Welcome!

You will be redirected in 30 seconds or close now.

ColdFusion Authors: Yakov Fain, Jeremy Geelan, Maureen O'Gara, Nancy Y. Nee, Tad Anderson

RSS Feed Item

Debugging RIA Services


Introduction

This is a call to action to everyone building clients, servers and frameworks for rich internet applications (RIAs) to improve the life of RIA developers by improving the debugging of backend services RIAs depend on.

Motivation

The relationship of an RIA to its backend is quite different than that of a traditional Web application. In a traditional, dynamic HTML generation Web app, the output stream is under the control of the developer and the application server. Developers can freely mix application output with diagnostic information. By contrast, RIAs have a narrow communication channel with the server, typically using a service-oriented architecture (SOA). Because the output format is typically XML or JSON (and because there are no established standards for augmenting message payloads) there is no opportunity to include any additional information. This is particularly problematic during debugging.

Consider the following with Adobe Flex as the example frontend and ColdFusion (CF) as the example backend although the discussion applies to any RIA:

  • An exception on the server would cause a service request to fail without providing any useful information to the developer. In particular, there is no way to see the exception information or the server-side stack trace, despite the fact that CF would generate ample information useful for debugging.
  • Turning on debug information output on the server would break the service by adding HTML at the end of the XML output. Developers have no good way of consuming that debugging information other than test-driving the service in an HTML test harness.
  • CFDump is a one of the most beloved tags in CFML. Almost every developer uses it in every application because it provides great debugging efficiency. There is no way to use CFDump in RIA development.
  • There is no way to generate any auxiliary, Flash trace()-like output in service responses, something any HTML developer is used to doing. Again, when using services with RIA front-ends, developers are flying blind.
  • Conversely, RIA developers have no good mechanism of creating any persistent application output. For example, while writing a message to a log takes one line with CFLog, an RIA developer would have to implement a logging service in order to achieve this capability and store some information for future analysis.

Debuggers are not the answer

Every backend environment has its own debugging capabilities. Also, there many ways to debug AJAX and Flex applications:

However, debuggers do not address the problem of efficiently debugging backend services for RIAs. Most Web developers don’t use or don’t know how to use debuggers effectively. Debuggers are good for step execution and occasional variable inspection. They are poor at displaying a lot of specific information efficiently. Also, using both a client-sde and a server-side debugger often slows down the develop-test-fix cycle. In short, using debuggers are no substitute for having flexible and powerful diagnostic output from backend services.

As an example, consider the actions a developer must take in a CF debugger to get the information equivalent to seeing the output generated by a CFQuery exception with stack trace enabled or a CFDump of a query with 200 rows. There is simply no comparison in terms of productivity.

The closest piece of technology I’ve found to what I’m proposing here is FirePHP. I think the industry needs a broader and more standardized solution.

A personal tangent

A recent experience underscored these problems and was the personal motivation for me to write this. The latest RIA I built had a Flex 3 frontend with a CF8 backend. Despite its simplicity-one component (CFC) on the backend and only a couple of thousand lines of MXML-I constantly had to work around the lack of visibility when I was invoking services from the client. Before long, I found myself installing Fiddler to see the HTTP traffic and logging WDDX packets and CFDump output which I then crudely displayed in a browser window using a quick’n'dirty Web page. When using the client-side and server-side debuggers I was frustrated by the number of clicks it took to get to data I cared about and the amount of irrelevant information presented, e.g., tons of underscore-prefixed internal variables for unnamed controls I had to scroll through to get to variables I cared about.

When I pinged a few people building AJAX and Flex apps I heard the very same feelings about their debugging experience and the difference between building RIAs vs. traditional Web applications.

Many of the ideas proposed in this document are not new. Back in the spring of 2001, I built what may have been the first prototype of Flash communicating to servers using SOA. For the backend I used CF with a dynamic dispatch layer to custom tags (CFCs weren’t there yet). In testing the prototype I hit the same debugging problems. I implemented a feature that took diagnostic output from the server and displayed it as trace() output in the player. It made my life easier but it wasn’t a generic solution because it relied on a particular response format.

Some years ago I would have jumped to code the solution I propose here and open-source it, like I did a decade ago with WDDX. For better or worse, I don’t code that much these days. Instead, I’m focusing on helping entrepreneurs start companies. I hope this post inspires someone to tackle this problem and share their work with the RIA developer community.

