diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e74cf0b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,7 @@
+# Rust
+/target
+/Cargo.lock
+
+# CLion
+/.idea/*
+!/.idea/runConfigurations
diff --git a/examples/no-fs-example.rs b/examples/no-fs-example.rs
new file mode 100644
index 0000000..a87ec60
--- /dev/null
+++ b/examples/no-fs-example.rs
@@ -0,0 +1,391 @@
+use cfdp::{
+    DummyFaultHook, FaultHandler, IndicationConfig, LocalEntityConfig, PduOwnedWithInfo,
+    RemoteEntityConfig, StdTimerCreator, TransactionId,
+    dest::DestinationHandler,
+    filestore::{FilestoreError, VirtualFilestore},
+    request::PutRequest,
+    source::SourceHandler,
+    user::{CfdpUser, FileSegmentRecvdParams, MetadataReceivedParams, TransactionFinishedParams},
+};
+use spacepackets::cfdp::{ChecksumType, ConditionCode, TransmissionMode};
+use spacepackets::seq_count::SequenceCounterSimple;
+use spacepackets::util::UnsignedByteFieldU16;
+use std::collections::HashMap;
+use std::sync::{
+    Arc, Mutex,
+    atomic::{AtomicBool, Ordering},
+    mpsc,
+};
+use std::thread;
+use std::time::Duration;
+
+// A virtual filestore that stores data in memory.
+#[derive(Debug, Clone)]
+pub struct NoFsFilestore {
+    files: Arc<Mutex<HashMap<String, Vec<u8>>>>,
+}
+
+impl Default for NoFsFilestore {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl NoFsFilestore {
+    pub fn new() -> Self {
+        Self {
+            files: Arc::new(Mutex::new(HashMap::new())),
+        }
+    }
+
+    pub fn add_file(&self, path: &str, data: Vec<u8>) {
+        self.files.lock().unwrap().insert(path.to_string(), data);
+    }
+
+    pub fn get_file(&self, path: &str) -> Option<Vec<u8>> {
+        self.files.lock().unwrap().get(path).cloned()
+    }
+}
+
+impl VirtualFilestore for NoFsFilestore {
+    fn create_file(&self, file_path: &str) -> Result<(), FilestoreError> {
+        println!("Filestore: create_file({})", file_path);
+        self.files
+            .lock()
+            .unwrap()
+            .insert(file_path.to_string(), Vec::new());
+        Ok(())
+    }
+
+    fn remove_file(&self, file_path: &str) -> Result<(), FilestoreError> {
+        println!("Filestore: remove_file({})", file_path);
+        self.files.lock().unwrap().remove(file_path);
+        Ok(())
+    }
+
+    fn truncate_file(&self, file_path: &str) -> Result<(), FilestoreError> {
+        println!("Filestore: truncate_file({})", file_path);
+        if let Some(file) = self.files.lock().unwrap().get_mut(file_path) {
+            file.clear();
+        }
+        Ok(())
+    }
+
+    fn remove_dir(&self, _dir_path: &str, _all: bool) -> Result<(), FilestoreError> {
+        println!("Filestore: remove_dir");
+        Ok(())
+    }
+
+    fn create_dir(&self, _dir_path: &str) -> Result<(), FilestoreError> {
+        println!("Filestore: create_dir");
+        Ok(())
+    }
+
+    fn read_data(
+        &self,
+        file_path: &str,
+        offset: u64,
+        read_len: u64,
+        buf: &mut [u8],
+    ) -> Result<(), FilestoreError> {
+        println!(
+            "Filestore: read_data({}, offset={}, len={})",
+            file_path, offset, read_len
+        );
+        let files = self.files.lock().unwrap();
+        if let Some(file_data) = files.get(file_path) {
+            let start = offset as usize;
+            let end = (offset + read_len) as usize;
+            let end = end.min(file_data.len());
+            let copy_len = end - start;
+            buf[..copy_len].copy_from_slice(&file_data[start..end]);
+            Ok(())
+        } else {
+            Err(FilestoreError::FileDoesNotExist)
+        }
+    }
+
+    fn write_data(&self, file_path: &str, offset: u64, buf: &[u8]) -> Result<(), FilestoreError> {
+        println!(
+            "Filestore: write_data({}, offset={}, len={})",
+            file_path,
+            offset,
+            buf.len()
+        );
+        let mut files = self.files.lock().unwrap();
+        let file_data = files.entry(file_path.to_string()).or_insert_with(Vec::new);
+
+        // Extend the file if necessary
+        let required_len = offset as usize + buf.len();
+        if file_data.len() < required_len {
+            file_data.resize(required_len, 0);
+        }
+
+        file_data[offset as usize..offset as usize + buf.len()].copy_from_slice(buf);
+        Ok(())
+    }
+
