diff --git a/samples/omniv2/customfileformats/jsonlog/.snapshots/TestSample b/samples/omniv2/customfileformats/jsonlog/.snapshots/TestSample
new file mode 100644
index 0000000..e5b0b98
--- /dev/null
+++ b/samples/omniv2/customfileformats/jsonlog/.snapshots/TestSample
@@ -0,0 +1,21 @@
+[
+	{
+		"message": "something is bad",
+		"severity": "E",
+		"source": "api",
+		"timestamp": "2020-09-08T12:34:57.124Z"
+	},
+	{
+		"message": "something is really bad",
+		"severity": "F",
+		"source": "api",
+		"timestamp": "2020-09-08T12:34:57.125Z"
+	},
+	{
+		"message": "it is getting better",
+		"severity": "W",
+		"source": "api",
+		"timestamp": "2020-09-08T12:34:59.130Z"
+	}
+]
+
diff --git a/samples/omniv2/customfileformats/jsonlog/jsonlogformat/jsonlogformat.go b/samples/omniv2/customfileformats/jsonlog/jsonlogformat/jsonlogformat.go
new file mode 100644
index 0000000..1e40370
--- /dev/null
+++ b/samples/omniv2/customfileformats/jsonlog/jsonlogformat/jsonlogformat.go
@@ -0,0 +1,53 @@
+package jsonlogformat
+
+import (
+	"fmt"
+	"io"
+
+	"github.com/antchfx/xpath"
+
+	"github.com/jf-tech/omniparser/omniparser/errs"
+	omniv2fileformat "github.com/jf-tech/omniparser/omniparser/schemaplugin/omni/v2/fileformat"
+	"github.com/jf-tech/omniparser/omniparser/schemaplugin/omni/v2/transform"
+	"github.com/jf-tech/omniparser/strs"
+)
+
+const (
+	FileFormatJSONLog = "jsonlog"
+)
+
+type jsonLogFileFormat struct {
+	schemaName string
+}
+
+func NewJSONLogFileFormat(schemaName string) omniv2fileformat.FileFormat {
+	return &jsonLogFileFormat{schemaName: schemaName}
+}
+
+func (p *jsonLogFileFormat) ValidateSchema(
+	format string, _ []byte, finalOutputDecl *transform.Decl) (interface{}, error) {
+	if format != FileFormatJSONLog {
+		return nil, errs.ErrSchemaNotSupported
+	}
+	if finalOutputDecl == nil {
+		return nil, p.FmtErr("'FINAL_OUTPUT' decl is nil")
+	}
+	if !strs.IsStrPtrNonBlank(finalOutputDecl.XPath) {
+		return nil, p.FmtErr("'FINAL_OUTPUT' must have 'xpath' specified")
+	}
+	_, err := xpath.Compile(*finalOutputDecl.XPath)
+	if err != nil {
+		return nil, p.FmtErr("'xpath' on 'FINAL_OUTPUT' (value: '%s') is invalid, err: %s",
+			*finalOutputDecl.XPath, err.Error())
+	}
+	return *finalOutputDecl.XPath, nil
+}
+
+func (p *jsonLogFileFormat) CreateFormatReader(
+	name string, r io.Reader, runtime interface{}) (omniv2fileformat.FormatReader, error) {
+	return NewReader(name, r, runtime.(string))
+}
+
+func (p *jsonLogFileFormat) FmtErr(format string, args ...interface{}) error {
+	return fmt.Errorf("schema '%s': %s", p.schemaName, fmt.Sprintf(format, args...))
+}
diff --git a/samples/omniv2/customfileformats/jsonlog/jsonlogformat/reader.go b/samples/omniv2/customfileformats/jsonlog/jsonlogformat/reader.go
new file mode 100644
index 0000000..b73fbd0
--- /dev/null
+++ b/samples/omniv2/customfileformats/jsonlog/jsonlogformat/reader.go
@@ -0,0 +1,140 @@
+package jsonlogformat
+
+import (
+	"bufio"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"sort"
+	"strconv"
+
+	node "github.com/antchfx/xmlquery"
+	"github.com/antchfx/xpath"
+	"github.com/jf-tech/iohelper"
+
+	"github.com/jf-tech/omniparser/omniparser/errs"
+	"github.com/jf-tech/omniparser/strs"
+)
+
+// ErrLogReadingFailed indicates the reader fails to read out a complete non-corrupted
+// log line. This is a fatal, non-continuable error.
+type ErrLogReadingFailed string
+
+func (e ErrLogReadingFailed) Error() string { return string(e) }
+
+// IsErrLogReadingFailed checks if an err is of ErrLogReadingFailed type.
