diff --git a/compiler/cpp/src/thrift/generate/t_php_generator.cc b/compiler/cpp/src/thrift/generate/t_php_generator.cc
index 515e165..9b5062c 100644
--- a/compiler/cpp/src/thrift/generate/t_php_generator.cc
+++ b/compiler/cpp/src/thrift/generate/t_php_generator.cc
@@ -760,10 +760,7 @@
  * type information to generalize serialization routines.
  */
 void t_php_generator::generate_php_struct_spec(ofstream& out, t_struct* tstruct) {
-  indent(out) << "if (!isset(self::$_TSPEC)) {" << endl;
-  indent_up();
-
-  indent(out) << "self::$_TSPEC = array(" << endl;
+  indent(out) << "static $_TSPEC = array(" << endl;
   indent_up();
 
   const vector<t_field*>& members = tstruct->get_members();
@@ -773,15 +770,14 @@
     indent(out) << (*m_iter)->get_key() << " => array(" << endl;
     indent_up();
     out << indent() << "'var' => '" << (*m_iter)->get_name() << "'," << endl;
+    out << indent() << "'isRequired' => " << ((*m_iter)->get_req() == t_field::T_REQUIRED ? "true" : "false") << "," << endl;
     generate_php_type_spec(out, t);
     indent(out) << ")," << endl;
     indent_down();
   }
 
   indent_down();
-  indent(out) << "  );" << endl;
-  indent_down();
-  indent(out) << "}" << endl;
+  indent(out) << "  );" << endl << endl;
 }
 
 /**
@@ -813,7 +809,9 @@
   out << " {" << endl;
   indent_up();
 
-  indent(out) << "static $_TSPEC;" << endl << endl;
+  out << indent() << "static $isValidate = " << (validate_ ? "true" : "false") << ";" << endl << endl;
+
+  generate_php_struct_spec(out, tstruct);
 
   for (m_iter = members.begin(); m_iter != members.end(); ++m_iter) {
     string dval = "null";
@@ -832,8 +830,6 @@
   out << indent() << "public function __construct(" << param << ") {" << endl;
   indent_up();
 
-  generate_php_struct_spec(out, tstruct);
-
   if (members.size() > 0) {
     for (m_iter = members.begin(); m_iter != members.end(); ++m_iter) {
       t_type* t = get_true_type((*m_iter)->get_type());
diff --git a/lib/php/src/ext/thrift_protocol/php_thrift_protocol.cpp b/lib/php/src/ext/thrift_protocol/php_thrift_protocol.cpp
index f9b3ad7..4c9062e 100644
--- a/lib/php/src/ext/thrift_protocol/php_thrift_protocol.cpp
+++ b/lib/php/src/ext/thrift_protocol/php_thrift_protocol.cpp
@@ -728,6 +728,42 @@
   return ((t1 == t2) || (ttype_is_int(t1) && ttype_is_int(t2)));
 }
 
+//is used to validate objects before serialization and after deserialization. For now, only required fields are validated.
+static
+void validate_thrift_object(zval* object) {
+
+  HashPosition key_ptr;
+  zval** val_ptr;
+
+  TSRMLS_FETCH();
+  zend_class_entry* object_class_entry = zend_get_class_entry(object TSRMLS_CC);
+  HashTable* spec = Z_ARRVAL_P(zend_read_static_property(object_class_entry, "_TSPEC", 6, false TSRMLS_CC));
+
+  for (zend_hash_internal_pointer_reset_ex(spec, &key_ptr); zend_hash_get_current_data_ex(spec, (void**)&val_ptr, &key_ptr) == SUCCESS; zend_hash_move_forward_ex(spec, &key_ptr)) {
+    ulong fieldno;
+    if (zend_hash_get_current_key_ex(spec, NULL, NULL, &fieldno, 0, &key_ptr) != HASH_KEY_IS_LONG) {
+      throw_tprotocolexception("Bad keytype in TSPEC (expected 'long')", INVALID_DATA);
+      return;
+    }
+    HashTable* fieldspec = Z_ARRVAL_PP(val_ptr);
+
+    // field name
+    zend_hash_find(fieldspec, "var", 4, (void**)&val_ptr);
+    char* varname = Z_STRVAL_PP(val_ptr);
+
+    zend_hash_find(fieldspec, "isRequired", 11, (void**)&val_ptr);
+    bool is_required = Z_BVAL_PP(val_ptr);
+
+    zval* prop = zend_read_property(object_class_entry, object, varname, strlen(varname), false TSRMLS_CC);
+
+    if (is_required && Z_TYPE_P(prop) == IS_NULL) {
+        char errbuf[128];
+        snprintf(errbuf, 128, "Required field %s.%s is unset!", object_class_entry->name, varname);
+        throw_tprotocolexception(errbuf, INVALID_DATA);
+    }
+  }
+}
+
 void binary_deserialize_spec(zval* zthis, PHPInputTransport& transport, HashTable* spec) {
   // SET and LIST have 'elem' => array('type', [optional] 'class')
   // MAP has 'val' => array('type', [optiona] 'class')
@@ -737,7 +773,10 @@
     zval** val_ptr = NULL;
 