+    fn filename_from_full_path(path: &str) -> Option<&str>
+    where
+        Self: Sized,
+    {
+        Some(path)
+    }
+
+    fn is_file(&self, path: &str) -> Result<bool, FilestoreError> {
+        let exists = self.files.lock().unwrap().contains_key(path);
+        println!("Filestore: is_file({}) = {}", path, exists);
+        Ok(exists)
+    }
+
+    fn exists(&self, path: &str) -> Result<bool, FilestoreError> {
+        let exists = self.files.lock().unwrap().contains_key(path);
+        println!("Filestore: exists({}) = {}", path, exists);
+        Ok(exists)
+    }
+
+    fn file_name<'a>(&self, full_path: &'a str) -> Result<Option<&'a str>, FilestoreError> {
+        Ok(Some(full_path))
+    }
+
+    fn file_size(&self, path: &str) -> Result<u64, FilestoreError> {
+        let size = self
+            .files
+            .lock()
+            .unwrap()
+            .get(path)
+            .map(|f| f.len() as u64)
+            .unwrap_or(0);
+        println!("Filestore: file_size({}) = {}", path, size);
+        Ok(size)
+    }
+
+    fn calculate_checksum(
+        &self,
+        file_path: &str,
+        checksum_type: ChecksumType,
+        _size_to_verify: u64,
+        _verification_buf: &mut [u8],
+    ) -> Result<u32, FilestoreError> {
+        println!(
+            "Filestore: calculate_checksum({}, {:?})",
+            file_path, checksum_type
+        );
+        // TODO: Real checksums?
+        Ok(0)
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct PrintUser {
+    pub transaction_finished: Arc<AtomicBool>,
+}
+
+impl CfdpUser for PrintUser {
+    fn transaction_indication(&mut self, id: &TransactionId) {
+        println!("User: Transaction indication for {:?}", id);
+    }
+
+    fn eof_sent_indication(&mut self, id: &TransactionId) {
+        println!("User: EOF sent indication for {:?}", id);
+    }
+
+    fn transaction_finished_indication(&mut self, params: &TransactionFinishedParams) {
+        println!("User: Transaction finished indication for {:?}", params);
+        self.transaction_finished.store(true, Ordering::Relaxed);
+    }
+
+    fn metadata_recvd_indication(&mut self, params: &MetadataReceivedParams) {
+        println!("User: Metadata received indication for {:?}", params);
+    }
+
+    fn file_segment_recvd_indication(&mut self, params: &FileSegmentRecvdParams) {
+        println!("User: File segment received indication for {:?}", params);
+    }
+
+    fn report_indication(&mut self, id: &TransactionId) {
+        println!("User: Report indication for {:?}", id);
+    }
+
+    fn suspended_indication(&mut self, id: &TransactionId, condition_code: ConditionCode) {
+        println!(
+            "User: Suspended indication for {:?} with condition {:?}",
+            id, condition_code
+        );
+    }
+
+    fn resumed_indication(&mut self, id: &TransactionId, progress: u64) {
+        println!(
+            "User: Resumed indication for {:?} with progress {}",
+            id, progress
+        );
+    }
+
+    fn fault_indication(
+        &mut self,
+        id: &TransactionId,
+        condition_code: ConditionCode,
+        progress: u64,
+    ) {
+        println!(
+            "User: Fault indication for {:?} with condition {:?} and progress {}",
+            id, condition_code, progress
+        );
+    }
+
+    fn abandoned_indication(
+        &mut self,
+        id: &TransactionId,
+        condition_code: ConditionCode,
+        progress: u64,
+    ) {
+        println!(
+            "User: Abandoned indication for {:?} with condition {:?} and progress {}",
+            id, condition_code, progress
+        );
+    }
+
+    fn eof_recvd_indication(&mut self, id: &TransactionId) {
+        println!("User: EOF received indication for {:?}", id);
+    }
+}
+
+const LOCAL_ID: UnsignedByteFieldU16 = UnsignedByteFieldU16::new(1);
+const REMOTE_ID: UnsignedByteFieldU16 = UnsignedByteFieldU16::new(2);
+
+fn main() {
+    let test_data = b"Hello PVDX";
+    println!("Original data: {:?}", String::from_utf8_lossy(test_data));
+    println!("Data length: {} bytes\n", test_data.len());
+
+    let (pdu_tx_to_dest, pdu_rx_from_source) = mpsc::channel::<PduOwnedWithInfo>();
+    let (pdu_tx_to_source, pdu_rx_from_dest) = mpsc::channel::<PduOwnedWithInfo>();
+
+    let stop_threads = Arc::new(AtomicBool::new(false));
+    let stop_threads_source = stop_threads.clone();