Proposed solution

Improving the debugging of RIA service backends requires a multi-faceted approach that spans clients, servers and tools. In order of importance, there are four inter-related pieces:

  1. Establishing a diagnostic output channel from the server to the client. The goal here is to give Web developers familiar capabilities such as the ability to see exception diagnostics, to display diagnostic output and dump complex variables.
  2. Providing a persistent output channel from the client to the server. The goal here is to enable structured logging from the client to the server so that important diagnostic output can be preserved for future analysis.
  3. Implementing structured logging on the server. The goal here is to improve the power of logging by building the kind of logging system that makes developers more productive during the debugging cycle.
  4. Improving debuggers. There is no such thing as a true RIA debugger out there. Since this part of the solution has much broader scope, it is not covered here.

Architecture

There are multiple ways to implement the proposed solution. The approach outlined here is probably one of the simplest. It involves a single diagnostic output specification, three new services on the backend for server-side diagnostic output, client-to-server logging and log viewing, and a reusable viewer of diagnostic output. These capabilities are exposed in an appropriate manner through the frontend and backend programming models and frameworks.

Figure 1. RIA diagnostic output architecture

Diagnostic output specification

The diagnostic output specification has three parts:

  • A schema for identifying the output format
  • A mechanism for identifying specific output stored remotely
  • A mechanism for passing diagnostic output identifiers from the server to the client

Diagnostic information is provided in “documents” (chunks, payloads, etc.) according to the schema. Each such document must be URI-addressable during its lifetime. The exact format of the URI is specific to a particular server environment. For example, in a ColdFusion deployment it can be a URL to the diagnostic output service. The URL will be parameterized such that the right diagnostic information is returned to the client. Let’s call this a DebugURI (dURI).

For performance reasons, the URI must be able to address sub-parts of any single pile of diagnostic information. For example, if the diagnostic information includes a reference to a 10,000 record query it wouldn’t make sense to either arbitrarily restrict how many rows the client can have access to or to ship all 10,000 lines with the diagnostic information request. However, to simplify implementation, the URI format need not be exposed to the client. For example, the client shouldn’t necessarily be able to request rows 9,212 - 9,532 of the query. Instead, the server can simply put a placeholder in a document saying “there is more data here and if you want it, request this URI and I’ll get it to you”. Let’s call this particular type of dURI a ContinuationURI (cURI).

The specific mechanism for passing diagnostic output identifiers from the server to the client is protocol and environment specific. An HTTP response header carrying the dURI is a simple choice that works well across languages and platforms and does not modify the response payload.

The diagnostic output schema is a format (not necessarily a formal XML Schema) for describing the information typically encountered while debugging applications, including but not limited to:

  • Exception information
  • Call stack information
  • Data structure dumps
  • Application state information
  • Service requests & responses
  • External service interactions, e.g., database queries and responses
  • Performance-related information
  • Developer-created diagnostics messages

There are trade-offs in the amount of detail in the schema. With more detail, providing support across environments will take a little more time but, on the other hand, the output viewer can be more capable, e.g., allowing dynamic expansion of data structures, etc. With minimal detail, developers will only be able to look at volumes of text in the viewer.

The schema should have built-in extensibility features.

Last but not least, the schema must specify the format of the cURI placeholder discussed above.

Backend support

Backend support includes a persistent and a transient store for diagnostic information and three new services.

Data stores

The backend must implement two data stores, one for run-time diagnostic information and one for persistent diagnostic information.

The runtime information store can leverage the traditional app server state management capabilities, in particular, session management. The information model is simple. Diagnostic information generated during the processing of a request can be maintained as an aggregate object indexed by dURIs. There needs to be a purging policy for efficient resource management.

The persistent information store can leverage the existing logging architecture of a server. However, a more efficient implementation may want to use an embedded database. See the following discussion on the log viewer.

Services

The debug output service is invoked via dURIs passed with a server response or generated by the log viewing service (see below) or with cURIs. It generates a diagnostic information document. It can use a default or user-configured policy governing the size and detail in these documents, adding cURIs where appropriate. The debug output service can pull information from both the transient and persistent stores.

The remote logging service takes a diagnostic information document and some additional meta-data describing where, when and how the diagnostic information was created and persists that information.

The log viewing service has two functions. It monitors the log for changes to know when new data is available. It also allows the log viewer to list and query (and potentially search inside) the available diagnostic information documents. Every available document is identified by a dURI that the client can pass to the debug output service to retrieve the document.

Client-side support

Client-side support comes via a pre-packaged viewer application. The viewer is an RIA that provides rich functionality for working with diagnostic output documents such as:

  • Communicating with the application running on the client, allowing it to deliver diagnostic output that can be displayed richly. For example, this would be substantial improvement compared to basic trace() output in Flash or Log4Ajax.
  • Listing of available information. Some information can be provided by the client. Transient information from multiple server interactions may be available. In addition, all the persisted information is available. The viewer should also be able to open a file in the diagnostic output format.
  • Allowing some information to be persisted for future analysis. This becomes particularly interesting if there is support for annotations and sharing of the information with team members (via a URL to the debug output service or as an email attachment).
  • Supporting flexible data structure navigation and basic search across the data structures and messages.
  • Providing appropriate formatting for exceptions, call stack information, performance information, etc.

