Module Layered View

4.1 Module Layered View Packet 1: The ECS System

4.1.1 Primary Presentation

4.1.2 Element Catalog

4.1.2.1 Elements and Their Properties

Properties of ECS layers, given in the following table, are

• Name
• Responsibilities
• Contents

Element Name	Responsibilities	Contents
Common Facilities	Common Facilities are defined as those interfaces and uniform sequencing semantics that are shared across applications. Common Facilities consist of generic facilities as defined by the OMG, ECS domain specific facilities, and other industry standards. Common Facilities includes legacy service categories such as File Access (ftp), Electronic Mail, and Remote Services (rlogin, rcp, rcmd . . . ).	Object Linking Service, Embedded Objects Service, Object Interchange Service, Clipboard Service, Cataloging and Browsing Service, Object Rendering Service, Document Interchange Service, Help Facilities Service, Printing and Spooling Service, Application Agents Service, File Access Service, Electronic Mail Service, Virtual Terminal Service, Bulletin Board/Information Search and Retrieval Service, and Management Data Access Service.
ORB	An Object Request Broker (ORB) provides the communication backbone for transparently making requests to and receiving responses from objects locally or remotely without client awareness of the mechanisms used to communicate with, activate, or store the objects. The ORB is the core set of object services that enables distributed processing of objects.	Interface definition language (IDL) compiler, an interface repository, an implementation repository, a static invocation interface, and a dynamic invocation interface.
Object Service	Object services provide low-level building-block capabilities. Since these services are (or are expected to be) mostly COTS, they represent potential building blocks for all ECS applications. An ORB does not provide interoperability by itself. Semantic support is provided by Object Services in the form of additional interfaces, protocols, and policies. The services are general purpose and necessary to construct any distributed application. Object Services augment the functionality of the ORB and are a collection of services (interfaces and objects) that support basic functions for using and implementing objects. Operations provided by Object Services serve as building blocks for OMG Common Facilities and Application Objects.	Event Service, Naming Service, LifeCycle Service, Security Service, Persistence Service, Association Service, Trading Service, Query Service, Property Service, Concurrency Service, Externalization Service, Transaction Service, Threads Service, Time Service, Change Management Service, Replication Service, Data Interchange Service, Archive Service, Backup/Restore Service, Startup/ Shut-down Service, Installation and Activation Service, and Operational Control Service.
Transport	The transport layer provides transparent transfer of data between higher level entities and relieves them from any concern with how reliable and cost-effective transfer of data is achieved. Cost/performance optimization is achieved within constraints imposed by the overall demands of all concurrent higher-level sessions, and the overall quality and capacity of the network-service available to the Transport layer. Primary services provided by the transport services for connection-mode communication include transport connection establishment, transport connection release, data transfer, expedited data transfer, and suspend. Connectionless-mode communication provides all of the above except that data transfer omits segmentation and PDU reassembly.	TCP transport service, UDP transport service, ISO Transport Protocol 4 service, and XTP transport service.
Network	The network layer provides the functional and procedural means to exchange network data units between transport entities over network connections, both for connection-mode and connectionless-mode communications. It relieves upper layers from concern of all routing and relay operations associated with network connection. The basic function of the network layer is to provide the transparent transfer of data between transport entities. This layer contains all functions to provide upper layers with a firm network/transport layer boundary, independent of underlying communications media in all things other than QoS. In this way, the network layer masks the differences in the characteristics of different transmission and subnetwork technologies into a consistent service.	IP services, ICMP Protocol service, ARP protocol service, OSPF protocol service, BGP protocol service, and RIP protocol service.
[etc.]	[etc.]	[etc.]

4.1.2.2 Relations and Their Properties

The relation in the layered view is allowed-to-use. Software in a layer is allowed to use other software in the same layer. Software in a layer is allowed to use software in any other layer immediately below, as shown in the primary presentation.

4.1.2.3 Element Interfaces

[omitted]

4.1.2.4 Element Behavior

Not applicable.

4.1.3 Context Diagram

The context for this view packet is established by the context diagram in Volume II, Section 1.1.3 in the highest-level view packet of the module decomposition view.

4.1.4 Variability Guide

None.

4.1.5 Architecture Background

[omitted]

4.1.6 Other Information

[omitted]

4.1.7 Related View Packets

• Parent: None.
• Children: None.
• Siblings: None in this view. View packets in other views that express the same scope as this onenamely, the whole systeminclude

  - Module Decomposition View Packet 1: The ECS System (Volume II, Section 1.1, page 414)

  - C&C Pipe-and-Filter View Packet 1: The ECS System (Volume II, Section 5.1, page 439)

  - Allocation Deployment View Packet 1: The ECS System (Volume II, Section 8.1, page 457)

  - Allocation Implementation View Packet 1: The ECS System (Volume II, Section 9.1, page 461)

  - Allocation Work Assignment View Packet 1: The ECS System (Volume II, Section 10.1, page 464)