+    let stop_threads_dest = stop_threads.clone();
+
+    let source_finished = Arc::new(AtomicBool::new(false));
+    let source_finished_user = source_finished.clone();
+
+    let dest_finished = Arc::new(AtomicBool::new(false));
+    let dest_finished_user = dest_finished.clone();
+
+    let source_filestore = NoFsFilestore::new();
+    source_filestore.add_file("source.txt", test_data.to_vec());
+
+    let dest_filestore = NoFsFilestore::new();
+    let dest_filestore_clone = dest_filestore.clone();
+
+    let source_thread = thread::spawn(move || {
+        let local_cfg = LocalEntityConfig {
+            id: LOCAL_ID.into(),
+            indication_cfg: IndicationConfig::default(),
+            fault_handler: FaultHandler::new(DummyFaultHook::default()),
+        };
+        let remote_cfg = RemoteEntityConfig::new_with_default_values(
+            REMOTE_ID.into(),
+            1024,
+            false,
+            false,
+            TransmissionMode::Acknowledged,
+            ChecksumType::NullChecksum,
+        );
+
+        let mut source_handler = SourceHandler::new(
+            local_cfg,
+            pdu_tx_to_dest,
+            source_filestore,
+            remote_cfg,
+            StdTimerCreator::default(),
+            SequenceCounterSimple::<u16>::default(),
+        );
+
+        let put_request =
+            PutRequest::new_regular_request(REMOTE_ID.into(), "source.txt", "dest.txt", None, None)
+                .unwrap();
+        source_handler.put_request(&put_request).unwrap();
+
+        let mut user = PrintUser {
+            transaction_finished: source_finished_user,
+        };
+
+        while !stop_threads_source.load(Ordering::Relaxed) {
+            let pdu_from_dest = pdu_rx_from_dest.try_recv().ok();
+            source_handler
+                .state_machine(&mut user, pdu_from_dest.as_ref())
+                .unwrap();
+            thread::sleep(Duration::from_millis(100));
+        }
+    });
+
+    let dest_thread = thread::spawn(move || {
+        let local_cfg = LocalEntityConfig {
+            id: REMOTE_ID.into(),
+            indication_cfg: IndicationConfig::default(),
+            fault_handler: FaultHandler::new(DummyFaultHook::default()),
+        };
+        let remote_cfg = RemoteEntityConfig::new_with_default_values(
+            LOCAL_ID.into(),
+            1024,
+            false,
+            false,
+            TransmissionMode::Acknowledged,
+            ChecksumType::NullChecksum,
+        );
+
+        let mut dest_handler = DestinationHandler::new(
+            local_cfg,
+            pdu_tx_to_source,
+            dest_filestore,
+            remote_cfg,
+            StdTimerCreator::default(),
+            cfdp::lost_segments::LostSegmentsList::default(),
+        );
+
+        let mut user = PrintUser {
+            transaction_finished: dest_finished_user,
+        };
+
+        while !stop_threads_dest.load(Ordering::Relaxed) {
+            if let Ok(pdu_from_source) = pdu_rx_from_source.try_recv() {
+                dest_handler
+                    .state_machine(&mut user, Some(&pdu_from_source))
+                    .unwrap();
+            }
+            thread::sleep(Duration::from_millis(100));
+        }
+    });
+
+    // Wait for both threads to finish
+    while !source_finished.load(Ordering::Relaxed) || !dest_finished.load(Ordering::Relaxed) {
+        thread::sleep(Duration::from_millis(100));
+    }
+
+    stop_threads.store(true, Ordering::Relaxed);
+
+    source_thread.join().unwrap();
+    dest_thread.join().unwrap();
+
+    println!("\n=== Transfer Complete ===");
+
+    if let Some(received_data) = dest_filestore_clone.get_file("dest.txt") {
+        println!(
+            "Received data: {:?}",
+            String::from_utf8_lossy(&received_data)
+        );
+        println!("Received length: {} bytes", received_data.len());
+
+        if received_data == test_data {
+            println!("\nSUCCESS: Data transferred correctly!");
+        } else {
+            println!("\nERROR: Data mismatch!");
+            println!("Expected: {:?}", String::from_utf8_lossy(test_data));
+            println!("Got:      {:?}", String::from_utf8_lossy(&received_data));
+        }
+    } else {
+        println!("\nERROR: No data received at destination!");
+    }
+
+    println!("\nExample finished.");
+}