An ideal implementation of the viewer would be as an AJAX or Flex application component that can communicate with both Flash/Flex and other AJAX applications independent of the server environment. Client-side debuggers can add the viewer capability also. Perhaps the FireBug Working Group can take this on?

From a user-experience standpoint, the viewer should be able to run next-to an application as a docked component as well as a pop-up in a separate window, which would be particularly useful for developers with multiple monitors.

Specific environment support

These capabilities should be supported as appropriate by specific RIA environments. Ideally, support should be implemented at the application server level for maximum performance, efficiency, etc. As a second option, it can be provided as native or side-along extensions to common frameworks.

Specifying invocation intent

In some such environments it may be helpful to know whether a server request is made by a browser for the purposes of HTML display or as a service call. In the case of service calls, certain display-oriented capabilities such as debug output or the output of the CFDump tag in ColdFusion can be automatically redirected to contribute data to the transient diagnostic output store. In some cases the context of request can be determined directly from the HTTP-level information, e.g., a POST with Content-Type application/XML. In other cases, such as a simple HTTP GET to a RESTful service, it is difficult to do this without knowing a priori that the URL is a service. Some server components such as ColdFusion CFCs can be addressed in a number of different ways. It therefore may be helpful to consider having RIA clients optionally send a custom HTTP request header to identify the intent of the request.

Additional considerations

Managing diagnostic information in this way adds substantial overhead to application processing. It should only be enabled in debugging scenarios.

Exposing detailed server state information to remote clients poses a security risk. The backend services should require authentication and they should be able to run over a secure connection to prevent data snooping and man-in-the-middle attacks.

Manipulating diagnostic information with such ease can benefit traditional HTML application development also. Therefore, it is worth thinking about ways to integrate the view application with traditional HTML applications.

Conclusion

This document outlines a simple approach to improving the debugging backend RIA services across languages and platforms. The approach is amenable to standardization as it includes a common format for diagnostic output and a common viewer application.

These could be developed with open extensibility in mind and remotely-hosted viewer extensions allowing, for example, Ruby-on-Rails (RoR) to provide some special RoR-specific structured output that can be natively viewed via an extension (implemented as a JavaScript or Flex component) hosted on rubyforge.org.

Postscript

The discussion here points out some of the fundamental differences between RIAs and traditional HTML applications. Beyond improving the debugging of RIA services, there are many more opportunities to provide better support for RIA applications. After all, the first Web application server shipped a dozen years ago. Too much of what app servers do assumes dynamic HTML generation as opposed to Flex/AJAX clients. I’m surprised I haven’t seen more innovation in this area from large platform vendors. Smaller players such as Aptana (with Jaxer) and JackBe are pushing the boundary but their lack of distribution on the backend limits the effects of their innovation.

Read the original blog entry...