+func IsErrLogReadingFailed(err error) bool {
+	switch err.(type) {
+	case ErrLogReadingFailed:
+		return true
+	default:
+		return false
+	}
+}
+
+type reader struct {
+	inputName string
+	r         *bufio.Reader
+	line      int
+	filter    *xpath.Expr
+}
+
+func (r *reader) Read() (*node.Node, error) {
+	for {
+		r.line++
+		l, err := iohelper.ReadLine(r.r)
+		if err == io.EOF {
+			return nil, errs.ErrEOF
+		}
+		if err != nil {
+			// If we fail to read a log line out (permission issue, disk issue, whatever)
+			// there is really no point to continue anymore, thus wrap the error in this
+			// non-continuable error ErrLogReadingFailed.
+			return nil, ErrLogReadingFailed(r.fmtErrStr(err.Error()))
+		}
+		if !strs.IsStrNonBlank(l) {
+			continue
+		}
+		n, err := parseJSON([]byte(l))
+		if err != nil {
+			// If we read out a log line fine, but unable to parse it, that shouldn't be
+			// a fatal error, thus not wrapping the error in non-continuable error
+			// ErrLogReadingFailed.
+			return nil, r.FmtErr(err.Error())
+		}
+		// Now we test this log-line-translated node (and its subtree) against the filter,
+		// if no match, then we'll move onto the next line.
+		if node.QuerySelector(n, r.filter) == nil {
+			continue
+		}
+		return n, nil
+	}
+}
+
+func parseJSONValue(x interface{}, parent *node.Node) {
+	switch v := x.(type) {
+	case []interface{}:
+		for _, vv := range v {
+			n := &node.Node{Type: node.ElementNode}
+			node.AddChild(parent, n)
+			parseJSONValue(vv, n)
+		}
+	case map[string]interface{}:
+		var keys []string
+		for k, _ := range v {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+		for _, key := range keys {
+			n := &node.Node{Data: key, Type: node.ElementNode}
+			node.AddChild(parent, n)
+			parseJSONValue(v[key], n)
+		}
+	case string:
+		node.AddChild(parent, &node.Node{Data: v, Type: node.TextNode})
+	case float64:
+		// The format fmt with 'f' means (-ddd.dddd, no exponent),
+		// The special precision -1 uses the smallest number of digits
+		s := strconv.FormatFloat(v, 'f', -1, 64)
+		node.AddChild(parent, &node.Node{Data: s, Type: node.TextNode})
+	case bool:
+		s := strconv.FormatBool(v)
+		node.AddChild(parent, &node.Node{Data: s, Type: node.TextNode})
+	}
+}
+
+func parseJSON(b []byte) (*node.Node, error) {
+	var v interface{}
+	if err := json.Unmarshal(b, &v); err != nil {
+		return nil, err
+	}
+	doc := &node.Node{Type: node.DocumentNode}
+	parseJSONValue(v, doc)
+	return doc, nil
+}
+
+func (r *reader) IsContinuableError(err error) bool {
+	return !IsErrLogReadingFailed(err) && err != errs.ErrEOF
+}
+
+func (r *reader) FmtErr(format string, args ...interface{}) error {
+	return errors.New(r.fmtErrStr(format, args...))
+}
+
+func (r *reader) fmtErrStr(format string, args ...interface{}) string {
+	return fmt.Sprintf("input '%s' line %d: %s", r.inputName, r.line, fmt.Sprintf(format, args...))
