Service), and the Network Provider 20, also called the "Network 
Protocol Stack". Thus, the Cooperative Service Interface 12, which is the 
focus of this disclosure, is the programmed interconnecting operational 
activities between the DSS 10 and the Network Provider 20, of FIG. 1. 
A brief overview of the Cooperative Service Interface 12 is shown in FIG. 
1, where the Distributed System Service 10 is interrelated to the Network 
Provider 20 through use of a set of buffer pools, and a lock pool. 
Thus, in FIG. 1, the DSS 10 has a Connection-Library Element 10e, which has 
a dialog lock pool 11d, a reference to which is transmitted to the Network 
Providers Connection-Library Element module 20.sub.e. A Connection Library 
10.sub.c contains the DSS's Connection Elements 10e. 
Further, the Network Provider 20 has a header buffer pool 20b which is 
associated with the Network Provider's Connection Library 20.sub.c. The 
Connection-Library Element 20.sub.c has an input buffer pool 20.sub.ip, 
whereby data is made available (shared) to the DSS Connection-Library 
Element 10.sub.e. Likewise, the DSS Connection-Library Element 10.sub.e. 
has an output buffer pool 10.sub.op whereby data is made available 
(shared) to the Network Provider's Connection-Library Element 20e. The 
Connection Library 20.sub.c contains the Network Provider's Connection 
Elements 20.sub.e. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
There are a number of significant features which are provided by the 
described Cooperative Service Interface 12. These features include the 
elimination (Seen in FIG. 3A) of a Port I/F (logical I/O 14) and ports 18 
which would normally be required for the DSS's data path. The Network 
Selector Module need not be used when the Cooperative System Service 
interface is used. The buffer sharing between the Network Provider 20 and 
the DSS 10 will be seen to (i) eliminate data copies, and (ii) eliminate 
call-back procedures. The arrangement for lock-sharing between the Network 
Provider 20 and the DSS 10 will be seen to (a) simplify the locking 
procedures, and (b) eliminate the lock-related timing holes. The 
Cooperative Service Interface 12 presents certain advantages over its 
predecessors which previously involved a synchronized port interface which 
used connection blocks (CBs); and the new Cooperative Service Interface 
now uses a CL-oriented interface, providing a CL-oriented (Connection 
Library) interface which allows the elimination of the logical I/O port, 
but also now allows buffer sharing. 
The Cooperative Service Interface 12 has certain key features of 
enhancement which involve (i) the locking strategy whereby dialog locks 
will be shared between the DSS 10 and a Network Provider 20. Further, (ii) 
the use of buffer-sharing whereby ownership of the Network Provider input 
buffers is logically transferred to the DSS 10 when the DSS 10 chooses to 
retain a buffer delivered to the DSs 10. The ownership of the DSS 10's 
output buffers is logically transferred to the Network Provider 20 for 
transmission when the output is requested. As a result, much data-copying 
is eliminated. 
The ownership of buffers shared in this way is later returned to their 
original owner when the borrower is finished with them. 
Referring to FIG. 2, there is seen a drawing of the utilization of the 
Cooperative Services Interface 12 by means of showing two main channels of 
the data flow, that is to say, the output path, and the input path. Here 
in FIG. 2, there is seen the DSS 10 having an outgoing buffer pool 
10.sub.op, a lock pool 10.sub.Lp, and an image of the input buffer pools, 
10.sub.ip, which consist of pointers to the actual pool, 20.sub.ip, in the 
Network Provider 20. 
In communication with the DSS 10, is the Network Provider 20, which is seen 
to have an input buffer pool 20.sub.ip, and where there occurs an image 
20.sub.ip of buffer pool 10.sub.ip (involving pointers of buffer pool 
20.sub.ip from the DSS's perspective). Additionally, the Network Provider 
20 has an image lock pool 20.sub.Lp which receives pointers from the 
actual lock pools 10.sub.Lp, and via a Connection Library element, 11c, 
from the lock pool 10.sub.Lp. 
The Network Provider 20 will be seen to have a set of buffer pool image 
pointers designated 20.sub.op, which are received from the buffer pool 
10.sub.op. Likewise, an Issue Buffer Send Command is sent to the header 
pool 20.sub.hp to build the protocol header in 20.sub.hp. 
In the Network Provider 20, there are other paths for carrying messages 
from other DSSs as seen on bus 22m, and further, there is a connection 21n 
for inserting headers and buffer information in a PIO (Physical I/O) queue 
of the Physical I/O 40. 
The Physical I/O 40 is a function of the master Control Program (MCP), 
where it is seen that "outgoing" messages are placed on the message queue 
46.sub.o, then transferred to the I/O storage unit 47 in order to build a 
header 48h, and the Write buffers 48, which are sent on bus 50b to the 
output unit 50o. The message-queue 46.sub.o involves one output queue, 
while 46.sub.i is actually multiple in number and constitutes 16 queues 
designated via dotted lines as 46.sub.i-16. 
Similarly, the Physical I/O 40 will be seen to have an "input" Read image 
block 42, which is connected to the unit 43 in order to store messages 
onto the message queue 46.sub.i and also to send information (Message 
Complete) on bus 45 to the buffer pools 20.sub.ip, and specifically for 
example, to a selected buffer 20.sub.ib. 
Data flows are shared according to the lines headed by arrows shown in FIG. 
2. The buffer pool 10.sub.op in FIG. 2, is the output buffer pool which is 
owned by the DSS 10 (shown in solid lines), and is exported to the Network 
Provider 20 where its imported image of pointers is shown as buffer pool 
(pointers) 20.sub.op. 
Similarly, there is shown the owners and imported images of other shared 
data items, such as the dialog lock pool 10.sub.Lp owned by the DSS 10, 
which is exported to the Network Provider 20. The "input buffer" pool 
20.sub.ip owned by the Network Provider 20 is exported to the DSS 10, 
where it is consumed by the DSS which writes it to disk if it is 
transferring a file. The DSS 10 also can put the information in a mail box 
if it is receiving mail. 
