Bridging the Digital Divide with Net-Centric Tactical Services

Transcription

1 Bridging the Digital Divide with Net-Centric Tactical Services Authors: Scott D. Crane, Charles Campbell, Laura Scannell Affiliation: Booz Allen Hamilton 1. Abstract The DoD Net-Centric Data Strategy (May 2003) goals are to make data assets visible, accessible, and understandable [1]. This strategy establishes a Service Oriented Architecture (SOA) approach as the preferred means by which data producers and capability providers can make their data assets and capabilities discoverable on the Global Information Grid (GIG). Likewise, the strategy establishes an SOA approach as the preferred means by which consumers can access these data assets and capabilities. Programs such as the Defense Information Systems Agency s (DISA s) Net-Centric Enterprise Services (NCES) are providing SOA-based infrastructure services to enable information sharing across the Department of Defense (DoD) [2]. The technologies employed in an SOA environment for exchanging data including Extensible Markup Language (XML) and Web Services are conducive for use in fixed environments that have reliable, high bandwidth TCP/IP networks. However, in a tactical environment where communications may be intermittent and bandwidth is limited, this presents problems. In order for data producers and consumers on a tactical network to leverage the capabilities available on the GIG, a framework is needed that will extend the power of enterprise services to users on low bandwidth networks at the tactical edge. This will allow the vision of the Net-Centric Data Strategy to provide value to users at all levels. Net-Centric Tactical Services (NCTS) provides a gateway and software framework for tactical users to realize the benefits of information sharing across an SOA environment. The framework resides in the tactical environment and supports a set of services and functions to enable communications and messaging translation, data publishing, data subscription, and tactical device management. It is an attempt to bridge the present day technology gap between low bandwidth and high bandwidth data producers and consumers. 2. Context Information and functional capabilities provided as services by NCES and similar programs will change the way the DoD fights wars and conducts its business. NCES will help change the ways in which people operating on the GIG execute their missions as well as execute their tasks. NCES offers a collection of capabilities that support Net-Centric development. The Core Enterprise Services that compose NCES will enable synchronous communication and asynchronous file sharing among people throughout the network, provide an infrastructure for optimizing the delivery of web-based information and applications over the GIG, provide web services and websites for performing searches across NCES registered data sources, provide the ability to monitor and manage current NCES web services, provide web services for reliably sending small messages between applications, provide web services that facilitate creating and executing XML transformations, allow searching and registering of metadata information, perform certificate validation and access control decisions, and also provide services that find people and devices in an enterprise-wide white pages directory [2]. Moreover, the GIG is a network of networks which links hundreds of information system elements to enable the rapid exchange of information among the U.S. military services, the Intelligence Community (IC), and multinational allies. The GIG is a globally connected, end-to-end set of information capabilities, associated processes, and personnel for collecting, processing, storing, disseminating, and managing information on demand. These capabilities will rely on standards and technologies that will significantly increase the amount of data transmitted over tactical networks that current legacy systems will be unable to support [3]. One critical issue will be the amount of non-compatible radio systems, waveforms, and networking protocols currently in use. Another major challenge in this environment is the lack of readily available bandwidth. In an office, workstations are 1

