1. Mission Data Product Distribution Services
A quick introduction into
Mission Data Product Distribution Services

2. Background 3 Concepts 5 Functionality 9 Cooperation with the other services 17
INDEX
A quick introduction into Mission Data Product Distribution Services
18/09/2015

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BACKGROUND
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4. BACKGROUND
A need for the service
The Mission Data Product Distribution Services (MDPDS) are a set of services which the main aim is to provide controlled access to mission data for the community of users who do not have access to the Mission Control System monitoring and control facilities. The goal of providing their specification is to increase the degree of portability and interoperability between sites that need such functionality and to reduce the time and costs required to access space mission data.
Thanks to the underlying assumptions the MDPDS allow distribution of virtually any kind of data to authorized users, no matter where they are located. Concepts introduced by the services serve to describe in detailed and standarized way any particular kind of data, how they are structured and represented, so that requester has all information needed to process them.
The specification provides methods for a retrieval of the data that match specified criteria in one of the two modes. The first one is foreseen for getting the data that are already archived, while the second one can be used for an on-line access to data that are being currently generated.
The MDPDS are in conformance with the service framework specified in Mission Operations Services Concept and are defined in terms of the MAL.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

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CONCEPTS
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6. CONCEPTS
Product
Mission Data Product (product) is a set of the space mission data available for the user community. Any data (parameters, actions, alerts, images, etc) distributed by the service are considered to be a product. The product concept has been introduced, in order to abstract from the structure, content and format in which diverse space mission data can be persisted, requested and provisioned. This abstraction allows the specification of a generic set of services for managing, requesting and provisioning of space mission data.
The MDPDS specifies three elements, which combination uniquely defines each product. That triple consists of the product type, the product source and the product format.
The product type represents a category of mission data, to which the product belongs (e.g. parameter value evolution in a given time period, action history).
The product source is an indication of the origin of the data. It points out what exactly generated the data (e.g. particular sensor of the particular satellite of the particular mission).
The product format is a standardized description detailing how to encode mission data products (e.g. raw binary value, XML). It provides means to represent the information, which product carries, in a standardized way.
An internal structure of each product is described by product specification. It is a formal specification of all the fields, called product attributes, that the product consists of, written in terms of MAL. It is connected only with product type and provides: a field name, a description and a MAL data type that is used for representing actual value of the field. Thus every product is described in an interoperable way and can be easly parsed.
So product specification describes what product consists of, where format describes how it is represented.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

7. CONCEPTS
Catalogue of products
When a user wants to use the service, the first thing he wants to do is to check what products are avaialble for him. For this purpose it is needed to get a register of available products. All available products are kept in the catalogue of products and every product, before it can be obtained, must be first defined in that catalogue.
As mentioned before, each product is characterized by a triple of the product type, source and format. Each product of the particular type can be an outcome of different sources, and in turn be available in many formats far different sources. Thus the catalogue consists of catalogue entries containing that triple (and some other details) and that triple uniquely defines particular product.
A concept of the catalogue allows a requester to familiarize with all available products, where they come from and in which formats they occur. Moreover, the catalogue may be filtered by certain criteria so that one could obtain a list of products only in which he/she is interested in.
The catalogue stores also additional information. Among them is a list of product attributes, being the subset of all the product attributes enumerated in product specification. This list informs which attributes can be used for filtering or sorting data returned for product requests. Furthermore, the catalogue entry contains a provisioning mode, compression methods, encryption methods and a description of the each product.
To make the product available it is required to add it to the catalogue and afterwards to define its internal structure, called the product specification. Then product is availalbe for distribution.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

8. CONCEPTS
Provision modes
Products can be distributed in one of two provision modes. Provison mode is a one of the two methods of the data retrieval: a batch mode or a stream mode.
Batch mode is a provisioning mode used for the retrieval of the archived data. It is used for obtaining finite set of data that has been already recorded. The data obtained in this mode can be delivered to a location pointed in the request, even if it is different that the requester. A request can be scheduled for execution in given point in the future and to be repeated regulary. Through the scheduling, users can get not only the data that has been archived for some mission, but refresh them periodically by recieving new portions in a batch. The batch mode is useful when some research center needs to do offline data analysis.
Stream Mode is a provisioning mode, in which the mission data is provided in small chunks as it becomes available to the consumers. The data are streamed to the user exactly at the point in time when they are recieved from the source and this process lasts till user disconnects from the stream on demand or the stream becomes closed. The stream mode is useful for monitoring purposes and on-line data analysis.
Both modes enable filtering data by complex expressions so that response meets user needs.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

9. ESTO ES UN EJEMPLO DE
FUNCTIONALITY
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10. Relation between MDPDS services
The Mission Data Product Distribution Services consist of two services: Products Management (PM) and Mission Data Product Distribution (MDPD).The purpose of each service is different, but they are related by a common concept. The relation is established by the catalogue of products.
The Mission Data Product Distribution service allows obtaining a list of products that the user is interested in and retrieving the selected product. From another perspective, it can be perceived as a specification of the interface for retrieval of the information about the products and the products themselves.
The Products Management service allows manipulation of the catalogue by providing means for defining available products. It can also be seen as a component responsible for the configuration of the Mission Data Product Distribution solution.

