EventHelix Update Q4 2003

Here is a list of updates that have been made to EventHelix.com since the last EventHelix Update. We would like to apologize for the irregular update frequency of the newsletter. In the future we plan to publish an update every quarter.

STL Design Patterns updated with code

Standard Template Library (STL) has been a part of C++ for a very long time but many people who have embraced C++ still hesitate in using STL in their projects. There is a feeling that STL is difficult and hard to learn. Nothing could be further from truth. STL is simple to use, debugged and efficient code. STL can reduce the amount on mundane repetitive code that takes up so much of project time.

In this series of articles we will consider some real life design patterns from Embedded and Real-time systems and develop them using STL. These examples will illustrate how easy it is to implement complex design patterns with very little coding.

STL Design Patterns II updated with code

We continue our discussion about STL design patterns. In this article we will discuss queuing and resource management patterns that can be implemented with ease using the STL queue and priority queue adaptors. A simple implementation of the following design patterns will be covered in this article:

Hierarchical State Machine updated with code

In this article, we will be highlighting the advantages of hierarchical state machine design over conventional state machine design.

In conventional state machine design, all states are considered at the same level. The design does not capture the commonality that exists among states. In real life, many states handle most messages in similar fashion and differ only in handling of few key messages. Even when the actual handling differs, there is still some commonality. Hierarchical state machine design captures the commonality by organizing the states as a hierarchy. The states at the higher level in hierarchy perform the common message handling, while the lower level states inherit the commonality from higher level ones and perform the state specific functions.

Synchronizer Design Pattern new

Many systems used in digital communication send data in synchronous back-to-back frames. When a receiver tunes to such a data stream, it has no knowledge of the frame boundaries. The Synchronizer Design Pattern is used to look at the raw incoming bit or byte stream and detect and align to the frame structure. The frame structure is detected by searching for a sync pattern in the frame.

Once the synchronization is achieved, the Synchronizer confirms the presence of the sync pattern in every frame. If the sync pattern in missed a certain number of times, loss of sync is declared.

Introducing EventStudio 2.0 new

EventStudio is a major upgrade. The following features have been added:

Four new type of documents can be generated:
- Collaboration Diagram
- Interface Collaboration Diagram
- Interaction Collaboration Diagram
- Message Filter Collaboration Diagram
Choose between collaboration diagram or context diagrams for any of the above document types.
Use the power of regular expressions to generate an infinite variety of documents.
Context Menus in Scenario Bar and Editor.
Generate PDF and HTML documents from command-line.
Block Remark Enhancements
- Block remarks can be formatted as left, right, center, justify or verbatim
- Paragraphs can be defined in block remarks
User interface enhancements
Better control over scenario diagram formatting. Choose between automatic and landscape orientation.
Strings are now allowed in message name, parameter name and parameter values.
Hungarian Notation Support in object name formatting.
Over 10 detailed examples are now included. Surfing the examples will get you started quickly.

HTTP Sequence Diagram pdf new

This sequence diagram describes the IP messages exchanged between the browser and servers on the internet. The message exchange presented here was obtained from an older version of EventHelix.com home page. Internet Explorer (IE) with HTTP 1.1 was used for this message trace. This is a trace of a real page load and shows all the messages that were involved in rendering the complete page. The actual sequence of packets as seen by the browser is preserved.

-- EventHelix.com Team