2 supported with various Local Area Networks (LANs) (e.g., Ethernet) that connect to the Internet through high speed connections and thus data rates are not a major concern. However, in the mobile tactical environment, communications require mobile wireless connections. Current military combat radios, such as Single Channel Ground and Airborne Radio System (SINCGARS), provide only limited data rates on the order of dial-up connections which provide much less bandwidth than in today's office environment [5]. This results in a very limiting environment when developing for a tactical environment and thus a framework is needed to leverage the benefits of NCES at the tactical edge. The tactical network consists of communication nodes that provide direct connectivity for users executing tactical missions. If the tactical user is to take advantage of GIG NCES Core Services (i.e. discovery of data assets, security), they must do so within the constraints of their disadvantaged networks and cannot afford the network overhead assumed by the enabling technologies of these services. Net- Centric Tactical Services (NCTS) will provide the ability to reach back from the tactical edge into services that are provided to the GIG by NCES. 3. Integration Challenge What is important in this discussion is not whether one approach to delivering services is right or wrong but what approach is supportable given the constraints Figure 1. Integration challenge of the supporting command and control application and communications network infrastructure. Today, and into the foreseeable future the digital divide is real and developing an integrated capability to share information across the divide requires different technologies to meet the common goal of providing relevant, timely data to the end user. Army Transformation to a brigade-centric Modular Force coupled with the fielding of the Joint Network Node (JNN) and Command Post Node (CPN) has set the conditions to support a strategy to bridge the digital divide which is not available to the current force. The JNN/CPN has brought wide band access to the GIG down to the Brigade and Battalion levels [4]. It is at the brigade and battalion levels where the junction of tactical networks and operational networks now takes place (see Figure 1) - exactly the right place for the implementation of a technical bridging strategy. At the strategic and operational level, where access to reliable wideband global networks is assured, the following network planning factors are common: Unconstrained bandwidth (capacities greater than 10Mbps) A stable communications infrastructure The ability to pass large amounts of data in a timely manner The ability to discover and share data across disparate systems without developing new interfaces 2

3 The ability to employ extensible, scalable and flexible standards to allow new systems to come on-line and integrate easily In light of these factors, Service Oriented Architectures (web services) and NCES core services provide an excellent opportunity to share data between unlimited numbers of decoupled systems and therefore provide an architecture conducive to operating within this environment based on the five factors given above. They also provide a mechanism for bringing new systems on-line easily, exposing new functionality and data assets for use by existing systems without requiring any direct knowledge or interface change to interact with the new system. These enabling technologies are known as NCES which are based on standard Extensible Markup Language (XML) technologies. Using XML as the basis for the message exchange format for this environment is advantageous because its extensible nature allows new data assets to be easily defined and implemented. At the tactical level, where mobility and ad hoc, line of sight networks are the norm, the following network realities are in play: Networks constrained by low bandwidth (less than 10 kbps) Networks are ad hoc, unstable, and dynamic Only need the relevant data for their purpose, mission and Area of Responsibility (AOR) Have well defined information needs Have an absolute need to receive actionable information in a timely manner that has immediate relevancy and accuracy. Tactical operators typically function over lowbandwidth, line of sight, vehicular mounted network connections. Communications are often intermittent and the devices are smaller mobile systems with limited power, which operate in restricted terrain with limited range. This all adds up to the inability to process excessive amounts of data or handle multiple requests for information from a large number of consumers because of bandwidth constraints and the overhead associated with typical Net-Centric IP technologies. Thus, on the tactical side of the digital divide, it is necessary to continue to employ more traditional network and messaging protocols which work reasonably well in the poor network conditions of the tactical force. For instance, a binary message format like Joint Variable Message Format (JVMF) is ideal given that this format is approximately times smaller than a full XML message. Further, network protocols such as MILSTD , unlike TCP/IP, are better suited to account for the unique constraints of combat radio nets. For the purposes of this white paper, the enabling technologies that support the execution side of the communication barrier are defined as Tactical Services. Net-Centricity is founded on the universal requirement for rapid access to critical essential information in a timely manner to support both battle planning and execution [1]. Traditional echelon boundaries have been blurred by DoD and Army Transformation. Unfortunately, network boundaries continue because of the inability of current force technology to adapt to ever changing and ever increasing demands for information. If the tactical user is to take advantage of GIG NCES Core Services (i.e. discovery of data assets, security), they must do so within the constraints of their disadvantaged networks and cannot afford the network overhead assumed by the enabling technologies of these services. There are technologies, however, that can bridge this gap between enterprise NCES and the tactical Core Service requirements. Net-Centric Tactical Services (NCTS) can provide this capability. 4. Tactical Services NCTS encapsulates several functions required in the tactical environment, exposed as tactical services to either the low bandwidth tactical interface of NCTS, or to the high bandwidth web-service interface of NCTS. These services allow data sharing between tactical devices and enterprise systems, particularly sensor, situational, and intelligence data. The tactical devices communicate with an NCTS server using their native messaging and communications protocols, such as JVMF over SINCGARS tactical radios. The NCTS server in turn communicates with the GIG using Web Service Definition Language (WSDL) and Extensible Markup Language (XML)/ Simple Object Access Protocol (SOAP). A sampling of tactical services are: Device Registration Service This service allows tactical devices to dynamically register with NCTS so that tactical data is accessible to enterprise systems. 3