One output unit message queue 46.sub.o (of which 16 are provided) is shown 
accepting output messages from "other" DSS's on bus 22m. 
In FIG. 2, there is seen one input unit 43, however, there may be multiple 
independent input unit queues 46.sub.i, in addition. 
As seen in FIG. 2, the input path may operate into a single channel adapter 
50 having a single receiving unit 50.sub.i, which feeds input data, which 
is fed to the receiving unit 43 and then to input message queues 
46.sub.i-16. The top of each queue has a Read Request 42. Each request 
references a particular buffer (20.sub.ib) from the input buffer pool 
20.sub.ip. When Network Provider 20 issues the buffer Read command to the 
message queue 46.sub.i, then the unit 43 will transmit to the buffer pool 
20.sub.ip, and thence to the image buffer pools and pointers 10.sub.ip of 
the DSS 10. The individual sequence of typical steps for the input channel 
path are indicated in FIGS. 4C and 4D. 
The interfaces between the DSS 10 (or other DSS's), and the Network 
Provider 20 is basically indicated in FIG. 2. These can be designated as 
system software interfaces. 
The purpose of these system software interfaces is to manage the 
initialization and termination of dialogs between the DSSs 10 and remote 
end points, and the flow of input and output data over these dialogs. 
The functions of these system software interfaces involve (a) 
initialization and termination, (b) utilization of the input data path, 
and (c) utilization of the output data path. These are later described and 
amplified in discussion under Section B, hereinafter. 
When initializing a dialog the Network Provider 20 is responsible for 
validating attributes from the DSS 10, and if no error is detected, the 
"Open Sequence" is initiated. The "Open Sequence" is a protocol-dependent 
exchange of messages which establishes a dialog. The Network Provider 20 
notifies the DSS 10 when the "Open Sequence" has been completed, and when 
the remote side has initiated or completed termination. The Network 
Provider 20 must continue to handle both passive and active "opens", and 
the orderly and immediate "closes" (close abort). 
On the "Input" path of FIG. 2, the Network Provider 20 is responsible for 
passing received data to the DSS 10 and providing the DSS the opportunity 
to retain the data for subsequent retrieval. If the DSS retains the data, 
the DSS 10 is then considered to be the "owner" of that buffer, and is 
responsible for notifying the Network Provider 20 when the buffer is 
available for re-use. 
On the "Output" data path, the Network Provider 20 is responsible for 
forwarding the buffer's data, passed to it by the DSS 10, over to the 
physical I/O 40, after attaching the appropriate headers. The Network 
Provider 20 is also responsible for notifying the DSS 10 when the buffer's 
data becomes available. Further, the Network Provider 20 is responsible 
for notifying the DSS 10 when outbound flow control is entered and is 
exited. 
In regard to FIG. 2 in earlier implementations (later discussed in 
connection with FIG. 5), a DSS would use the buffer pool 10.sub.op, and 
the DSS would indicate that it needs to send a message to the service on 
another machine, so that the DSS would call the Network Provider 20. Then 
the Network Provider 20 would copy the data again, and the Network 
Provider 20 would now have his own copy of the data from the buffer pool 
10.sub.op. Then the Network Provider 20 would send the data down to be 
copied by the Physical I/O 40 through the queue 46.sub.o, and the data 
would get copied into the memory of the Channel Adapter 50 (FIG. 2). 
Now in the present system, the DSS 10 builds the data directly into the 
buffer pool 10.sub.op. However, since the system is now sharing the 
references to this buffer pool 10.sub.op, it is not necessary to copy it 
over to the Network Provider 20. What happens here is that the Network 
Provider 20 builds a header in header pool 20.sub.hp, which will be useful 
for sending or transmitting the data in 10.sub.op to the DSS 10 or another 
machine. The Network Provider 20 uses the image pool 20.sub.op, of the 
buffer pool 10.sub.op which involves a selection of pointers. 
Under the earlier methodology, the User would have some data, and would 
call the DSS 10 to send the data to a buffer pool in the Network Provider 
20, plus a header pool to describe what was going to happen to the data. 
Then the User would say he needs to send that information and would call 
the Network Provider 20, which would operate to say "I put my own header 
material on the front, and then behind this I have the messages from the 
DSS 10, and I will pass this down another level to the Physical I/O 40 to 
be sent to the Channel Adapter." Thus, what was done was to copy the User 
data into the DSS buffer, and then "again copy" the User data and the DSS 
data into the Network Provider buffer, (in the Network Provider 20). Then 
the entire message data and header package would be sent out to the I/O 40 
and the Channel Adapter in 50. 
Quite contrarily, under the presently described system, the real buffer 
10.sub.op of the DSS 10 is then placed as an image pointer in the Network 
Provider 20. This image is merely just a reference into the memory of the 
DSS 10. 
So what is done is to copy the User's data into the DSS's buffer 10.sub.op, 
and still put the DSS's header on the front of it, but now, under the 
present system, it is not necessary to copy this data into the Network 
Provider 20. The image buffer pointer pool 2.sub.op of the Network 
Provider 20 is not a copy of the data, but is merely a reference unit 
using pointers, which involves functions similar to that of a pointer 
looking into another person's memory. So a considerable savings is 
initiated since it is much faster, in that it is not necessary to "copy" 
the data, but merely to set up a reference pointer to a memory. 
What is still utilized here, is the Network Provider's header pool 
20.sub.hp, and then using the "Gather" operation where it is possible to 
concentrate and pass the two buffers (10.sub.db and 20.sub.hp) 
collectively, i.e. first one, and then the second, on just one request, so 
no data was necessary to be copied. So now the present operation copies 
the data out of the User's buffer, but is not required to copy the DSS's 
data, or copy the DSS's copy of the User's data. 
This data still sits in a section of memory and it gets sent out on the 
wire, and when the "send" is finished, it tells the DSS 10 that the 
transmission was completed. 