11. Creation of the Product
FUNCTIONALITY
Products management
The main role of the service is to manage the catalogue of products. Each product, before it can be accessed, must have been created in the catalogue. Hence, the management of the catalogue relies on defining entries containing the product type, source and format along with additional details and removing entries for unavailable products.
As mentioned earlier, the product becomes available when two conditions are met. The first one is defining the product in the catalogue and the second one is providing its specification. To satisfy the second requirement, the Product Management service allows setting the specification of each product. Moreover, some of the attributes of the product specification can be configured to be used to filter or sort instances of the requested product.
Another aspect of the service is a possibility to define product streams. The MDPDS provides products in batch and stream provisioning modes.
Creation of the Product
To allow provision of products in the latter mode, the stream must have been created in Product Management service first. The service allows creation of streams used for transmitting only products of the specified type, source and format, which match certain criteria.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

12. Detailed flow of actions to create a product
FUNCTIONALITY
Detailed flow of actions to create a product
A typical use case scenario of the Product Management service is following. For each available product, the Consumer sends to the Provider a series of messages that result in creation of a product catalogue entry in the COM Archive. First message, passed by addProductType() operation, contains a request to add a new product type, along with its short description. Next, there are issued addProductSource() messages defining all the sources, from where particular type of product can be obtained. For each combination of the product type and the source, the Consumer calls addProductDetail() operation to specify formats, provisioning modes and optionally other details describing the product. When a unique triple of the product type, source and details has been provided, the Provider automatically creates catalogue entry.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

13. FUNCTIONALITY
...continued
Next step is concerned with setting the product specification by executing setProductSpecification() operation for each particular product. The product becomes fully described and from now on can be requested. At the end, it is optional to define which attributes of the product specification can be used for product filtering or sorting (addProductAttributes() operation). In case no attributes for the product has been defined, usage of filter or sort fields in a request for this product will cause an error.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

14. Mission Data Product Distribution
FUNCTIONALITY
Mission Data Product Distribution
The service allows the retrieval of the catalogue of products that has been defined in the Product Management service. It provides the functionality to query the catalogue by a given set of criteria, in order to limit the number of catalogue entries only to those, in which the client may be interested.
The main goal of the service is to deliver the mission data products to user who requested them. There are two provisioning modes – a batch mode and a stream mode. They differ in how they work and in functionality they offer. The batch mode enables to retrieve the historical data in a bunch, as well as the future data by scheduled periodic polling to check if some new is available. On the other hand, the stream mode provides the data once it is available and does it until the user is interested in receiving updates. Both provisioning modes enable limiting the number of the products to retrieve, by specifying filter criteria.
The service allows the client to obtain a list of attributes that can be used to compose a filter. The specification of the product can also be downloaded. An execution of each request may be cancelled at any moment. Additionally, batch requests can be suspended and resumed on demand. The service maintains the list of historical product requests and provides ability to browse them.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

15. Detailed flow of actions to retrieve a product
FUNCTIONALITY
Detailed flow of actions to retrieve a product
A typical use case scenario of the MDPD service is following. By invoking the getProductsCatalogue() operation, the Consumer retrieves from the Provider a list of product catalogue entries, which he may be interested in. To limit a number of potential matches, filter criteria that the response must meet may be provided. This is annotated in the picture by filter parameter of the getProductsCatalogue() operation. As the catalogue entries are actually stored in the COM archive, the Provider passes the request to the archive and returns a filtered list of matching entries. Next, the Consumer selects one of the products and retrieves, directly from the archive, its
detailed information (the type, source, format, provisioning mode and attributes). Through the Provider, the Consumer obtains the detailed specification of the product. For that purpose the getProductSpecification() operation is executed. Its parameter is the type of the selected product.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

16. FUNCTIONALITY
...continued
Finally, the Consumer sends to the Provider a customized product request in either a batch or a stream provisioning mode. The request specifies all the conditions that the product to retrieve must meet. In case of the batch mode, product is obtained through the requestProduct() operation. All the matching product instances are received one by one in the loop. Optionally, the execution of the request can be cancelled, suspended and resumed at any time. In turn, for the stream mode, the Consumer first creates stream containing instances of the specified product. The stream is created by the enableStreaming() operation of the Product Management service. Then the monitorProduct() operation is invoked by the Consumer to subscribe for all messages from that stream and to receive upcoming updates. At the end, the stream is closed by the disableStreaming() operation of the Product Management service.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

17. Cooperation with the other services
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Cooperation with the other services
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18. MDPDS vs COM and M&C Services
Cooperation with the other services
MDPDS vs COM and M&C Services
The MDPDS functionality relies on availability of the COM archive service. Storage of all information kept in the products catalogue is actually delegated to the COM archive. Also all product requests and their statistics are archived there. A usage of the COM archive makes the MDPDS independent from any vendor of a particular database and allows assuming that there exists standarized interface to manipulate objects.
The MDPDS makes use of the other COM service - event service. Events extend the MDPDS capabilities by providing notifications about situations important to users, like adding/removing of a product: type, source, format, specification, atribute or a catalogue entry.
The M&C defines basic information units (parameters, actions, alerts, etc.) that are used in monitoring and control context. The MDPDS extends those definitions by additional information so that enabling to use them as mission data products. Thus, it is possible to retrieve a list of parameter values in given time range, fetch actions sent to be executed by a spacecraft or to get alerts risen by a malfunctioning subsystem.
The Login service can be incorporated to work with the MDPDS to limit which users are allowed to execute particular operations. The division of the MDPDS to two services: Products Management and Mission Data Distribution System is foreseen to allow creation of two distinct categories of users: administrators, who manage the catalogue of available products and regular users who download products they are interested in.
Usage of the mentioned MO services fits into MO architecture, where every single service is responsible for its own core functionality. This provides great interoperability, flexibility and extensibility, therby satisfying core assumptions of the MO framework.
A quick introduction into Mission Data Product Distribution Services
18/09/2015

19. Thank you Maciej Prokopczyk Software engineer, Project manager