4 Device Discovery Service This service allows discovery of tactical devices registered with NCTS. Report Publishing Service This service provides the ability for tactical devices to publish reports to the enterprise. Subscription Service This service provides a mechanism for tactical devices to subscribe to data, such as situational awareness data, on the enterprise. Disconnected Messaging Service This service maintains data subscription results for the tactical devices to support disconnected communication situation. Data Discovery Service This service allows enterprise systems to identify types of data available on the tactical networks through NCTS. 5. A Tactical Framework The architecture for NCTS is broken up into three major components which consist of the user interface components, business logic and data access components. 5.1 Business Logic Components Mediation Engine, the Device Manager, and the Subscription Manager. The Tactical Network Interface component of NCTS provides the communications gateway to send messages to or receive messages from tactical systems and sensors operating on low-bandwidth tactical radio networks. The Mediation Engine handles the translation of tactical messages into Extensible Markup Language (XML) which then can be consumed by or published to the GIG. The Device Manager handles registration of tactical devices that NCTS interfaces with and the Subscription Manager handles subscription requests Tactical Network Interface The Tactical Network Interface (TNI) component of NCTS provides a communications interface that reads messages originating from tactical devices operating on low-bandwidth tactical radio networks. This component interacts with the Device Manager in order to validate the data source based on registered tactical devices and interacts with the Mediation Engine in order to parse tactical messages and translate them into a standard exchange language such as XML. Conversely, the TNI is used to transmit data over the low-bandwidth network that has been retrieved from the GIG and translated into tactical messages. The Business Logic Components consist of four subcomponents. The Tactical Network Interface, the 4

5 Mobile Tactical Device Mobile Tactical Device Low Bandwidth Tactical Network NCTS Administrative User Interface Components Business Logic Components Tactical Network Mediation Device Subscription Interface Engine Manager Manager Data Access & Service Components Web Service Interface Device Tactical Registry Data Store Discovery Services Disconnected Message Queue Subscription Registry Publishing Services Subscription Services Enterprise Services Network Figure 2. NCTS framework Transmitting messages in a low bandwidth environment between tactical devices and NCTS calls for the use of a flexible, standardized, light weight messaging format. JVMF is one of the existing DoD message standards that may be leveraged initially to meet this criteria. JVMF is currently being utilized on existing tactical networks and is optimized for the low bandwidth environment. The benefits of a standard such as JVMF in a tactical environment include: Light-weight, binary military message format that supports restricted bandwidth networks Provides a scaleable, flexible standard Only passes the information required at the time it is sent, thereby preserving bandwidth Information can be selectively adapted to suit the operational situation of the moment Data fields can be selected or omitted from a message as required Ability to repeat certain fields in a message without sending another message Accommodates multiple data types Directed by the Army as the solution to the battlefield digitization interoperability problem Part of the Tactical Data Link (TDL) MIL standards The process for sending JVMF messages between tactical devices and NCTS involves embedding message objects, such as reports or Areas of Interest (AOIs), into text based message objects. These objects are then encoded as binary messages based on the JVMF specifications for transmission over lowbandwidth tactical radio networks. Once the NCTS TNI receives a JVMF message, it is passed to the NCTS Mediation Engine. This component parses the JVMF message, and the embedded data is placed into an object that can be acted upon by NCTS. While the focus of this discussion has been on leveraging JVMF, not all tactical devices currently utilize the JVMF standard. As a result, the TNI of NCTS has been designed to be scalable in order to accommodate other existing or emerging messaging formats. This component provides a great deal of 5