@ThingsExpo Stories
In his session at 21st Cloud Expo, Carl J. Levine, Senior Technical Evangelist for NS1, will objectively discuss how DNS is used to solve Digital Transformation challenges in large SaaS applications, CDNs, AdTech platforms, and other demanding use cases. Carl J. Levine is the Senior Technical Evangelist for NS1. A veteran of the Internet Infrastructure space, he has over a decade of experience with startups, networking protocols and Internet infrastructure, combined with the unique ability to it...
"There's plenty of bandwidth out there but it's never in the right place. So what Cedexis does is uses data to work out the best pathways to get data from the origin to the person who wants to get it," explained Simon Jones, Evangelist and Head of Marketing at Cedexis, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"Cloud Academy is an enterprise training platform for the cloud, specifically public clouds. We offer guided learning experiences on AWS, Azure, Google Cloud and all the surrounding methodologies and technologies that you need to know and your teams need to know in order to leverage the full benefits of the cloud," explained Alex Brower, VP of Marketing at Cloud Academy, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clar...
Large industrial manufacturing organizations are adopting the agile principles of cloud software companies. The industrial manufacturing development process has not scaled over time. Now that design CAD teams are geographically distributed, centralizing their work is key. With large multi-gigabyte projects, outdated tools have stifled industrial team agility, time-to-market milestones, and impacted P&L stakeholders.
Gemini is Yahoo’s native and search advertising platform. To ensure the quality of a complex distributed system that spans multiple products and components and across various desktop websites and mobile app and web experiences – both Yahoo owned and operated and third-party syndication (supply), with complex interaction with more than a billion users and numerous advertisers globally (demand) – it becomes imperative to automate a set of end-to-end tests 24x7 to detect bugs and regression. In th...
"Akvelon is a software development company and we also provide consultancy services to folks who are looking to scale or accelerate their engineering roadmaps," explained Jeremiah Mothersell, Marketing Manager at Akvelon, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
"MobiDev is a software development company and we do complex, custom software development for everybody from entrepreneurs to large enterprises," explained Alan Winters, U.S. Head of Business Development at MobiDev, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
SYS-CON Events announced today that CrowdReviews.com has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5–7, 2018, at the Javits Center in New York City, NY. CrowdReviews.com is a transparent online platform for determining which products and services are the best based on the opinion of the crowd. The crowd consists of Internet users that have experienced products and services first-hand and have an interest in letting other potential buye...
"IBM is really all in on blockchain. We take a look at sort of the history of blockchain ledger technologies. It started out with bitcoin, Ethereum, and IBM evaluated these particular blockchain technologies and found they were anonymous and permissionless and that many companies were looking for permissioned blockchain," stated René Bostic, Technical VP of the IBM Cloud Unit in North America, in this SYS-CON.tv interview at 21st Cloud Expo, held Oct 31 – Nov 2, 2017, at the Santa Clara Conventi...
SYS-CON Events announced today that Telecom Reseller has been named “Media Sponsor” of SYS-CON's 22nd International Cloud Expo, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Telecom Reseller reports on Unified Communications, UCaaS, BPaaS for enterprise and SMBs. They report extensively on both customer premises based solutions such as IP-PBX as well as cloud based and hosted platforms.
"Space Monkey by Vivent Smart Home is a product that is a distributed cloud-based edge storage network. Vivent Smart Home, our parent company, is a smart home provider that places a lot of hard drives across homes in North America," explained JT Olds, Director of Engineering, and Brandon Crowfeather, Product Manager, at Vivint Smart Home, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Coca-Cola’s Google powered digital signage system lays the groundwork for a more valuable connection between Coke and its customers. Digital signs pair software with high-resolution displays so that a message can be changed instantly based on what the operator wants to communicate or sell. In their Day 3 Keynote at 21st Cloud Expo, Greg Chambers, Global Group Director, Digital Innovation, Coca-Cola, and Vidya Nagarajan, a Senior Product Manager at Google, discussed how from store operations and ...
It is of utmost importance for the future success of WebRTC to ensure that interoperability is operational between web browsers and any WebRTC-compliant client. To be guaranteed as operational and effective, interoperability must be tested extensively by establishing WebRTC data and media connections between different web browsers running on different devices and operating systems. In his session at WebRTC Summit at @ThingsExpo, Dr. Alex Gouaillard, CEO and Founder of CoSMo Software, presented ...
WebRTC is great technology to build your own communication tools. It will be even more exciting experience it with advanced devices, such as a 360 Camera, 360 microphone, and a depth sensor camera. In his session at @ThingsExpo, Masashi Ganeko, a manager at INFOCOM Corporation, introduced two experimental projects from his team and what they learned from them. "Shotoku Tamago" uses the robot audition software HARK to track speakers in 360 video of a remote party. "Virtual Teleport" uses a multip...
A strange thing is happening along the way to the Internet of Things, namely far too many devices to work with and manage. It has become clear that we'll need much higher efficiency user experiences that can allow us to more easily and scalably work with the thousands of devices that will soon be in each of our lives. Enter the conversational interface revolution, combining bots we can literally talk with, gesture to, and even direct with our thoughts, with embedded artificial intelligence, whic...
SYS-CON Events announced today that Evatronix will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
Leading companies, from the Global Fortune 500 to the smallest companies, are adopting hybrid cloud as the path to business advantage. Hybrid cloud depends on cloud services and on-premises infrastructure working in unison. Successful implementations require new levels of data mobility, enabled by an automated and seamless flow across on-premises and cloud resources. In his general session at 21st Cloud Expo, Greg Tevis, an IBM Storage Software Technical Strategist and Customer Solution Architec...
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
An increasing number of companies are creating products that combine data with analytical capabilities. Running interactive queries on Big Data requires complex architectures to store and query data effectively, typically involving data streams, an choosing efficient file format/database and multiple independent systems that are tied together through custom-engineered pipelines. In his session at @BigDataExpo at @ThingsExpo, Tomer Levi, a senior software engineer at Intel’s Advanced Analytics gr...
When talking IoT we often focus on the devices, the sensors, the hardware itself. The new smart appliances, the new smart or self-driving cars (which are amalgamations of many ‘things’). When we are looking at the world of IoT, we should take a step back, look at the big picture. What value are these devices providing? IoT is not about the devices, it’s about the data consumed and generated. The devices are tools, mechanisms, conduits. In his session at Internet of Things at Cloud Expo | DXWor...