The Space Station Information System (SSIS) provides the data processing capability for the Space Station Program (SSP). The Software Support Environment (SSE) System for the SSP is the collection of software, procedures, standards, hardware specification, documentation, policy, and training materials. The Ada programming language was baselined by the Space Station Program Office as the language for development and maintenance of all space station software including the software of the SSE itself. The Test And Validation Environment for Remote Networked Systems (TAVERNS) is a distributed philosophy for development and validation of Ada applications software for the space station and as such is closely related to the SSE. An overview of the system is provided

Howes, Norman R.

Raines, Gary K.

English

NASA Technical Reports Server

, , 
TAVERNS and the Space Sdation Software Support Environment 
N o r m a n  R .  Hones 
Lockheed Engineering and Management Services Co. 
2400 NASA Road 1 ,  Houston, TX 77058 
Gary K. Raines 
Houston, TX 77058 
NASA Lyndon B.  Johnson Space Center 
f $ Introduction 
tn 1 
%%The Space Station Information System (SSIS) provides the data 
Mwprocessing capability for the Space Station Program (SSP). It 
kc ,  consists of the ground and onboard computers, networks and 
k software that work together as a system to manage the operational 
and data handling requirements of the Space Station Program 
~bElements. The Space Station Data Management System (DMS) is the 
W M  onboard component of the SSIS that supports the various core and 
ncn payload subsystems of the Space Station. 
M W  "The Software Support Environment (SSE) System for the SSP is the 
collection of software, procedures, standards, hardware specifi- 
cations, documentation, policy, and training materials which, 
Egwhen implemented in hardware and a computer network(s), provides 
-*the environment that is to be used by the SSP for the life cycle 
E w  management of all operational SSP software" according to the 
ZZRequest for Proposal for the SSE. It goes on to say that "The 
0 0 SSE is not a computer system that provides data processing ser- 
n e  vices, but rather a set of methods, tools, rules, and standards 
P + B U  v, that establisn an environment for Space Station Program software 
0 ~ l r  support. I '  
Gi The Ada programming language has been baselined by the Space 
w Station Program Office as the language for development and 
maintenance of all Space Sta6ion software including the software \ 6 
J for the SSE itself. The use of program products not written in 
Ada will only be allowed on a waiver basis in accordance with 
L+) b gcriteria outlined in the SSE Software Management Plan. The SSE 
4 0  be include the Ada compiler(s) and run time environment(s) for 
o a  -the SSE and for the SSP baselined target space based and ground 
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Further, the RFP states that "The principle objective of the SSE 
concept is to provide a common environment for software support 
to the SSP. Therefore, a l l  individuals and organizations with 
responsibility for the acquisition, integration, testing, 
configuration management, maintenance, or utilization of the 
1 
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https://ntrs.nasa.gov/search.jsp?R=19870009567 2020-03-20T11:32:00+00:00Z
operational SSP software are potential SSE users. 
is a list of the general classes of user functions: 
The following 
1. 
2. 
3 .  
4 .  
5. 
6. 
7 .  
SSP Software Managenent, 
SSP Software Development, 
Systems Engineering and Integration, 
Software Integration and Testing, including Safety, 
Reliability & Quality Assurance and Independent 
Verification & Validation, 
Sustaining Engineering, 
Operations of SSE, 
SSP Operations, including flight crew and the various 
real-time ground scpport members. " 
The TAVERNS Concept. 
TAVERNS is a distributed philosophy for development and valida- 
tion of Ada applications software for the Space Station and as 
such is closely related to the SSE. The acronymn TAVERNS stands 
for Test And Validation Environment for Remote Networked Systems. 
The TAVERNS concept assumes that the different subsystems will be 
developed by different cDntractors who will be geographically 
separated. 
The TAVERNS concept has not yet been baselined as the architectu- 
ral concept for the SSE, but significant funding has be dedicated 
to developing and prototyping various aspects of TAVERNS and no 
doubt TAVERNS or something closely akin to TAVERNS will ultimate- 
ly be the architecture for the SSE. In fact, the RFP for the SSE 
already embraces many of the concepts of TAVERNS in its present 
form. 
To understand the TAVET(h'S concept, a few words are in order 
concerning the DMS. Figcre 1 shows the core and payload subsys-  
tems connected to the core and payload networks via Network 
Interface Units (NIUs). Each subsystem is implemented on a 
Standard Data Processor ( S D P ) .  This does not imply that a stan- 
dard computer has already been selected for this role but that 
all subsystem computers' shduld have the same instruction set 
architecture (ISA). It is possible that a single SDP may host 
more that one subsystem. 
The NIU is itself a computer; possibly with the same ISA as the 
SDP. The NIUs host the Network Operation System (NOS) component 
of the DMS where as the S3Ps host the rest of the DMS. The SDPs, 
NIUs, networks and DMS software constitutes the DMS. The subsys- 
tem application software that runs on the SDPs is not considered 
part of the DMS. 
In the TAVERNS approach, each software development contractor for 
the station will be provided with a miniature version of the 