The data in memory remains in the DSS buffer pool 10.sub.op, so that there 
is the concept of "buffer sharing" which is operating in the outward path 
direction. Likewise, this is also done in the inward, or input path 
direction. 
Thus, the module which owns the buffer, for example, the Network Provider 
owning the buffer pool 20.sub.ip, passes the reference pointers to 
10.sub.ip of the DSS 10 and it does not have to copy the data and pass it 
on. 
So rather than copying, for example, on the input path channel, it is only 
necessary to get in the "messages" which has three parts to it; (i) the 
Network Provider portion 20 on the front, then (ii) the DSS 10 part in the 
middle, and then (iii) the "User" part on the end. Thus, rather than 
copying (which formerly had to be done), it is just now necessary to copy 
this particular part into the buffer 20.sub.ip, which would then be copied 
into the User's Buffer by utilization of the image pointers or buffer 
pools 10.sub.ip. These pointers are a view pointing to the memory, so that 
the DSS 10 has a view of the memory that belongs to the Network Provider 
20. 
Then the Network Provider 20 sends the pointers which access the memory for 
transmission to the User buffer. 
So what is actually being done is to tell the DSS 10 where the dialog 
information is located in the buffer, 20.sub.ip of the Network Provider 
20. 
The Cooperative Service Interface involves a series of line interactions. 
It involves the projection of the two buffer pools 10.sub.op, and 
20.sub.ip, from one environment into the other, using a set of pointers 
which are in the interface, these image pointers being 20.sub.op and 
10.sub.ip. 
It may be noted there is a similar set of image pointers for the lock pool 
20.sub.Lp which operates for coordination to make sure that two requesters 
are not trying to access the same memory location at the same time. 
The following discussion will involve one example of the algorithmic 
sequence of steps by which the present system can move and transfer 
dialogs from between the DSS 10 and the Network Provider 20 using the 
medium of the Network Data Path interface 30 and the master Control 
Program (FIG. 3) and the Physical I/O 40. A more detailed set of step 
sequences is described later in connection with FIG. 5 and FIG. 2. 
This sample initial sequence will be shown in two different flow 
directions, that is to say, the flow direction designated as the "Output 
Channel Interface" path of FIG. 2 which will be illustrated in FIGS. 4A 
and 4B. 
The flow path shown as the "Input Channel Interface" path of FIG. 2 will be 
illustrated in FIGS. 4C and 4D. 
Now referring to FIGS. 4A and 4B, there will be illustrated the Output 
Channel Interface Path. 
OUTPUT CHANNEL INTERFACE PATH: 
At step O(i), the DS8 10 will be seen as allocating a lock from the lock 
pool 10.sub.Lp with a specific lock designated 10.sub.dL. This is 
connected to the lock pool 20.sub.Lp (FIG. 2) of the Network Provider 20. 
At step O(ii), the DSS 10 tells the Network Provider 20 which lock is to be 
used for this dialog. For example, this could be the lock 10.sub.dL of the 
lock pool 10.sub.Lp. 
A dialog is initiated and identified when the DSS 10 uses its protocols and 
then calls "Open Request" after which the Network Provider 20 uses its 
protocols and then calls "Open Indications". 
At step O(iii), the DSS locks the lock. 
At step O(iv), the DSS 10 allocates a particular buffer 10.sub.db from its 
buffer pool 10.sub.op ; then it calls Issue Buffer Send Command with the 
specific buffer 10.sub.db to be sent to I/O module 40 using the data 
buffer 10.sub.db. 
At step O(v), the DSS 10 builds an output message in the buffer pool 
10.sub.op. 
At step O(vi), the DSS 10 then acquires the previously agreed-upon lock, 
10.sub.dL. This protects the dialog-related state thus keeping any other 
input from arriving at the same time that ongoing output is being sent. 
At step O(vii), the DSS 10 calls an Output.sub.-- Request and passes the 
data in buffer 10.sub.db through the Network Data Path interface 30 and 
into the message queue 46.sub.o. 
At step O(viii), the Network Provider 20 allocates a header buffer 
20.sub.hb from the header buffer pool 20.sub.hp in order to build the 
protocol header, which is utilized as 20.sub.hb ; the Network Provider NP 
20 then calls the header pool 20.sub.hb which takes the buffer 20.sub.hb 
and unlocks this dialog so that it can be sent to the message queue 
46.sub.o through the line 21n. 
At step O(ix) the Network Provider 20 creates the Header in buffer header 
pool 20.sub.hb. 
At step O(x), using line 21n (FIG. 2), the Network Provider 20 uses the 
Network Data Path interface 30 to insert the dialog message in the message 
queue 46.sub.o ; it issues a I/O to the Network Interface Card 50 directly 
from the buffer 10.sub.db over to the header pool 20.sub.hb (no data is 
copied). 
At step O(xi), the Network Provider 20 returns control to the DSS 10. 
At step O(xii), the DSS 10 now drops (unlocks) the lock on 10.sub.dL. 
At step O(xiii), the Network Provider 20 receives a I/O complete signal via 
line 45 of FIG. 2. 
At step O(xiv), the Network Provider 20 now grabs the lock 10.sub.dL which 
was previously agreed-to in the lock pool 10.sub.Lp of the DSS 10. 
At step O(xv), the Network Provider 20 notifies the DSS 10 that the buffer 
10.sub.db is no longer in use, and thus it is now available for future 
use. 
At step O(xvi), the DSS 10 then de-allocates the buffer 10.sub.db. 
At step O(xvii), the Network Provider 20 de-allocates the buffer 20.sub.hb 
(FIG. 2) in the Header Pool 20.sub.hp. 
At step O(xviii), the Network Provider 20 drops (unlocks) the lock, 
10.sub.dL. 
INPUT CHANNEL INTERFACE: 
Now in regard to the "Input Channel" path, as was indicated in FIG. 2, the 
following sequence of steps will be illustrated in FIGS. 4C and 4D. 
At step I(i), the Network Provider 20 allocates a buffer or buffers from 
the buffer pool 20.sub.ip and targets the utilization of buffer 20.sub.ib. 
