Reverse proxy with IIS - iis

Question

I'm trying to integrate ASP.net and Node.js on a server.
My expectation is here.
client ----> IIS Server ----> ASP.NET (except /api/. localhost:80)
(test.foo.com) |---> Node.js (starting with /api/. localhost:4000)
Node app is executed as a windows service, and serve localhost:4000/api/ in locally. And should be accessed with http://test.foo.com/api/signin
All request excepting /api/ should be served normal IIS asp.net. (ex. http://test.foo.com/index.aspx)
My trial:
- Installed urlrewrite module and application request routing cache module.
- Added rewriting rule as below
pattern: /api/(.*)
URL rewrite : http://localhost:4000/api/{R:1}
My result:
- http://test.foo.com/api/signin returned as 503 Service Unavaile
Question:
- Using URLrewrite is the right solution for my case?
Append
I tried to with 127.0.0.1 instead localhost with below web.config setting.
That result was same "503".
<rewrite>
<rules>
<rule name="ReverseProxyInboundRule1" stopProcessing="true">
<match url="/api/(.*)" />
<action type="Rewrite" url="http://127.0.0.1:4000/api/{R:1}" />
</rule>
</rules>
<outboundRules>
<rule name="ReverseProxyOutboundRule1" preCondition="ResponseIsHtml1">
<match filterByTags="A, Form, Img" pattern="^http(s)?://127.0.0.1/(.*)" />
<action type="Rewrite" value="http{R:1}://127.0.0.1:4000/{R:2}" />
</rule>
<preConditions>
<preCondition name="ResponseIsHtml1">
<add input="{RESPONSE_CONTENT_TYPE}" pattern="^text/html" />
</preCondition>
</preConditions>
</outboundRules>
</rewrite>
Append again
Instead loop adapter, change to ipv4 address. And tried to access anther PC. But result was same.
<rewrite>
<rules>
<rule name="ReverseProxyInboundRule1" stopProcessing="true">
<match url="(.*)" />
<action type="Rewrite" url="http://192.168.123.12:4000/api/{R:1}" />
</rule>
</rules>
<outboundRules>
<rule name="ReverseProxyOutboundRule1" preCondition="ResponseIsHtml1">
<match filterByTags="A, Form, Img" pattern="^http(s)?://192.168.123.12:4000/api/(.*)" />
<action type="Rewrite" value="http{R:1}://192.168.123.12/{R:2}" />
</rule>
<preConditions>
<preCondition name="ResponseIsHtml1">
<add input="{RESPONSE_CONTENT_TYPE}" pattern="^text/html" />
</preCondition>
</preConditions>
</outboundRules>
</rewrite>