Space Station DMS complete with three SDPs. One of the SDPs is 
for developing the subsystem software, one hosts the Displays and 
Controls software and the third hosts a simulation of the network 
2 
'core subsystems (e.g., the Environmental Control & Life Support 
'Subsystem or the Communications & Tracking Subsystem) and the 
network loads. A diagram of such a TAVERNS DMS System is illus- 
trated in Figure 2.  
C & T  G N L C  
(m il-*-,-, PAY LOAD 
I I I S D P  I . .  .  -
ECLSS PAYLOAD IYmOflK 
Figure 1. 
The SDPs and NIUs on this mini Space Station DMS will host the 
same DMS Services as the real DMS, so to the applications pro- 
grammer, it will appear that the entire Space Station DMS envi- 
ronment is present. In this way, software can be developed and 
checked out by different contractors at different locations. 
Completed and tested applications can then be transferred to the 
Integration Facility of the SSE for validation. 
In the SSE RFP these individual software development elements are 
referred to as Software Production Facilities (SPFs). According 
to the RE'P there will be SPFs at several NASA facilities and in 
various contractor facilities. These SPFs will be connected 
together via the Program Support Communications Network (PSCN) 
and other commercial networks as required. Also connected will 
be the SSE Integration Facility and the SSE Development Facility 
(SSEDF) . 
The SSEDF will be theaSPF where the software for the SSE is 
developed, maintained, controlled and distributed to the other 
SPFS on the SSE network. A diagram of the SSE network is shown 
in Figure 3 and the elements of a typical SPF are shown in Figure 
4 .  The TMIS Element shown in Figure 3 stands for the Technical 
3 
I and Management Information System, a discussion of which is 
' beyond the scope of this paper. 
T A V E R N S  
SIMULATED LOADS DEVELOPUENY DISPLAYS & CONTROL 
DMS SERVICES USER APPXATONS DISPLAY D R M R S  
CORE SUBSYSTEMS USER INTERFACE 
NETWORK LOADS 
Figure 2 
The TAVERNS Emulator Project is an Ada simulation of a TAVERNS 
System on the Avionics Systems Division (ASD) VAX at the Johnson 
Space Center. The purpose of this simulation is to 
(1) provide a DMS software er-vironment that consists of a 
library of DMS services th?a+, can be used by the various 
subsystem test bed develcaers to interconnect their test 
bed subsystems, 
capabilities by implementing this library of services in 
such a way that the services will work equally well with 
any data type thereby maxircizing code reusability, 
( 3 )  provide a library of tesring tools (subsystem simulat- 
ions) that can be used by subsystem test bed developers, 
( 4 )  test the functionality of these DMS Services, 
(5) gain experience with the EEC Ada development environment 
( 2 )  gain experience with the Ada generic and overloading 
in order to better underetmd what tools are needed in 
a development environment, and 
can be evaluated and improved. 
(6) provide an environment where the TAVERNS concept itself 
4 
I i  
1' J SC SPF I I
I 
! 
I ! -i SSEDF I 
1 Y S K  SPF , 
! I 
! I 1 
1 
i i 
i- 1 KSC spF 
r 
I 
i -! GSFC SPF j 
! jI I ' Integration 
I 
I 
I 1- LeRCSPF I 
I 
Communication capebitity 
(PSCN a d  Other) 
Figure 3. 
To date, each of the DMS services to be simulated has been docu- 
mented and an Ada specification written and compiled. About 25% 
of the services have been implemented in a first phase demonstra- 
tion of a TAVERNS Emulator. Work will continue on implementing 
the remaining services through the next two years. 
The library of DMS services. can be subdivided into four 
classifications at present, namely the message handling services, 
the distributed file handling services, the data acquisition and 
distribution services and the data base management services. 
5 
. Work on the specification of the crew workstazicn services and 
.the operations management services are underway in other 
divisions at the Johnson Space Center. As these specifications 
emerge they will be integrated into the TAVEWS environment to 
the extent possible in a simulation. 
, -  
S IMUUTED 
LOADS 
OMS W 
SSE NETWORK 
INTERFACE 
CREW 
WORKSTATION 
DISPLAYS 1, 
CONTROLS slw HOST 
FLIGHT A P R  
SOFTWARE 
OMS S N  OMS SIY SYSTEM 
T 
N I U  '9' N l U  
SOFTWARE 
- s  
I SSE 
B ' SOFTWARE 
APPLICATION 
DEVELOPMENT 
SOFTIARE 
DATA COUUUN/CAT/OffS MTWORK i PROGRAMMER 
J WORKSTATIONS 
Figure 4 .  
The message handling services can be further subdivided into the 
datagram services and the virtual circuit services. The distri- 
buted file management services can be subdivided into the file 
handling services, the file access services and the file tran- 
sport services. The data acquisition and distribution services 
can be subdivided into the data request services and data reply 
services (services that replace the master measurement reading 
function on the shuttle). 
Currently, Ada specifications for the library af testing tools 
have not been written. A couple of test simclations have been 
implemented to support the first phase TAVERNS demonstrs$ion, but 
much more work needs to be done in specing the Testing services 
to be made available. 
A great deal of experience has been gained wizh the DEC Ada 
development environment in regards to its strer?b,hs and weaknes- 
ses and much has been learned about the peculiarities of the DEC 
Ada compiler. Partially as a result of this effort, the SSE RFP 
specifies a more sophisticated software developaent environment 
and an extensive set of testing tools. 
6 


TAVERNS and the space station software support environment

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