June 2015 – .NET BLOG

I think that everyone who has ever been working with WCF knows that we can enable metadata exchange by adding ServiceMetadataBehavior to App.config file

<behaviors>
     <serviceBehaviors>
       <behavior>
         <serviceMetadata httpGetEnabled="true"></serviceMetadata>
       </behavior>
     </serviceBehaviors>
</behaviors>

</behavior>

</serviceBehaviors>

</behaviors>

Up until yesterday the build in solution works fine for me. However recently I’ve had to expose metadata over TCP protocol. ServiceMetadataBehavior doesn’t have something like TcpGetEnabled property so in order to expose metadata over other protocols (in my case TCP) it is necessary to add custom MEX endpoint.

<system.serviceModel>
    <services>
          <service name="AudioLib.Services.AudioService">
            <endpoint address="AudioService/MEX" binding="mexTcpBinding" contract="IMetadataExchange">
    <!-- application endpoints -->
            <host>
              <baseAddresses>
                <add baseAddress="net.tcp://localhost:8080"></add>
              </baseAddresses>
            </host>
          </endpoint>
        </service>
    </services> 
    <!-- rest of the config -->
</system.serviceModel>

<system.serviceModel>

<host>

</baseAddresses>

</host>

</endpoint>

</service>

</services>

</system.serviceModel>

The endpoint configuration has to have a specific binding – in my case mexTcpBinding (there are of course MEX bindings available for other protocols). What is more, the contract has to be set to IMetadataExchange. The address value is up to us, we can use full blown address as well as leverage base address. At this point if we run service we will get the exception

Even though we added custom endpoint for metadata exchange we still have to use ServiceMetadataBehavior. This time however we can skip httpGetEnabled property

<!-- rest of the config -->
<serviceBehaviors>
        <behavior>
          <serviceMetadata httpgetenabled="true"></serviceMetadata>
        </behavior>
</serviceBehaviors>
<!-- rest of the config -->

</behavior>

</serviceBehaviors>

From now on we can access metadata over TCP

Source code for this post can be found here

I wanted to improve a code quality of my TypeScript project, so I decided to add linting to my gulp build process. My original build task looked pretty straightforward

function buildTypeScript() {
    return gulp.src(['app/**/*.ts','typings/**/*.ts'])
               .pipe(sourcemaps.init())
               .pipe(ts({
                   sortOutput: true,
                   noExternalResolve: true,
                   noEmitOnError: true,
                   target: 'ES5'
               }))
               .pipe(concat(constants.appall))
               .pipe(sourcemaps.write())
               .pipe(gulp.dest(paths.app));
}

function buildTypeScript() {

return gulp.src(['app/**/*.ts','typings/**/*.ts'])

.pipe(sourcemaps.init())

.pipe(ts({

sortOutput: true,

noExternalResolve: true,

noEmitOnError: true,

target: 'ES5'

}))

.pipe(concat(constants.appall))

.pipe(sourcemaps.write())

.pipe(gulp.dest(paths.app));

}

and according to gulp-tslint manual adding linting requires including only two additional lines of code

//..
.pipe(tslint())
.pipe(tslint.report('verbose'));
//..

//..

.pipe(tslint())

.pipe(tslint.report('verbose'));

//..

This works fine until you start using type definitions (d.ts files) from external resources (which is the usual way of combining TypeScript with existing JavaScript libraries). Usually these files have different code styling rules than our own, which means that our build will fail.

There are couple of ways of solving this problem. The obvious one is to split the task into two separate tasks, one for linting and one for building, but in my opinion a much cleaner way is to use gulp-filter. Gulp-filter has an ability to filter the stream on the fly, but what is more interesting it can also restore it to previous unfiltered state. Using these two features we can filter the stream from d.ts files before linting process begins and then restore the stream and pass it to TypeScript compiler. We can do it with two additional lines of code. Improved build script is presented below

function buildTypeScript() {
    // include all typescript files but exclude definitions
    var filter = gulpFilter(['**/*.ts', '!**/*d.ts']);

    return gulp.src(['app/**/*.ts','typings/**/*.ts'])
               .pipe(filter)    // use the filter
               .pipe(tslint())
               .pipe(tslint.report('prose', {
                   emitError: true
               }))
               .pipe(filter.restore()) // clear filter
               .pipe(sourcemaps.init())
               .pipe(ts({
                   sortOutput: true,
                   noExternalResolve: true,
                   noEmitOnError: true,
                   target: 'ES5'
               }))
               .pipe(concat(constants.appall))
               .pipe(sourcemaps.write())
               .pipe(gulp.dest(paths.app));
}

function buildTypeScript() {

// include all typescript files but exclude definitions

var filter = gulpFilter(['**/*.ts', '!**/*d.ts']);

return gulp.src(['app/**/*.ts','typings/**/*.ts'])

.pipe(filter) // use the filter

.pipe(tslint())

.pipe(tslint.report('prose', {

emitError: true

}))

.pipe(filter.restore()) // clear filter

.pipe(sourcemaps.init())

.pipe(ts({

sortOutput: true,

noExternalResolve: true,

noEmitOnError: true,

target: 'ES5'

}))

.pipe(concat(constants.appall))

.pipe(sourcemaps.write())

.pipe(gulp.dest(paths.app));

}

Source code for this post can be found here

.NET BLOG

.NET, C# blog

Month: June 2015

WCF – exposing metadata over TCP

Gulp – exluding type definitions files from TypeScript linting