Update Nextflow examples

src/components/Menu.astro

@@ -37,16 +37,10 @@ const isHomepage = currentPath === "/" || currentPath === "/index.html";
           <a href="#" class="dropdown-toggle" data-toggle="dropdown">Examples <b class="caret"></b></a>
           <ul class="dropdown-menu">
             <li><a href="/example1.html">Basic pipeline</a></li>
-            <li><a href="/example2.html">Mixing scripting languages</a></li>
-            <li><a href="/example3.html">BLAST pipeline</a></li>
-            <li><a href="/example4.html">RNA-Seq pipeline</a></li>
+            <li><a href="/example2.html">Mixed language pipeline</a></li>
+            <li><a href="/example3.html">RNA-Seq pipeline</a></li>
+            <li><a href="/example4.html">Variant calling pipeline</a></li>
             <li><a href="/example5.html">Machine Learning pipeline</a></li>
-            <li>
-              <a href="https://github.com/nextflow-io/rnaseq-nf" target="_blank">
-                Simple RNAseq pipeline
-                <i class="fa fa-sm fa-external-link" aria-hidden="true"></i>
-              </a>
-            </li>
           </ul>
         </li>
 

src/pages/example1.md

@@ -7,96 +7,83 @@ layout: "@layouts/MarkdownPage.astro"
 <h3>Basic pipeline</h3>
 
 <p class="text-muted" >
-    This example shows how to write a pipeline with two simple Bash processes, so that the results produced by the first process are consumed by the second process.
+    This example shows a simple Nextflow pipeline consisting of two Bash processes.
 </p>
 
 ```groovy
 #!/usr/bin/env nextflow
 
-params.in = "$baseDir/data/sample.fa"
+/*
+ * Pipeline parameters
+ */
+
+// Primary input
+params.greeting = "Hello World!"
 
 /*
- * Split a fasta file into multiple files
+ * Redirect a string to a text file
  */
-process splitSequences {
+process sayHello {
 
     input:
-    path 'input.fa'
+    val x
 
     output:
-    path 'seq_*'
+    path 'output.txt'
 
+    script:
     """
-    awk '/^>/{f="seq_"++d} {print > f}' < input.fa
+    echo '$x' > output.txt
     """
 }
 
 /*
- * Reverse the sequences
+ * Convert lowercase letters to uppercase letters
  */
-process reverse {
+process convertToUpper {
 
     input:
-    path x
+    path y
 
     output:
     stdout
 
+    script:
     """
-    cat $x | rev
+    cat $y | tr '[a-z]' '[A-Z]'
     """
 }
 
 /*
- * Define the workflow
+ * Workflow definition
  */
 workflow {
-    splitSequences(params.in) \
-      | reverse \
-      | view
-}
-```
-
-</div>
-
-### Synopsis
-
-- **Line 1** The script starts with a shebang declaration. This allows you to launch your pipeline just like any other Bash script.
 
-- **Line 3**: Declares a pipeline parameter named `params.in` that is initialized with the value `$HOME/sample.fa`. This value can be overridden when launching the pipeline, by simply adding the option `--in <value>` to the script command line.
+    // Redirects a string to a text file
+    sayHello(params.greeting)
 
-- **Lines 8-19**: The process that splits the provided file.
+    // Concatenates a text file and transforms lowercase letters to uppercase letters
+    convertToUpper(sayHello.out)
 
-  - **Line 10**: Opens the input declaration block. The lines following this clause are interpreted as input definitions.
-
-  - **Line 11**: Declares the process input file, which will be named `input.fa` in the process script.
-
-  - **Line 13**: Opens the output declaration block. The lines following this clause are interpreted as output declarations.
-
-  - **Line 14**: Files whose names match the pattern `seq_*` are declared as the output of this process.
-
-  - **Lines 16-18**: The actual script executed by the process to split the input file.
-
-- **Lines 24-35**: The second process, which receives the splits produced by the
-  previous process and reverses their content.
-
-  - **Line 26**: Opens the input declaration block. Lines following this clause are
-    interpreted as input declarations.
+    // View convertToUpper output
+    convertToUpper.out.view()
+}
+```
 
-  - **Line 27**: Defines the process input file.
+</div>
 
-  - **Line 29**: Opens the output declaration block. Lines following this clause are
-    interpreted as output declarations.
+### Script synopsis
 
-  - **Line 30**: The standard output of the executed script is declared as the process
-    output.
+This example shows a simple Nextflow pipeline consisting of two Bash processes. The `sayHello` process takes a string as input and redirects it to an output text file. The `convertToUpper` process takes the output text file from `sayHello` as input, concatenates the text, and converts all of the lowercase letters to uppercase letters. The output from the `convertToUpper` process is then printed to screen.
 
-  - **Lines 32-34**: The actual script executed by the process to reverse the content of the input files.
+### Try it
 
-- **Lines 40-44**: The workflow that connects everything together!
+To try this pipeline:
 
-  - **Line 41**: First, the input file specified by `params.in` is passed to the `splitSequences` process.
+1. Follow the [Nextflow installation guide](https://www.nextflow.io/docs/latest/install.html#install-nextflow) to install Nextflow (if not already available).
+2. Copy the script above and save as `hello-world.nf`.
+3. Launch the pipeline:
 
-  - **Line 42**: The outputs of `splitSequences` are passed as inputs to the `reverse` process, which processes each split file in parallel.
+    nextflow run hello-world.nf
 
-  - **Line 43**: Finally, each output emitted by `reverse` is printed.
+**NOTE**: To run this example with versions of Nextflow older than 22.04.0, you must include the `-dsl2` flag with `nextflow run`.

src/pages/example2.md

@@ -1,24 +1,33 @@
 ---
-title: Mixing scripting languages
+title: Mixed language pipeline
 layout: "@layouts/MarkdownPage.astro"
 ---
 
 <div class="blg-summary example">
-<h3>Mixing scripting languages</h3>
+<h3>Mixed language pipeline</h3>
 
 <p class="text-muted">
-    With Nextflow, you are not limited to Bash scripts -- you can use any scripting language! In other words, for each <i>process</i> you can use the language that best fits the specific task or that you simply prefer.
+    This example shows a simple Nextflow pipeline consisting of two processes written in different languages.
 </p>
 