At step l(ii), the Network Provider 20 issues a buffer Read to the message 
queue 46i through the network Data Path Interface 30. 
At step I(iii), the I/O module 40 indicates a completion on line 45 to the 
buffer pools 20.sub.ip. 
At step I(iv), the Network Provider 20 determines the particular DSS and 
the particular dialog that the data belongs to. 
At step I(v), the Network Provider 20 accesses the previously agreed-upon 
lock, 10.sub.dL in the lock pool 10.sub.Lp of the DSS 10. 
At step I(vi), the Network Provider 20 calls an Input.sub.-- Indication in 
the DSS 10 so that there is a passing of data that had arrived in 
20.sub.ib, over to the DSS 10, via the image buffer pool pointers 
10.sub.ip. 
At step I(vii), the DSS 10 processes the data and queues it into a consumer 
stack, such as a mailbox or other file, etc. 
At step I(viii), the DSS 10 returns control to the NP 20. 
At step I(ix), the Network Provider 20 drops (removes) the lock 10.sub.dL. 
At step I(x), the DSS 10 consumes the data, i.e., passes the data to a 
mailbox or other terminal. 
At step I(xi), the DSS 10 grabs (locks) the lock, 10.sub.dL. 
At step I(xii), the DSS 10 calls the Network Provider 20 in order to return 
ownership of the buffer 20.sub.ib to the Network Provider 20. 
At step I(xiii), the Network Provider 20 "de-allocates" (releases) the 
buffer 20.sub.ib, and puts back dialog availability in the buffer pool 
20.sub.ip. 
At step I(xiv), the Network Provider returns control back to the DSS 10 
over buffer pool 20.sub.ip. 
At step I(xv), the DSS 10 drops the lock, 10.sub.dL. 
The Cooperative Service Interface provides additional performance over the 
earlier types of Sync.sub.-- Ports by allowing a Network Provider and a 
DSS to bypass the Port File code in the Master Control Program (MCP), by 
allowing it to share data and by relaxing the rules about what can be 
performed as part of an input notification. 
The interface between the MCP's Port File code and the Network Providers 
was previously implemented as an old-style Connection Block (CB) FIG. 5. 
By changing this condition to a Connection Library (CL) FIG. 1. This 
provided a performance advantage by eliminating the MCP overhead required 
to access entry points exported via a Connection Library (CL). Because 
Connection Libraries can export data items in addition to procedures, this 
change also allows for Port File code and the Network Providers to "share" 
dialog-oriented locks. Such sharing allows elimination of the elaborate 
lock-deadlock avoidance code previously employed and is now permitted to 
be simplified greatly, thereby not only improving performance, but also 
closing numerous timing windows. Sharing locks this way also obviates the 
need for several of the more complex interfaces previously required. 
The E-mode-based portions of Network Providers currently commicate with 
their ICP-based (Integrated Communication Processor) components via an 
interface provided by NP Support. The NP Support provides a complex path 
CB (Connection Block) interface which Network Providers use to get the 
data they wish to send into a I/O capable buffer, and it generates and 
parses the Queue Service Provider (QSP) protocol in order to multiplex the 
numerous dialogs the Network Providers have over a single physical unit 
queue. 
In the improved architecture, multiple queues are provided between the 
E-mode environment, and a given Channel Adapter environment, obviating the 
need for the earlier multiplexing function, and eliminating the 
de-multiplexing bottleneck on the NP/Controller stack on the input. Since 
the QSP protocol generation is very simple, that function has been moved 
into the Network Providers. This redistribution of function allows the NP 
Support to be eliminated from the data path. 
To avoid the necessity of copying data in order to assemble Network 
Provider-generated header data, and data from multiple-user buffers into 
one contiguous memory area, the ability to Gather data from multiple 
buffers on output is added to the I/O processor. The physical I/O 
simulates Gather in cases where the I/O processor does not support it 
directly. 
In addition, a Scatter feature is provided, so that a single incoming data 
message can be split across multiple buffers. This is used by the Network 
Providers to ease their memory mangement problems they have consolation 
code to cope with cases where Scatter is not provided by the I/O 
processor. 
DATA AND STATE SHARING: 
The buffer pool 10.sub.op shown in FIG. 2 is the output buffer pool which 
is owned by the DSS 10, and is exported to the Network Provider 20 where 
its imported image is shown with the dashed lines as 20.sub.op, which 
holds pointers. 
Similarly, the same solid and dashed lines are used to show the "owners" 
and the imported images of other shared data items. The dialog lock pool 
10.sub.Lp is owned by the DSS 10, at 10.sub.ip for holding pointers and is 
exported to the Network Provider 20. Likewise in FIG. 2, the input buffer 
pool 20.sub.ip which is owned by the Network Provider 20, is exported to 
the DSS 10. 
One output unit queue is shown accepting output messages from other DSS's 
on line 22m. The diagram in FIG. 2 shows multiple input unit queues. In 
actual implementation, there can be multiple independent input unit 
queues, up to 16 for example. 
The purpose of the Cooperative Service Interface is to manage the 
initialization and termination of dialogs between DSS's and remote end 
points, and manage the flow of input and output data over those dialogs. 
INITIALIZATION AND TERMINATION: 
The Network Provider 20 is responsible for validating attributes from the 
DSS 10, and if no error is detected, an "Open Sequence" is initiated. The 
Network Provider 20 notifies the DSS 10 when the Open Sequence has 
completed, and also when the remote side has initiated or completed 
termination. Network Providers must continue to handle both passive and 
active "opens", and orderly and immediate closes. 
INPUT DATA PATH: 
On the input data path of FIG. 2, the Network Provider 20 is responsible 
for passing received data to the DSS 10 and providing the DSS the 
opportunity to "retain" the data for subsequent retrieval. If the DSS 
retains the data, the DSS 10 is then considered to the "owner" of that 
buffer, and is responsible for notifying the Network Provider when the 
buffer is available for re-use (de-allocation). 
