Skip to main content

Posts

Local YUI combo loader

Quite a while ago I had users complaining they could not use my application from another secure network zone. It appeared the root cause was in using Yahoo CDN for serving YUI resources while there was no internet access in that specific network zone. Also living behind a proxy, our regular users used to suffer from longer delays from time to time due to proxying. An obvious solution turned out to be using a locally served YUI. For this a combo loader is required if you care about efficiency on Production. Installation To start with, there are several alternative open-source tools that can be used for combo loading: Official PHP loader by Yahoo – is obsolete and is said not to work with any version over 3.3.0. CGI script combo – I cannot say much about it besides that it's 3 years old. Node.js combo handler – is kept updated and is the one that I decided to use. The Node.js combo handler is supplied with rather self-contained README file at github. Nevertheless, I...

Using XML Catalogs in Cocoon

In this article I'm going to show a common use case of XML Catalogs . Their usage is not only recommended to avoid certain issues but can also drastically improve the performance. I'll start with explaining the issue that I've faced recently and will conclude with the resolution. Issue To start with, I've got the following exception: java.io.IOException: Server returned HTTP response code: 429 for URL: http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd The HTTP code 429 stands for "Too Many Requests" that can appear when: The user has sent too many requests in a given amount of time. Intended for use with rate limiting schemes Just to provide some context, I have an Apache Cocoon based application that does a lot of XSLT processing with Saxon . It appears that every time Saxon reads an xml document with a DTD reference, it tries to fetch the DTD source for validation. Obviously, if the processing rate is high enough and there is no caching, you can cre...

Sedna XML DB and RelWithDebugInfo mode

Once we had a severe issue with Sedna hanging regularly. It was caused by broken indexes after an upgrade at that moment. The issue caused quite a nightmare and led to a lot of time wasted until we solved it together with Sedna devs. Since that moment it has become very important to be able to look into what is happening inside Sedna at any particular moment. Fortunately, there is a suitable way although it's not documented properly on the Sedna website. All you need is to build Sedna from source with a special flag RelWithDebugInfo . Cmake build modes. Using gdb. Using netstat. Cmake build modes Cmake has several build modes with Release and Debug obviously among them. Another mode that can be of big use is called RelWithDebugInfo . There is a perfect explanation for it on the mailing list : The difference between Debug and RelwithDebInfo is that RelwithDebInfo is quite similar to Release mode. It produces fully optimised code, but also builds the program database, and in...

Customizing oXygen Author Component

In this article I'm going to guide you through the process of customization of oXygen Author Component . More specifically I'm going to create a new operation for the DITA framework that will generate and insert an xml fragment into the current document. While you can find the official documentation on this topic very useful, it misses any real code examples. Of course, you can download the author component startup project but it'll help those looking how to integrate the component as a Java Applet, thus, it's slightly irrelevant for us. Requirements In order to make a customization for the Author Component you need to have an oXygen standalone installation. For the development of Java customizations you'll need oxygen.jar on the classpath. This library is available in the oXygen installation directory as well as in the Author SDK project and in the author component startup project. Moreover, inside last two resources you can find javadocs and partial source...

Play Framework with RequireJS and YUI

I've concluded an older post with a promise to investigate the issues of integration of Play Framework with RequireJS and YUI . Finally I've got some time to resolve all issues so I'm going to showcase a working sample multi-page project in this article. Sample project. Issues. Sample project Play Framework offers a nice official tutorial for RequireJS-support . However, it appeared that not all RequireJS features are fully supported by Play Framework yet (see below in Issues section). So it required some tuning before everything started working. I've published a sample project on github so you're welcome to look into it. Some of the issues that I faced are described in the section below. Here I'm going to show a couple of screenshots of the sample application. This is how one page of the application looks like: Below is the screenshot of the network tab of the Google Chrome developer tools showing all page resources in the production mode. You c...

YUI Cross-Domain transactions without Flash

Recently I've worked on the application making cross-domain ajax calls with YUI . While YUI offers io-xdr module for making cross-domain requests via Flash transport , it seems to me quite unnatural as it leads to unnecessary complexity. Moreover, io-xdr was marked deprecated several months ago without explicit mentioning the preferred way. An obvious alternative is using XMLHttpRequest as a transport for cross-domain requests. However, it has some limitations and undocumented pitfalls that I'd like to review in this post. Cross-Domain request using XMLHttpRequest. YUI IO Utility. YUI Datasource IO. Cross-Domain request using XMLHttpRequest Cross-domain requests can be sent using a common XMLHttpRequest object. The only requirement is that the server must be configured to properly handle those requests. Specifically, it should set the Access-Control-Allow-Origin response header according to Cross-Origin Resource Sharing specification . For more details and good tuto...

Analysis of network issues with tcpdump and wireshark

I've recently had to deal with the application connectivity issue (details on stackoverflow ) that appeared after the migration of the application to a new server. It resulted in "Connection timed out" Java exceptions in certain cases. The answer was on the surface but I didn't know where to look at exactly. So I had to investigate and apply network sniffing tools such as tcpdump and Wireshark . Here I'd like to share my experience with the network analysis. The issue and the cause. Wireshark. Tcpdump. The issue and the cause The following exception was thrown by Saxon XSLT processor when the document function was invoked: Caused by: org.apache.commons.lang.exception.NestableRuntimeException: net.sf.saxon.trans.DynamicError: net.sf.saxon.trans.DynamicError: java.net.ConnectException: Connection timed out at java.net.PlainSocketImpl.socketConnect(Native Method) at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333) at j...