6 flexibility and scalability with the potential to support multiple tactical message standards and versions Device Manager Component The Device Manager (DM) component provides the ability to register tactical devices that NCTS interfaces with for authentication and data management purposes. This component provides two methods for registering tactical devices. The first is a manual registration process that may be accessed through the NCTS Administrative User Interface component in which devices are entered into NCTS manually, essentially creating a tactical device address book. This is required to support devices that cannot provide dynamic device registration and tactical networks that require a static, manually configured address or unit list. The DM also provides a registration capability that allows devices to register dynamically using a tactical message. In order to implement this dynamic registration capability Sensor Data Link (SDL) protocol is leveraged. Sensor Data Link (SDL) is an Army sensor communications standard, developed by Project Manager, Night Vision/Reconnaissance, Surveillance, and Target Acquisition (PM NV/RSTA) and their parent organization Program Executive Office, Intelligence, Electronic Warfare, and Sensors (POE IEW&S). It was developed to accommodate tactical sensors which typically function over low-bandwidth network connections where communications are often intermittent and the devices are often smaller mobile systems that may not have the power or ability to process excessive amounts of data or handle multiple requests for information from a large number of consumers. The SDL standard is designed for use in a joint, net-centric environment and is an extension of the low-bandwidth binary message specification JVMF. As such, it is a perfect candidate for the integration of device management with NCTS. The Device Manager also interacts with the TNI component to maintain the communications status of registered devices. It stores tactical messages in the Disconnected Message Queue when transmission to a tactical device fails Mediation Engine Message translation is a key tactical SOA foundation piece. The Mediation Engine is a subcomponent within the NCTS business logic layer. The Mediation Engine converts tactical messages received from the tactical network into XML messages and vice versa. Once this conversion has taken place, the Mediation Engine then determines the subscriber to publish the message to or whether a different action needs to be taken on the message such as registering or un-registering a tactical device. It interacts with the Device Manager to handle tactical device registration messages and interacts with the Subscription Manager to handle data request/subscription messages. The Mediation Engine leverages a workflow engine that determines how to process the metadata from parsed messages. In addition, the Mediation Engine utilizes the Web Service Interface to facilitate the exchange of information with other systems Subscription Manager The Subscription Manager component manages subscriptions to tactical data by enterprise systems and subscriptions to enterprise data by tactical devices. In the case where subscription services are not yet available on certain enterprise systems, this component performs a persistent query for information. The Subscription Manager interacts with the Web Service Interface to consume or subscribe to enterprise data. 5.2 Data Access Logic Components Data access components provide access to data sources such as databases or remote data sources accessed through Simple Object Access Protocol (SOAP) web services Web Service Interface Access to GIG capabilities necessitates the use of web services. A web service is a web-based application incorporating a collection of protocols and standards used for exchanging data between systems over an Internet Protocol backbone. Web services are platform independent meaning that any client application running on any operating system can be used to exploit their capabilities. NCTS leverages web services to publish and retrieve information from other systems operating on the GIG. The NCTS Mediation Engine interacts with the Web Service Interface. The Mediation Engine uses the Web Service Interface to discover services and sources of information, handle security, and interface with enterprise systems to publish or subscribe to enterprise services. In order to facilitate the exchange of information with these systems, the Mediation Engine 6