OUTPUT DATA PATH: 
On the output path of FIG. 2, the Network Provider 20 is responsible for 
forwarding the buffers passed to it by the DSS 10 over to the Physical I/O 
40 after attaching the appropriate headers from the header pool 20.sub.hp. 
The Network Provider 20 is also responsible for notifying the DSS 10 when 
buffers become available. Additionally, the Network Provider 20 is 
responsible for notifying the DSS 10 when outbound flow control is entered 
and exited. 
ARCHITECTURE: 
In order to provide additional performance requirements, the Cooperative 
Service Interface will make use of the Connection Library mechanism, shown 
in FIGS. 1 and 2. Linkage is initiated by the DSS 10. This interface will 
not be operative before a Network Provider 20 has been established with NP 
Support, and may be terminated unexpectedly if the NP Support changes 
versions while the Network Provider 20 is running. A single Connection 
Library may support multiple dialogs. Thus the DSS 10 has a Connection 
Library 10.sub.c and the Network Provider 20 has a Connection Library 
20.sub.c. 
DSS CONNECTION LIBRARY DATA ITEMS: 
These data items are exported by the DSS Connection Library (CL) 10.sub.c 
and imported by Network Provider Connection Library (CL) 20.sub.c. 
The buffer pool 10.sub.op in FIG. 2 is used for DSS-initiated outbound data 
requests. A reference to the same buffer may be passed on to the Network 
Provider 20 for more than one dialog at a time. It may also be passed to 
more than one Network Provider at a time. As such, the Network Provider 20 
may not write into the buffer. If this kind of sharing across dialogs and 
Network Providers is done, the DSS 10 must ensure that the "same lock" is 
used for all dialogs to which the buffer reference may be passed. This for 
example, in FIG. 2, could be a lock such as item 10.sub.dL. 
In FIG. 2, the shared lock pool is designated 10.sub.Lp and is used for 
guarding the "state" related to dialogs implemented over this instance of 
the Cooperative Service Interface 12. when calling imported Network 
Provider procedures, the DSS will be "holding" the shared dialog lock. The 
Network Provider 20 may not release the lock before returning from the 
call. When the Network Provider 20 calls one of the exported DSS 
procedures, it must do so while holding the dialog lock. The DSS 10 may 
not release the lock before returning from the call. 
To avoid deadlocks, both the DSS 10 and the Network Provider 20 must 
enforce consistent lock-ordering rules regarding locks which are held at 
the same time as the dialog lock. In addition, if either entity needs to 
hold two or more dialog locks simultaneously, it must grab the one with 
the lowest lock number first. 
NETWORK PROVIDER CONNECTION LIBRARY DATA ITEMS: 
These are the data items which are exported by the Network Provider 
Connection Library 20.sub.c, and which are imported by the DSS Connection 
Library 10.sub.c. 
In FIG. 2, the buffer pool 20.sub.ip is the buffer pool which contains 
inbound requests. The DSS 10 may not Write into the Network Provider's 
buffer pool 20.sub.ip. 
INITIALIZATION, TERMINATION, OTHER ADMINISTRATION INTERFACE ITEMS: 
The Connection Library 10.sub.c of FIG. 1 between the Network Provider 20 
and the DSS 10 provides support for dialog initiation and for termination 
for the DSS 10. It also provides a mechanism whereby the DSS 10 and the 
Network Provider 20 can exchange information global to all dialogs 
associated with this connection library, such as the IDs of the buffer 
pools that will be used for input and output. 
There is no automatic mechanism for returning buffers to their declarers. 
This must be done by the DSS 10 and the Network Provider 20. It is the 
responsibility of the DSS 10 to return all Network Provider buffers 
retained by the DSS. Similarly, it is the responsibility of the Network 
Provider 20 to return all DSS buffers passed to the Network Provider for 
transmission over the network. Buffers are to be returned as soon as 
convenient, but there is no requirement that buffers be returned before 
the dialog, that they are associated with, terminates. 
In order to illustrate the improved advantages of the newly developed 
Co-operative Service Interface in its operational functional working in a 
message dialog network, an illustrative discussion section "A" will be 
discussed below to first indicate how the prior network architecture 
operated. After this, a discussion designated Section "B" will illustrate 
the improved operation of the presently developed network using the new 
Co-Operative Service Interface. 
Section A: Prior Network Architecture 
Referring to FIG. 5 which is a block diagram of the prior message dialog 
network, there is seen a Distributed System Services unit 10.sub.x having 
a buffer pool 10.sub.hp, a lock pool 10.sub.Lp, a file 10f connected to a 
Sync Port Connection Block (CB) 10.sub.sp. 
The Ports unit 20x has its own lock pool 20.sub.Lp and also provides its 
own Sync Port CB with 20.sub.sp which connects to the DSS Sync Port CB 
10sp. The Ports unit 20x also holds a PIN-CB (Processor 
Inter-Communication Manager-Connection Block) 20.sub.mx. and a Processor 
Inter-Communication Element Connection block (PIE-CB) 20.sub.px. 
The PIM-CD, 20.sub.ms and PIE-CB, 20.sub.px have respective connections to 
the corresponding units PIM-CB, 30.sub.mx and PIE-CB 30px in the Network 
Provider 30x. 
The Network Provider 30x will be seen to its own buffer pool 30.sub.Lp and 
lock pool 30.sub.Lp which connect to an underlying interface 40x. 
The sequences of operation for the prior DSS-Sync Port Networks and the 
various phases involved are shown below as items A1 through A8. 
A. Prior Message Dialog Interface Methods DSS Interface (sync ports). 
Operations: 
A1. Initialization 
A2. Dialog Setup initiation 
A3. Dialog Setup completion 
A4. Sending Data 
A5. Resending Data 
A6. Receiving Data--Setup 
A7. Receiving Data 
A8. Delayed processing of data 
A1: Initialization 
1. DSS declares a file object 10f 
2. DSS Connects its sync.sub.-- port Connection Block 10sp to Ports 
sync.sub.-- port CB 20sp 
3. DSS calls Ports to associate the file object 10f with the Connection 
Blocks 10sp/20sp. 
