Notes on software and the ideas behind it

Find the meaning
behind the code.

I’m Fred Yang. I write about software—how it works, why it behaves the way it does, and the ideas that make code easier to reason about.

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Working notes / 2026

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Architecture, reactivity, and the hidden relationships that shape frontend systems.

WF

EventHandling in WF

<p> In WF, CallExternalMethod is used to transfer data from workflow instance to host, and HandleExternalEvent is used to transfer data from host to workflow instance. The pattern of HandleExternalEvent is similar to the...
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instrument

Performance counter

<p> Performance counter is used to monitor the running status of an application. The application itself just output the performance data. The data itself don't need to be calcuated by the application, the data...
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codesmith

Output a tempalte to file

<p> You can output the result of a template to file system but use the command line and the code smith project file. The default behavior is that code smith engine, call the template's...
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WF

Call External Method

<p>In a workflow, to call the external method, you need the following ready.</p> <ul> <li>The workflow need a interface marked with ExternalDataExchange. In the callExternalMethodActivity node, you need to configure the InterfaceType, MethodName, MethodInvoking,...
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multithreading

Monitor and lock

<p>Below is sample code about how to use Monitor. </p>
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