7 leverages web-service methods that provide data discovery functionality. The Web Service Interface leverages SOAP (Simple Object Access Protocol) to invoke these methods and transfers the XML data between a web-service provider and the web-service consumer (NCTS). XSL (extensible Stylesheet Language) is the language specification used to translate messages originating from one system to another format. XSD (XML Schema Definition), is the standard used to define the format of the XML data that is transmitted. The Web Services Interface leverages standard service oriented technologies to communicate with other systems. WSDL interfaces are used to describe the NCTS services. XSD s are used to describe the data, XML is used to tag data, and SOAP is used to transfer data. Each of the technologies is used in conjunction with one another to facilitate the mechanics of the service oriented architecture Disconnected Message Queue Communications reliability if one of the major hindrances to successfully implementing an SOA approach in the tactical environment. NCTS provides the ability to support message queuing for tactical devices that have lost connections or have disconnected with the network before the requested information was received. As tactical devices submit data requests to NCTS, NCTS takes these data requests and leverages NCES by retrieving the requested information and then provides this information back to NCTS. Once NCTS receives these responses, the data is aligned with the specific requesting device and data request. Next, if the tactical device is still connected to the network then the information is passed back to the device. However, if the device is not connected to NCTS, the Disconnected Message Queue stores the message and makes it available once the device is connected. The Disconnected Message Queue functions similarly to an service. User/Devices create or register accounts and can receive certain information. If logged off or disconnected from the network information continues to collect in a repository and the device can retrieve the information once it reconnects Device and Subscription Registry, Tactical Data Store Device management and data guarantee delivery can only be accomplished with appropriate device and data stores. The Device Registry stores information about devices that have been registered with NCTS. Particularly this registry holds information about what types of data is being made available for consumption by these devices and their last known communications statuses. As devices are registered and unregistered this information is stored and can be retrieved in order to discover which devices have been registered with NCTS. The Tactical Data Store holds the tactical data originating from the tactical environment. The tactical data is then made available to enterprise systems who have subscribed to the tactical data. The Subscription Registry is used by the Subscription Manager to track the subscriptions. 5.3 Administrative User Interface Components The Administrative User Interface Components have been architected in a layered approach which separates the User Interface (UI) logic from the business logic in order to accommodate changing UI needs. To help synchronize and orchestrate user interactions, separate user process components have been created. This way, the process flow and state management logic is not hard coded in the user interface elements themselves and the same user interaction engine can be scaled in order to accommodate multiple user interfaces. 5.4 Integrating Tactical Services The components listed above provide the basic foundation for the NCTS framework, and an overview of how NCTS handles the bridge/mediation capability between the low-bandwidth and high-bandwidth networks. This framework is intended to be scaleable to add additional service capabilities and functionality (tactical services) to enhance the capabilities of the warfighter and provide the enterprise with information from the tactical edge that has traditionally been unavailable in a SOA environment. Therefore, the specific tactical services that are deployed on an implementation of NCTS may vary, depending on the needs of the tactical environment. 6. Conclusion DISA s NCES initiative and the GIG Bandwidth Expansion (GIG-BE) have been developed by the DoD 7

8 to deliver unprecedented information superiority for operational forces over high bandwidth networks. However, these initiatives are derived from commercial industry standards which are based on Internet Protocol architectures that assume ubiquitous access to commercial quality wideband networks. There is a need within the DoD to adopt a set of standards and mediation services that will provide access to NCES from bandwidth constrained tactical networks that operate at the Army s Modular Force. This paper has introduced the concept of Net-Centric Tactical Services (NCTS) as a solution to this problem. NCTS is a framework for extending the concepts of NCES beyond the enterprise. NCTS solves the digital divide by extending the value of NCES to Army platforms and dismounted soldiers. NCTS recommends the continued use of VMF as a standard for data sharing for tactical applications. NCTS provides a bridge between the two disparate networks and NCTS technology is available now for immediate application to the Army s Modular Force Battle Command networks allowing low-bandwidth tactical users the ability to participate in the Net-Centric information sharing paradigm. focused on tactical system and sensor integration for the U.S. Army. Mr. Crane provides the U.S. Army with full lifecycle development of mobile systems and is working to provide solutions that bridge-the-gap between low-bandwidth tactical radio networks and enterprise SOA architectures. Laura Scannell has over 13 years experience developing tactical system solutions for the U.S. Army and other DoD clients. Currently, she is focused on providing the U.S. Army with full lifecycle development of mobile systems and is working to provide solutions that bridge-the-gap between lowbandwidth tactical radio networks and enterprise SOA architectures. Reference: 1. DoD CIO Memo: DoD Net-Centric Data Strategy, May NCES Developer Guide: ne=true. 3. DoD CIO, Department of Defense Global Information Grid Architectural Vision version 1.0, DoD, June Army CIO/G6 Campaign Plan, pdf. 5. Global Information Grid (GIG) Tactical Edge Networks (TEN) Navy SBIR Topic N Biographies: Scott Crane has over 11 years experience in system integration and software solution development for DoD and other government clients. Currently, he is 8