+}
+
+func NewReader(inputName string, src io.Reader, filterXPath string) (*reader, error) {
+	filter, err := xpath.Compile(filterXPath)
+	if err != nil {
+		return nil, err
+	}
+	return &reader{
+		inputName: inputName,
+		r:         bufio.NewReader(src),
+		line:      0,
+		filter:    filter,
+	}, nil
+}
diff --git a/samples/omniv2/customfileformats/jsonlog/sample.log b/samples/omniv2/customfileformats/jsonlog/sample.log
new file mode 100644
index 0000000..9a6eef5
--- /dev/null
+++ b/samples/omniv2/customfileformats/jsonlog/sample.log
@@ -0,0 +1,10 @@
+{"timestamp":"2020-09-08T12:34:56.123Z", "severity":"INFO", "source":"balancer", "message":"balancer is happy"}
+
+{"timestamp":"2020-09-08T12:34:57.123Z", "severity":"INFO", "source":"api", "message":"api is happy"}
+{"timestamp":"2020-09-08T12:34:57.124Z", "severity":"ERROR", "source":"api", "message":"something is bad"}
+{"timestamp":"2020-09-08T12:34:57.125Z", "severity":"CRITICAL", "source":"api", "message":"something is really bad"}
+{"timestamp":"2020-09-08T12:34:58.321Z", "severity":"WARNING", "source":"balancer", "message":"balancer senses some trouble"}
+
+{"timestamp":"2020-09-08T12:34:59.130Z", "severity":"WARNING", "source":"api", "message":"it is getting better"}
+{"timestamp":"2020-09-08T12:34:59.323Z", "severity":"INFO", "source":"api", "message":"api is happy"}
+{"timestamp":"2020-09-08T12:34:59.623Z", "severity":"INFO", "source":"balancer", "message":"balancer is happy"}
diff --git a/samples/omniv2/customfileformats/jsonlog/sample_schema.json b/samples/omniv2/customfileformats/jsonlog/sample_schema.json
new file mode 100644
index 0000000..3c37506
--- /dev/null
+++ b/samples/omniv2/customfileformats/jsonlog/sample_schema.json
@@ -0,0 +1,17 @@
+{
+    "parser_settings": {
+        "version": "omni.2.0",
+        "file_format_type": "jsonlog"
+    },
+    "transform_declarations": {
+        "FINAL_OUTPUT": { "xpath": ".[(severity='WARNING' or severity='ERROR' or severity='CRITICAL') and source='api']", "object": {
+            "timestamp": { "xpath": "timestamp" },
+            "source": { "const": "api" },
+            "severity": { "custom_func": {
+                "name": "normalize_severity",
+                "args": [{ "xpath": "severity" }]
+            }},
+            "message": { "xpath": "message" }
+        }}
+    }
+}
diff --git a/samples/omniv2/customfileformats/jsonlog/sample_test.go b/samples/omniv2/customfileformats/jsonlog/sample_test.go
new file mode 100644
index 0000000..1d2757d
--- /dev/null
+++ b/samples/omniv2/customfileformats/jsonlog/sample_test.go
@@ -0,0 +1,80 @@
+package jsonlog
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/bradleyjkemp/cupaloy"
+	"github.com/stretchr/testify/assert"
+
+	"github.com/jf-tech/omniparser/jsons"
+	"github.com/jf-tech/omniparser/omniparser"
+	"github.com/jf-tech/omniparser/omniparser/customfuncs"
+	omniv2 "github.com/jf-tech/omniparser/omniparser/schemaplugin/omni/v2"
+	"github.com/jf-tech/omniparser/omniparser/transformctx"
+	"github.com/jf-tech/omniparser/samples/omniv2/customfileformats/jsonlog/jsonlogformat"
+)
+
+func normalizeSeverity(_ *transformctx.Ctx, sev string) (string, error) {
+	switch strings.ToUpper(sev) {
+	case "DEBUG":
+		return "D", nil
+	case "INFO":
+		return "I", nil
+	case "WARNING":
+		return "W", nil
+	case "ERROR":
+		return "E", nil
+	case "CRITICAL":
+		return "F", nil
+	default:
+		return "?", nil
+	}
+}
+
+func TestSample(t *testing.T) {
+	schemaFile := "./sample_schema.json"
+	schemaFileBaseName := filepath.Base(schemaFile)
+	schemaFileReader, err := os.Open(schemaFile)
+	assert.NoError(t, err)
+	defer schemaFileReader.Close()
+
+	inputFile := "./sample.log"
+	inputFileBaseName := filepath.Base(inputFile)
+	inputFileReader, err := os.Open(inputFile)
+	assert.NoError(t, err)
+	defer inputFileReader.Close()
+
+	parser, err := omniparser.NewParser(
+		schemaFileBaseName,
+		schemaFileReader,
+		// Use this SchemaPluginConfig to effectively replace the
+		// builtin omniv2 schema plugin (and its builtin fileformats)
+		// with, well, omniv2 schema plugin :) with our own custom
+		// fileformat. Also let's demo how to add a new custom func.
+		omniparser.SchemaPluginConfig{
+			ParseSchema: omniv2.ParseSchema,
+			PluginParams: &omniv2.PluginParams{
+				CustomFileFormat: jsonlogformat.NewJSONLogFileFormat(schemaFileBaseName),
+			},
+			CustomFuncs: customfuncs.CustomFuncs{
+				"normalize_severity": normalizeSeverity,
+			},
+		})
+	assert.NoError(t, err)
+	op, err := parser.GetTransformOp(
+		inputFileBaseName,
+		inputFileReader,
+		&transformctx.Ctx{})
+	assert.NoError(t, err)
+
+	var records []string
+	for op.Next() {
+		recordBytes, err := op.Read()
+		assert.NoError(t, err)
+		records = append(records, string(recordBytes))
+	}
+	cupaloy.SnapshotT(t, jsons.BPJ("["+strings.Join(records, ",")+"]"))
+}