4. Ports allocates a lock 20L from its lock pool 20.sub.LP for use with 
dialogs that use the sync port CB 10sp/20sp and the file 10f 
A2: Dialog Setup--Initiation 
1. DSS selects a dialog id and lock 10L from lock pool 10.sub.LP 
2. DSS calls Open (file, dialog id) in Ports via file 10f 
3. Ports grabs its dialog lock 20L 
4. Ports validates the request and decides which Network Provider to use 
5. Ports drops its lock 20L 
6. Ports calls Initiate.sub.-- Dialog in the selected Network Provider 30x 
via the PIM.sub.-- CB 20m 
7. Network Provider 30x allocates a dialog state table and dialog lock 30L 
from lock pool 30.sub.Lp 
8. Network Provider grabs its dialog lock 30L 
9. Network Provider does further validation of the request. 
10. Network Provider takes protocol-specific action to begin dialog 
initiation. This involves sending data out on the network via the 
underlying interface 40. 
11. Network Provider drops its dialog lock 30L 
12. Network Provider returns to Ports 
13. Ports grabs its lock 20L 
14. Ports adjusts its state information 
15. Ports drops its lock 20L 
16. Ports returns to the DSS 10x 
17. DSS waits to be notified that dialog has been initiated 
A3: Dialog Setup--Completion 
1. Network Provider 30x receives input data from the network. 
2. Network Provider looks at data and decides which dialog it is related 
to. 
3. Network Provider grabs appropriate dialog lock 30.sub.L 
4. Network Provider completes its dialog table. 
5. Network Provider calls Ports (Request.sub.-- Authority via the 
PIM.sub.-- CB 30.sub.mx) to tell it dialog has been established. 
6. Ports grabs its lock 20.sub.L 
7. Ports creates a PIE CB 20.sub.px and links it to the Network Provider's 
PIE CB 30p 
8. Ports causes event to notify DSS that dialog establishment is complete. 
9. Ports drops its lock. 
10. Ports returns to Network Provider 
11. Network Provider drops its lock 30.sub.L 
A4: Sending Data 
1. DSS 10x grabs its dialog lock 10L 
2. DSS selects a buffer 10b from buffer pool 10.sub.bp and fills it with 
data 
3. DSS drops its lock 10L 
4. DSS calls SP.sub.-- Write in Ports via sync.sub.-- port CB 10sp to send 
the data via 20sp to 20b. 
5. Ports 20x grabs its dialog lock 20L 
6. Ports verifies that the dialog has been properly established and that 
writing is allowed 
7. Ports drops its lock 20L 
8. Ports calls Send.sub.-- Data.sub.-- Syncport 30x in the Network Provider 
via the PIE CB 20px 
9. Network Provider 30x grabs its lock 30L 
10. Network Provider allocates a buffer 30b from buffer pool 30.sub.bp 
11. Network Provider builds a protocol header in the front of the buffer 
30b 
12. Network Provider copies the DSS's data from the DSS's buffer 10b into 
the Network Provider's buffer 30b (after the header). 
13. Network Provider calls underlying interface 40x to send the data out on 
the network. 
14. Network Provider drops its lock 30L 
15. Network Provider returns to Ports 20x 
16. Ports grabs its lock 20L 
17. Ports adjusts its state information 
18. Ports drops its lock 20L 
19. Ports returns to DSS 10x 
20. DSS may now reuse its buffer 10b 
A5: Resending Data 
1. Network Provider 30x determines that data has not arrived at its remote 
destination 
2. Network Provider grabs dialog lock 20L 
3. Network Provider reuses buffer 20b built in the sending data step to 
send the data over the network another time. 
4. Network Provider 30x drops its dialog lock 20L 
A6: Receiving Data--Setup 
1. Network Provider allocates a buffer 30.sub.ib from buffer pool 30.sub.bp 
2. Network Provider makes the buffer available to underlying interface 40 
for input delivery 
A7: Receiving Data 
1. Network Provider 30x receives data from network into buffer 30.sub.ib 
via underlying interface, 40x. 
2. Network Provider determines which dialog the data belongs to. 
3. Network Provider grabs its dialog lock 30L 
4. Network Provider adjusts its dialog state 
5. Network Provider calls Data.sub.-- Indication.sub.-- Syncport in Ports 
via PIE.sub.-- CB 30px 
6. Ports calls DSS SP.sub.-- Input.sub.-- Delivery via SyncPort.sub.-- CB 
20sp 
7. DSS grabs its lock 10L 
8. DSS processes the data and decides whether input buffer can be reused 
9. DSS drops its lock 10L 
10. DSS returns to Ports 20x 
11. Ports grabs its lock 20L 
12. Ports adjusts its dialog state 
13. Ports drops its lock 20L 
14. Ports returns to Network Provider 30x 
15. If DSS says input buffer 30.sub.ib can be reused, Network Provider 
returns buffer to the buffer pool 30.sub.bp 
A8: Delayed Processing of Data 
1. DSS 10x grabs its lock 10L 
2. DSS calls SP.sub.-- Retrieve.sub.-- Data in Ports 20x via Sync.sub.-- 
Port.sub.-- CB 10sp 
3. Ports grabs its lock 20L 
4. Ports validates that dialog is active 
5. Ports drops its lock 20L 
6. Ports calls Retreive.sub.-- Data.sub.-- Syncport in Network Provider via 
PIE.sub.-- CB 20px 
7. Network Provider grabs its lock 30L 
8. Network Provider locates the data the DSS is requesting in buffer 30ib 
and calls the formal parameter so that the DSS can process it. 
