Copyright © Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy. All rights reserved. Brief Introduction to Software Connectors Software Architecture

Foundations, Theory, and Practice Software Architecture 2 What is a Software Connector? Architectural element that models u Interactions among components u Rules that govern those interactions Simple interactions u Procedure calls u Shared variable access Complex & semantically rich interactions u Client-server protocols u Database access protocols u Asynchronous event multicast Each connector provides u Interaction duct(s) u Transfer of control and/or data

Foundations, Theory, and Practice Software Architecture 3 Example Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 4 Software Connector Roles and Types Roles u Communication u Coordination u Conversion u Facilitation Types u Procedure call u Data access u Event u Stream u Linkage u Distributor u Arbitrator u Adaptor

Foundations, Theory, and Practice Software Architecture 5 Classifying Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 6 Procedure Call Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 7 Event Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 8 Data Access Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 9 Linkage Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 10 Stream Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 11 Arbitrator Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 12 Adaptor Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 13 Distributor Connectors Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 14 How Does One Select a Connector? Determine a system’s interconnection and interaction needs u Software interconnection models can help Determine roles to be fulfilled by the system’s connectors u Communication, coordination, conversion, facilitation For each connector u Determine its appropriate type(s) u Determine its dimensions of interest u Select appropriate values for each dimension For multi-type, i.e., composite connectors u Determine the atomic connector compatibilities

Foundations, Theory, and Practice Software Architecture 15 Simple Example System components will execute in two processes on the same host u Mostly intra-process u Occasionally inter-process The interaction among the components is synchronous The components are primarily computation-intensive u There are some data storage needs, but those are secondary

Foundations, Theory, and Practice Software Architecture 16 Simple Example (cont’d)  Select procedure call connectors for intra-process interaction  Combine procedure call connectors with distributor connectors for inter-process interaction  RPC  Select the values for the different connector dimensions  What are the appropriate values?  What values are imposed by your favorite programming language(s)?

Foundations, Theory, and Practice Software Architecture 17 Two Connector Types in Tandem Select the appropriate values for PC and RPC! Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.

Foundations, Theory, and Practice Software Architecture 18 Connector Dimension Inter-Relationships Requires – u Choice of one dimension mandates the choice of another Prohibits – u Two dimensions can never be composed into a single connector Restricts – u Dimensions are not always required to be used together u Certain dimension combinations may be invalid Cautions – u Combinations may result in unstable or unreliable connectors

Foundations, Theory, and Practice Software Architecture 19 Dimension Inter-Relationships in a Nutshell Software Architecture: Foundations, Theory, and Practice; Richard N. Taylor, Nenad Medvidovic, and Eric M. Dashofy; © 2008 John Wiley & Sons, Inc. Reprinted with permission.