 ```groovy
 #!/usr/bin/env nextflow
 
+/*
+ * Pipeline parameters
+ */
+
+// Range
 params.range = 100
 
 /*
  * A trivial Perl script that produces a list of number pairs
  */
 process perlTask {
+
+    input:
+    val x
+
     output:
     stdout
 
@@ -29,7 +38,7 @@ process perlTask {
     use warnings;
 
     my $count;
-    my $range = !{params.range};
+    my $range = !{x};
     for ($count = 0; $count < 10; $count++) {
         print rand($range) . ', ' . rand($range) . "\n";
     }
@@ -40,12 +49,14 @@ process perlTask {
  * A Python script which parses the output of the previous script
  */
 process pyTask {
+
     input:
     stdin
 
     output:
     stdout
 
+    script:
     """
     #!/usr/bin/env python
     import sys
@@ -64,17 +75,32 @@ process pyTask {
 }
 
 workflow {
-    perlTask | pyTask | view
+
+    // A Perl script that produces a list of number pairs
+    perlTask(params.range)
+
+    // A Python script which parses the output of the previous script
+    pyTask(perlTask.out)
+
+    // View pyTask output
+    pyTask.out.view()
 }
 ```
 
 </div>
 
 ### Synopsis
 
-In the above example we define a simple pipeline with two processes.
+This example shows a simple Nextflow pipeline consisting of two processes written in different languages. The `perlTask` process starts with a Perl _shebang_ declaration and executes a Perl script that produces pairs of numbers. Since Perl uses the `$` character for variables, the special `shell` block is used instead of the normal `script` block to distinguish the Perl variables from Nextflow variables. Similarly, the `pyTask` process starts with a Python _shebang_ declaration. It takes the output from the Perl script and executes a Python script that averages the number pairs. The output from the `pyTask` process is then printed to screen.
+
+### Try it
+
+To try this pipeline:
+
+1. Follow the [Nextflow installation guide](https://www.nextflow.io/docs/latest/install.html#install-nextflow) to install Nextflow (if not already available).
+2. Copy the script above and save as `mixed-languages.nf`.
+3. Launch the pipeline:
 
-The first process executes a Perl script, because the script block definition starts
-with a Perl _shebang_ declaration (line 14). Since Perl uses the `$` character for variables, we use the special `shell` block instead of the normal `script` block to easily distinguish the Perl variables from the Nextflow variables.
+    nextflow run mixed-languages.nf
 
-In the same way, the second process will execute a Python script, because the script block starts with a Python shebang (line 36).
+**NOTE**: To run this example with versions of Nextflow older than 22.04.0, you must include the `-dsl2` flag with `nextflow run`.