     int8_t ttype = transport.readI8();
-    if (ttype == T_STOP) return;
+    if (ttype == T_STOP) {
+      validate_thrift_object(zthis);
+      return;
+    }
     int16_t fieldno = transport.readI16();
     if (zend_hash_index_find(spec, fieldno, (void**)&val_ptr) == SUCCESS) {
       HashTable* fieldspec = Z_ARRVAL_PP(val_ptr);
@@ -903,6 +942,9 @@
 
 
 void binary_serialize_spec(zval* zthis, PHPOutputTransport& transport, HashTable* spec) {
+
+  validate_thrift_object(zthis);
+
   HashPosition key_ptr;
   zval** val_ptr;
 
diff --git a/lib/php/src/ext/thrift_protocol/php_thrift_protocol7.cpp b/lib/php/src/ext/thrift_protocol/php_thrift_protocol7.cpp
index da5b3de..6d8b76f 100644
--- a/lib/php/src/ext/thrift_protocol/php_thrift_protocol7.cpp
+++ b/lib/php/src/ext/thrift_protocol/php_thrift_protocol7.cpp
@@ -849,6 +849,44 @@
   return ((t1 == t2) || (ttype_is_int(t1) && ttype_is_int(t2)));
 }
 
+//is used to validate objects before serialization and after deserialization. For now, only required fields are validated.
+static
+void validate_thrift_object(zval* object) {
+    zend_class_entry* object_class_entry = Z_OBJCE_P(object);
+    zval* is_validate = zend_read_static_property(object_class_entry, "isValidate", sizeof("isValidate")-1, false);
+    zval* spec = zend_read_static_property(object_class_entry, "_TSPEC", sizeof("_TSPEC")-1, false);
+    HashPosition key_ptr;
+    zval* val_ptr;
+
+    if (Z_TYPE_INFO_P(is_validate) == IS_TRUE) {
+        for (zend_hash_internal_pointer_reset_ex(Z_ARRVAL_P(spec), &key_ptr);
+           (val_ptr = zend_hash_get_current_data_ex(Z_ARRVAL_P(spec), &key_ptr)) != nullptr;
+           zend_hash_move_forward_ex(Z_ARRVAL_P(spec), &key_ptr)) {
+
+            zend_ulong fieldno;
+            if (zend_hash_get_current_key_ex(Z_ARRVAL_P(spec), nullptr, &fieldno, &key_ptr) != HASH_KEY_IS_LONG) {
+              throw_tprotocolexception("Bad keytype in TSPEC (expected 'long')", INVALID_DATA);
+              return;
+            }
+            HashTable* fieldspec = Z_ARRVAL_P(val_ptr);
+
+            // field name
+            zval* zvarname = zend_hash_str_find(fieldspec, "var", sizeof("var")-1);
+            char* varname = Z_STRVAL_P(zvarname);
+
+            zval* is_required = zend_hash_str_find(fieldspec, "isRequired", sizeof("isRequired")-1);
+            zval rv;
+            zval* prop = zend_read_property(object_class_entry, object, varname, strlen(varname), false, &rv);
+
+            if (Z_TYPE_INFO_P(is_required) == IS_TRUE && Z_TYPE_P(prop) == IS_NULL) {
+                char errbuf[128];
+                snprintf(errbuf, 128, "Required field %s.%s is unset!", ZSTR_VAL(object_class_entry->name), varname);
+                throw_tprotocolexception(errbuf, INVALID_DATA);
+            }
+        }
+    }
+}
+
 static
 void binary_deserialize_spec(zval* zthis, PHPInputTransport& transport, HashTable* spec) {
   // SET and LIST have 'elem' => array('type', [optional] 'class')
@@ -857,6 +895,7 @@
   while (true) {
     int8_t ttype = transport.readI8();
     if (ttype == T_STOP) {
+      validate_thrift_object(zthis);
       return;
     }
 
@@ -892,6 +931,9 @@
 
 static
 void binary_serialize_spec(zval* zthis, PHPOutputTransport& transport, HashTable* spec) {
+
+  validate_thrift_object(zthis);
+
   HashPosition key_ptr;
   zval* val_ptr;