9. DSS processes the data 
10. DSS decides whether the buffer can be reused 
11. DSS returns to Network Provider 30x 
12. If the buffer 30.sub.ib can be reused, Network Provider returns it to 
the buffer pool 30.sub.bp 
13. Network Provider drops its lock 30L 
14. Network Provider returns to Ports 20x 
15. Ports returns to the DSS 10x 
16. DSS drops its lock 10L 
The subsequent Section "B" hereinunder describes the newly developed 
Message Dialog Method of the Cooperative Service Interface as indicated in 
sub-paragraphs B1 through B8. Reference is now made to FIG. 2 whereby the 
following discussion indicates a broader expansion of FIGS. 4A, 4B, 4C, 4D 
in regard to the Co-op Service Interface operations which will be 
discussed with regard to FIG. 2 whereby Connection Library units 
PIE.sub.-- CL and PIN.sub.-- CL now replace the earlier used PIE.sub.-- CB 
20px/30px and PIM.sub.-- CB 20mx/30mx, previously shown in FIG. 5. 
Section B--Output Channel 
B. Newly Developed Message Dialog Interface Method New DSS Interface for 
(Co-op Interface Operations): 
B1. Initialization 
B2. Dialog Setup initiation 
B3. Dialog Setup completion 
B4. Sending Data 
B5. Resending Data 
B6. Receiving Data--Setup 
B7. Receiving Data 
B8. Delayed processing of data 
B1: Initialization 
1. DSS 10 Connects its co-op interface CL 10c to the Network Provider Co-op 
CL 20c 
2. Pointers 20.sub.op in Network Provider 20 are created to point to buffer 
pool 10.sub.op in DSS 10. 
3. Pointers 20.sub.op in Network Provider 20 are created to point to lock 
pool 10.sub.LP in DSS 10. 
4. Pointers 10.sub.ip in DSS 10 are created to point to buffer pool 
20.sub.ip in Network Provider 20. 
B2: Dialog Setup--Initiation 
1. DSS 10 selects a dialog id and lock 10.sub.dL from lock pool 10.sub.Lp 
2. DSS grabs lock 10.sub.dL 
3. DSS calls Open.sub.-- Request in the Network Provider 20 via co-op CL 
10c 
4. Network Provider allocates a dialog state table 
5. Network Provider validates the request. 
6. Network Provider takes protocol-specific action to begin dialog 
initiation. (This involves sending data out on the network via the 
underlying interface 40). 
7. Network Provider returns to the DSS 10 
8. DSS drops lock 10.sub.dL 
9. DSS waits to be notified that dialog has been initiated 
B3: Dialog Setup--Completion 
1. Network Provider 20 receives input data from the network. 
2. Network Provider looks at data and decides which dialog it is related 
to. 
3. Network Provider grabs appropriate dialog lock 10.sub.dL via its 
reference in 20.sub.Lp 
4. Network Provider completes its dialog table. 
5. Network Provider calls Open Indication in DSS 10 via co-op CL 20c. 
6. DSS notices that dialog has been initiated 
7. DSS returns to Network Provider 20 
8. Network Provider drops lock 10.sub.dL. 
B4: Sending Data (Output Channel Interface Transmission) 
1. DSS grabs its dialog lock 10.sub.dL 
2. DSS selects a buffer 10.sub.db from buffer pool 10.sub.op and fills it 
with data 
3. DSS calls Output.sub.-- Request in Network Provider 20 via co-op CL 20c 
4. Network Provider allocates a buffer 20.sub.hb from header buffer pool 
20.sub.hp 
5. Network Provider builds a protocol header in buffer 20.sub.hb 
6. Network Provider calls underlying interface 40 to send the data out on 
the network. Both 20.sub.hb and 10.sub.hb are passed to the underlying 
interface without copying the data. 
7. DSS may not reuse buffer 10.sub.db until notified that Network Provider 
is done with it. 
8. DSS drops dialog lock 10.sub.dL 
B5: Resending Data 
1. Network Provider determines that data has not arrived at its remote 
destination 
2. Network Provider grabs lock 10.sub.dL via reference 20.sub.Lp 
3. Network Provider reuses buffers 10.sub.db and 20.sub.hb built in the 
sending data step to send the data over the network another time. 
4. Network Provider drops lock 10.sub.dL. 
B6: Receiving Data--Setup 
1. Network Provider 20 allocates a buffer 20.sub.ib from buffer pool 
20.sub.ip. 
2. Network Provider makes the buffer available to underlying interface 40 
for input delivery. 
B7: Receiving Data 
1. Network Provider 20 receives data from network into buffer 20.sub.ib via 
underlying interface, 40. 
2. Network Provider determines which dialog the data belongs to. 
3. Network Provider grabs its dialog lock 10.sub.dL via reference 
20.sub.Lp. 
4. Network Provider adjusts its dialog state 
5. Network Provider calls Input.sub.-- Indication in DSS via co-op CL 20c. 
6. DSS processes the data and decides whether input buffer can be reused 
7. DSS returns to Network Provider 20 
8. If DSS says input buffer 20.sub.ib can be reused, Network Provider 
returns buffer to the buffer pool 20.sub.ip. 
9. Network Provider drops lock 10.sub.dL. 
B8: Delayed Processing of Data 
1. DSS grabs lock 10.sub.dL 
2. DSS references data in buffer 20.sub.ib via its pointer reference 
10.sub.ip. 
3. DSS processes the data 
4. If DSS decides the buffer can be reused, it calls Return.sub.-- 
Input.sub.-- Buffer in the Network Provider via co-op CL 10c. 
a) Network Provider returns buffer 20.sub.ib to inputbuffer pool 20.sub.ip 
b) Network provider returns to DSS 
5. DSS drops its lock 10.sub.dL 
PROCEDURAL AND AMETER FUNCTIONS OF THE INPUT INTERFACE OPERATION IN THE 
COOPERATIVE SERVICE INTERFACE 
INPUT INTERFACE: 
A Connection Library between the Network Provider 20 and the DSS 10 
provides the Input data path support for all dialogs associated with that 
Connection Library 10.sub.c, 20.sub.c. 
DSS INPUT INDICATION: 
This is a procedure which is exported from the DSS Connection Library 
10.sub.c and called by the Network Provider 20 when data is available for 
the application. For services which guarantee ordering, data is always 
delivered in order, regardless of the number of stacks on which it may be 
delivered. If the most recently received frame filled a hole in data that 
was previously out of order, this procedure may be called multiple times 
in succession. The Network Provider 20 must have the dialog lock when this 
procedure is called; further, the DSS 10 must not drop the lock. 
PROCEDURE HEADER: 
Here, there is a BOOLEAN PROCEDURE designated Input.sub.-- Indication which 
involves: 
(i) User.sub.-- Dialog.sub.-- Id, Buffer.sub.-- Id, Total.sub.-- Length, 
Segment.sub.-- Length, Start.sub.-- offset, Input.sub.-- Attrs. 
INPUT AMETERS: 
These involve: 
(i) User Dialog Id: This is the DSS's unique identifier of the dialog; 
(ii) Buffer Id: This is the identifier of the buffer; 
(iii) Total Lenath: This is the total length of the message; 
(iv) Segment Length: This is the length of the segment being delivered; 
(v) Start Offset: This is the offset in the buffer where the data begins; 
(vi) Input Attrs: This is a Data Path Options Word identifying the input 
packet characteristics; 
(vii) Procedure Results: A True indication indicates the buffer was 
consumed by the DSS and is now available for re-use; A False indication 
indicates that the DSS iS Retaining the buffer; 
(vii) Service-Specific Information: For flow control purposes, retained 
data is considered to remain in the receive window until the buffer 
containing it is returned to the Network Provider 20. The "Input.sub.-- 
Indication" is called only for TCP when data that is non-urgent is 
received and delivered to the user. 
DSS INPUT INDICATION WITH INFORMATION: 
This is a procedure which is exported from the DSS Connection Library 10c 
and called by the Network Provider 20 when data is available for the 
application and there is additional information related to the data that 
requires the Input.sub.-- Attrs.sub.-- Array (Input Attributes Array). It 
is never called if the Input Attributes Array is empty. For services which 
guarantee ordering, data is always delivered in order, regardless of the 
number of stacks on which it might be delivered. 
Both this procedure and the Input.sub.-- Indication are supplied because it 
is anticipated that performance advantages could be gained in Input.sub.-- 
Indication because it needs to handle fewer cases and could avoid parsing 
the Input.sub.-- Attrs.sub.-- Array structure. Since the Cooperative 
Services Interface is a performance-oriented interface, the potential 
duplication of code is considered a reasonable price to pay for improved 
performance. When this procedure is called, the Network Provider 20 must 
have the dialog lock and further the DSS 10 must not drop the lock. The 
designation "Input.sub.-- Attrs.sub.-- Array" designates an Attribute 
Update Structure which identifies the Input packet characteristics. 
The Input.sub.-- Indication.sub.-- WithInfo is called for TCP users when 
the incoming frame contains urgent data in order to tell the user how much 
of the data being delivered is "urgent". For example, the frame may 
contain 60 bytes of urgent data, followed by 200 bytes of regular data. 
NETWORK PROVIDER INPUT FLOW CONTROL REOUEST: 
This is a procedure which is exported from the Network Provider Connection 
Library 20c and called by the DSS 10 to put a dialog in or take a dialog 
out of Flow Control. This request is not immediate; since additional data 
(which may be in-transit) can be delivered after Flow Control is 
requested. The DSS 10 must accept such data and process it in an 
appropriate manner. The DSS 10 must have the dialog lock when this 
procedure is called; and the Network Provider 20 must not drop the lock. 
PROCEDURE READER FOR NETWORK PROVIDER INPUT FLOW CONTROL REQUEST: 
This involves the INTEGER PROCEDURE designated Input.sub.-- Flow.sub.-- 
Control.sub.-- Request which involves certain Input Parameters designated: 
(i) NP.sub.-- Dialog.sub.-- ID: which is the Network Provider's unique 
identifier of the dialog; and then 
(ii) FC.sub.-- On: which is a flag indicating whether the dialog has just 
"entered" or just "exited" flow control. If "True", the dialog has just 
entered flow control, and the Network Provider 20 should initiate 
protocol-specific procedures to limit receipt of additional data. If the 
indication is "False", then the dialog has already exited flow control. 
NETWORK PROVIDER RETURN INPUT BUFFER: 
This is a procedure which is exported from the Network Provider Connection 
Library 20c and called by the DSS 10 when a buffer that was previously 
"retained" is available for re-use by the Network Provider 20. If the 
dialog that retained this buffer is still active, the DSS 10 must have the 
dialog lock when this procedure is called; and the Network Provider 20 
must not drop the lock. 
PROCEDURE HEADER FOR NETWORK PROVIDER RETURN INPUT BUFFER: 
This involves a INTEGER PROCEDURE which involves Return.sub.-- Input.sub.-- 
Buffer which involves two Input parameters designated: 
(i) Buffer.sub.-- Id: The identifier of the buffer; 
(ii) NP.sub.-- Dialog-ID: This is the Network Provider's unique identifier 
of the dialog. A value of "zero" must be passed as the dialog ID if the 
connection, that was retaining the buffer, has already closed. 
Described herein has been a specialized Input Interface function for a 
Cooperative Service Interface between a Network provider (NP) and a 
Distributed System Service unit (DSS). 
After initialization and dialog setup, the Network Provider can receive 
input data from the network, after which it relates the data to a specific 
dialog and grabs a dialog lock in the DSS. The Network Provider opens a 
channel to the DSS via a connection library to initiate the dialog after 
which the Network Provider drops the lock. Then the Network Provider 
receives data from the network into a selected buffer, identifies the 
dialog that the data belong to, grabs a dialog lock in the DSS and opens a 
channel from the Network Provider to the DSS. Thereafter the DSS receives 
and processes the data in the DSS and enables the NP (Network Provider) to 
drop the lock on the Np's input buffer. 
While the subject Input Interface can be implemented as described herein, 
it should be understood that the subject invention is defined according to 
the appended claims.